feat(coder): v2.6 Phase 0 — AgentBackend foundations (no behavior change)

Schema, interface, and service scaffold for v2.6 persistent agent sessions. Nothing in this batch alters runtime behavior. - schema.sql: add session_worktrees (one shared worktree per session, FK sessions(id)) and agent_sessions (one backend session per (session, agent), with backend/status CHECKs); add pending_changes.agent column for DiffPanel attribution. All three statements idempotent (IF NOT EXISTS). - services/agent-backend.ts: AgentBackend interface + AgentSessionHandle, EnsureSessionOpts, PromptCtx, TurnResult, and the normalized transport-agnostic AgentEvent union (text/reasoning/tool_call/tool_update/commands). Types only. - services/agent-pool.ts: lazy get-or-create AgentPool keyed by `${sessionId}:${agent}` + shared `agentPool` singleton. Empty in Phase 0. - index.ts: widen onClose to await dispatcher.stop() then agentPool.dispose() (pool empty, so dispose() is inert). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Merge coder-hardening: acp-client-fs path-guard fix + untrack live provider config
2026-05-30 02:50:17 +00:00 · 2026-05-29 22:23:20 +00:00 · 2026-05-29 22:23:13 +00:00 · 2026-05-29 22:22:51 +00:00 · 2026-05-29 21:24:18 +00:00 · 2026-05-29 21:24:10 +00:00
277 changed files with 26663 additions and 2466 deletions
--- a/.codecontextignore
+++ b/.codecontextignore
@@ -21,6 +21,7 @@ out/
 .opencode/
 .vscode/
 .idea/
+.claude/worktrees/

 # Test artifacts / coverage
 coverage/
--- a/.env.example
+++ b/.env.example
@@ -1,6 +1,6 @@
 NODE_ENV=production
 PORT=3000
-DATABASE_URL=postgres://boocode:CHANGE_ME@boocode_db:5432/boocode
+DATABASE_URL=postgres://boocode:CHANGE_ME@boocode_db:5432/boochat
 LLAMA_SWAP_URL=http://100.101.41.16:8401
 PROJECT_ROOT_WHITELIST=/opt
 BOOTSTRAP_ROOT=/opt/projects
@@ -11,6 +11,11 @@ POSTGRES_PASSWORD=CHANGE_ME
 # point BooCode at a different SearXNG instance.
 SEARXNG_URL=http://100.114.205.53:8888

+# Task model: lightweight model for auto-naming, search rewrite, etc.
+# Direct llama-server instance (NOT llama-swap). Falls back to LLAMA_SWAP_URL
+# with FAST_MODEL when unset.
+# TASK_MODEL_URL=http://100.90.172.55:7995
+
 # v1.13.15-tools: BOOCODE_TOOLS narrows the tool whitelist sent to the LLM.
 # Unset (default) → all tools (~21k schema). Useful primarily for single-purpose
 # sessions where the model only needs read-only filesystem access.
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,11 @@
 node_modules
 dist
 .env
+
+# Claude / Cursor (local agent & IDE config — CLAUDE.md and AGENTS.md stay tracked)
+.claude/
+.cursor/
+.cursorignore
 CLAUDE.local.md
 *.log
 .DS_Store
@@ -10,3 +15,6 @@ secrets/
 data/*
 !data/AGENTS.md
 !data/skills/
+!data/mcp.json
+!data/coder-providers.example.json
+codecontext/fork.tar.gz
--- a/BOOCHAT.md
+++ b/BOOCHAT.md
@@ -28,10 +28,24 @@
 - Prefer codecontext (`search_symbols`, `get_symbol_info`, `get_dependencies`) over `grep` for symbol-level questions. Fall back to `grep` / `view_file` when codecontext returns degraded or empty results — that signals an unsupported language or parse failure.
 - Verify before reporting work complete: run the relevant test/build/smoke command and confirm output matches the claim. Evidence first, assertion second.

+## Output format
+
+- Stay in Markdown by default for every reply, short or long.
+- Switch to a self-contained `<!DOCTYPE html>...</html>` artifact only when the user explicitly asks (e.g. "render this as HTML", "make me a dashboard", "build an interactive diagram"). Detection is opportunistic — the BooChat backend tags the assistant message as an HTML artifact, opens it in a sandboxed pane, and offers Download. Do not emit HTML unprompted; long Markdown is the right answer for most explanatory output.
+- When asked to produce HTML, avoid generic AI aesthetics: no excessive centered layouts, no purple gradients, no uniform rounded corners, no Inter font. Prefer interactive controls (sliders / knobs / SVG / side-by-side diffs) over passive prose-in-HTML. Pattern reference: claude.com/blog/using-claude-code-the-unreasonable-effectiveness-of-html (Thariq Shihipar, May 2026).
+- The HTML artifact is rendered in a sandboxed iframe with `connect-src 'none'` — `fetch()`, WebSockets, and tracking pixels do not work. All logic must be client-side.
+
 ## Convention: rules vs recipes

 Always-true rules (process discipline, refusals, behavior contracts) live here in `BOOCHAT.md` — and in `BOOCODER.md` / `CLAUDE.md` per their scopes — where they are 100% present in every turn. On-demand recipes (specific procedures, scaffolds, checklists) live in `/data/skills/` and invoke roughly 6% of the time in clean multi-turn flow (Codeminer42 measurement, 2026). Don't file workflow rules as skills — they silently misfire. See Anthropic agent-skills best-practices (platform.claude.com/docs/en/agents-and-tools/agent-skills/best-practices) for the canonical conventions.

+## Verification discipline
+
+- When assessing implementation status, verify against the running container (`curl /api/health`) and latest git commit (`git log --oneline -3`), not just source file contents. Source files can be mid-edit. The deployed state is the truth.
+- Never count `dist/` directory sizes as source lines. Only count `src/**/*.ts` files. Compiled output is inflated by inlined types and transpilation artifacts.
+- Before claiming a feature works, run the actual command and show the output. "Should work" is not verification. Acceptable evidence: test output (`pnpm test`), build output (`pnpm build`), curl response, docker logs, `\d tablename` output. If you can't run it, say so explicitly — don't assert success without evidence.
+- When reporting counts (tools, tests, files, routes, lines), derive the number from a command (`grep -c`, `wc -l`, test runner output) — not from memory or approximation.
+
 ## Known limitations

 - Codecontext re-analyzes the project graph on each call against a different target_dir. First call to a new project may take 1-3 seconds; subsequent calls to the same project return in ~10ms.
--- a/BOOCODER.md
+++ b/BOOCODER.md
@@ -1,27 +1,117 @@
-# BooCoder
+# BooCoder — Container Guidance

-> (Stub. v2.0 implementation pending. This file documents the intended contract.)
+You are BooCoder, a write-capable coding agent. You can read AND modify files within the project scope.

-## Capabilities
+## You can

- Everything in `BOOCHAT.md`
- Write tools (pending): `write_file`, `edit_file`, `delete_file` (all gated through pending-changes sandbox)
- Shell (pending): `run_command` (Docker-isolated per-session)
+- Read files (view_file, list_dir, grep, find_files)
+- Edit files (edit_file, create_file, delete_file) — all changes queue in pending_changes
+- Apply pending changes to disk (apply_pending)
+- Revert applied changes (rewind)
+- Dispatch tasks to external agents (dispatch_external_agent)
+- Use MCP tools from configured servers

-## Constraints
+## You cannot

- All writes land in a pending-changes virtual layer; nothing touches the real filesystem until `/apply`
- `run_command` executes inside the session sandbox, not the host
- No git commits, pushes, or pulls — Sam owns those
- Stop and ask before destructive operations (delete, overwrite, recreate)
+- Write outside the project root (path-guard enforced)
+- Write to secret files (.env, *.pem, id_rsa*, credentials.json)
+- Apply changes without explicit user approval (unless auto-apply is enabled per task)
+- Push to git remotes
+- Access the internet except via configured MCP servers
+
+## Pending changes discipline
+
+Every file modification queues in `pending_changes` before touching disk. The user sees a diff preview and approves/rejects each change. Never bypass this queue — it is the safety boundary between inference and the filesystem.

 ## Behavior

- Show a diff preview before any write
- Group related edits into a single `/apply` batch
- If a tool fails, surface the error verbatim — don't paper over it
+- Show diffs clearly. Explain what you're changing and why.
+- For multi-file changes, organize as a logical unit (one task = one coherent change set).
+- If uncertain about scope, use smaller edits and verify between steps.
+- Cite file paths + line numbers for context.
 - Verify before reporting work complete: run the relevant test/build/smoke and confirm output matches the claim. Evidence first, assertion second.

-## Convention: rules vs recipes
+## Verification discipline

-Always-true rules live here, in `BOOCHAT.md`, and in `CLAUDE.md` (100% present each turn). On-demand recipes live in `/data/skills/` (roughly 6% invoke rate in multi-turn per Codeminer42, 2026). Don't file workflow rules as skills — they misfire. See Anthropic agent-skills best-practices (platform.claude.com/docs/en/agents-and-tools/agent-skills/best-practices).
+- When assessing implementation status, verify against the running container (`curl /api/health`) and latest git commit (`git log --oneline -3`), not just source file contents. Source files can be mid-edit. The deployed state is the truth.
+- Never count `dist/` directory sizes as source lines. Only count `src/**/*.ts` files. Compiled output is inflated by inlined types and transpilation artifacts.
+- Before claiming a feature works, run the actual command and show the output. "Should work" is not verification. Acceptable evidence: test output (`pnpm test`), build output (`pnpm build`), curl response, docker logs, `\d tablename` output. If you can't run it, say so explicitly — don't assert success without evidence.
+- When reporting counts (tools, tests, files, routes, lines), derive the number from a command (`grep -c`, `wc -l`, test runner output) — not from memory or approximation.
+
+## Provider lifecycle (v2.3)
+
+BooCoder's coding agents are a **config-backed registry**: built-ins live in `provider-registry.ts`, and `data/coder-providers.json` layers overrides + custom entries on top. Registration ≠ installation — the config lists what you *want*; a probe reports what's *ready*.
+
+### Config file: `data/coder-providers.json`
+
+Resolved from `CODER_PROVIDERS_PATH` (default `/data/coder-providers.json`; dev/host path `/opt/boocode/data/coder-providers.json`). It is **gitignored** — it's live runtime config that the coder reads *and writes* (UI toggles `PATCH` it), so tracking it would churn `git status`. The tracked reference is `data/coder-providers.example.json`; copy it to `coder-providers.json` to seed overrides. A missing file, invalid JSON, or a schema mismatch all fall back to built-ins-only — loading never throws at startup.
+
+```json
+{
+  "providers": {
+    "goose": { "enabled": false },
+    "amp-acp": {
+      "extends": "acp",
+      "label": "Amp",
+      "description": "ACP wrapper for Amp",
+      "command": ["amp-acp"],
+      "enabled": true
+    }
+  }
+}
+```
+
+Per-provider override fields (all optional):
+
+| Field | Meaning |
+|-------|---------|
+| `extends` | `"acp"` — required for a NEW (custom) provider; built-in overrides omit it |
+| `label` | Display name (required for custom) |
+| `description` | Sub-label shown in the picker / settings |
+| `command` | `[binary, ...args]` to spawn (required for custom; overrides a built-in's default argv) |
+| `env` | Extra env vars merged into the spawn |
+| `enabled` | Default `true`; `false` hides it from the composer |
+| `order` | UI sort key |
+| `models` / `additionalModels` | Replace / merge onto the discovered model list |
+
+A PATCH to one provider id **replaces that id's override object wholesale** (per-id shallow merge), so to flip a single field keep the rest; a `null` value for an id deletes its override (reverts to the built-in default).
+
+### Refresh contract
+
+The snapshot is cached and a provider's cold ACP probe (tier-2) is **skipped** while `available_agents.last_probed_at` is younger than `PROVIDER_PROBE_TTL_MS` (default `86400000` = 24h). Opening the composer is therefore fast and does not re-probe. To force a cold re-probe (after installing a CLI or editing models): **`POST /api/providers/refresh`** (the Refresh button in the Providers settings tab), which clears the cache and re-probes.
+
+### Enable / disable
+
+Two ways:
+- **Settings → Providers tab** — open the sidebar → **Settings** → **Providers**: toggle a provider on/off, refresh it, or open its diagnostic. (Earlier builds exposed a gear in the composer; that control was moved into Settings.)
+- **Edit the config** (`"enabled": false`) then `POST /api/providers/refresh`.
+
+A **disabled** provider leaves the composer's provider picker but stays listed in the Providers tab (status "Disabled") so you can re-enable it. **Native `boocode` is always-on** — an `enabled:false` on it is ignored (with a warn log) and it is never rendered as toggleable.
+
+### Adding a custom ACP provider
+
+- **Catalog modal**: Providers tab → **Add provider** → pick an entry → it PATCHes the config (`extends:'acp'` + label + command, enabled) and refreshes that provider.
+- **Hand-edit** `data/coder-providers.json`: add an id with `extends:'acp'`, `label`, and `command`, then `POST /api/providers/refresh`.
+
+Either way, **adding to config does NOT install the binary.** Until the CLI is on `PATH` the provider shows **"Not installed"** (status `unavailable`) and does not appear in the composer picker.
+
+### Known limitation — subset refresh
+
+`POST /api/providers/refresh` accepts an optional `{ "providers": ["id", ...] }` body and returns a `refreshed` count scoped to that subset — **but the underlying cold re-probe currently covers ALL installed providers**, not just the requested subset. True per-provider force is a future change (it needs a snapshot-internal parameter). This is intentional for now, not a bug: a subset refresh still re-probes everything; only the reported count is scoped.
+
+### Deploy + smoke
+
+Two deploy targets:
+- **Routes (host service):** `pnpm -C apps/server build && pnpm -C apps/coder build && sudo systemctl restart boocoder`
+- **Web UI (container):** `docker compose up --build -d boocode`
+
+Green gate (verified across phases 1–5): `pnpm -C apps/coder test` (134 passing) `&& pnpm -C apps/coder build`.
+
+Smoke (via Tailscale):
+
+```bash
+curl http://100.114.205.53:9502/api/providers/snapshot       # lists every registered provider
+curl http://100.114.205.53:9500/api/coder/providers/config   # raw config, through the BooChat proxy
+# Settings → Providers: disable goose → it leaves the composer picker, stays in the tab
+# POST refresh → models repopulate; Add a catalog entry → it appears after refresh (unavailable until its CLI is installed)
+```
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,154 @@

 All notable changes per release tag. Most recent on top, ordered by tag creation date (which matches the git history). Tag names follow `vMAJOR.MINOR.PATCH-slug` — the slug describes what shipped, so the tag name alone is enough to recall the batch.

+## v2.5.15-acp-path-guard — 2026-05-29
+
+Security fix + repo hygiene. Fixes a path-traversal in the ACP filesystem bridge (`acp-client-fs.ts`, flagged by the automated push security review): the worktree guard used an unbounded `startsWith(resolve(worktreePath))`, so a sibling path sharing the worktree as a string prefix (`<worktree>-evil/…`) escaped the scope — and `writeWorktreeTextFile` writes to disk directly (no `pending_changes` gate), so a confused/buggy ACP agent could write outside its worktree. Now uses a separator-bounded check matching `write_guard.ts` (`resolve()` + `startsWith(root + sep)` / `=== root`) via a shared `resolveInWorktree`, with a regression test covering `../` traversal and the sibling-prefix bug. Symlink-swap/`O_NOFOLLOW` hardening was intentionally skipped — consistent with `write_guard`'s no-realpath stance, and the agent already runs with host FS access so this is a containment guard, not a trust boundary. Separately, stops tracking the live `data/coder-providers.json` (it's runtime config the UI reads *and writes* on provider toggles, which churned `git status`) — it's now gitignored with a tracked `data/coder-providers.example.json` reference; the loader falls back to built-ins-only when the live file is absent. The provider-type duplication (coder ↔ web) stays guarded by the existing text-identity `provider-types-parity.test.ts` — a shared package was considered and declined (drift is already prevented; not worth the Docker/build-order risk at solo scale).
+
+## v2.5.14-claude-md — 2026-05-29
+
+Docs-only — CLAUDE.md session-learnings update, no code. Adds gotchas surfaced while shipping the v2.3 provider-lifecycle batch: the host `boocoder.service` keeps running the old process after `pnpm -C apps/coder build` (stale-process tell = new routes 404 while old routes 200, restart don't re-debug); the `boocode` container `build: .` deploys the working tree, so web edits are live on the Vite dev server but not production until `docker compose up --build -d boocode`; `PATCH /api/providers/config` replaces a provider's override wholesale (send `{...existing, enabled}` or a custom ACP entry's command is wiped) and `data/coder-providers.json` is live config not to be committed as code; external agents dispatch one-shot with no context/token tracking (only native `boocode` tracks ctx; OpenCode-as-server is the unshipped `v2-6-persistent-agent-sessions` plan); the `ui/` primitive inventory with `button role=switch` / Dialog fallbacks for the absent switch/sheet; and the mobile Dialog-with-list scroll-containment recipe. Also backfills previously-uncommitted doc bullets for the `v2.5.7`–`v2.5.11` coder work (provider-type parity test, async ACP command discovery, AgentComposerBar `installed` filter, provider-registry path disambiguation).
+
+## v2.5.13-provider-lifecycle-phase5 — 2026-05-29
+
+Closeout of the v2.3 provider-lifecycle batch — the web UI (Phase 5) plus docs (Phase 6). Provider management moved into **Settings → Providers**: a tab listing every registered provider with a status badge (Available / Disabled / Not installed / Error / Loading), an enable/disable toggle, a per-provider refresh, and a plaintext diagnostic; toggling sends the provider's *full* override (preserving a custom ACP entry's command under the wholesale-replace PATCH merge) then refetches the snapshot. The composer's provider picker now filters to `enabled && (status === 'ready' || 'loading')`, so disabled and unavailable providers drop out of the picker and are managed only in settings (native `boocode` always shows). A curated ACP catalog (`apps/web/src/data/acp-provider-catalog.ts`) + `AddProviderModal` register custom providers via `PATCH /api/providers/config` then a subset refresh, and the web client gained `getProvidersConfig` / `patchProvidersConfig` / `refreshProviders` / `getProviderDiagnostic`. Two mobile fixes ship alongside: the Settings pane is now reachable on phones (opening it pushes `?pane=` atomically so the mobile URL-sync effect keeps it active instead of snapping back to the chat pane), and the Add-provider modal caps to the viewport with a single `overscroll-contain` scroll region so the list scrolls instead of dragging the whole modal. This completes the arc begun in `v2.5.4-provider-lifecycle-phase1` (config-backed registry over the built-ins) → `v2.5.5-provider-lifecycle-phase2` (loading/unavailable snapshot lifecycle + tier-2 probe TTL gate) → `v2.5.6-provider-lifecycle-phase3` (generic `resolveLaunchSpec` ACP dispatch) → `v2.5.12-provider-lifecycle-phase4` (config GET/PATCH, subset refresh, diagnostic HTTP API). Docs landed in `BOOCODER.md` (config file, refresh contract, enable/disable, custom ACP, the honest subset-refresh known limitation) and `docs/DEFERRED-WORK.md` §2 is marked addressed; the remaining Tier-2 follow-ups (WS `provider_snapshot_updated` frame, `available_agents.enabled` column, shared types package, MCP provider tools) stay deferred.
+
+## v2.5.12-provider-lifecycle-phase4 — 2026-05-29
+
+Phase 4 of the v2.3 provider-lifecycle batch (`openspec/changes/v2-3-provider-lifecycle/design.md` §6): the HTTP API to read, patch, refresh, and diagnose providers. `routes/providers.ts` gains `GET /api/providers/config` (the raw loaded `CoderProvidersFile`), `PATCH /api/providers/config` (a partial providers map — an id's override object is replaced wholesale, a `null` value deletes it), an optional `{ providers?: string[] }` body on `POST /api/providers/refresh` (the `refreshed` count reflects the requested subset; the force probe itself still covers all installed providers, since per-provider force is a snapshot-internal change left to a later phase), and `GET /api/providers/:id/diagnostic` returning JSON `{ diagnostic: string }` — a read-only report (resolved def, install_path, last_probed_at, enabled, `which` availability, last cached probe error) with no probe spawn. PATCH correctness is the whole story: the order is validate→save→reload→clear, a malformed body or an invalid merged config returns 422 without writing the file, and a `save()` failure returns 500 without reloading the registry or clearing the snapshot cache, so on-disk and in-memory state can never diverge. New pure `mergeProviderConfigPatch` + `ProviderConfigPatchSchema` in `provider-config.ts`, a read-only `peekSnapshotEntry` cache accessor (source of the diagnostic's last-error — no probe/cache logic change), and a new `provider-diagnostic.ts` formatter. The web client gains `api.coder.getProvidersConfig` / `patchProvidersConfig` / `refreshProviders(providers?)` / `getProviderDiagnostic`, with mirrored `ProviderOverride` / `CoderProvidersFile` / `ProviderConfigPatch` types; the existing `/api/coder/*` proxy blanket-forwards the new routes with no change. +28 tests (134 coder total: pure merge/validate, the diagnostic formatter, and `app.inject` route tests proving the 422-no-write and save-fail-no-divergence guards). The diagnostic returns JSON rather than the §8 plaintext so it flows through the JSON `request` client helper (reconciling design §6.4's `{ diagnostic }` with §8's string report). No UI (Phase 5). Builds on `v2.5.6-provider-lifecycle-phase3`.
+
+## v2.5.11-claude-skill-discovery — 2026-05-29
+
+Surface Claude Code's real enabled commands + plugin skills in the coder slash menu, with icons separating commands from plugin skills. New `claude-command-discovery.ts` reads (user-global scope) `~/.claude/commands/*.md` plus every enabled plugin in `~/.claude/settings.json:enabledPlugins` — each plugin's user-scope install path contributes `skills/<name>/SKILL.md` (kind `skill`) and `commands/*.md` (kind `command`), parsed from frontmatter, bare names, deduped. The snapshot's claude branch discovers these **live** (claude is PTY, no ACP probe; the snapshot cache rate-limits the fs reads). The `/` menu now renders up to three icon'd groups: **`<agent> commands`** (Terminal), **`<agent> skills`** (Puzzle — claude's plugin skills / opencode is all commands), and **BooCoder skills** (Sparkles), via a new optional `icon` on `SlashCommandGroup`. `AgentCommand` gains a `kind` field, added identically to the coder and web copies (the `provider-types-parity` test enforces it); `mergeCommandsByName` is now generic so it preserves the tag. Invocation is unchanged — picking a claude command/skill sends `/name` to claude (PTY), which executes it. Project-local plugins + `<cwd>/.claude/commands` deferred. BooChat unaffected (flat skills). Smoke-test the claude skill slash-execution on the host.
+
+## v2.5.10-opencode-live-commands — 2026-05-29
+
+Surface opencode's real (live ACP) command set in the coder slash menu without needing a dispatch. Two fixes: (1) the cold ACP probe (`acp-probe.ts`) captured `available_commands` but read `probedCommands` synchronously right after `newSession` — racing opencode's async `available_commands_update` notification, so it captured **zero** and only the 7-item static manifest showed. The probe now waits briefly (poll up to 3s for the first batch + a 300ms settle, capped under the 30s probe timeout) so the commands are actually captured. (2) Captured commands are persisted to a new `available_agents.commands` JSONB column and served (merged with the manifest) on the tier-2-probe-skip path, so the agent's discovered commands survive once the model list is warm and show without a dispatch. Boot warms this via the `force: true` startup snapshot. apps/coder only (probe + schema + snapshot). Caveat: depends on opencode emitting `available_commands_update` on session creation rather than only after a prompt — to be confirmed on the host. Claude (PTY) disk/plugin discovery deferred.
+
+## v2.5.9-agent-slash-commands — 2026-05-29
+
+Segmented per-agent slash menu in the coder pane, plus cross-agent skills. The `/` menu now shows two labeled groups — **the active agent's commands first** (opencode/claude/qwen manifest + live ACP `available_commands`), **BooCoder skills second** — instead of always showing BooCoder's skills regardless of provider. `SlashCommandPicker` gains an opt-in `groups` prop (the flat `items` path is unchanged, so **BooChat's menu is byte-identical** — parity verified: no BooChat caller passes the grouped prop, and the skills lookup / invocation routing are untouched); `ChatInput` takes `slashGroups`; `CoderPane` builds the groups from the selected provider's commands + skills. Skills now **run under the selected agent**: the coder `skill_invoke` route accepts a `provider` and, when external, injects the server-side skill body into a dispatched task (instead of native inference) — so a skill like brainstorming executes through opencode/claude with the body kept server-side, mirroring the messages-route external dispatch. Also folds in the earlier initial-chat fix: invoking a skill on the landing chat now runs the same create-chat → assign-to-pane → invoke transition as a text send (`handleLandingSkill`) rather than invoking invisibly without a pane transition (the blank-screen repro). Web tsc + coder build clean.
+
+## v2.5.8-mobile-composer-row — 2026-05-29
+
+Mobile fix for the `AgentComposerBar`: the refresh button was wrapping to a second line. Root cause was layout order, not width — the status dot carried `ml-auto` (pinned to the far-right edge) and the refresh button followed it in DOM order, so it overflowed and wrapped. The dot + refresh are now one right-aligned (`ml-auto`) unit, keeping the refresh on the top line. Additionally, `CompactPicker` gained an `iconOnly` option and the Mode (permission) picker now renders icon-only on mobile (shield + chevron, no "Bypass"/"Plan" text label; `aria-label`/`title` and the tap-to-open list still convey the value) to free row width. Desktop is unchanged (full labels). Web-only change.
+
+## v2.5.7-claude-models-and-picker-fix — 2026-05-29
+
+Two provider-layer changes. **(1) Fix the empty provider picker** — a regression from `v2.5.5` (Phase 2): on a cache miss `getProviderSnapshot` returned synchronous `installed:false` `loading` entries, which `AgentComposerBar` filters out (`e.installed && e.status !== 'error'`); with the client-side poll deferred to Phase 5, a single fetch landed on `loading` forever and no providers appeared. `getProviderSnapshot` now awaits the build and returns terminal entries (the sync `loading` return is deferred until Phase 5 ships the poll); builds stay fast via the tier-2 cold-probe skip. **(2) Claude models** — the list was a hardcoded 2-entry static list (Opus 4 / Sonnet 4, May 2025), and the v2.3 config schema's `models`/`additionalModels` were parsed but never wired. `buildResolvedRegistry` now carries config `models` (replace) + `additionalModels` (merge) onto `ResolvedProviderDef`, and `provider-snapshot` applies them to every ready model list — so `/data/coder-providers.json` can add or replace any provider's models with no code change. Claude `staticModels` bumped to `opus`/`sonnet`/`haiku` latest-aliases plus pinned `claude-opus-4-8` / `claude-sonnet-4-6` / `claude-haiku-4-5-20251001` (passed verbatim to `claude --model`; the CLI accepts both aliases and pinned full names). +2 unit tests (109 total). Builds on `v2.5.6-provider-lifecycle-phase3`.
+
+## v2.5.6-provider-lifecycle-phase3 — 2026-05-29
+
+Phase 3 of the v2.3 provider-lifecycle batch (`openspec/changes/v2-3-provider-lifecycle/design.md` §5): generic ACP dispatch. `acp-spawn.ts` gains `resolveLaunchSpec(resolved, installPath)` — it consults the resolved registry's `launchCommand` (a config override or a custom-ACP entry's command) first, falling back to the kept `resolveAcpSpawnArgs` switch for built-ins. `acp-dispatch.ts` now spawns `spec.binary`/`spec.args` with `env: { ...process.env, ...spec.env }` instead of the hardcoded per-name argv, and `dispatcher.ts` loads the resolved def by `task.agent` and passes it through. This lets config-defined custom ACP providers dispatch with no new switch case. Built-in dispatch (claude/opencode/goose/qwen) is **byte-identical** to pre-v2.3 — proven by a regression test asserting opencode→`['acp']`, goose→`['acp']`, qwen→`['--acp']`, binary=`installPath ?? id`, and empty config env → plain `process.env`. One deliberate deviation from the spec's literal `!installPath → null`: the `installPath ?? id` fallback is preserved so a missing install path still spawns the bare agent name as before. `setSessionMode`/permission/streaming and the dispatcher poll/NOTIFY/running-guard are untouched. 7 new `acp-spawn.test.ts` cases. No routes/UI (Phase 4+). Builds on `v2.5.5-provider-lifecycle-phase2`.
+
+## v2.5.5-provider-lifecycle-phase2 — 2026-05-29
+
+Phase 2 of the v2.3 provider-lifecycle batch (`openspec/changes/v2-3-provider-lifecycle/design.md` §4). `provider-snapshot.ts` stops returning `null` for uninstalled/disabled providers — it now emits one entry per registered provider with a lifecycle status (`loading | ready | unavailable | error`), an `enabled` flag, and a two-tier probe. Tier-1 is a fast `which`-style availability check (`command-availability.ts`, `execFile`/no-shell); tier-2 — the 5–30s cold ACP probe — is now SKIPPED unless forced (`POST /refresh`), the `available_agents.last_probed_at` row is older than `PROVIDER_PROBE_TTL_MS` (24h default), or the DB model list is empty, which kills snapshot latency on warm reads. A cache miss returns `status:'loading'` synchronously while the build settles in the background (client polling is deferred to Phase 5). `ProviderSnapshotStatus`/`ProviderSnapshotEntry` regained `loading`/`unavailable` and gained `enabled`, `description?`, `fetchedAt?` in both the coder and web copies, guarded by a runtime parity test (`provider-types-parity.test.ts`, mirroring the `ws-frames.test.ts` convention) that fails on any field drift — a compile-time cross-project assignability check was attempted first but blocked by TS6307 (web is a composite tsconfig project). Also tracks the previously-gitignored `data/coder-providers.json` seed via a `.gitignore` exception, completing the Phase 1 config file. No dispatch/route/UI changes (Phase 3+); AgentComposerBar filtering unchanged. Builds on `v2.5.4-provider-lifecycle-phase1`.
+
+## v2.5.4-provider-lifecycle-phase1 — 2026-05-29
+
+Phase 1 of the v2.3 provider-lifecycle batch (`openspec/changes/v2-3-provider-lifecycle/design.md` §2–3): a config-backed provider layer merged over the hardcoded built-ins, with no runtime change when no config file exists. Adds `CODER_PROVIDERS_PATH` (default `/data/coder-providers.json`); `provider-config.ts` (Zod `ProviderOverride`/`CoderProvidersFile` schemas + a loader that never throws at startup — a missing file, invalid JSON, or schema mismatch all fall back to built-ins-only — plus `save` for the Phase 4 PATCH route); and `provider-config-registry.ts` (`ResolvedProviderDef` + `buildResolvedRegistry` merge: built-in overrides, custom `extends:'acp'` entries requiring label+command, `boocode` always enabled, plus a module singleton). `agent-probe.ts` now iterates the resolved registry instead of the hardcoded list — custom ACP entries resolve their binary from `command[0]` via `execFile` (no shell), disabled providers skip probing without losing their row, and `enabled` is read from memory only (no DB column this phase). Six unit tests, including a regression proving an empty config yields exactly the built-ins. No snapshot/dispatch/route/UI changes (Phase 2+). The `data/coder-providers.json` seed exists on disk but is gitignored (`data/*`). Lands on top of `v2.5.3-remove-cursor-copilot`.
+
+## v2.5.3-remove-cursor-copilot — 2026-05-29
+
+Retire the cursor and copilot providers from BooCoder entirely. Removes their `acp-spawn` argv cases, `provider-manifest` mode blocks + manifest keys, `provider-commands` command maps, the `provider-snapshot` cursor model-CLI branch (and the now-orphaned `exec`/`promisify` imports), and the `agent-probe` copilot ACP-detect branch; deletes the dead `cursor-models.ts` module and its test. The `PROVIDERS` registry array already lacked both entries, so only the doc comment needed correcting. Built-ins unchanged: claude, opencode, goose, qwen, native boocode. Standalone cleanup; pairs with `v2.5.4-provider-lifecycle-phase1` which builds on it.
+
+## v2.5.2-coder-ux-fixes — 2026-05-29
+
+Working-tree checkpoint bundling this session's fixes with in-progress coder UI work. This session: the BooCoder dispatcher now reacts to new tasks immediately via a Postgres `LISTEN/NOTIFY` (`tasks_new`) AFTER INSERT trigger, with the poll loop kept at 2s as a missed-notification fallback (`dispatcher.ts`, `apps/coder/src/schema.sql`); the mobile nav drawer no longer sticks open after returning to a backgrounded tab — `useViewport` re-syncs on `pageshow`/`visibilitychange`/`resize`/`orientationchange` (iOS reported a stale width on bfcache restore, leaving `isMobile=false`); assistant reasoning renders as a collapsible "Thinking" block in `MessageBubble`, surfacing ACP `agent_thought_chunk` from opencode/goose/qwen and native `reasoning_parts`; paste-to-chip inserts pasted text verbatim instead of wrapping it in a code fence; and a "New file from pasted text" affordance in the RightRail browser queues a `pending_changes` create through the new `POST /api/sessions/:id/pending/create` endpoint, paired with a fix repointing the DiffPanel's dead approve/reject calls to the real `/api/pending/:id/apply` and `/reject` routes. Also carried in the tree but not authored this session: the CoderPane `ChatInput` migration and `AgentComposerBar` refinements, plus backend tweaks to `auto_name`, inference `tool-phase`/`turn`, `secret_guard`, and `provider-registry`. Ships the `v2-6-persistent-agent-sessions` openspec proposal/design/tasks (free agent-switching with per-agent memory, opencode-as-server) as planning docs only — the feature is unimplemented and reserves the `v2.6.0` tag for it. Build green across server/coder/web; server suite 531 passing. (CHANGELOG note: the v2.3–v2.5.1 entries were never backfilled and remain absent above.)
+
+## v2.2.2-xml-placeholder-reject — 2026-05-26
+
+Reject placeholder XML tool args at parse time in `extractToolCallBlocks` (`xml-parser.ts`). Drops calls when any string arg is `...`, empty/whitespace, `<path>`, `<file>`, `placeholder`, or angle-bracket sentinels; appends the raw XML block to flushed prose instead of silently deleting it. Fixes qwen3.6 answer-then-spurious-tools tail that caused duplicate assistant rows (full answer + failed `xml_call_*` tools + regenerated answer). Four new tests in `xml-parser.test.ts`. Known nit: rejection logs via `console.debug` instead of pino — filed in `docs/DEFERRED-WORK.md` §6 for a later cleanup.
+
+## v2.2.1-pane-scoped-chats — 2026-05-26
+
+Follow-up fixes on the v2.2 Paseo provider stack. Pane-scoped chat resolution: `resolveChatId(sql, sessionId, paneId)` reads `sessions.workspace_panes`, requires `pane_id` on coder POST routes, and creates a scoped chat per coder/terminal pane instead of falling back to the session's first open chat (which fused BooCoder writes into the BooChat pane). Client `useWorkspacePanes` seeds new coder/terminal panes with dedicated chats on create, hydrate, and workspace sync; `CoderPane` blocks send until seeded and filters WS frames + `GET /messages?chat_id=` to that chat. External-agent tool UI: new `CoderMessageList` renders BooChat-style `ToolCallLine` timeline (tools before answer text on combined ACP rows). WS user-delta handling replaces content instead of appending (fixes garbled duplicate user messages when optimistic UI met full-body deltas). BooChat inference: `buildMessagesPayload` strips orphan assistant `tool_calls` without matching `tool` rows and skips stray tool rows when the owning assistant turn is incomplete (fixes "Tool results are missing for tool calls" on shared chats with ACP history). Pairs with `v2.2-paseo-providers`.
+
+## v2.2-paseo-providers — 2026-05-26
+
+Paseo-equivalent provider stack for BooCoder. Seven providers (boocode, cursor, claude, opencode, goose, qwen, copilot) with snapshot API (`provider-snapshot.ts`, ACP cold probe, per-provider model merge, cursor models from ACP). Frontend `AgentComposerBar` replaces `ProviderPicker` — provider / mode / model / thinking in the coder composer; `SlashCommandPicker` + `useProviderSnapshot` hook. ACP dispatch rewritten (`acp-dispatch.ts`, `acp-stream.ts`, `acp-spawn.ts`, `agent-turn-persist.ts`, `acp-tool-snapshot.ts`) with Paseo merge/stream/persist pattern, inline `PermissionCard` prompts, and `reasoning_delta` WS frames. Agent slash-command hints via ACP `available_commands_update` cached in `agent-commands-cache.ts` + `AgentCommandsHint`. Arena and MCP entry points accept `mode_id` / `thinking_option_id`. SSH helpers removed; all host exec via `host-exec.ts` direct spawn. Server adds coder proxy route + shared skill invoke. New tests: acp-derive, acp-tool-snapshot, cursor-models, provider-commands, provider-snapshot, agents. Docs: `AGENTS.md`, `docs/ARCHITECTURE.md`, openspec `v2-2-paseo-providers`.
+
+## v2.1.1-roadmap-cleanup — 2026-05-25
+
+Roadmap reconciliation, README updates, and openspec archive housekeeping. No runtime behavior changes.
+
+## v2.1.0-provider-picker — 2026-05-25
+
+Provider picker: BooCoder moves from Docker container to host systemd service (`boocoder.service`). All agent dispatch (ACP + PTY) switches from SSH tunnel to direct `spawn`/`exec` — no more `sshSpawn`/`sshExec`/`sshSpawnWithStdin` (marked `@deprecated`). New provider registry (`provider-registry.ts`) with 5 providers (boocode, opencode, goose, claude, qwen), per-provider model discovery (llama-swap for ACP agents, `~/.qwen/settings.json` for qwen, static for claude), and `agent-probe.ts` runs direct `which`/`exec` instead of SSH. `GET /api/providers` route assembles the provider list with installed status, models, and transport (ACP→PTY fallback if `supports_acp` is false). Frontend `ProviderPicker` component in CoderPane header lets users pick provider/model per message; messages route through `tasks` row for external providers instead of inference enqueue. Smart scroll: `MessageList` only auto-scrolls when user is near bottom (150px threshold). DB schema adds `models`, `label`, `transport` columns to `available_agents`. Bug fixes: `loadContext` SELECT now includes `allowed_read_paths` (cross-repo read grants were silently failing), cap hit sentinel insertion moved before `buildMessagesPayload` call.
+
+## v2.0.5 — 2026-05-25
+
+FAST_MODEL routing: optional `FAST_MODEL` env var routes cheaper models (titles, summaries, labeling) to a small model on llama-swap (e.g. `nemotron-nano-4b`) instead of loading the 35B for 20-token calls. Falls back to session model or DEFAULT_MODEL. Tool-use summaries: `runCapHitSummary` now writes the cap_hit sentinel before building the summary payload (bug fix — sentinel was written after, causing it to appear after the summary text in the message list). Qwen Code dispatch: `qwen -p "<task>" --output-format stream-json` via PTY (non-interactive mode, no `--yolo` flag needed). Arena: `POST /api/arena` dispatches the same task to N models/agents in parallel, each with its own task + worktree; `GET /api/arena/:id` for results; `POST /api/arena/:id/select/:task_id` picks winner.
+
+## v2.0.4-hardening — 2026-05-25
+
+Path-guard fuzz suite: 25+ traversal-attack tests covering ../ sequences (all depths), encoded traversal (%2e%2e), null byte injection, absolute path escape, prefix-without-separator, backslash traversal, and the full secret-file deny list (.env, *.pem, id_rsa*, *.key, credentials.json, *.kdbx, .netrc). Plus 5 valid-path positive tests confirming normal writes aren't blocked and 5 edge-case tests (empty, whitespace-only, very long path, triple-dot, multiple slashes). Null-byte and whitespace-only guards added to `resolveWritePath` (previously only checked empty string). DB-integration test skeleton for pending_changes full-cycle (queue create/edit/delete, apply, rewind) gated on DATABASE_URL via `describe.runIf`. Production readiness verified: all services healthy, all builds clean, 57 tests passing (23 existing + 34 new).
+
+## v2.0.3 — 2026-05-25
+
+CLI client (`apps/coder/src/cli.ts`, 249 lines) for headless agent interaction. Human inbox view (`human_inbox` view) surfaces tasks in `blocked`/`failed` state. Cost tracking: `tool_cost_stats` view with per-tool 100-call rolling window. `new_task` tool (Boomerang pattern): creates tasks with project context and optional arena contestants. `check_task_status` and `list_tasks` tools for task lifecycle management. Stats routes (`GET /api/stats`) for cost aggregation. Dispatcher extended to support new task states.
+
+## v2.0.2 — 2026-05-25
+
+BooCoder MCP server (`mcp-server.ts`, 201 lines) exposing 6 write-capable tools over stdio: `edit_file`, `create_file`, `delete_file`, `view_pending_changes`, `apply_pending`, `rewind`. Registered in `apps/coder/src/index.ts` as an MCP stdio server. Enables external agents (opencode, claude, qwen) to call BooCoder's write tools through the MCP protocol.
+
+## v2.0.1 — 2026-05-25
+
+ACP dispatch (`acp-dispatch.ts`, 271 lines): runs ACP-capable agents (opencode, goose) via SSH tunnel wrapping stdio into NDJSON streams for `@agentclientprotocol/sdk` JSON-RPC sessions. PTY dispatch (`pty-dispatch.ts`, 139 lines): runs non-ACP agents (claude, qwen) via SSH with stdin pipe for non-interactive mode. Worktree management (`worktrees.ts`, 118 lines): per-task git worktree creation and cleanup. SSH helper (`ssh.ts`, 126 lines): `sshSpawn`, `sshExec`, `sshSpawnWithStdin` for host command execution. Dispatcher extended to route tasks to ACP vs PTY based on agent capability. Agent probe updated to verify ACP support.
+
+## v2.0.0-final — 2026-05-25
+
+Dispatcher (`dispatcher.ts`, 191 lines): task queue with polling loop, Path A (native inference) and Path B (external agent dispatch). Task routes (`tasks.ts`, 138 lines): CRUD for tasks with state transitions. Agent probe (`agent-probe.ts`, 51 lines): startup scan of host for installed agents (opencode, goose, claude, pi, qwen), version detection, ACP capability verification. Schema adds `tasks` table. CLAUDE.md updated with v2.0.0 architecture docs covering BooCoder, DB rename, MCP config, workspace deps.
+
+## v2.0.0 — 2026-05-25
+
+BooCoder frontend: `CoderPane.tsx` (432 lines) as a `'coder'` pane type within BooChat's SPA — chat pane + diff pane (pending changes) + session picker. Standalone fallback SPA in `apps/coder/web/` (Vite + React) served at `:9502` directly. Session streaming via `useSessionStream` WS hook. API client with typed endpoints. Workspace pane persistence via `useWorkspacePanes`. Server routes for pending changes (`PATCH/POST /api/coder/sessions/:id/pending`). Verification discipline rules + chat naming from assistant response.
+
+## v2.0.0-beta — 2026-05-25
+
+Write tools: `edit_file`, `create_file`, `delete_file`, `apply_pending`, `rewind` — queue in `pending_changes` table, nothing hits disk until applied. `write_guard.ts` validates paths (resolve + prefix-check, no realpath for creates). Inference loop integration via `inference_context.ts` (bridges inference turn state to tool execution). API routes: `messages.ts` (POST /api/coder/sessions/:id/messages), `pending.ts` (GET/POST /api/coder/sessions/:id/pending). WebSocket support (`ws.ts`) for real-time pending changes updates. Tool adapter (`adapter.ts`) converts inference tool calls to tool execution. Write guard tests (115 lines). Server-side inference loop wired to BooCoder tools.
+
+## v2.0.0-alpha — 2026-05-25
+
+BooCoder foundation: Docker container (`apps/coder/Dockerfile`), docker-compose service, host env file. Schema: `sessions`, `chats`, `messages`, `pending_changes`, `tasks`, `message_parts` tables. DB renamed from `boocode` to `boochat`. Config module, PostgreSQL connection (porsager/postgres). Initial Fastify server with health endpoint. BOOCODER.md guidance file. Implementation plan (8 phases). Proposal updated with AGENTS.md extensions, Boomerang pattern, observation hooks.
+
+## v2.0-proposal — 2026-05-24
+
+v2.0 proposal: BooCoder write tools, pending-changes queue, ACP dispatch, MCP server. Openspec proposal (`proposal.md`, 274 lines) and task breakdown (`tasks.md`, 130 lines) defining the v2.0 feature scope — write-capable coding agent with file operations, external agent dispatch via ACP/PTY, and MCP server for tool exposure.
+
+## v1.16.0-codesight-merge — 2026-05-24
+
+Ports codesight's highest-value analysis capabilities into the codecontext sidecar as 4 new MCP tools. Tier 1 (graph queries on existing edges, no re-parsing): `get_blast_radius` (BFS reverse-edge traversal — "what breaks if I change this file?", with depth tracking) and `get_hot_files` (most-imported files ranked by incoming edge count — change-risk indicators). Tier 2 (tree-sitter AST re-parsing on demand): `get_routes` (Fastify/Express HTTP route extraction with method, path, file, line, inferred tags for db/auth/cache) and `get_middleware` (middleware registration detection via import-name heuristics and app.register/addHook/setErrorHandler patterns, classifying as auth/cors/rate-limit/security/error-handler/logging/validation). All 4 tools use `defer s.graphMu.RUnlock()` for consistent mutex discipline (reviewer caught that the initial implementation released the lock early on the Tier 2 tools). Route object-property extraction delegates to `extractStringValue` for template-literal handling (reviewer catch). codecontext sidecar rebuilt from `/opt/forks/codecontext` commit `b19e646`, tagged `v1.16.0-codesight-merge`. BooCode wrapper tools follow the existing codecontext pattern — 4 new files in `apps/server/src/services/tools/codecontext/`, registered in ALL_TOOLS. 29 new Go tests + 363/363 BooCode server tests passing. No schema changes, no frontend changes.
+
+## v1.15.0-mcp-multi — 2026-05-24
+
+Multi-server MCP client with stdio + Streamable HTTP transports, JSON config file, and per-agent tool glob patterns. Generalizes the v1.14.1 single-server Context7 PoC into a registry of named MCP servers with per-server graceful degradation. JSON config at `/data/mcp.json` (bind-mounted alongside `AGENTS.md`) matches opencode's `mcpServers` schema shape so server entries are copy-pasteable. Config file missing = no MCP (opt-in by file presence). Stdio transport spawns a persistent subprocess via the SDK's `StdioClientTransport` with NDJSON framing; Streamable HTTP reuses the v1.14.1 pattern via `StreamableHTTPClientTransport`. Tool prefix generalized from `context7_<name>` to `<serverName>_<toolName>` with a reverse `toolToServer` map for dispatch routing. Per-agent AGENTS.md `tools:` field now supports glob patterns (`context7_*`, `!web_*`) via `matchToolGlob` (last-match-wins, `!` prefix denies); replaces the exact-match `.includes()` in `stream-phase.ts`. Glob patterns bypass `ALL_TOOL_NAMES` validation in the parser since MCP tool names aren't known at parse time. `refreshToolNames()` in `agents.ts` rebuilds the `DEFAULT_TOOLS` snapshot after `appendMcpTools` so agents without explicit `tools:` lists see MCP tools — reviewer caught that the module-load-time snapshot would permanently exclude late-registered tools. Read-only invariant preserved: all MCP tools with `readOnlyHint: false` rejected at discovery. Result size capped at 5MB. Shutdown hook closes all transports. v1.14.1 env vars (`MCP_CONTEXT7_URL`, `MCP_CONTEXT7_API_KEY`) removed — superseded by the config file. Default `data/mcp.json` ships with Context7 disabled; flip `"enabled": true` to activate. 363/363 server tests passing (27 new: multi-server wrapping, glob matching, routing, degradation). No schema changes, no frontend changes.
+
+## v1.14.1-mcp-poc — 2026-05-23
+
+Single-server MCP client PoC against Context7. New `apps/server/src/services/mcp-client.ts` (~200 lines) wraps `@modelcontextprotocol/sdk` v1.29.0 with Streamable HTTP transport. On startup (when `MCP_CONTEXT7_URL` is set), connects to Context7, discovers tools via `tools/list`, wraps each as a `ToolDef` prefixed `context7_<name>`, and appends to `ALL_TOOLS` (alpha-sorted for prompt-cache stability). `appendMcpTools()` in `tools.ts` handles the late-registration; `ALL_TOOLS` changed from `ReadonlyArray` to mutable to support it. Read-only invariant guard rejects any MCP tool with `readOnlyHint: false` (MCP SDK v1.29.0 uses `readOnlyHint`, not `readOnly`). Tool dispatch is transparent — `executeToolCall` routes MCP tool calls through the `ToolDef.execute` wrapper, which strips the `context7_` prefix before calling the MCP server. Graceful degradation: MCP server down at startup → zero tools, warn log; MCP server down mid-session → error-shaped result, model self-corrects. Result size capped at 5MB with truncation (matches native `view_file`'s `MAX_FILE_BYTES`). Adversarial review caught that the Zod `.default('https://...')` on the URL config made MCP effectively always-on instead of opt-in — fixed by removing the default. 348/348 server tests passing (16 new mcp-client tests covering tool wrapping, read-only guard, name prefixing, content extraction). No schema changes, no frontend changes. Proves the MCP tool-discovery → tool-call → result-render loop end-to-end before the full v1.15 port.
+
+## v1.14.0-outer-loop — 2026-05-23
+
+Converts the inference engine's ad-hoc `executeToolPhase → runAssistantTurn` recursion into an explicit `while` loop with a configurable step cap. A step is one stream-and-tool-execute iteration; the loop terminates on non-tool finish, step-cap hit, doom-loop, budget exhaustion, abort, or synthesis success. `MAX_STEPS = 200` is the hard ceiling (4x the old effective limit from budget); per-agent `steps:` field in AGENTS.md frontmatter sets tighter caps (Refactorer: 5, Architect: 20, others: unset = bounded only by MAX_STEPS). `executeToolPhase` no longer recurses — returns a `ToolPhaseResult` struct (`action: 'continue' | 'paused' | 'synthesis_done'`) so the caller (the while loop) decides whether to continue or break. `steps: 0` is handled as "no tool calls allowed" — one text-only stream phase, tool calls ignored with a warn log. Step-cap hits produce a sentinel summary (reuses `cap_hit` kind so `CapHitSentinel.tsx` renders it without frontend changes; text distinguishes "Step limit reached" from "Tool budget exhausted"). Doom-loop check migrated from pre-recursion position to top of loop body — same predicate (`detectDoomLoop`), same threshold (3 identical calls), `break` instead of `return`. `step_start` parts are in the schema CHECK but not emitted as message_parts in v1.14 — writing to the assistant message before the stream phase creates a sequence-0 collision with `partsFromAssistantMessage`; a structured log line is emitted instead. Adversarial review caught the collision pre-deploy. 332/332 server tests passing; no frontend changes. Pairs with `v1.13.20-drop-legacy-cols` (parts is now the sole source of truth, and this batch's loop operates entirely through parts).
+
+## v1.13.20-drop-legacy-cols — 2026-05-23
+
+Final phase of the v1.13.0 strangler-fig migration. Removes the dual-write into `messages.tool_calls` / `messages.tool_results` JSON columns and drops the columns themselves; `message_parts` is now the only source of truth for tool-call and tool-result data. 10 dual-write sites stripped (5 in `tool-phase.ts`, 2 in `routes/skills.ts`, 2 in `routes/messages.ts`, 1 in `routes/chats.ts` fork-clone) — recon's grep-driven inventory caught 2 sites beyond the original v1.13.2 roadmap count. `messages_with_parts` view simplified to parts-only subselects (COALESCE fallbacks gone) and rewritten via `CREATE OR REPLACE VIEW` BEFORE the column DROP since Postgres rejects column-drop on view-referenced cols. Adversarial review caught a runtime bug the green test suite missed: `chats.ts:/api/chats/:id/discard_stale` had a `RETURNING ... tool_calls, tool_results, ...` clause referencing the dropped columns; would have crashed on every 60s-no-token-activity recovery in production. Fixed by switching to two-step UPDATE-then-SELECT-from-view so the response keeps the parts-synthesized fields. `Message` API type retains `tool_calls?` / `tool_results?` fields (override on the original v1.13.2 plan) — the view continues to populate them from parts, so the wire shape is unchanged and the frontend needs no updates. v1.12.1 cleanup block (`DROP CONSTRAINT messages_status_check`/`messages_role_check`) removed — those one-shots have done their work. `tool_cost_stats.test.ts` had a direct `INSERT INTO messages` touching the legacy columns that wasn't in the roadmap's inventory; rewritten to parts-table inserts and confirmed semantically faithful. 339/339 server tests passing including the 7 DB-integration tests (live-DB applied the schema migration and ran the parts-only view end-to-end). Pairs with `v1.13.0-ai-sdk-v6` (which introduced the dual-write) and `v1.13.1-B` (which moved the read path to `messages_with_parts`); umbrella `v1.13` tag ships on the same commit.
+
+## v1.13.19-html-artifact-panes — 2026-05-23
+
+Pane-based artifact viewer with on-request HTML support. Every assistant message gets an "Open in pane" icon button (`PanelRightOpen`, mobile 44px tap-target) in `MessageBubble`'s ActionRow; click opens the message in the workspace splitter as either a Markdown pane (Copy raw source + Download `.md`) or an HTML pane (Download `.html` only, no Copy). The HTML path triggers when the model emits a self-contained `<!DOCTYPE html>` or fenced ` ```html` artifact (opt-in only — `BOOCHAT.md` rule says Markdown is default at every length; HTML only on explicit user request like "render this as HTML"). Backend detection in `finalizeCompletion` (`error-handler.ts`) writes a new `message_parts.kind='html_artifact'` row with payload `{html_content, char_count, title}` (`<title>` → first `<h1>` → first 80 chars of inner text). Schema CHECK extended via the v1.13.13 drop-and-re-add pattern. 1MB cap is graceful — over-cap artifacts skip the part write and plain content lands; decision factored into a pure `decideHtmlArtifactWrite` helper so the warn-and-skip branch is unit-testable without mocking the full InferenceContext. Pane state is reference-only (`{chat_id, message_id, title}`) — content is fetched on mount, keeping `sessions.workspace_panes` jsonb small and avoiding 1MB blobs riding the `session_workspace_updated` WS frame. New `services/artifacts.ts` ships slug derivation (Markdown: first `#` heading → first 6 words; HTML: `<title>` → `<h1>` → inner text) and write helpers that realpath the artifacts directory after `mkdir` to close a symlink-escape gap (`assertArtifactsDirSafe`). `routes/artifacts.ts` exposes POST `/api/chats/:id/messages/:msg_id/artifacts/download?fmt=md|html` (writes to `<projectRoot>/.boocode/artifacts/<slug>-<ts>.<ext>`) plus GET `/api/projects/:project_id/artifacts/:filename` with `Content-Disposition: attachment`, `X-Content-Type-Options: nosniff`, and `Content-Security-Policy: sandbox` defense-in-depth on LLM-served HTML. iframe sandbox locks to `allow-scripts allow-clipboard-write allow-downloads` with no `allow-same-origin` and uses `srcDoc` (not `src`) for opaque-origin isolation. Frontend extracts `MarkdownRenderer.tsx` from `MessageBubble`'s inline `MarkdownBody` for reuse; `MarkdownArtifactPane.tsx` / `HtmlArtifactPane.tsx` render with loading + error states. 404-vs-real-error discrimination in `openInPane`: a real network/500 failure toasts and bails instead of silently masquerading as a Markdown pane. 31 new server unit tests (slug derivation, detection positive/negative, write helpers, symlink-escape, 1MB cap, real-symlink filesystem test); 332/332 server tests passing; `tsc -p apps/web/tsconfig.app.json --noEmit` clean; `pnpm -C apps/web build` green. Smoke deferred to first deploy.
+
+## v1.13.18-codecontext-file-path — 2026-05-22
+
+Fix: four codecontext wrappers (`get_file_analysis`, `get_symbol_info`, `get_dependencies`, `get_semantic_neighborhoods`) forwarded `file_path` to the sidecar unchanged, but the sidecar's index is keyed on absolute paths — every relative path from the model returned "File not found in graph" (three back-to-back failures in one chat at 17:56 UTC, ~48 s of wasted tool budget). New `resolveProjectPath` helper in `codecontext_client.ts:64-89` realpath-resolves the candidate, applies the same escape check as the existing `target_dir` resolver (matching the error template byte-for-byte except the field name), and falls through with the normalised absolute on ENOENT so the sidecar issues its own self-correctable "File not found" error. Wired into `callCodecontext` once at the args-spread site — all four wrappers benefit without per-wrapper edits. `.trim()` added to all four `file_path` Zod schemas to absorb trailing newlines from model output. Adversarial review caught a P2 escape-bypass: an absolute path with `..` (e.g. `<projectRoot>/../etc/passwd`) that ENOENTs at realpath would slip through the literal prefix-check, fixed by `resolve()`-normalising the absolute branch too. 9 new test cases in `codecontext_client.test.ts` (7 spec scenarios + symlink-out-of-root + absolute-with-`..` ENOENT) plus a 1-line update in `codecontext_tools.test.ts` asserting the new resolved-absolute contract. Pairs with `v1.13.17-cross-repo-reads` — both harden path traversal, but v1.13.18 stays inside the project root while v1.13.17 widens access outside it.
+
+## v1.13.17-cross-repo-reads — 2026-05-22
+
+On-demand read access to paths outside the session's primary project root. Closes the dead-end where `pathGuard` rejected every cross-repo read with no recovery path. New `request_read_access(path, reason)` tool emits an `ask_user_input`-style pause; user picks Allow/Deny via inline chips in `RequestReadAccessCard.tsx`; on Allow, the new `POST /api/chats/:id/grant_read_access` endpoint re-resolves the grant root and appends to `sessions.allowed_read_paths` (new `TEXT[]` column, default empty). Grant unit per design D1 = nearest registered `projects.path` ancestor → else nearest repo-shaped ancestor (`.git/` / `package.json` / `go.mod` / `Cargo.toml`) under `PROJECT_ROOT_WHITELIST` → else refuse without prompting. `pathGuard` extended with an optional `extraRoots` argument threaded from `session.allowed_read_paths` through `executeToolCall` to the four filesystem tools (view_file, list_dir, grep, find_files); `view_file` re-anchors the secret-guard check on `basename(real)` whenever the path resolved via a grant root so `.env` / `id_rsa*` deny still fires across grants. `grant_resolver.ts`'s ancestor walk checks the whitelist invariant on every iteration (not just final parent) so a symlinked input can't escape mid-walk. PATCH `/api/sessions/:id` exposes `allowed_read_paths` only for revocation: zod refines paths to absolute + no traversal markers, and a runtime subset guard (`findUnauthorizedAdditions`) rejects any entry not already present in the row, so a malicious `curl -X PATCH -d '{"allowed_read_paths":["/etc"]}'` 400s instead of bypassing the grant flow. Settings pane gains a per-session revoke list; archiving the session clears grants implicitly. 11 grant_resolver tests pin the symlink-escape-mid-walk guard (Sam's checkpoint-1 ask) and the nearest-project disambiguation; 8 path_guard tests cover extraRoots traversal; 8 sessions PATCH tests cover the subset guard including the `/etc` bypass attempt. Pairs with `v1.13.16-xml-parser` (model now both self-recovers from a wrong tool name AND from a refused path).
+
 ## v1.13.16-xml-parser — 2026-05-22

 Two-part fix for the model-emitted XML drift the v1.13.15 investigation surfaced. **Parser extension:** `xml-parser.ts` now recognizes the Anthropic `<invoke name="…"><parameter name="…">…</parameter></invoke>` shape alongside the existing Qwen/Hermes `<tool_call><function=…>…</function></tool_call>` shape. qwen3.6-35b-a3b-mxfp4 drifts to the Anthropic format when prompted as an Architect-style agent (Claude Code documentation in its pre-training corpus). Both formats route through the same synthetic-id `xml_call_${idx}` ToolCall path. The existing Qwen parser was tightened to tolerate whitespace around `=` (`<function = name>` shape) so a stray space doesn't get absorbed into the function name. **Unknown-tool recovery hint:** new `tool-suggestions.ts` exports `levenshtein()` + `suggestToolName()` + `formatUnknownToolError()`. When the dispatcher (`tool-phase.ts:executeToolCall`) receives an unknown tool name, the error returned to the model includes a "Did you mean: X?" hint based on Levenshtein distance ≤3 or substring match against `Object.keys(TOOLS_BY_NAME)`. Targets the qwen3.6 drift to `read_file` → suggest `view_file`. Test coverage in `xml-parser.test.ts` (46 tests, all green) covers both parsers, the partial-opener detector for both flavors, the unified extraction helper, and the new error formatter.
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -2,6 +2,8 @@

 This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

+**Cursor agents:** start with `AGENTS.md` (navigation) and `docs/ARCHITECTURE.md` (diagram). This file is the deep engineering reference.
+
 ## What is BooCode

 Self-hosted single-user developer chat app. AI assistant with read-only file tools (view_file, list_dir, grep, find_files) running against a local llama-swap inference server. Sessions organized by project, with a multi-pane workspace (chat + file browser side by side).
@@ -46,7 +48,7 @@ Tests: `pnpm -C apps/server test` runs the vitest suite. No test harness on `app
 - **Zod** for request validation and config parsing.

 Key services:
- **`services/inference/`** — Public surface re-exported via `inference/index.ts`; callers import from `./services/inference/index.js` explicitly (NodeNext doesn't honor directory-index resolution). Layout: `turn.ts` (runAssistantTurn / runInference / createInferenceRunner; exports `InferenceFrame`, `InferenceContext`, `TurnArgs`, `StreamResult`), `stream-phase.ts` (streamCompletion as a v1.13.1-A AI SDK adapter + executeStreamPhase), `provider.ts` (`upstreamModel(baseURL, modelId)` wrapping `createOpenAICompatible` against llama-swap), `tool-phase.ts` (executeToolPhase; value back-edges into turn.ts for the runAssistantTurn recursion — cycle safe because deref at call time, not module top-level), `sentinel-summaries.ts` (runCapHitSummary + runDoomLoopSummary + their sentinel inserters), `error-handler.ts` (handleAbortOrError, finalizeCompletion), `payload.ts` (buildMessagesPayload, loadContext, maybeFlagForCompaction, `OpenAiMessage`), `sentinels.ts` (`detectDoomLoop`, `DOOM_LOOP_THRESHOLD`, sentinel predicates), `budget.ts` (resolveToolBudget), `xml-parser.ts` (qwen3.6 XML tool-call fallback — KEEP, AI SDK doesn't handle inline-XML tool calls), `parts.ts` (v1.13.0 dual-write helpers: `partsFromAssistantMessage`, `partsFromToolMessage`, `insertParts`), `prune.ts` (v1.13.4 two-tier compaction; `selectPruneTargets` is the pure decision helper), `types.ts` (`StreamPhaseState`, `DB_FLUSH_INTERVAL_MS`). **`TurnArgs`** is the per-turn state envelope threaded through the `executeToolPhase → runAssistantTurn` recursion; reset in `runInference` at user-message boundary. Add new per-turn state to `TurnArgs`, not module-level closures.
+- **`services/inference/`** — Public surface re-exported via `inference/index.ts`; callers import from `./services/inference/index.js` explicitly (NodeNext doesn't honor directory-index resolution). Layout: `turn.ts` (runAssistantTurn / runInference / createInferenceRunner; exports `InferenceFrame`, `InferenceContext`, `TurnArgs`, `StreamResult`, `MAX_STEPS`), `stream-phase.ts` (streamCompletion as a v1.13.1-A AI SDK adapter + executeStreamPhase), `provider.ts` (`upstreamModel(baseURL, modelId)` wrapping `createOpenAICompatible` against llama-swap), `tool-phase.ts` (executeToolPhase → returns `ToolPhaseResult`; no longer recurses into runAssistantTurn — v1.14.0 converted the recursion to an explicit while loop in turn.ts), `sentinel-summaries.ts` (runCapHitSummary + runDoomLoopSummary + runStepCapSummary + their sentinel inserters), `error-handler.ts` (handleAbortOrError, finalizeCompletion), `payload.ts` (buildMessagesPayload, loadContext, maybeFlagForCompaction, `OpenAiMessage`), `sentinels.ts` (`detectDoomLoop`, `DOOM_LOOP_THRESHOLD`, sentinel predicates), `budget.ts` (resolveToolBudget), `xml-parser.ts` (qwen3.6 XML tool-call fallback — KEEP, AI SDK doesn't handle inline-XML tool calls), `parts.ts` (parts-table write helpers: `partsFromAssistantMessage`, `partsFromToolMessage`, `insertParts` — v1.13.20 made parts the sole source of truth), `prune.ts` (v1.13.4 two-tier compaction; `selectPruneTargets` is the pure decision helper), `types.ts` (`StreamPhaseState`, `DB_FLUSH_INTERVAL_MS`). **`TurnArgs`** is the per-turn state envelope populated from loop locals each iteration; reset in `runInference` at user-message boundary. The outer loop in `runAssistantTurn` (v1.14.0) runs `while (stepNumber < effectiveCap)` where `effectiveCap = Math.min(agent.steps ?? Infinity, MAX_STEPS=200)`. Per-agent `steps:` field in AGENTS.md frontmatter. `steps: 0` means text-only (no tool execution). Step-cap hit writes a `cap_hit` sentinel so `CapHitSentinel.tsx` renders it.
 - **AI SDK v6 streamCompletion adapter** (v1.13.1-A; `services/inference/stream-phase.ts`). `streamText` is the underlying call; the BooCode layer above (executeStreamPhase, finalize, dual-write) is shape-preserved via an adapter. Five gotchas the LSP/test suite won't catch:
  - **Abort signals are swallowed.** `streamText`'s `fullStream` iterator exits cleanly when `abortSignal` fires — no throw. Post-iteration `if (signal?.aborted) throw <AbortError>` is required; without it the row finalizes as `complete` instead of `cancelled`. Comment in stream-phase.ts pins this; don't refactor it away.
  - **Usage lands only at stream end** via `await result.usage` (`inputTokens` / `outputTokens` v6 names → mapped to `promptTokens` / `completionTokens` for the existing onUsage callback). Mid-stream live tok/s is gone vs v1.12.2; ChatThroughput shows a single value at stream end.
@@ -63,12 +65,32 @@ Key services:
 - **`services/compaction.ts`** + **`services/model-context.ts`** — v1.11.0 anchored rolling summary (single `summary=true` assistant row per chat, supersedes itself on each compaction). Triggered when `chats.needs_compaction` is set after an inference turn exceeds `usable(ctx_max) = floor(0.85 × ctx_max)` (v1.13.9 opencode-pattern early trigger; was `ctx_max - 20k` pre-v1.13.9, which gave only 7.6% headroom at 262k and 0 budget for ≤20k contexts). **`ctx_max` comes from `model-context.getModelContext()` which fetches `${LLAMA_SWAP_URL}/upstream/<model>/props`** — NOT from `parsed.timings.n_ctx` (the stream completion's `timings` doesn't carry n_ctx; that read was dead code until v1.11.3 ripped it out). First inferences after a boocode boot may have `ctx_max=NULL` if llama-swap hasn't loaded the model yet; negative cache TTL is 60s, recovers on next turn. v1.13.6: `buildHeadPayload` embeds `reasoning_parts` as a `<reasoning>...</reasoning>` prose prefix on the assistant `content` (OpenAI wire shape has no structured reasoning field; the summarizer reads text). Standalone tag when content is empty (tool-call-only turn). `buildHeadPayload` + `OpenAiMessage` exported for test access — keep them exported.
 - **`services/system-prompt.ts`** — `buildSystemPrompt` is the string-returning shim; `buildSystemPromptWithFingerprint` is the canonical impl returning `{prompt, fingerprint, drift}`. v1.13.8 instrumentation: SHA-256 of the assembled prefix is logged per `buildMessagesPayload` call (msg `prefix-fingerprint`, level=info); a `Map<sessionId, lastHash>` observer fires `prefix-drift` (level=warn) on hash change with a field-level `changed_inputs` diff. Smoke proved the prefix is byte-stable across turns in steady-state — the originally-planned `system_prompt_cache` DB table was dropped as redundant against the v1.12.0 input-layer mtime caches (BOOCHAT.md here + AGENTS.md global+per-project in `agents.ts:safeStat`).
 - **`services/inference/budget.ts`** — tool-call budgets: `BUDGET_READ_ONLY = 30`, `BUDGET_NON_READ_ONLY = 10` (forward-looking; no write tools yet), `BUDGET_NO_AGENT = 30` (v1.13.7; was 15 — every tool in `ALL_TOOLS` is read-only today, so no-agent mode shares the read-only-agent cap). Per-agent `max_tool_calls` from AGENTS.md frontmatter overrides.
- **`messages_with_parts` view** (v1.13.1-B; `schema.sql`). Read sites that need `tool_calls` / `tool_results` / `reasoning_parts` SELECT from this view, NOT `messages` directly. `COALESCE`s parts-table rows over the legacy JSON columns, so pre-v1.13.0 history still resolves. Writes still target `messages`; the v1.13.0 dual-write into `message_parts` keeps both halves in sync. New payload-assembly code must use the view — calling `messages.tool_calls` directly will miss anything written post-v1.13.1-B if the JSON column ever drifts (and dual-write makes that easy to miss). Shapes: `tool_calls jsonb[]`, `tool_results jsonb` single object, `reasoning_parts jsonb[]` of `{text}`.
+- **`messages_with_parts` view** (v1.13.1-B; `schema.sql`). Read sites that need `tool_calls` / `tool_results` / `reasoning_parts` SELECT from this view, NOT `messages` directly. v1.13.20 dropped the legacy `messages.tool_calls` / `messages.tool_results` JSON columns; the view now reads parts-only subselects. Writes target `message_parts` exclusively via `insertParts` (or via the helpers `partsFromAssistantMessage` / `partsFromToolMessage`). The `Message` wire type still carries `tool_calls?` / `tool_results?` because the view synthesizes them from parts — frontend reads are unchanged. Shapes: `tool_calls jsonb[]`, `tool_results jsonb` single object, `reasoning_parts jsonb[]` of `{text}`. If you ever need to UPDATE a message and return its full Message shape, do a two-step UPDATE returning `id` followed by SELECT from the view — RETURNING off the bare `messages` table no longer carries the tool fields.
 - **`services/file_ops.ts`** — Shared file operation implementations used by both inference tools and HTTP routes.
 - **`services/auto_name.ts`** — Non-streaming LLM call to generate 4-word session titles after first assistant reply.
+- **`apps/coder/src/services/provider-registry.ts`** (BooCoder, NOT apps/server) — Static registry of provider metadata (label, transport, model source). `PROVIDERS` array, `PROVIDERS_BY_NAME` map. 5 providers: boocode (native), opencode (acp), goose (pty), claude (pty), qwen (pty).
+- **`apps/coder/src/services/agent-probe.ts`** (BooCoder) — Startup probe using direct `exec()` (not SSH). Discovers installed agents on host, their versions, ACP support, and models. Qwen models read from `~/.qwen/settings.json`. Claude models are static from the registry. Results persisted to `available_agents` table.
+- **`apps/coder/src/routes/providers.ts`** (BooCoder) — `GET /api/providers` returns installed providers with models. Transport field reflects actual capability (checks `supports_acp` from DB, not just registry preference). The apps/server side of this flow is the "Provider picker dispatch" bullet below.
+- **Provider picker dispatch**: when `provider !== 'boocode'`, the message route creates a `tasks` row (with `session_id` set) instead of calling `inference.enqueue`. The dispatcher picks it up and dispatches via ACP or PTY using the agent's `install_path`.

 Route registration: all routes registered in `index.ts` via `register*Routes(app, sql, ...)` functions. Routes are in `routes/*.ts`.

+### BooCoder (`apps/coder/src/`)
+
+- Write-capable coding agent. Runs as a **systemd service on the host** (`boocoder.service`), NOT in Docker. Fastify server at port 9502, connects to postgres at `127.0.0.1:5500`.
+- **Workspace dependency on `@boocode/server`**: imports `createInferenceRunner`, `createBroker`, `ALL_TOOLS`, `appendMcpTools` from the server's compiled `dist/`. apps/server's `package.json` has an `exports` map with `types` conditions for NodeNext resolution. apps/server must build FIRST.
+- Build + deploy: `pnpm -C apps/server build && pnpm -C apps/coder build && sudo systemctl restart boocoder`. Env file at `apps/coder/.env.host`. Service file at `/etc/systemd/system/boocoder.service`.
+- After `pnpm -C apps/coder build` the host `boocoder.service` keeps running the OLD process until `sudo systemctl restart boocoder` — a stale process shows **new routes 404 with `{error:'not found'}` while old routes still 200** (the `/api` not-found handler returns that shape). Restart, don't re-debug.
+- Agent dispatch spawns binaries directly using `install_path` from `available_agents` — no `spawn('sh', ['-c', ...])` (fails under systemd). Follows Paseo's pattern: `spawn(fullBinaryPath, argsArray, { cwd })`.
+- systemd hardening: only `NoNewPrivileges=true` is safe. `ProtectSystem`, `ProtectHome`, `PrivateTmp` all break agent dispatch (agents need full filesystem access to read configs, write to worktrees).
+- `apps/server/tsconfig.json` has `declaration: true` so `.d.ts` files exist for workspace consumers.
+- Write tools (`edit_file`, `create_file`, `delete_file`, `apply_pending`, `rewind`) queue in `pending_changes` table. Nothing hits disk until `apply_pending` is called. `write_guard.ts` validates paths (resolve + prefix-check, no realpath since files may not exist for creates).
+- Frontend: NOT a separate SPA. BooCoder is a `'coder'` pane type within BooChat's SPA (`apps/web/`). `CoderPane.tsx` in `apps/web/src/components/panes/`. API requests go through `/api/coder/*` proxy (Vite dev + Fastify production) which rewrites to the boocoder host service (`BOOCODER_URL` env var, default `http://100.114.205.53:9502`). WS connects directly to `:9502`.
+- `apps/coder/web/` is a STANDALONE fallback SPA served at `:9502` directly. The PRIMARY BooCoder frontend is the `CoderPane` in BooChat's SPA (`apps/web/src/components/panes/CoderPane.tsx`), accessible via the "Coder" pane in the workspace at `code.indifferentketchup.com`. Both exist; the pane is what Sam uses.
+- **Provider snapshot lifecycle** (`apps/coder/src/services/`): `provider-config.ts` (Zod config, never-throws on bad input) → `provider-config-registry.ts` (`buildResolvedRegistry`, singleton) → `provider-snapshot.ts` (two-tier probe: tier-1 fast presence, tier-2 cold ACP probe skipped unless force / stale `PROVIDER_PROBE_TTL_MS` 24h / dbEmpty; cached). Verify live: `curl http://100.114.205.53:9502/api/providers/snapshot` — returns providers + models + commands, the exact shape `AgentComposerBar` renders.
+- `PATCH /api/providers/config` replaces a provider id's override object **wholesale** (per-id shallow merge) — to flip one field send `{...existing, enabled}`, or a custom ACP entry's `command`/`label` is wiped and it drops out of the resolved registry. `data/coder-providers.json` is **gitignored** (it's live runtime config — the coder reads AND writes it on UI toggles); the tracked reference is `data/coder-providers.example.json`. The loader falls back to `{providers:{}}` (built-ins only) when the live file is absent, so a fresh checkout needs no copy.
+- External agents dispatch **one-shot** (`opencode acp` / `goose acp` / `qwen --acp`) and report no context-window/token usage; only native `boocode` (llama-swap engine) tracks ctx. OpenCode-as-HTTP-server (warm process + `@opencode-ai/sdk`, the source of a real context bar) is the **planned, unshipped** `openspec/changes/v2-6-persistent-agent-sessions` batch; Paseo's per-provider native clients (design §12) were deliberately not ported.
+
 ### Frontend (`apps/web/src/`)

 - **React 18** + React Router v6 + **Tailwind v4** + shadcn/radix-ui primitives.
@@ -105,24 +127,34 @@ Sessions hold 1–5 panes (chat / empty / placeholder terminal+agent). v1.12.1 m

 ## Database

-PostgreSQL 16. Tables: `projects`, `sessions`, `chats`, `messages`, `settings`, `message_parts` (v1.13.0). Views: `messages_with_parts` (v1.13.1-B parts-merge read path), `tool_cost_stats` (v1.13.10 per-tool 100-call rolling window). (`session_panes` was dropped in v1.12.1; workspace pane state lives in `sessions.workspace_panes jsonb`.) Schema applied idempotently on startup via `applySchema()`. Use `clock_timestamp()` (not `NOW()`) inside transactions. CHECK constraints in place: `projects_status_chk` ('open'|'archived'), `sessions_status_chk` (same), `chats_status_chk` (same), `messages_role_chk`, `messages_status_chk` — keep in sync with the `*_STATUSES` const arrays in `apps/server/src/types/api.ts`. The older anonymous `messages_status_check` (without 'cancelled') and `messages_role_check` (without 'system') were dropped in v1.12.1; only the `_chk` variants remain.
+PostgreSQL 16. Database name: `boochat` (renamed from `boocode` in v2.0.0-alpha; Docker service name stays `boocode_db`). Tables: `projects`, `sessions`, `chats`, `messages`, `settings`, `message_parts` (v1.13.0), `pending_changes` (v2.0.0), `tasks` (v2.0.0), `available_agents` (v2.0.0). Views: `messages_with_parts` (v1.13.1-B parts-merge read path), `tool_cost_stats` (v1.13.10 per-tool 100-call rolling window), `human_inbox` (v2.0.0 — tasks WHERE state IN blocked/failed). (`session_panes` was dropped in v1.12.1; workspace pane state lives in `sessions.workspace_panes jsonb`.) Schema applied idempotently on startup via `applySchema()`. Use `clock_timestamp()` (not `NOW()`) inside transactions. CHECK constraints in place: `projects_status_chk` ('open'|'archived'), `sessions_status_chk` (same), `chats_status_chk` (same), `messages_role_chk`, `messages_status_chk` — keep in sync with the `*_STATUSES` const arrays in `apps/server/src/types/api.ts`. The older anonymous `messages_status_check` (without 'cancelled') and `messages_role_check` (without 'system') were dropped in v1.12.1; only the `_chk` variants remain.

 Schema CHECK migration order when renaming allowed values: (1) `ALTER TABLE ... DROP CONSTRAINT IF EXISTS <system_name>` (inline `CREATE TABLE` checks get `<table>_<column>_check`), (2) `UPDATE` rows to new values, (3) wrap new constraint ADD in `DO $$ ... pg_constraint` guard — that block is the only way to get `ADD CONSTRAINT IF NOT EXISTS`.


 ## Environment

-Required: `DATABASE_URL`, `LLAMA_SWAP_URL`. Optional: `PORT` (3000), `HOST` (0.0.0.0), `PROJECT_ROOT_WHITELIST` (/opt, read-only scope for add-existing path resolution), `BOOTSTRAP_ROOT` (/opt/projects, writable scope for create-new-project bootstrap mkdir target — host must `mkdir -p /opt/projects` before container start), `DEFAULT_MODEL`, `LOG_LEVEL`, `SEARXNG_URL` (default `http://100.114.205.53:8888` — internal Tailscale Fathom; the public `search.indifferentketchup.com` is behind Authelia and unusable from server context), `BOOCODE_TOOLS` (`core` | `standard` | `all`, default `all`; v1.13.15-tools tier filter — ceiling, never expands an agent's whitelist).
+Required: `DATABASE_URL`, `LLAMA_SWAP_URL`. Optional: `PORT` (3000), `HOST` (0.0.0.0), `PROJECT_ROOT_WHITELIST` (/opt, read-only scope for add-existing path resolution), `BOOTSTRAP_ROOT` (/opt/projects, writable scope for create-new-project bootstrap mkdir target — host must `mkdir -p /opt/projects` before container start), `DEFAULT_MODEL`, `LOG_LEVEL`, `SEARXNG_URL` (default `http://100.114.205.53:8888` — internal Tailscale Fathom; the public `search.indifferentketchup.com` is behind Authelia and unusable from server context), `BOOCODE_TOOLS` (`core` | `standard` | `all`, default `all`; v1.13.15-tools tier filter — ceiling, never expands an agent's whitelist), `MCP_CONFIG_PATH` (optional; default `/data/mcp.json` — JSON config for MCP servers matching opencode's `mcpServers` shape; file missing = no MCP).
+
+BooCoder at port 9502: `curl http://100.114.205.53:9502/api/health`. Runs as `boocoder.service` on the host (not Docker). Deploy: `pnpm -C apps/server build && pnpm -C apps/coder build && sudo systemctl restart boocoder`. Health reports tool count: `{"ok":true,"db":true,"tools":33}`.
+
+- `FAST_MODEL` (optional) — cheaper model for titles, summaries, labeling (auto_name.ts, tool-summaries.ts). Falls back to session model or DEFAULT_MODEL when unset. Set to a small model on llama-swap (e.g. `nemotron-nano-4b`) to avoid loading the 35B for 20-token calls.
+- Qwen Code dispatch: `OPENAI_BASE_URL=http://100.101.41.16:8401/v1 OPENAI_API_KEY=dummy qwen -p "<task>" --output-format stream-json`. Install: `npm install -g @qwen-code/qwen-code@latest`. Node ≥22 required on host (container stays Node 20; BooCoder dispatches via direct spawn on host). No `--yolo` flag — non-interactive mode (`-p`) runs autonomously without approval prompts. ACP bridge is HTTP daemon (not stdio); use PTY dispatch.
+- Arena (v2.0.5): `POST /api/arena {project_id, input, contestants: [{agent?, model?}]}` dispatches the same task to N models/agents in parallel. Each contestant gets its own task + worktree. `GET /api/arena/:id` for results. `POST /api/arena/:id/select/:task_id` picks winner.

 ## Workflow

 - Sam reviews all diffs and commits manually. Do not commit unless explicitly asked.
 - Per-batch docs live under `openspec/changes/<slug>/{proposal,tasks,design}.md`. Already-shipped batches are snapshots in `openspec/changes/archived/`. New batches follow the proposal+tasks shape; see `openspec/README.md` for the convention.
+- Tag naming: `vMAJOR.MINOR.PATCH-slug` (e.g. `v1.13.13-ws-publish`). Monotonic per minor — the slug describes the batch's content so the tag name alone is enough to recall what shipped. No letter suffixes (`-a`/`-b`), no pseudo-ranges (`v1.11.x`), no slug-only sub-versions sharing a number (`v1.13.15-tools` + `-openspec` + `-agentlint` — split into sequential patches instead).
+- `CHANGELOG.md` is the per-tag release log, most-recent on top. When a new tag is created, add a `## <tag> — <YYYY-MM-DD>` section with a 3–6 sentence paragraph summarizing what shipped, drawn from the commit body. Cross-reference other tags by name when the batch builds on, fixes, or pairs with prior work (e.g. "pairs with `v1.13.12-ws-schemas`", "fixed in `v1.13.5-stability-bundle`"). No nested bullets — one paragraph.
 - Deploy: `cd /opt/boocode && docker compose up --build -d` (or `docker compose build --no-cache boocode && docker compose up -d` if you suspect a layer-cache issue).
+- The `boocode` container is `build: .` — it builds web+server from the **working tree**, so uncommitted changes deploy. Web edits are live on the Vite dev server (HMR) but NOT on production (`:9500` / code.indifferentketchup.com) until `docker compose up --build -d boocode`.
 - Git push to Gitea: `GIT_SSH_COMMAND="ssh -i /opt/boocode/secrets/boocode_gitea -o IdentitiesOnly=yes" git push origin <branch>`. The default agent identity is rejected; the in-repo deploy key (`secrets/`, gitignored) is the working one. Transient `Connection reset by peer` retries cleanly after `sleep 5`.
 - Don't accumulate `.bak-*` files. Clean them up in the same batch or immediately after merge.
- DB-integration tests opt-in via env var: `DATABASE_URL='postgres://boocode:devpass@localhost:5500/boocode' pnpm -C apps/server test`. Host port is 5500 (mapped from `boocode_db:5432`); password is `${POSTGRES_PASSWORD}` from `.env` (`devpass`), NOT the literal in `.env`'s `DATABASE_URL=postgres://boocode:Ketchup1479@boocode_db:5432/...` line. Pattern: `describe.runIf(!!process.env.DATABASE_URL)(...)` with a `beforeAll` that applies the schema via `sql.unsafe(readFileSync(schemaPath))`. Tests skip cleanly when var is unset. `tool_cost_stats.test.ts` is the reference.
+- DB-integration tests opt-in via env var: `DATABASE_URL='postgres://boocode:devpass@localhost:5500/boochat' pnpm -C apps/server test`. Host port is 5500 (mapped from `boocode_db:5432`); password is `${POSTGRES_PASSWORD}` from `.env` (`devpass`), NOT the literal in `.env`'s `DATABASE_URL=postgres://boocode:Ketchup1479@boocode_db:5432/...` line. `psql` is not on the host PATH — for an interactive query use `docker exec boocode_db psql -U boocode -d boochat -c "..."`. Pattern: `describe.runIf(!!process.env.DATABASE_URL)(...)` with a `beforeAll` that applies the schema via `sql.unsafe(readFileSync(schemaPath))`. Tests skip cleanly when var is unset. `tool_cost_stats.test.ts` is the reference.
 - Host-side smoke endpoint: `curl http://100.114.205.53:9500/api/...`. The boocode container's port mapping binds to the Tailscale IP, not `0.0.0.0`, so `localhost:9500` doesn't work from the host shell. Same for booterm at `:9501`.
+- Frontend blank-screen / runtime crash: get the stack-trace column offset from the browser console, then `cut -c <start>-<end> apps/web/dist/assets/index-*.js | sed -n '<line>p'` to read the exact minified expression that threw. Faster than bisecting source. Watch for `=== null`/`!== null` on optional fields fed an `as unknown as` cast — those bypass tsc.
 - Fastify global JSON parser tolerates empty bodies (overridden in `index.ts`); bodyless POSTs (archive, unarchive, stop) work without setting `Content-Type` tricks on the client.
 - Event dedup discipline: for any mutation the server publishes via `broker.publishUser`, do NOT add a local `sessionEvents.emit(...)` after the API call — `useUserEvents` forwards the WS frame onto the bus. Frontend mutation handlers must be idempotent (dedup by id, no-op on already-present).
 - `node:20-*` base images ship a `node` user at uid/gid 1000 — delete it (`userdel`/`groupdel` on debian, `deluser`/`delgroup` on alpine) before adding samkintop at 1000.
@@ -131,7 +163,9 @@ Required: `DATABASE_URL`, `LLAMA_SWAP_URL`. Optional: `PORT` (3000), `HOST` (0.0
 - A local PreToolUse hook (`security_reminder_hook.py`) regex-flags Node's older `child_process` spawn helpers as unsafe (false positive even on the File-suffixed variant). Use `spawn` — it's accepted.
 - `/opt/boolab` hosts a working sibling BooCode terminal at `boocode.indifferentketchup.com`. Useful for visual side-by-side comparison on the same iPhone when debugging booterm rendering. Boolab uses Tailwind v3 (`@tailwind base`); boocode uses v4 — many subtle build differences. Don't assume parity.
 - booterm SSHs to the host as `samkintop@100.114.205.53` (the Tailscale IP). The hostname `ubuntu-homelab` (shown in the bash prompt after login) does NOT resolve from inside the container — only the host's `/etc/hosts` knows it. Override via `BOOTERM_SSH_HOST` / `BOOTERM_SSH_USER` env vars in docker-compose if you ever move the shell to a different machine.
- codecontext sidecar lives at `/opt/boocode/codecontext/`. Sidecar HTTP API at `http://codecontext:8080/v1/<tool_name>` over the `boocode_net` bridge (no host port). BooCode wrappers in `apps/server/src/services/tools/codecontext/`. The `.codecontextignore.template` documents recommended ignore patterns; users copy and adapt to project root manually.
+- codecontext sidecar lives at `/opt/boocode/codecontext/`. Sidecar HTTP API at `http://codecontext:8080/v1/<tool_name>` over the `boocode_net` bridge (no host port). BooCode wrappers in `apps/server/src/services/tools/codecontext/`. The `.codecontextignore` at project root is honored when `--respect-gitignore` is passed (enabled in the shim).
+- codecontext fork at `/opt/forks/codecontext/` — separate git repo (branch `boocode-ts`), pushed via the same boocode_gitea SSH key to `indifferentketchup/codecontext`. Build: `go build ./...`. Test: `go test ./...`. Docker rebuild requires staging the fork source first: `tar -czf codecontext/fork.tar.gz -C /opt/forks/codecontext --exclude=.git --exclude=bin .` then `docker compose build --no-cache codecontext`. The Dockerfile COPYs `fork.tar.gz` into the builder stage (Gitea is behind Authelia, no HTTP clone). `fork.tar.gz` is gitignored.
+- Go binary: `/snap/go/current/bin/go` (not on PATH by default). Use `export PATH=$PATH:/snap/go/current/bin` or full path for Go commands.
 - `os/exec` child supervisors must explicitly call `child.Wait()` in a goroutine and `os.Exit` on child death. `Signal(0)` returns nil on zombies and is NOT a liveness check. Without `Wait()`, docker's `restart: unless-stopped` policy never fires because the parent stays alive. The `codecontext/shim.go` implementation is the reference pattern.

 ## Conventions
@@ -143,10 +177,12 @@ Required: `DATABASE_URL`, `LLAMA_SWAP_URL`. Optional: `PORT` (3000), `HOST` (0.0
 - Discriminated unions for type narrowing: `Pane` (by `kind`), `SessionEvent` (by `type`), `InferenceFrame` (by `type`).
 - **Adding a new WS frame type** requires updating BOTH the server's `InferenceFrame` (loose `type:` union + optional fields in `services/inference/turn.ts`) AND the web `WsFrame` (strict discriminated union in `apps/web/src/api/types.ts`). Server publish is permissive; the frontend type is the wire-format gate. The `'usage'` frame added in v1.12.2 needed both sides; missing the web side silently drops the frame at JSON-parse.
 - shadcn primitives live in `components/ui/`. Don't modify them unless adding a new primitive.
+- `ui/` primitives present: button, card, context-menu, dialog, dropdown-menu, input, label, radio-group, sonner, textarea. No switch/sheet/drawer/badge/checkbox — use a `<button role="switch" aria-checked>` toggle (a hand-rolled `Switch` already lives in `SettingsPane.tsx`) and a Dialog-based panel for "drawers".
 - `inferLanguage()` from `lib/attachments.ts` is the canonical file-extension-to-language map. `CodeBlock.tsx` keeps its own `LANG_MAP` because it also resolves markdown fence names.
 - Two UI event buses: `hooks/sessionEvents.ts` for DB-state events (chat_created, session_updated); `lib/events.ts` for ephemeral UI (`sendToTerminal`, `terminalsRegistry`). Don't merge — different subscriber lifecycles.
 - `vite.config.ts` proxy entries are order-sensitive: more-specific prefixes (`/api/term`, `/ws/term`) must come BEFORE `/api`.
 - Mobile pane URL sync (`Session.tsx`): the `?pane=<id>` effect resets `activePaneIdx` whenever `panes` changes. New-pane creation on mobile must push `?pane=` atomically — `addPaneAndSwitch` is the wrapper that does this. `addSplitPane` returns the new pane id for callers.
+- A scrollable list inside a Dialog on mobile: cap `DialogContent` (`max-h-[85vh]` + `grid-rows-[auto_minmax(0,1fr)_auto]`) and make the list the single scroll region with `overscroll-contain` — otherwise touch-scroll drags the whole fixed modal / chains to the page.
 - xterm.js v5 uses canvas rendering — browser doesn't see xterm's selection; the native right-click menu has no working Copy for terminal text. App keybindings (`Cmd/Ctrl-C`, `Cmd/Ctrl-Shift-C`) are the path.
 - **New tools** live in their own `services/<name>.ts` file (see `web_search.ts`, `web_fetch.ts`) — exports a pure `executeFoo(input, ...deps)` for direct test access plus a `ToolDef` wrapper that `loadConfig()`s its real dependencies. Register the ToolDef in `tools.ts` `ALL_TOOLS` (and `READ_ONLY_TOOL_NAMES` if applicable). Inject `fetcher: typeof fetch = fetch` rather than `vi.spyOn(globalThis, 'fetch')` — cleanup is simpler and the production call site stays unchanged.
 - **Sentinels** are `role='system'` rows with structured `metadata.kind` (`cap_hit`, `doom_loop`). UI-only — `buildMessagesPayload` strips them via `isAnySentinel` so the LLM never sees them. A new kind requires arms in `MessageMetadata` in BOTH `apps/server/src/types/api.ts` AND `apps/web/src/api/types.ts`, plus a render branch in `apps/web/src/components/MessageBubble.tsx`.
@@ -154,3 +190,17 @@ Required: `DATABASE_URL`, `LLAMA_SWAP_URL`. Optional: `PORT` (3000), `HOST` (0.0
 - Tool-name whitelists must derive from `ALL_TOOLS` in `services/tools.ts`, never hardcoded. `services/agents.ts` `ALL_TOOL_NAMES` had this drift class until v1.12 — same pattern applies to any future tool-aware code.
 - Agent registry lives at `data/AGENTS.md` (global, bind-mounted at `/data/AGENTS.md`). No per-project `AGENTS.md` in this repo — removed in v1.12 to eliminate the two-files-must-stay-in-sync drift. The `getAgentsForProject` per-project override mechanism remains for *other* projects.
 - MCP stdio transport uses newline-delimited JSON (NDJSON), NOT LSP-style `Content-Length` headers. The `codecontext/shim.go` framing implementation is the reference; per the MCP spec (modelcontextprotocol.io/specification/server/transports).
+- **Workspace dependency pattern** (`apps/coder` → `@boocode/server`): the consuming package adds `"@boocode/server": "workspace:*"` in `package.json`. The provider's `package.json` needs `exports` with `types` + `default` conditions per subpath: `"./inference": { "types": "./dist/.../index.d.ts", "default": "./dist/.../index.js" }`. Without the `types` condition, NodeNext resolution can't find `.d.ts` files and tsc fails with "Cannot find module" in the consumer.
+- **JSONB columns**: use `sql.json(value as never)` — NOT `${JSON.stringify(value)}::jsonb` which double-serializes (stores a JSON string instead of a JSON object/array). Pattern established in `parts.ts`, `settings.ts`.
+- **`payload.ts:loadContext` SELECT**: must include every `Session` field that downstream code reads. The tool phase reads `session.allowed_read_paths`; if the SELECT omits it, cross-repo read grants silently fail. The `Session` TypeScript type doesn't catch this because `sql<Session[]>` doesn't enforce column coverage.
+- **Sidecar routing** (`services/inference/provider.ts`): `upstreamModel(config, modelId, agent)` routes to `LLAMA_SIDECAR_URL` when agent has `llama_extra_args`, otherwise `LLAMA_SWAP_URL`. `resolveRoute(agent)` returns `{route: 'swap'|'sidecar', flags}`. Sidecar provider created fresh per call (not cached) because `X-Agent-Flags` header varies per agent. Boot-time guard in `index.ts` refuses to start if any agent has `llama_extra_args` but `LLAMA_SIDECAR_URL` is unset.
+- **Secret guard safe patterns** (`services/secret_guard.ts`): `.env.example`, `.env.sample`, `.env.template`, `.env.defaults` are allowlisted via `SAFE_PATTERNS` set. Do NOT add `.env.production`/`.env.development`/`.env.test` — those can hold real secrets.
+- **CoderPane uses ChatInput** (`components/panes/CoderPane.tsx`): shares the same `ChatInput` component as BooChat for full parity — attachments, paste-to-chip, auto-grow textarea, queued messages during send. CoderPane's `sendOneMessage` is the send callback; queued messages drain via `useEffect` when `sending` goes false.
+- **Adding a new `SessionEvent` type**: add the interface, add it to the `SessionEvent` union, add a `case` in `useSidebar.ts` `applyEvent` switch (no-op `return prev` is fine), and subscribe in any hook that needs it (e.g. `useSessionStream` for `refetch_messages`).
+- **BooCoder provider registry** (`apps/coder/src/services/provider-registry.ts`): static list of provider defs (boocode, opencode, goose, claude, qwen). `PROBED_AGENT_NAMES` derives from it. Adding/removing providers means editing this file, not the frontend.
+- **AgentComposerBar filters `e.installed`**: provider snapshot entries with `installed:false` (loading/unavailable) are dropped from the dropdown. `getProviderSnapshot` must await the full build — returning synchronous `loading` placeholders makes every provider vanish (the v2.5.7 "no providers showing up" regression); surfacing loading states needs a client poll.
+- **Coder↔web provider-type parity** (`apps/coder/src/services/provider-types.ts` ↔ `apps/web/src/api/types.ts`): enforced by runtime `provider-types-parity.test.ts` (compile-time cross-import is blocked by TS6307 on web's composite tsconfig). Mirror of the ws-frames parity pattern — edit both copies together or the test fails.
+- **ACP command discovery is async**: `acp-probe.ts` must poll after `newSession` for `available_commands_update` (commands arrive in a later notification; reading synchronously captures 0). PTY providers (claude) instead discover from disk via `claude-command-discovery.ts` (`~/.claude/commands` + `enabledPlugins` `skills/`+`commands/`, bare names, deduped). `AgentCommand.kind` tags `'command'` vs `'skill'`; `CoderPane`'s `slashGroups` splits them into icon'd groups. `SlashCommandPicker`'s `groups?` prop is opt-in — BooChat passes flat `items` (unchanged).
+- **Pane header architecture (mobile vs desktop)**: Desktop coder pane header (BooCode label + [+] [×]) lives in `Workspace.tsx` gated by `isCoder && !isMobile`. Mobile coder controls (● ×) live in `Session.tsx` header row next to `MobileTabSwitcher`/`NewPaneMenu`. `AgentComposerBar` (provider/mode/model pickers) renders inside `CoderPane.tsx` on both. The ● status dot is passed via `connected` prop from CoderPane to AgentComposerBar.
+- **MessageBubble shared between BooChat and BooCoder** (`components/MessageBubble.tsx`): accepts optional `actions?: MessageActions` callbacks (onRegenerate, onResend, onFork, onDelete) and `hideActions?: ('fork'|'delete'|'openInPane')[]`. Defaults use BooChat API; CoderPane overrides via `CoderMessageList` props. `CoderTextBubble` was removed. **`CoderMessageList` passes `CoderMessageWire as unknown as Message`** — the coder wire shape lacks `metadata`/`kind`/`summary`, so those fields are `undefined` (not `null`) on coder messages. Null-guards on any `Message` field MUST use loose `!= null`, not strict `!== null` (`undefined !== null` is `true` → `.kind` throws → blank-screen crash). The `as unknown as` cast hides this from tsc; build + typecheck pass while runtime crashes.
+- **llama-sidecar** (`/opt/forks/llama-sidecar/`): Go daemon for per-agent llama-server process pool. Cross-compile: `GOOS=windows GOARCH=amd64 /snap/go/current/bin/go build -o bin/llama-sidecar.exe ./cmd/llama-sidecar`. Gitea: `indifferentketchup/llama-sidecar`. Windows child process gotchas: use `context.Background()` for child lifetime (not request ctx), `os.Open(os.DevNull)` for stdin, `os.Pipe()` for stdout with drain goroutine, `DETACHED_PROCESS | CREATE_NEW_PROCESS_GROUP` creation flags. SSH to sam-desktop: `ssh samki@100.101.41.16`; use `schtasks` for persistent process spawning (SSH `start /B` doesn't survive session close).
--- a/CURRENT.md
+++ b/CURRENT.md
@@ -0,0 +1,10 @@
+# Current focus
+
+Last updated: 2026-05-26
+
+- **Batch:** v2.3-provider-lifecycle (openspec drafted; not started)
+- **Branch:** `main`
+- **Blockers:** none
+- **Last shipped:** `v2.2.2-xml-placeholder-reject`
+
+Update this file when starting or finishing a batch. Agents: read this first for session intent; if stale vs `CHANGELOG.md`, trust CHANGELOG for shipped state.
--- a/661
+++ b/661
@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
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--- a/README.md
+++ b/README.md
@@ -1,6 +1,10 @@
 # boocode

-Self-hosted single-user developer chat app. v1: chat only.
+Self-hosted single-user developer chat app. 3-app monorepo: BooChat (read-only chat), BooCoder (write tools + agent dispatch), BooTerm (PTY terminals).
+
+**Latest release:** `v2.2.1-pane-scoped-chats` (2026-05-26) · [`CHANGELOG.md`](CHANGELOG.md) · **Current focus:** [`CURRENT.md`](CURRENT.md)
+
+**Agent navigation:** [`AGENTS.md`](AGENTS.md) · **Architecture:** [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) · **Engineering reference:** [`CLAUDE.md`](CLAUDE.md)

 ## Stack

@@ -13,6 +17,8 @@ Self-hosted single-user developer chat app. v1: chat only.

 - `apps/server` — Fastify API + WebSocket + inference loop + file-read tools
 - `apps/web` — React frontend; served by Fastify in production, Vite in dev
+- `apps/booterm` — Fastify + node-pty + tmux for in-browser terminal panes
+- `apps/coder` — Fastify write tools + ACP/PTY dispatcher + MCP server (BooCoder)

 ## Local dev

@@ -28,7 +34,7 @@ cp .env.example .env
 docker compose up -d boocode_db

 # run server (port 3000) and web (port 5173) in two shells
-DATABASE_URL=postgres://boocode:devpass@127.0.0.1:5500/boocode \
+DATABASE_URL=postgres://boocode:devpass@127.0.0.1:5500/boochat \
 LLAMA_SWAP_URL=http://100.101.41.16:8401 \
 pnpm dev:server

@@ -49,11 +55,32 @@ docker compose up --build -d
 Binds to `100.114.205.53:9500` (Tailscale). Authelia is expected to gate the
 upstream and inject `Remote-User`. Postgres binds loopback only.

-## What v1 has
+BooCoder runs as a **host systemd service** (`boocoder.service`, port `:9502`), not in Docker:

-Project sidebar, sessions per project, chat with streaming responses over
-WebSocket, four file-read tools scoped to the project root (`view_file`,
-`list_dir`, `grep`, `find_files`), and a model picker driven by llama-swap's
-`/v1/models`.
+```bash
+pnpm -C apps/server build && pnpm -C apps/coder build
+sudo systemctl restart boocoder
+curl http://100.114.205.53:9502/api/health
+```

-What v1 does not have lives in v2 (terminal pane) and v3 (Coder pane).
+## Services
+
+|Service|Port|Description|
+|---|---|---|
+|BooChat|`100.114.205.53:9500`|Read-only chat + SPA |
+|BooTerm|`100.114.205.53:9501`|PTY/tmux terminal panes |
+|BooCoder|host:9502|Write tools + agent dispatch + MCP server (systemd service, not Docker) |
+|Postgres|`127.0.0.1:5500`|Shared database (`boochat`; Docker service `boocode_db`) |
+|codecontext|internal `:8080`|Code graph sidecar (Docker network only) |
+
+## What's shipped
+
+See [`boocode_roadmap.md`](boocode_roadmap.md) for full version history. Highlights as of **v2.2.1**:
+
+- **BooChat**: streaming chat, file-read tools, compaction, reasoning support, HTML/Markdown artifact panes, cross-repo read grants, MCP client (multi-server + stdio), tool-cost tracking, skills system, builtin agent registry, multi-pane workspace (chat / terminal / coder)
+- **BooTerm**: in-browser terminal panes via tmux + xterm.js, per-session tmux sessions, SSH-out support
+- **BooCoder (v2.2)**: write tools (`edit_file`, `create_file`, `delete_file`, `apply_pending`, `rewind`), pending-changes queue with diff UI, Paseo-style provider snapshot (7 providers: boocode, cursor, claude, opencode, goose, qwen, copilot), `AgentComposerBar` (provider / mode / model / thinking), ACP dispatch with inline permission prompts + tool/reasoning streaming, PTY fallback, Arena, MCP server (6 tools, stdio), CLI client, human inbox, Boomerang orchestration, path-guard fuzz suite, **pane-scoped chats** (v2.2.1 — each coder/terminal pane owns its chat)
+
+## Planned
+
+- **v2.3 provider lifecycle** — config-backed provider registry (`/data/coder-providers.json`), enable/disable toggles, two-tier probe (openspec drafted). See [`CURRENT.md`](CURRENT.md).
--- a/apps/booterm/package.json
+++ b/apps/booterm/package.json
@@ -23,5 +23,6 @@
    "@types/pg": "^8.11.10",
    "tsx": "^4.16.2",
    "typescript": "^5.5.0"
-  }
+  },
+  "license": "AGPL-3.0-only"
 }
--- a/apps/coder/.env.host
+++ b/apps/coder/.env.host
@@ -0,0 +1,16 @@
+NODE_ENV=production
+PORT=9502
+HOST=100.114.205.53
+DATABASE_URL=postgres://boocode:devpass@127.0.0.1:5500/boochat
+LLAMA_SWAP_URL=http://100.101.41.16:8401
+PROJECT_ROOT_WHITELIST=/opt
+BOOTSTRAP_ROOT=/opt/projects
+DEFAULT_MODEL=qwen3.6-35b-a3b-mxfp4
+LOG_LEVEL=info
+SEARXNG_URL=http://100.114.205.53:8888
+GITEA_BASE_URL=https://git.indifferentketchup.com
+GITEA_USER=indifferentketchup
+GITEA_SSH_HOST=100.114.205.53:2222
+MCP_CONFIG_PATH=/data/mcp.json
+SKILLS_ROOT=/opt/boocode/data/skills
+CODER_PROVIDERS_PATH=/opt/boocode/data/coder-providers.json
--- a/apps/coder/Dockerfile
+++ b/apps/coder/Dockerfile
@@ -0,0 +1,35 @@
+# syntax=docker/dockerfile:1.7
+
+FROM node:20-alpine AS builder
+RUN corepack enable
+WORKDIR /build
+
+COPY package.json pnpm-workspace.yaml pnpm-lock.yaml tsconfig.base.json ./
+COPY apps/server/package.json ./apps/server/
+COPY apps/coder/package.json ./apps/coder/
+COPY apps/coder/web/package.json ./apps/coder/web/
+
+RUN pnpm install --frozen-lockfile
+
+# Build server first (coder depends on it via workspace dep for types + inference)
+COPY apps/server ./apps/server
+RUN pnpm -C apps/server build
+
+COPY apps/coder ./apps/coder
+RUN pnpm -C apps/coder/web build
+RUN pnpm -C apps/coder build
+
+RUN pnpm deploy --filter=@boocode/coder --prod --legacy /out/coder
+
+
+FROM node:20-bookworm-slim AS runtime
+RUN apt-get update && apt-get install -y --no-install-recommends ripgrep git openssh-client && rm -rf /var/lib/apt/lists/*
+WORKDIR /app
+
+COPY --from=builder /out/coder ./
+COPY --from=builder /build/apps/coder/web/dist ./web
+
+ENV NODE_ENV=production
+EXPOSE 3000
+
+CMD ["node", "dist/index.js"]
--- a/apps/coder/package.json
+++ b/apps/coder/package.json
@@ -0,0 +1,34 @@
+{
+  "name": "@boocode/coder",
+  "version": "2.0.0",
+  "private": true,
+  "type": "module",
+  "main": "dist/index.js",
+  "scripts": {
+    "dev": "tsx watch src/index.ts",
+    "build": "tsc && node -e \"import('node:fs').then(fs=>fs.copyFileSync('src/schema.sql','dist/schema.sql'))\"",
+    "start": "node dist/index.js",
+    "cli": "tsx src/cli.ts",
+    "typecheck": "tsc --noEmit",
+    "test": "vitest run"
+  },
+  "dependencies": {
+    "@agentclientprotocol/sdk": "^0.22.1",
+    "@boocode/server": "workspace:*",
+    "@fastify/static": "^7.0.4",
+    "@fastify/websocket": "^10.0.1",
+    "@modelcontextprotocol/sdk": "^1.29.0",
+    "fastify": "^4.28.1",
+    "postgres": "^3.4.4",
+    "ws": "^8.18.0",
+    "zod": "^3.23.8"
+  },
+  "devDependencies": {
+    "@types/node": "^20.14.10",
+    "@types/ws": "^8.5.10",
+    "tsx": "^4.16.2",
+    "typescript": "^5.5.0",
+    "vitest": "^3.0.0"
+  },
+  "license": "AGPL-3.0-only"
+}
--- a/apps/coder/src/cli.ts
+++ b/apps/coder/src/cli.ts
@@ -0,0 +1,249 @@
+#!/usr/bin/env node
+/**
+ * BooCoder CLI client.
+ *
+ * Usage:
+ *   boocode run "task description" [--agent opencode] [--model claude-opus-4-7] [--project <id>]
+ *   boocode ls [--state pending|running|completed|failed]
+ *   boocode attach <task-id>
+ *   boocode send <task-id> "message"
+ */
+import { WebSocket } from 'ws';
+
+const BASE_URL = process.env.BOOCODER_URL ?? 'http://100.114.205.53:9502';
+
+// ─── Arg parsing ─────────────────────────────────────────────────────────────
+
+function getFlag(args: string[], name: string): string | undefined {
+  const idx = args.indexOf(name);
+  if (idx === -1 || idx + 1 >= args.length) return undefined;
+  return args[idx + 1];
+}
+
+function hasFlag(args: string[], name: string): boolean {
+  return args.includes(name);
+}
+
+// ─── HTTP helpers ────────────────────────────────────────────────────────────
+
+async function api(method: string, path: string, body?: unknown): Promise<unknown> {
+  const url = `${BASE_URL}${path}`;
+  const res = await fetch(url, {
+    method,
+    headers: body ? { 'Content-Type': 'application/json' } : undefined,
+    body: body ? JSON.stringify(body) : undefined,
+  });
+  if (!res.ok) {
+    const text = await res.text().catch(() => '');
+    throw new Error(`${method} ${path} → ${res.status}: ${text}`);
+  }
+  return res.json();
+}
+
+// ─── WS streaming ────────────────────────────────────────────────────────────
+
+function streamSession(sessionId: string): void {
+  const wsUrl = BASE_URL.replace(/^http/, 'ws') + `/api/ws/sessions/${sessionId}`;
+  const ws = new WebSocket(wsUrl);
+
+  ws.on('message', (data) => {
+    try {
+      const frame = JSON.parse(data.toString()) as { type: string; content?: string; name?: string; arguments?: string };
+      if (frame.type === 'delta' && frame.content) {
+        process.stdout.write(frame.content);
+      } else if (frame.type === 'tool_call') {
+        process.stdout.write(`\n[tool: ${frame.name ?? '?'}(${(frame.arguments ?? '').slice(0, 80)})]\n`);
+      } else if (frame.type === 'tool_result') {
+        process.stdout.write(`[tool_result]\n`);
+      } else if (frame.type === 'status' || frame.type === 'chat_status') {
+        // Silent
+      }
+    } catch {
+      // Non-JSON frame, ignore
+    }
+  });
+
+  ws.on('error', (err) => {
+    process.stderr.write(`WS error: ${err.message}\n`);
+  });
+
+  ws.on('close', () => {
+    process.stdout.write('\n');
+    process.exit(0);
+  });
+
+  process.on('SIGINT', () => {
+    ws.close();
+    process.exit(0);
+  });
+}
+
+// ─── Commands ────────────────────────────────────────────────────────────────
+
+async function cmdRun(args: string[]): Promise<void> {
+  const input = args.find((a) => !a.startsWith('--'));
+  if (!input) {
+    process.stderr.write('Usage: boocode run "task description" [--agent X] [--model X] [--project X]\n');
+    process.exit(1);
+  }
+
+  const agent = getFlag(args, '--agent');
+  const model = getFlag(args, '--model');
+  const project_id = getFlag(args, '--project');
+
+  if (!project_id) {
+    process.stderr.write('Error: --project <uuid> is required\n');
+    process.exit(1);
+  }
+
+  const result = (await api('POST', '/api/tasks', {
+    project_id,
+    input,
+    ...(agent && { agent }),
+    ...(model && { model }),
+  })) as { id: string; state: string };
+
+  process.stdout.write(`Task created: ${result.id} (state: ${result.state})\n`);
+
+  // Poll until task has session_id, then stream; or poll until terminal state
+  const POLL_MS = 2000;
+  for (;;) {
+    await sleep(POLL_MS);
+    const task = (await api('GET', `/api/tasks/${result.id}`)) as {
+      id: string; state: string; session_id?: string; output_summary?: string;
+    };
+
+    if (task.session_id) {
+      process.stdout.write(`Streaming session ${task.session_id}...\n`);
+      streamSession(task.session_id);
+      return; // streamSession handles exit
+    }
+
+    if (task.state === 'completed') {
+      process.stdout.write(`\nCompleted: ${task.output_summary ?? '(no summary)'}\n`);
+      return;
+    }
+    if (task.state === 'failed') {
+      process.stderr.write(`\nFailed: ${task.output_summary ?? '(no summary)'}\n`);
+      process.exit(1);
+    }
+    if (task.state === 'cancelled') {
+      process.stderr.write(`\nCancelled.\n`);
+      process.exit(1);
+    }
+  }
+}
+
+async function cmdLs(args: string[]): Promise<void> {
+  const state = getFlag(args, '--state');
+  const query = state ? `?state=${state}` : '';
+  const tasks = (await api('GET', `/api/tasks${query}`)) as Array<{
+    id: string; state: string; agent: string | null; input: string; created_at: string;
+  }>;
+
+  if (tasks.length === 0) {
+    process.stdout.write('No tasks.\n');
+    return;
+  }
+
+  // Table header
+  process.stdout.write(
+    pad('ID', 38) + pad('STATE', 12) + pad('AGENT', 14) + pad('INPUT', 52) + 'CREATED\n',
+  );
+  process.stdout.write('-'.repeat(120) + '\n');
+
+  for (const t of tasks) {
+    process.stdout.write(
+      pad(t.id, 38) +
+      pad(t.state, 12) +
+      pad(t.agent ?? '-', 14) +
+      pad(t.input.slice(0, 50), 52) +
+      (t.created_at?.slice(0, 19) ?? '') + '\n',
+    );
+  }
+}
+
+async function cmdAttach(args: string[]): Promise<void> {
+  const taskId = args[0];
+  if (!taskId) {
+    process.stderr.write('Usage: boocode attach <task-id>\n');
+    process.exit(1);
+  }
+
+  const task = (await api('GET', `/api/tasks/${taskId}`)) as { session_id?: string };
+  if (!task.session_id) {
+    process.stderr.write('Task has no session yet (still pending?).\n');
+    process.exit(1);
+  }
+
+  streamSession(task.session_id);
+}
+
+async function cmdSend(args: string[]): Promise<void> {
+  const taskId = args[0];
+  const message = args[1];
+  if (!taskId || !message) {
+    process.stderr.write('Usage: boocode send <task-id> "message"\n');
+    process.exit(1);
+  }
+
+  const task = (await api('GET', `/api/tasks/${taskId}`)) as { session_id?: string };
+  if (!task.session_id) {
+    process.stderr.write('Task has no session yet.\n');
+    process.exit(1);
+  }
+
+  // Find active chat
+  const sessionId = task.session_id;
+  // POST message to the session's chat (the messages route expects session_id in path)
+  await api('POST', `/api/sessions/${sessionId}/messages`, { content: message });
+
+  // Then attach to stream the response
+  streamSession(sessionId);
+}
+
+// ─── Utils ───────────────────────────────────────────────────────────────────
+
+function pad(s: string, width: number): string {
+  return s.length >= width ? s.slice(0, width) : s + ' '.repeat(width - s.length);
+}
+
+function sleep(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+// ─── Main ────────────────────────────────────────────────────────────────────
+
+const [cmd, ...rest] = process.argv.slice(2);
+
+switch (cmd) {
+  case 'run':
+    cmdRun(rest).catch(fatal);
+    break;
+  case 'ls':
+    cmdLs(rest).catch(fatal);
+    break;
+  case 'attach':
+    cmdAttach(rest).catch(fatal);
+    break;
+  case 'send':
+    cmdSend(rest).catch(fatal);
+    break;
+  default:
+    process.stdout.write(
+      'BooCoder CLI\n\n' +
+      'Commands:\n' +
+      '  run "task"  [--agent X] [--model X] [--project <id>]   Create and stream a task\n' +
+      '  ls          [--state pending|running|completed|failed]   List tasks\n' +
+      '  attach      <task-id>                                    Stream a running task\n' +
+      '  send        <task-id> "message"                          Send input to a task\n' +
+      '\n' +
+      `Base URL: ${BASE_URL} (set BOOCODER_URL to override)\n`,
+    );
+    if (cmd && cmd !== '--help' && cmd !== '-h') process.exit(1);
+}
+
+function fatal(err: unknown): void {
+  process.stderr.write(`Error: ${err instanceof Error ? err.message : String(err)}\n`);
+  process.exit(1);
+}
--- a/apps/coder/src/config.ts
+++ b/apps/coder/src/config.ts
@@ -0,0 +1,54 @@
+import { z } from 'zod';
+
+// BooCoder's config is a superset of the server's Config type so it can be
+// passed directly into the inference runner's InferenceContext. Fields the
+// inference loop reads: LLAMA_SWAP_URL, PROJECT_ROOT_WHITELIST. The rest
+// default to values that satisfy the server's Zod schema without BooCoder
+// needing to supply them in its environment.
+const ConfigSchema = z.object({
+  NODE_ENV: z.enum(['development', 'production', 'test']).default('development'),
+  PORT: z.coerce.number().int().positive().default(3000),
+  HOST: z.string().default('0.0.0.0'),
+  DATABASE_URL: z.string().url(),
+  LLAMA_SWAP_URL: z.string().url(),
+  PROJECT_ROOT_WHITELIST: z.string().default('/opt'),
+  BOOTSTRAP_ROOT: z.string().default('/opt/projects'),
+  DEFAULT_MODEL: z.string().default('qwen3.6-35b-a3b-mxfp4'),
+  LOG_LEVEL: z.string().default('info'),
+  CONTAINER_GUIDANCE_FILE: z.string().optional(),
+  // Fields needed to satisfy the server's Config type but unused by BooCoder:
+  SEARXNG_URL: z.string().url().default('http://100.114.205.53:8888'),
+  GITEA_BASE_URL: z.string().url().default('https://git.indifferentketchup.com'),
+  GITEA_USER: z.string().default('indifferentketchup'),
+  GITEA_TOKEN: z.string().optional(),
+  GITEA_SSH_HOST: z.string().default('100.114.205.53:2222'),
+  MCP_CONFIG_PATH: z.string().optional(),
+  // v2.3: config-backed provider overrides/custom-ACP entries merged over the
+  // hardcoded built-ins. Missing file = built-ins only (see provider-config.ts).
+  CODER_PROVIDERS_PATH: z.string().default('/data/coder-providers.json'),
+  // v2.3 phase 2: tier-2 (cold ACP probe) is skipped when available_agents was
+  // probed more recently than this. 24h default — stale model lists self-heal
+  // on the next snapshot; an explicit /refresh always re-probes.
+  PROVIDER_PROBE_TTL_MS: z.coerce.number().int().positive().default(86_400_000),
+  // v2.0.5: cheaper model for titles, summaries, labeling.
+  FAST_MODEL: z.string().optional(),
+  // SSH access to the host for external agent dispatch (Phase 5)
+  BOOCODER_SSH_HOST: z.string().default('100.114.205.53'),
+  BOOCODER_SSH_USER: z.string().default('samkintop'),
+});
+
+export type Config = z.infer<typeof ConfigSchema>;
+
+let cached: Config | null = null;
+
+export function loadConfig(): Config {
+  if (cached) return cached;
+  const parsed = ConfigSchema.safeParse(process.env);
+  if (!parsed.success) {
+    console.error('Invalid environment configuration:');
+    console.error(parsed.error.flatten().fieldErrors);
+    process.exit(1);
+  }
+  cached = parsed.data;
+  return cached;
+}
--- a/apps/coder/src/db.ts
+++ b/apps/coder/src/db.ts
@@ -0,0 +1,45 @@
+import postgres from 'postgres';
+import { readFile } from 'node:fs/promises';
+import { fileURLToPath } from 'node:url';
+import { dirname, resolve } from 'node:path';
+import type { Config } from './config.js';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+
+export type Sql = ReturnType<typeof postgres>;
+
+let sqlInstance: Sql | null = null;
+
+export function getSql(config: Config): Sql {
+  if (sqlInstance) return sqlInstance;
+  sqlInstance = postgres(config.DATABASE_URL, {
+    max: 10,
+    idle_timeout: 30,
+    connect_timeout: 10,
+    onnotice: () => {},
+  });
+  return sqlInstance;
+}
+
+export async function applySchema(sql: Sql): Promise<void> {
+  const schemaPath = resolve(__dirname, 'schema.sql');
+  const ddl = await readFile(schemaPath, 'utf8');
+  await sql.unsafe(ddl);
+}
+
+export async function pingDb(sql: Sql): Promise<boolean> {
+  try {
+    await sql`SELECT 1`;
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+export async function closeDb(): Promise<void> {
+  if (sqlInstance) {
+    await sqlInstance.end({ timeout: 5 });
+    sqlInstance = null;
+  }
+}
--- a/apps/coder/src/index.ts
+++ b/apps/coder/src/index.ts
@@ -0,0 +1,239 @@
+import { resolve, dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { existsSync } from 'node:fs';
+import Fastify from 'fastify';
+import fastifyWebsocket from '@fastify/websocket';
+import fastifyStatic from '@fastify/static';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+import { loadConfig } from './config.js';
+import { getSql, applySchema, pingDb, closeDb } from './db.js';
+import { startMcpServer } from './services/mcp-server.js';
+// v2.0.0 Phase 2B: workspace dependency on @boocode/server — reuse the
+// inference loop, broker, and tool registry without duplication.
+import { createInferenceRunner } from '@boocode/server/inference';
+import { createBroker } from '@boocode/server/broker';
+import { appendMcpTools, ALL_TOOLS } from '@boocode/server/tools';
+import type { Config as ServerConfig } from '@boocode/server/config';
+import type { WsFrame } from '@boocode/server/ws-frames';
+// v2.0.0 Phase 2C: write tools + adapter for BooChat ToolDef compatibility.
+import { WRITE_TOOLS } from './services/tools/index.js';
+import { adaptWriteTool } from './services/tools/adapter.js';
+import { setInferenceContext, clearInferenceContext } from './services/tools/inference_context.js';
+// Routes
+import { registerMessageRoutes } from './routes/messages.js';
+import { registerSkillRoutes } from './routes/skills.js';
+import { registerPendingRoutes } from './routes/pending.js';
+import { registerTaskRoutes } from './routes/tasks.js';
+import { registerInboxRoutes } from './routes/inbox.js';
+import { registerStatsRoutes } from './routes/stats.js';
+import { registerArenaRoutes } from './routes/arena.js';
+import { registerProviderRoutes } from './routes/providers.js';
+import { registerWebSocket } from './routes/ws.js';
+// Phase 4: dispatcher + agent probe
+import { createDispatcher } from './services/dispatcher.js';
+import { agentPool } from './services/agent-pool.js';
+import { probeAgents } from './services/agent-probe.js';
+import { getProviderSnapshot, persistProbedModels } from './services/provider-snapshot.js';
+import { setPermissionHooks } from './services/permission-waiter.js';
+import { homedir } from 'node:os';
+
+async function main() {
+  // MCP mode: stdio transport, no HTTP server
+  if (process.argv.includes('--mcp')) {
+    const config = loadConfig();
+    const sql = getSql(config);
+    await applySchema(sql);
+    await startMcpServer(sql);
+    return;
+  }
+
+  const config = loadConfig();
+
+  const app = Fastify({
+    logger: { level: config.LOG_LEVEL },
+  });
+
+  // Allow empty JSON bodies (same pattern as apps/server).
+  app.removeContentTypeParser(['application/json']);
+  app.addContentTypeParser('application/json', { parseAs: 'string' }, (_req, body, done) => {
+    const str = (body as string) ?? '';
+    if (str.trim().length === 0) {
+      done(null, {});
+      return;
+    }
+    try {
+      done(null, JSON.parse(str));
+    } catch (err) {
+      done(err as Error, undefined);
+    }
+  });
+
+  const sql = getSql(config);
+  await applySchema(sql);
+  app.log.info('database schema applied');
+
+  // Broker: in-memory pub/sub for session + user channel streaming.
+  const broker = createBroker(app.log);
+
+  setPermissionHooks({
+    onPrompt: async (prompt) => {
+      await sql`
+        UPDATE tasks SET state = 'blocked' WHERE id = ${prompt.taskId} AND state = 'running'
+      `;
+      broker.publishFrame(prompt.sessionId, {
+        type: 'permission_requested',
+        task_id: prompt.taskId,
+        session_id: prompt.sessionId,
+        kind: prompt.kind,
+        tool_title: prompt.toolTitle,
+        ...(prompt.input ? { input: prompt.input } : {}),
+        options: prompt.options.map((o) => ({ option_id: o.optionId, label: o.label })),
+      } as WsFrame);
+    },
+    onResolved: async (taskId, sessionId) => {
+      await sql`
+        UPDATE tasks SET state = 'running' WHERE id = ${taskId} AND state = 'blocked'
+      `;
+      broker.publishFrame(sessionId, {
+        type: 'permission_resolved',
+        task_id: taskId,
+        session_id: sessionId,
+      } as WsFrame);
+    },
+  });
+
+  // --- Tool registry extension ---
+  // Append BooCoder write tools (adapted to BooChat's ToolDef interface) to
+  // the shared ALL_TOOLS registry. appendMcpTools re-sorts and rebuilds
+  // TOOLS_BY_NAME so tool-phase.ts dispatch sees the full set.
+  const adaptedWriteTools = WRITE_TOOLS.map((t) => adaptWriteTool(t));
+  appendMcpTools(adaptedWriteTools);
+  app.log.info(`tool registry: ${ALL_TOOLS.length} tools loaded (${WRITE_TOOLS.length} write tools)`);
+
+  // Inference runner: same engine as BooChat, uses ALL_TOOLS (which includes
+  // the appended write tools) for tool dispatch.
+  const inference = createInferenceRunner(
+    {
+      sql,
+      config: config as unknown as ServerConfig,
+      log: app.log,
+      publish: (sessionId, frame) => {
+        broker.publishFrame(sessionId, frame as unknown as WsFrame);
+      },
+      broker,
+    },
+    (user, frame) => {
+      broker.publishUserFrame(user, frame as unknown as WsFrame);
+    }
+  );
+
+  // Wrap the inference runner to set/clear the write-tool context around each run.
+  // The inference runner calls enqueue() which fires asynchronously — we hook
+  // into the enqueue to set context before the run starts.
+  const inferenceApi = {
+    enqueue: (sessionId: string, chatId: string, assistantId: string, user: string) => {
+      // Set the inference context so write tools can access sql + sessionId.
+      // The context persists for the duration of the inference run. Since
+      // BooCoder is single-user and runs one inference at a time per session,
+      // this module-level state is safe.
+      setInferenceContext({ sql, sessionId, taskId: null });
+      inference.enqueue(sessionId, chatId, assistantId, user);
+    },
+    cancel: async (sessionId: string, chatId: string) => {
+      const result = await inference.cancel(sessionId, chatId);
+      clearInferenceContext();
+      return result;
+    },
+    hasActive: (chatId: string) => inference.hasActive(chatId),
+  };
+
+  // Register WebSocket support
+  await app.register(fastifyWebsocket);
+
+  // Health endpoint
+  app.get('/api/health', async (_req, reply) => {
+    const dbOk = await pingDb(sql);
+    const status = dbOk ? 200 : 503;
+    return reply.status(status).send({
+      ok: dbOk,
+      db: dbOk,
+      tools: ALL_TOOLS.length,
+    });
+  });
+
+  // Phase 4: probe available agents on startup
+  await probeAgents(sql, app.log);
+
+  // Warm provider snapshot in background (ACP cold probes + model merges)
+  void getProviderSnapshot(sql, config, homedir(), true)
+    .then((entries) => persistProbedModels(sql, entries, app.log))
+    .catch((err) => {
+      app.log.warn(
+        { err: err instanceof Error ? err.message : String(err) },
+        'provider-snapshot: warm failed',
+      );
+    });
+
+  // Phase 4: dispatcher — polls tasks table and runs inference
+  const dispatcher = createDispatcher({ sql, inference: inferenceApi, broker, log: app.log, config });
+  dispatcher.start();
+  app.addHook('onClose', async () => {
+    // stop() first so in-flight dispatcher turns settle, then drain the pool.
+    // Pool is empty in Phase 0 (nothing spawns yet) — dispose() is inert.
+    await dispatcher.stop();
+    await agentPool.dispose();
+  });
+
+  // Register routes
+  registerMessageRoutes(app, sql, broker, inferenceApi);
+  registerSkillRoutes(app, sql, broker, inferenceApi);
+  registerPendingRoutes(app, sql);
+  registerTaskRoutes(app, sql, inferenceApi);
+  registerInboxRoutes(app, sql);
+  registerStatsRoutes(app, sql);
+  registerArenaRoutes(app, sql);
+  registerProviderRoutes(app, sql, config);
+  registerWebSocket(app, sql, broker);
+
+  // Serve static frontend (built web app). In production, the dist/ is
+  // copied to ../web relative to the dist/ directory at /app/web. In dev,
+  // check adjacent to the source.
+  const webRoot = resolve(__dirname, '../web');
+  if (existsSync(webRoot)) {
+    await app.register(fastifyStatic, {
+      root: webRoot,
+      prefix: '/',
+      // Don't intercept /api routes — static only serves files that exist.
+      wildcard: false,
+    });
+    // SPA fallback: serve index.html for non-API routes that don't match a file.
+    app.setNotFoundHandler(async (req, reply) => {
+      if (req.url.startsWith('/api')) {
+        reply.code(404);
+        return { error: 'not found' };
+      }
+      return reply.sendFile('index.html');
+    });
+    app.log.info(`serving frontend from ${webRoot}`);
+  }
+
+  // Graceful shutdown
+  const shutdown = async () => {
+    app.log.info('shutting down');
+    await app.close();
+    await closeDb();
+    process.exit(0);
+  };
+  process.on('SIGTERM', shutdown);
+  process.on('SIGINT', shutdown);
+
+  await app.listen({ port: config.PORT, host: config.HOST });
+  app.log.info(`BooCoder listening on ${config.HOST}:${config.PORT}`);
+}
+
+main().catch((err) => {
+  console.error('fatal:', err);
+  process.exit(1);
+});
--- a/apps/coder/src/routes/tests/providers.routes.test.ts
+++ b/apps/coder/src/routes/tests/providers.routes.test.ts
@@ -0,0 +1,211 @@
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+import Fastify, { type FastifyInstance } from 'fastify';
+import { existsSync, readFileSync, writeFileSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { registerProviderRoutes } from '../providers.js';
+import { load } from '../../services/provider-config.js';
+import { loadProviderConfig } from '../../services/provider-config-registry.js';
+import { clearProviderSnapshotCache } from '../../services/provider-snapshot.js';
+import type { Config } from '../../config.js';
+import type { Sql } from '../../db.js';
+
+/** Minimal sql stub: available_agents reads return []. */
+function mockSql(): Sql {
+  return vi.fn((strings: TemplateStringsArray) => {
+    const q = strings.join('');
+    if (q.includes('available_agents')) return Promise.resolve([]);
+    return Promise.resolve([]);
+  }) as unknown as Sql;
+}
+
+let tmpCounter = 0;
+function freshPath(): string {
+  tmpCounter += 1;
+  return join(tmpdir(), `coder-providers-routes-${process.pid}-${tmpCounter}.json`);
+}
+
+function buildApp(providersPath: string): FastifyInstance {
+  const app = Fastify();
+  // Mirror index.ts: tolerate empty JSON bodies.
+  app.removeContentTypeParser(['application/json']);
+  app.addContentTypeParser('application/json', { parseAs: 'string' }, (_req, body, done) => {
+    const str = (body as string) ?? '';
+    if (str.trim().length === 0) return done(null, {});
+    try {
+      done(null, JSON.parse(str));
+    } catch (err) {
+      done(err as Error, undefined);
+    }
+  });
+  const config = {
+    CODER_PROVIDERS_PATH: providersPath,
+    LLAMA_SWAP_URL: 'http://llama-swap.test',
+    PROVIDER_PROBE_TTL_MS: 86_400_000,
+  } as unknown as Config;
+  registerProviderRoutes(app, mockSql(), config);
+  return app;
+}
+
+const JSON_HEADERS = { 'content-type': 'application/json' };
+const createdPaths: string[] = [];
+
+beforeEach(() => {
+  clearProviderSnapshotCache();
+  loadProviderConfig('/nonexistent-coder-providers.json'); // reset registry to built-ins
+  vi.restoreAllMocks();
+  vi.stubGlobal('fetch', vi.fn().mockRejectedValue(new Error('no network in test')));
+});
+
+afterEach(() => {
+  for (const p of createdPaths.splice(0)) {
+    try {
+      rmSync(p, { force: true });
+    } catch {
+      /* ignore */
+    }
+  }
+});
+
+describe('GET /api/providers/config', () => {
+  it('returns the current config file (built-ins-only when missing)', async () => {
+    const path = freshPath();
+    createdPaths.push(path);
+    const app = buildApp(path);
+    const res = await app.inject({ method: 'GET', url: '/api/providers/config' });
+    expect(res.statusCode).toBe(200);
+    expect(res.json()).toEqual({ providers: {} });
+    await app.close();
+  });
+
+  it('reflects an existing file', async () => {
+    const path = freshPath();
+    createdPaths.push(path);
+    writeFileSync(path, JSON.stringify({ providers: { goose: { enabled: false } } }));
+    const app = buildApp(path);
+    const res = await app.inject({ method: 'GET', url: '/api/providers/config' });
+    expect(res.json()).toEqual({ providers: { goose: { enabled: false } } });
+    await app.close();
+  });
+});
+
+describe('PATCH /api/providers/config', () => {
+  it('valid patch → 200, writes the merged file (order: validate→save→reload→clear)', async () => {
+    const path = freshPath();
+    createdPaths.push(path);
+    writeFileSync(path, JSON.stringify({ providers: { goose: { label: 'Goose' } } }));
+    const app = buildApp(path);
+
+    const res = await app.inject({
+      method: 'PATCH',
+      url: '/api/providers/config',
+      headers: JSON_HEADERS,
+      payload: JSON.stringify({ providers: { opencode: { enabled: false } } }),
+    });
+
+    expect(res.statusCode).toBe(200);
+    expect(res.json()).toMatchObject({ ok: true });
+    // File written + merged (goose untouched, opencode added).
+    const onDisk = load(path);
+    expect(onDisk.providers).toEqual({
+      goose: { label: 'Goose' },
+      opencode: { enabled: false },
+    });
+    await app.close();
+  });
+
+  it('null value deletes the override', async () => {
+    const path = freshPath();
+    createdPaths.push(path);
+    writeFileSync(path, JSON.stringify({ providers: { goose: { enabled: false }, opencode: { enabled: false } } }));
+    const app = buildApp(path);
+
+    const res = await app.inject({
+      method: 'PATCH',
+      url: '/api/providers/config',
+      headers: JSON_HEADERS,
+      payload: JSON.stringify({ providers: { goose: null } }),
+    });
+
+    expect(res.statusCode).toBe(200);
+    expect(load(path).providers).toEqual({ opencode: { enabled: false } });
+    await app.close();
+  });
+
+  it('INVALID body → 422 and the file is NOT written (validate before save)', async () => {
+    const path = freshPath();
+    createdPaths.push(path);
+    const before = JSON.stringify({ providers: { goose: { enabled: true } } });
+    writeFileSync(path, before);
+    const app = buildApp(path);
+
+    const res = await app.inject({
+      method: 'PATCH',
+      url: '/api/providers/config',
+      headers: JSON_HEADERS,
+      payload: JSON.stringify({ providers: { goose: { enabled: 'yes' } } }), // bad type
+    });
+
+    expect(res.statusCode).toBe(422);
+    // File must be byte-for-byte unchanged — nothing written on a 422.
+    expect(readFileSync(path, 'utf8')).toBe(before);
+    await app.close();
+  });
+
+  it('save failure → 500 and the file is NOT created (no state divergence)', async () => {
+    const path = join(tmpdir(), `no-such-dir-${process.pid}-${Date.now()}`, 'coder-providers.json');
+    const app = buildApp(path);
+
+    const res = await app.inject({
+      method: 'PATCH',
+      url: '/api/providers/config',
+      headers: JSON_HEADERS,
+      payload: JSON.stringify({ providers: { goose: { enabled: false } } }),
+    });
+
+    expect(res.statusCode).toBe(500);
+    expect(existsSync(path)).toBe(false);
+    await app.close();
+  });
+});
+
+describe('POST /api/providers/refresh', () => {
+  it('no body → refreshes all registered providers', async () => {
+    const app = buildApp(freshPath());
+    const res = await app.inject({ method: 'POST', url: '/api/providers/refresh' });
+    expect(res.statusCode).toBe(200);
+    expect(res.json().refreshed).toBeGreaterThan(0);
+    await app.close();
+  });
+
+  it('subset body → refreshed count reflects only the requested providers', async () => {
+    const app = buildApp(freshPath());
+    const res = await app.inject({
+      method: 'POST',
+      url: '/api/providers/refresh',
+      headers: JSON_HEADERS,
+      payload: JSON.stringify({ providers: ['boocode'] }),
+    });
+    expect(res.statusCode).toBe(200);
+    expect(res.json()).toEqual({ refreshed: 1 });
+    await app.close();
+  });
+});
+
+describe('GET /api/providers/:id/diagnostic', () => {
+  it('known provider → 200 JSON { diagnostic }', async () => {
+    const app = buildApp(freshPath());
+    const res = await app.inject({ method: 'GET', url: '/api/providers/boocode/diagnostic' });
+    expect(res.statusCode).toBe(200);
+    expect(res.headers['content-type']).toContain('application/json');
+    expect(res.json().diagnostic).toContain('provider: boocode');
+    await app.close();
+  });
+
+  it('unknown provider → 404', async () => {
+    const app = buildApp(freshPath());
+    const res = await app.inject({ method: 'GET', url: '/api/providers/nope/diagnostic' });
+    expect(res.statusCode).toBe(404);
+    await app.close();
+  });
+});
--- a/apps/coder/src/routes/arena.ts
+++ b/apps/coder/src/routes/arena.ts
@@ -0,0 +1,136 @@
+/**
+ * v2.0.5: Arena routes — competitive dispatch of the same task to multiple agents.
+ *
+ * POST /api/arena        — create an arena with 2-5 contestants
+ * GET  /api/arena/:id    — get all tasks in an arena
+ * POST /api/arena/:id/select/:task_id — mark a task as the arena winner
+ */
+import type { FastifyInstance } from 'fastify';
+import { z } from 'zod';
+import type { Sql } from '../db.js';
+
+const ContestantSchema = z.object({
+  agent: z.string().max(100).optional(),
+  model: z.string().max(200).optional(),
+  mode_id: z.string().max(200).optional(),
+  thinking_option_id: z.string().max(200).optional(),
+});
+
+const CreateArenaBody = z.object({
+  project_id: z.string().uuid(),
+  input: z.string().min(1).max(64_000),
+  contestants: z.array(ContestantSchema).min(2).max(5),
+});
+
+interface TaskRow {
+  id: string;
+  agent: string | null;
+  model: string | null;
+  mode_id: string | null;
+  thinking_option_id: string | null;
+  state: string;
+}
+
+export function registerArenaRoutes(app: FastifyInstance, sql: Sql): void {
+  // POST /api/arena — create a new arena
+  app.post('/api/arena', async (req, reply) => {
+    const parsed = CreateArenaBody.safeParse(req.body);
+    if (!parsed.success) {
+      reply.code(400);
+      return { error: 'invalid body', details: parsed.error.flatten() };
+    }
+
+    const { project_id, input, contestants } = parsed.data;
+    const arenaId = crypto.randomUUID();
+
+    const tasks: TaskRow[] = [];
+    for (const contestant of contestants) {
+      const [task] = await sql<TaskRow[]>`
+        INSERT INTO tasks (project_id, input, agent, model, mode_id, thinking_option_id, arena_id)
+        VALUES (
+          ${project_id},
+          ${input},
+          ${contestant.agent ?? null},
+          ${contestant.model ?? null},
+          ${contestant.mode_id ?? null},
+          ${contestant.thinking_option_id ?? null},
+          ${arenaId}
+        )
+        RETURNING id, agent, model, mode_id, thinking_option_id, state
+      `;
+      tasks.push(task!);
+    }
+
+    reply.code(201);
+    return {
+      arena_id: arenaId,
+      tasks: tasks.map((t) => ({
+        id: t.id,
+        agent: t.agent,
+        model: t.model,
+        mode_id: t.mode_id,
+        thinking_option_id: t.thinking_option_id,
+        state: t.state,
+      })),
+    };
+  });
+
+  // GET /api/arena/:arena_id — list all tasks in an arena
+  app.get<{ Params: { arena_id: string } }>('/api/arena/:arena_id', async (req, reply) => {
+    const { arena_id } = req.params;
+
+    // Validate UUID format
+    const uuidRegex = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
+    if (!uuidRegex.test(arena_id)) {
+      reply.code(400);
+      return { error: 'invalid arena_id format' };
+    }
+
+    const tasks = await sql`
+      SELECT id, project_id, state, input, output_summary, agent, model, mode_id, thinking_option_id, execution_path, session_id, started_at, ended_at, created_at, arena_id
+      FROM tasks
+      WHERE arena_id = ${arena_id}
+      ORDER BY created_at
+    `;
+
+    if (tasks.length === 0) {
+      reply.code(404);
+      return { error: 'arena not found' };
+    }
+
+    return { arena_id, tasks };
+  });
+
+  // POST /api/arena/:arena_id/select/:task_id — mark the winner
+  app.post<{ Params: { arena_id: string; task_id: string } }>(
+    '/api/arena/:arena_id/select/:task_id',
+    async (req, reply) => {
+      const { arena_id, task_id } = req.params;
+
+      // Verify the task belongs to this arena
+      const rows = await sql<{ id: string; state: string; arena_id: string | null }[]>`
+        SELECT id, state, arena_id FROM tasks WHERE id = ${task_id}
+      `;
+
+      if (rows.length === 0) {
+        reply.code(404);
+        return { error: 'task not found' };
+      }
+
+      const task = rows[0]!;
+      if (task.arena_id !== arena_id) {
+        reply.code(409);
+        return { error: 'task does not belong to this arena' };
+      }
+
+      // Mark as selected via output_summary prefix (lightweight — no schema change)
+      await sql`
+        UPDATE tasks
+        SET output_summary = COALESCE('[SELECTED] ' || output_summary, '[SELECTED]')
+        WHERE id = ${task_id}
+      `;
+
+      return { selected: true, task_id, arena_id };
+    }
+  );
+}
--- a/apps/coder/src/routes/chat-resolve.ts
+++ b/apps/coder/src/routes/chat-resolve.ts
@@ -0,0 +1,81 @@
+import type { Sql } from '../db.js';
+
+interface WorkspacePaneRow {
+  id: string;
+  kind: string;
+  chatId?: string;
+  chatIds?: string[];
+  activeChatIdx?: number;
+}
+
+function chatNameForKind(kind: string): string {
+  if (kind === 'coder' || kind === 'agent') return 'BooCoder';
+  if (kind === 'terminal') return 'Terminal';
+  return 'Chat';
+}
+
+function activeChatIdForPane(pane: WorkspacePaneRow): string | undefined {
+  const chatIds = pane.chatIds ?? [];
+  const idx = pane.activeChatIdx ?? 0;
+  if (idx >= 0 && idx < chatIds.length) return chatIds[idx];
+  return pane.chatId;
+}
+
+/** Resolve the active chat for a workspace pane; auto-seed when empty. */
+export async function resolveChatId(
+  sql: Sql,
+  sessionId: string,
+  paneId: string,
+): Promise<string | null> {
+  return sql.begin(async (tx) => {
+    const sessionRows = await tx<{ workspace_panes: WorkspacePaneRow[] }[]>`
+      SELECT workspace_panes FROM sessions WHERE id = ${sessionId} FOR UPDATE
+    `;
+    if (sessionRows.length === 0) return null;
+
+    const panes = sessionRows[0]!.workspace_panes ?? [];
+    const paneIdx = panes.findIndex((p) => p.id === paneId);
+    if (paneIdx < 0) return null;
+
+    const pane = panes[paneIdx]!;
+    const existingChatId = activeChatIdForPane(pane);
+    if (existingChatId) {
+      const chatRows = await tx<{ id: string }[]>`
+        SELECT id FROM chats
+        WHERE id = ${existingChatId}
+          AND session_id = ${sessionId}
+          AND status = 'open'
+      `;
+      if (chatRows.length > 0) return existingChatId;
+    }
+
+    const [newChat] = await tx<{ id: string }[]>`
+      INSERT INTO chats (session_id, name, status)
+      VALUES (${sessionId}, ${chatNameForKind(pane.kind)}, 'open')
+      RETURNING id
+    `;
+    if (!newChat) return null;
+
+    const nextChatIds = [...(pane.chatIds ?? []), newChat.id];
+    const nextActiveIdx = nextChatIds.length - 1;
+    const nextPanes = panes.map((p, i) =>
+      i === paneIdx
+        ? {
+            ...p,
+            chatIds: nextChatIds,
+            activeChatIdx: nextActiveIdx,
+            chatId: newChat.id,
+          }
+        : p,
+    );
+
+    await tx`
+      UPDATE sessions
+      SET workspace_panes = ${tx.json(nextPanes as never)},
+          updated_at = clock_timestamp()
+      WHERE id = ${sessionId}
+    `;
+
+    return newChat.id;
+  });
+}
--- a/apps/coder/src/routes/inbox.ts
+++ b/apps/coder/src/routes/inbox.ts
@@ -0,0 +1,33 @@
+import type { FastifyInstance } from 'fastify';
+import type { Sql } from '../db.js';
+
+export function registerInboxRoutes(app: FastifyInstance, sql: Sql): void {
+  // GET /api/inbox — tasks needing human attention (blocked or failed)
+  app.get('/api/inbox', async () => {
+    return sql`
+      SELECT id, project_id, parent_task_id, state, input, output_summary, agent, model, session_id, started_at, ended_at, created_at
+      FROM human_inbox
+      ORDER BY created_at DESC
+      LIMIT 100
+    `;
+  });
+
+  // POST /api/inbox/:id/retry — reset a blocked/failed task to pending for re-dispatch
+  app.post<{ Params: { id: string } }>('/api/inbox/:id/retry', async (req, reply) => {
+    const taskId = req.params.id;
+
+    const result = await sql`
+      UPDATE tasks
+      SET state = 'pending', started_at = NULL, ended_at = NULL, output_summary = NULL
+      WHERE id = ${taskId} AND state IN ('blocked', 'failed')
+      RETURNING id, state
+    `;
+
+    if (result.length === 0) {
+      reply.code(404);
+      return { error: 'task not found or not in retryable state' };
+    }
+
+    return { id: result[0]!.id, state: result[0]!.state };
+  });
+}
--- a/apps/coder/src/routes/messages.ts
+++ b/apps/coder/src/routes/messages.ts
@@ -0,0 +1,402 @@
+import type { FastifyInstance } from 'fastify';
+import { z } from 'zod';
+import type { Sql } from '../db.js';
+import type { Broker } from '@boocode/server/broker';
+import type { WsFrame } from '@boocode/server/ws-frames';
+import { resolveChatId } from './chat-resolve.js';
+
+const AnswerUserInputBody = z.object({
+  tool_call_id: z.string().min(1),
+  answers: z
+    .array(
+      z.object({
+        question: z.string(),
+        selected_options: z.array(z.string()),
+        free_text: z.string().nullable(),
+      }),
+    )
+    .min(1)
+    .max(3),
+});
+
+const AskUserInputArgs = z.object({
+  questions: z
+    .array(
+      z.object({
+        question: z.string(),
+        type: z.enum(['single_select', 'multi_select']),
+        options: z.array(z.string()).min(1),
+      }),
+    )
+    .min(1)
+    .max(3),
+});
+
+const SendBody = z.object({
+  content: z.string().min(1).max(64_000),
+  pane_id: z.string().min(1).max(200),
+  chat_id: z.string().uuid().optional(),
+  provider: z.string().max(100).optional(),
+  model: z.string().max(200).optional(),
+  mode_id: z.string().max(200).optional(),
+  thinking_option_id: z.string().max(200).optional(),
+});
+
+interface InferenceApi {
+  enqueue: (sessionId: string, chatId: string, assistantId: string, user: string) => void;
+  cancel: (sessionId: string, chatId: string) => Promise<boolean>;
+  hasActive: (chatId: string) => boolean;
+}
+
+interface MessageRow {
+  id: string;
+  role: string;
+  content: string | null;
+  status: string | null;
+  tool_calls: Array<{ id: string; name: string; args?: Record<string, unknown> }> | null;
+  tool_results: {
+    tool_call_id: string;
+    output: unknown;
+    truncated?: boolean;
+    error?: string;
+  } | null;
+  reasoning_parts: Array<{ text?: string }> | null;
+}
+
+function mapCoderMessageRow(row: MessageRow) {
+  if (row.role === 'tool') {
+    if (!row.tool_results?.tool_call_id) return null;
+    return {
+      id: row.id,
+      role: 'tool' as const,
+      tool_results: row.tool_results,
+    };
+  }
+  if (row.role !== 'user' && row.role !== 'assistant' && row.role !== 'system') {
+    return null;
+  }
+  const tool_calls = row.tool_calls?.map((tc) => ({
+    id: tc.id,
+    function: {
+      name: tc.name,
+      arguments: JSON.stringify(tc.args ?? {}),
+    },
+  }));
+  const reasoningText = row.reasoning_parts?.map((p) => p.text ?? '').join('') ?? '';
+  return {
+    id: row.id,
+    role: row.role as 'user' | 'assistant' | 'system',
+    content: row.content ?? '',
+    status: (row.status ?? 'complete') as 'streaming' | 'complete' | 'failed',
+    ...(reasoningText ? { reasoning_text: reasoningText } : {}),
+    ...(tool_calls?.length ? { tool_calls } : {}),
+  };
+}
+
+export function registerMessageRoutes(
+  app: FastifyInstance,
+  sql: Sql,
+  broker: Broker,
+  inference: InferenceApi,
+): void {
+  // GET /api/sessions/:sessionId/messages — hydrate CoderPane on load / reconnect
+  app.get<{ Params: { sessionId: string }; Querystring: { chat_id?: string } }>(
+    '/api/sessions/:sessionId/messages',
+    async (req, reply) => {
+      const sessionId = req.params.sessionId;
+      const chatId = req.query.chat_id;
+      const sessionRows = await sql<{ id: string }[]>`
+        SELECT id FROM sessions WHERE id = ${sessionId}
+      `;
+      if (sessionRows.length === 0) {
+        reply.code(404);
+        return { error: 'session not found' };
+      }
+
+      if (chatId) {
+        const chatRows = await sql<{ id: string }[]>`
+          SELECT id FROM chats
+          WHERE id = ${chatId} AND session_id = ${sessionId} AND status = 'open'
+        `;
+        if (chatRows.length === 0) {
+          reply.code(404);
+          return { error: 'chat not found or not open in this session' };
+        }
+      }
+
+      const rows = chatId
+        ? await sql<MessageRow[]>`
+            SELECT id, role, content, status, tool_calls, tool_results, reasoning_parts
+            FROM messages_with_parts
+            WHERE session_id = ${sessionId} AND chat_id = ${chatId}
+            ORDER BY created_at ASC, id ASC
+          `
+        : await sql<MessageRow[]>`
+            SELECT id, role, content, status, tool_calls, tool_results, reasoning_parts
+            FROM messages_with_parts
+            WHERE session_id = ${sessionId}
+            ORDER BY created_at ASC, id ASC
+          `;
+
+      return rows.map(mapCoderMessageRow).filter((m) => m !== null);
+    },
+  );
+
+  // POST /api/sessions/:sessionId/messages — send a user message + kick off inference
+  app.post<{ Params: { sessionId: string } }>(
+    '/api/sessions/:sessionId/messages',
+    async (req, reply) => {
+      const parsed = SendBody.safeParse(req.body);
+      if (!parsed.success) {
+        reply.code(400);
+        return { error: 'invalid body', details: parsed.error.flatten() };
+      }
+
+      const sessionId = req.params.sessionId;
+      const { content, pane_id, chat_id: explicitChatId, provider, model, mode_id, thinking_option_id } =
+        parsed.data;
+      const isExternal = provider && provider !== 'boocode';
+
+      // Validate session exists
+      const sessionRows = await sql<{ id: string; project_id: string }[]>`
+        SELECT id, project_id FROM sessions WHERE id = ${sessionId}
+      `;
+      if (sessionRows.length === 0) {
+        reply.code(404);
+        return { error: 'session not found' };
+      }
+
+      const resolved = await resolveChatId(sql, sessionId, pane_id);
+      if (!resolved) {
+        reply.code(404);
+        return { error: 'pane not found' };
+      }
+
+      let chatId = resolved;
+      if (explicitChatId) {
+        const chatRows = await sql<{ id: string }[]>`
+          SELECT id FROM chats WHERE id = ${explicitChatId} AND session_id = ${sessionId} AND status = 'open'
+        `;
+        if (chatRows.length === 0) {
+          reply.code(404);
+          return { error: 'chat not found or not open in this session' };
+        }
+        chatId = explicitChatId;
+      }
+
+      if (!isExternal) {
+        // Reject if inference is already running on this chat
+        if (inference.hasActive(chatId)) {
+          reply.code(409);
+          return { error: 'inference already running on this chat' };
+        }
+      }
+
+      // Create user message
+      const [userMsg] = await sql<{ id: string }[]>`
+        INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+        VALUES (${sessionId}, ${chatId}, 'user', ${content}, 'complete', clock_timestamp())
+        RETURNING id
+      `;
+      await sql`UPDATE sessions SET updated_at = clock_timestamp() WHERE id = ${sessionId}`;
+      await sql`UPDATE chats SET updated_at = clock_timestamp() WHERE id = ${chatId}`;
+
+      // Publish user message frames
+      broker.publishFrame(sessionId, {
+        type: 'message_started',
+        message_id: userMsg!.id,
+        chat_id: chatId,
+        role: 'user',
+      } as unknown as WsFrame);
+      broker.publishFrame(sessionId, {
+        type: 'delta',
+        message_id: userMsg!.id,
+        chat_id: chatId,
+        content,
+      } as unknown as WsFrame);
+      broker.publishFrame(sessionId, {
+        type: 'message_complete',
+        message_id: userMsg!.id,
+        chat_id: chatId,
+      } as unknown as WsFrame);
+
+      if (isExternal) {
+        // External provider: create a task for the dispatcher
+        const projectId = sessionRows[0]!.project_id;
+        const [task] = await sql<{ id: string; state: string }[]>`
+          INSERT INTO tasks (project_id, input, agent, model, mode_id, thinking_option_id, session_id)
+          VALUES (${projectId}, ${content}, ${provider}, ${model ?? null}, ${mode_id ?? null}, ${thinking_option_id ?? null}, ${sessionId})
+          RETURNING id, state
+        `;
+        reply.code(202);
+        return { user_message_id: userMsg!.id, task_id: task!.id, dispatched: true };
+      }
+
+      // Native provider: create streaming assistant row + enqueue inference
+      const [assistantMsg] = await sql<{ id: string }[]>`
+        INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+        VALUES (${sessionId}, ${chatId}, 'assistant', '', 'streaming', clock_timestamp())
+        RETURNING id
+      `;
+
+      inference.enqueue(sessionId, chatId, assistantMsg!.id, 'default');
+
+      reply.code(202);
+      return { user_message_id: userMsg!.id, assistant_message_id: assistantMsg!.id };
+    },
+  );
+
+  // POST /api/chats/:id/answer_user_input — answer a pending ask_user_input
+  app.post<{ Params: { id: string } }>(
+    '/api/chats/:id/answer_user_input',
+    async (req, reply) => {
+      const parsed = AnswerUserInputBody.safeParse(req.body);
+      if (!parsed.success) {
+        reply.code(400);
+        return { error: 'invalid_body', details: parsed.error.flatten() };
+      }
+      const { tool_call_id, answers } = parsed.data;
+
+      const chatRows = await sql<{ id: string; session_id: string }[]>`
+        SELECT id, session_id FROM chats WHERE id = ${req.params.id} AND status = 'open'
+      `;
+      if (chatRows.length === 0) {
+        reply.code(404);
+        return { error: 'chat_not_found' };
+      }
+      const chat = chatRows[0]!;
+      const sessionId = chat.session_id;
+
+      const callerRows = await sql<{
+        message_id: string;
+        payload: { id: string; name: string; args: Record<string, unknown> };
+      }[]>`
+        SELECT p.message_id, p.payload
+        FROM message_parts p
+        JOIN messages m ON m.id = p.message_id
+        WHERE m.chat_id = ${chat.id}
+          AND m.role = 'assistant'
+          AND p.kind = 'tool_call'
+          AND p.payload->>'id' = ${tool_call_id}
+        ORDER BY m.created_at DESC
+        LIMIT 1
+      `;
+      if (!callerRows[0]) {
+        reply.code(404);
+        return { error: 'unknown_tool_call_id' };
+      }
+      const foundCall = callerRows[0].payload;
+      if (foundCall.name !== 'ask_user_input') {
+        reply.code(400);
+        return { error: 'tool_call_not_ask_user_input' };
+      }
+
+      const argsParsed = AskUserInputArgs.safeParse(foundCall.args);
+      if (!argsParsed.success) {
+        reply.code(400);
+        return { error: 'mismatched_answer_shape', detail: 'tool_call args invalid' };
+      }
+      const questions = argsParsed.data.questions;
+      if (answers.length !== questions.length) {
+        reply.code(400);
+        return { error: 'mismatched_answer_shape', detail: `expected ${questions.length} answer(s), got ${answers.length}` };
+      }
+      for (let i = 0; i < questions.length; i++) {
+        const q = questions[i]!;
+        const a = answers[i]!;
+        for (const sel of a.selected_options) {
+          if (!q.options.includes(sel)) {
+            reply.code(400);
+            return { error: 'mismatched_answer_shape', detail: `answer ${i + 1} option not in question: ${sel}` };
+          }
+        }
+        if (q.type === 'single_select' && a.selected_options.length > 1) {
+          reply.code(400);
+          return { error: 'mismatched_answer_shape', detail: `answer ${i + 1} multi on single_select` };
+        }
+        if (a.selected_options.length === 0 && (!a.free_text || !a.free_text.trim())) {
+          reply.code(400);
+          return { error: 'mismatched_answer_shape', detail: `answer ${i + 1} is empty` };
+        }
+      }
+
+      const toolRows = await sql<{
+        message_id: string;
+        payload: { tool_call_id: string; output: unknown };
+      }[]>`
+        SELECT p.message_id, p.payload
+        FROM message_parts p
+        JOIN messages m ON m.id = p.message_id
+        WHERE m.chat_id = ${chat.id}
+          AND m.role = 'tool'
+          AND p.kind = 'tool_result'
+          AND p.payload->>'tool_call_id' = ${tool_call_id}
+        ORDER BY m.created_at DESC
+        LIMIT 1
+      `;
+      if (!toolRows[0]) {
+        reply.code(404);
+        return { error: 'unknown_tool_call_id', detail: 'tool message not found' };
+      }
+      if (toolRows[0].payload?.output !== null) {
+        reply.code(409);
+        return { error: 'tool_call_already_answered' };
+      }
+
+      const answerSet = { answers };
+      const newToolResults = { tool_call_id, output: answerSet, truncated: false };
+      const toolMessageId = toolRows[0].message_id;
+
+      const result = await sql.begin(async (tx) => {
+        await tx`DELETE FROM message_parts WHERE message_id = ${toolMessageId} AND kind = 'tool_result'`;
+        await tx`
+          INSERT INTO message_parts (message_id, sequence, kind, payload)
+          VALUES (${toolMessageId}, 0, 'tool_result', ${tx.json(newToolResults as never)})
+        `;
+        const [assistantMsg] = await tx<{ id: string }[]>`
+          INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+          VALUES (${sessionId}, ${chat.id}, 'assistant', '', 'streaming', clock_timestamp())
+          RETURNING id
+        `;
+        await tx`UPDATE sessions SET updated_at = clock_timestamp() WHERE id = ${sessionId}`;
+        await tx`UPDATE chats SET updated_at = clock_timestamp() WHERE id = ${chat.id}`;
+        return { tool_message_id: toolMessageId, assistant_message_id: assistantMsg!.id };
+      });
+
+      broker.publishFrame(sessionId, {
+        type: 'tool_result',
+        tool_message_id: result.tool_message_id,
+        tool_call_id,
+        chat_id: chat.id,
+        output: answerSet,
+        truncated: false,
+      } as unknown as WsFrame);
+      inference.enqueue(sessionId, chat.id, result.assistant_message_id, 'default');
+
+      reply.code(202);
+      return result;
+    },
+  );
+
+  // POST /api/sessions/:sessionId/stop — cancel active inference
+  app.post<{ Params: { sessionId: string } }>(
+    '/api/sessions/:sessionId/stop',
+    async (req, reply) => {
+      const sessionId = req.params.sessionId;
+
+      // Find active chats in this session
+      const chats = await sql<{ id: string }[]>`
+        SELECT id FROM chats WHERE session_id = ${sessionId} AND status = 'open'
+      `;
+      let cancelled = false;
+      for (const chat of chats) {
+        if (inference.hasActive(chat.id)) {
+          cancelled = await inference.cancel(sessionId, chat.id);
+          break;
+        }
+      }
+
+      return { cancelled };
+    },
+  );
+}
--- a/apps/coder/src/routes/pending.ts
+++ b/apps/coder/src/routes/pending.ts
@@ -0,0 +1,172 @@
+import type { FastifyInstance } from 'fastify';
+import { z } from 'zod';
+import type { Sql } from '../db.js';
+import {
+  listPending,
+  applyOne,
+  applyAll,
+  rejectOne,
+  rewindOne,
+  queueCreate,
+} from '../services/pending_changes.js';
+import { WriteGuardError } from '../services/write_guard.js';
+
+const CreateBody = z.object({
+  file_path: z.string().min(1),
+  content: z.string(),
+});
+
+/**
+ * Resolve project root from a session's project path.
+ */
+async function resolveProjectRoot(sql: Sql, sessionId: string): Promise<string | null> {
+  const rows = await sql<{ path: string }[]>`
+    SELECT p.path FROM sessions s
+    JOIN projects p ON s.project_id = p.id
+    WHERE s.id = ${sessionId}
+  `;
+  return rows.length > 0 ? rows[0]!.path : null;
+}
+
+/**
+ * Resolve project root from a pending change's session.
+ */
+async function resolveProjectRootForChange(sql: Sql, changeId: string): Promise<string | null> {
+  const rows = await sql<{ path: string }[]>`
+    SELECT p.path FROM pending_changes pc
+    JOIN sessions s ON pc.session_id = s.id
+    JOIN projects p ON s.project_id = p.id
+    WHERE pc.id = ${changeId}
+  `;
+  return rows.length > 0 ? rows[0]!.path : null;
+}
+
+export function registerPendingRoutes(app: FastifyInstance, sql: Sql): void {
+  // GET /api/sessions/:sessionId/pending — list pending changes for a session
+  app.get<{ Params: { sessionId: string } }>(
+    '/api/sessions/:sessionId/pending',
+    async (req, reply) => {
+      const sessionId = req.params.sessionId;
+
+      const session = await sql<{ id: string }[]>`SELECT id FROM sessions WHERE id = ${sessionId}`;
+      if (session.length === 0) {
+        reply.code(404);
+        return { error: 'session not found' };
+      }
+
+      const pending = await listPending(sql, sessionId);
+      return pending;
+    },
+  );
+
+  // POST /api/sessions/:sessionId/pending/create — queue a new-file create
+  // (manual create from the RightRail file browser; no inference involved).
+  // queueCreate runs resolveWritePath internally, so a path that escapes the
+  // project root or hits a secret file throws WriteGuardError → 422 with the
+  // guard message. Mirrors the { error } 404 shape used by the other routes
+  // and the 422 status used by apply/rewind on failure.
+  app.post<{ Params: { sessionId: string } }>(
+    '/api/sessions/:sessionId/pending/create',
+    async (req, reply) => {
+      const sessionId = req.params.sessionId;
+
+      const parsed = CreateBody.safeParse(req.body);
+      if (!parsed.success) {
+        reply.code(400);
+        return { error: 'invalid body', details: parsed.error.flatten() };
+      }
+
+      const projectRoot = await resolveProjectRoot(sql, sessionId);
+      if (!projectRoot) {
+        reply.code(404);
+        return { error: 'session or project not found' };
+      }
+
+      try {
+        const change = await queueCreate(
+          sql,
+          sessionId,
+          null,
+          parsed.data.file_path,
+          parsed.data.content,
+          projectRoot,
+        );
+        return change;
+      } catch (err) {
+        if (err instanceof WriteGuardError) {
+          reply.code(422);
+          return { error: err.message };
+        }
+        throw err;
+      }
+    },
+  );
+
+  // POST /api/sessions/:sessionId/pending/apply — apply all pending changes
+  app.post<{ Params: { sessionId: string } }>(
+    '/api/sessions/:sessionId/pending/apply',
+    async (req, reply) => {
+      const sessionId = req.params.sessionId;
+
+      const projectRoot = await resolveProjectRoot(sql, sessionId);
+      if (!projectRoot) {
+        reply.code(404);
+        return { error: 'session or project not found' };
+      }
+
+      const results = await applyAll(sql, sessionId, projectRoot);
+      return { results };
+    },
+  );
+
+  // POST /api/pending/:id/apply — apply a single pending change
+  app.post<{ Params: { id: string } }>(
+    '/api/pending/:id/apply',
+    async (req, reply) => {
+      const changeId = req.params.id;
+
+      const projectRoot = await resolveProjectRootForChange(sql, changeId);
+      if (!projectRoot) {
+        reply.code(404);
+        return { error: 'pending change or project not found' };
+      }
+
+      const result = await applyOne(sql, changeId, projectRoot);
+      if (!result.success) {
+        reply.code(422);
+      }
+      return result;
+    },
+  );
+
+  // POST /api/pending/:id/reject — reject a single pending change
+  app.post<{ Params: { id: string } }>(
+    '/api/pending/:id/reject',
+    async (req, reply) => {
+      const changeId = req.params.id;
+
+      await rejectOne(sql, changeId);
+      return { ok: true };
+    },
+  );
+
+  // POST /api/pending/:id/rewind — rewind (undo) an applied change
+  app.post<{ Params: { id: string } }>(
+    '/api/pending/:id/rewind',
+    async (req, reply) => {
+      const changeId = req.params.id;
+
+      const projectRoot = await resolveProjectRootForChange(sql, changeId);
+      if (!projectRoot) {
+        reply.code(404);
+        return { error: 'pending change or project not found' };
+      }
+
+      const result = await rewindOne(sql, changeId, projectRoot);
+      if (!result.success) {
+        reply.code(422);
+      }
+      return result;
+    },
+  );
+}
--- a/apps/coder/src/routes/providers.ts
+++ b/apps/coder/src/routes/providers.ts
@@ -0,0 +1,127 @@
+import type { FastifyInstance } from 'fastify';
+import { z } from 'zod';
+import type { Sql } from '../db.js';
+import type { Config } from '../config.js';
+import {
+  getProviderSnapshot,
+  clearProviderSnapshotCache,
+  peekSnapshotEntry,
+} from '../services/provider-snapshot.js';
+import {
+  load,
+  save,
+  CoderProvidersFileSchema,
+  ProviderConfigPatchSchema,
+  mergeProviderConfigPatch,
+} from '../services/provider-config.js';
+import {
+  reloadProviderConfig,
+  getResolvedRegistry,
+} from '../services/provider-config-registry.js';
+import {
+  getProviderDiagnostic,
+  type DiagnosticAgentRow,
+} from '../services/provider-diagnostic.js';
+
+const RefreshBodySchema = z.object({ providers: z.array(z.string()).optional() });
+
+export function registerProviderRoutes(app: FastifyInstance, sql: Sql, config: Config): void {
+  app.get<{ Querystring: { cwd?: string } }>('/api/providers/snapshot', async (req, _reply) => {
+    const cwd = req.query.cwd;
+    return getProviderSnapshot(sql, config, cwd);
+  });
+
+  // 4.1 — current loaded config file (raw CoderProvidersFile, not the resolved registry).
+  app.get('/api/providers/config', async (_req, _reply) => {
+    return load(config.CODER_PROVIDERS_PATH);
+  });
+
+  // 4.2 — patch the config file (design.md §6.2). Strict order is the whole
+  // correctness story: validate → save → reload → clear. A malformed body or an
+  // invalid merged result returns 422 and NEVER writes; a save failure returns
+  // 500 and leaves in-memory state untouched (no file/registry divergence).
+  app.patch('/api/providers/config', async (req, reply) => {
+    // 1. Validate the PATCH body shape (malformed → 422, never reaches merge).
+    const parsed = ProviderConfigPatchSchema.safeParse(req.body);
+    if (!parsed.success) {
+      return reply.code(422).send({
+        error: 'invalid provider config patch',
+        issues: parsed.error.flatten(),
+      });
+    }
+
+    // 2. Shallow per-id merge over the current file (null deletes; object replaces).
+    const current = load(config.CODER_PROVIDERS_PATH);
+    const merged = mergeProviderConfigPatch(current, parsed.data);
+
+    // 3. Validate the merged result — refuse to write a config that won't load.
+    const validated = CoderProvidersFileSchema.safeParse(merged);
+    if (!validated.success) {
+      return reply.code(422).send({
+        error: 'merged provider config is invalid',
+        issues: validated.error.flatten(),
+      });
+    }
+
+    // 4. Persist. If save throws, STOP here — do NOT reload/clear, so the file on
+    // disk and the in-memory resolved registry can never diverge.
+    try {
+      save(config.CODER_PROVIDERS_PATH, validated.data);
+    } catch (err) {
+      req.log.error(
+        { err: err instanceof Error ? err.message : String(err), path: config.CODER_PROVIDERS_PATH },
+        'provider-config: save failed — in-memory state untouched',
+      );
+      return reply.code(500).send({ error: 'failed to write provider config' });
+    }
+
+    // 5 + 6. Rebuild the in-memory resolved registry from the new file, then drop
+    // the snapshot cache so the next /snapshot reflects the change.
+    reloadProviderConfig();
+    clearProviderSnapshotCache();
+
+    // 7. Return the new config (per §6.2 `{ ok: true }`, plus the merged providers
+    // so the client can update without a follow-up GET).
+    return { ok: true, providers: validated.data.providers };
+  });
+
+  // 4.3 — force a cold probe. Optional { providers?: string[] } narrows the
+  // reported subset (design.md §6.3 Paseo pattern). The force=true snapshot is
+  // the only existing re-probe primitive (per-provider force would be a
+  // snapshot-internal change, out of Phase 4 scope), so the probe runs for all
+  // installed providers; the `refreshed` count reflects the requested subset.
+  app.post('/api/providers/refresh', async (req, reply) => {
+    const parsed = RefreshBodySchema.safeParse(req.body ?? {});
+    if (!parsed.success) {
+      return reply.code(422).send({ error: 'invalid refresh body', issues: parsed.error.flatten() });
+    }
+    const subset = parsed.data.providers;
+    clearProviderSnapshotCache();
+    const entries = await getProviderSnapshot(sql, config, undefined, true);
+    const refreshed =
+      subset && subset.length > 0
+        ? entries.filter((e) => subset.includes(e.name)).length
+        : entries.length;
+    return { refreshed };
+  });
+
+  // 4.4 — per-provider diagnostic (design.md §6.4 → JSON `{ diagnostic: string }`).
+  // Read-only: reports cached state (resolved def + available_agents row + warm
+  // snapshot cache for the last probe error) plus a `which` PATH check. No probe
+  // spawn. The report itself is a plaintext block (§8); the route wraps it as JSON.
+  app.get<{ Params: { id: string } }>('/api/providers/:id/diagnostic', async (req, reply) => {
+    const id = req.params.id;
+    const resolved = getResolvedRegistry().get(id);
+    if (!resolved) {
+      return reply.code(404).send({ error: `unknown provider '${id}'` });
+    }
+    const rows = await sql<DiagnosticAgentRow[]>`
+      SELECT name, install_path, supports_acp, models, last_probed_at
+      FROM available_agents WHERE name = ${id}
+    `;
+    const report = await getProviderDiagnostic(resolved, rows[0], {
+      cachedEntry: peekSnapshotEntry(id),
+    });
+    return { diagnostic: report };
+  });
+}
--- a/apps/coder/src/routes/skills.ts
+++ b/apps/coder/src/routes/skills.ts
@@ -0,0 +1,124 @@
+import type { FastifyInstance } from 'fastify';
+import { z } from 'zod';
+import type { Sql } from '../db.js';
+import type { Broker } from '@boocode/server/broker';
+import type { WsFrame } from '@boocode/server/ws-frames';
+import { getSkillBody } from '@boocode/server/skills';
+import {
+  buildSkillInvokeSyntheticFrames,
+  buildSkillInvokeUserFrames,
+  DEFAULT_SKILL_USER_MESSAGE,
+  runSkillInvokeTransaction,
+} from '@boocode/server/skill-invoke';
+import { resolveChatId } from './chat-resolve.js';
+
+const SkillInvokeBody = z.object({
+  pane_id: z.string().min(1).max(200),
+  skill_name: z.string().min(1),
+  user_message: z.string().max(64_000).nullable().optional(),
+  // v2.5.9: when set to an external provider, the skill runs UNDER that agent —
+  // its body is injected into a dispatched task instead of native inference.
+  provider: z.string().max(100).optional(),
+  model: z.string().max(200).optional(),
+  mode_id: z.string().max(200).optional(),
+  thinking_option_id: z.string().max(200).optional(),
+});
+
+interface InferenceApi {
+  enqueue: (sessionId: string, chatId: string, assistantId: string, user: string) => void;
+  hasActive: (chatId: string) => boolean;
+}
+
+export function registerSkillRoutes(
+  app: FastifyInstance,
+  sql: Sql,
+  broker: Broker,
+  inference: InferenceApi,
+): void {
+  app.post<{ Params: { sessionId: string } }>(
+    '/api/sessions/:sessionId/skill_invoke',
+    async (req, reply) => {
+      const parsed = SkillInvokeBody.safeParse(req.body);
+      if (!parsed.success) {
+        reply.code(400);
+        return { error: 'invalid body', details: parsed.error.flatten() };
+      }
+
+      const sessionId = req.params.sessionId;
+      const { pane_id, skill_name, provider, model, mode_id, thinking_option_id } = parsed.data;
+      const sessionRows = await sql<{ id: string; project_id: string }[]>`
+        SELECT id, project_id FROM sessions WHERE id = ${sessionId}
+      `;
+      if (sessionRows.length === 0) {
+        reply.code(404);
+        return { error: 'session not found' };
+      }
+
+      const chatId = await resolveChatId(sql, sessionId, pane_id);
+      if (!chatId) {
+        reply.code(404);
+        return { error: 'pane not found' };
+      }
+
+      if (inference.hasActive(chatId)) {
+        reply.code(409);
+        return { error: 'inference already running on this chat' };
+      }
+
+      const userText = parsed.data.user_message?.trim()
+        ? parsed.data.user_message
+        : DEFAULT_SKILL_USER_MESSAGE;
+
+      const body = await getSkillBody(skill_name);
+      if (body === null) {
+        reply.code(404);
+        return { error: 'unknown_skill', message: `unknown skill: ${skill_name}` };
+      }
+
+      // v2.5.9: external agent → run the skill UNDER that agent. The skill body
+      // stays server-side (like the native path's tool message) and is injected
+      // into a dispatched task; the agent receives the skill instructions + the
+      // user's text. Mirrors the messages-route external-provider dispatch.
+      if (provider && provider !== 'boocode') {
+        const [userMsg] = await sql<{ id: string }[]>`
+          INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+          VALUES (${sessionId}, ${chatId}, 'user', ${userText}, 'complete', clock_timestamp())
+          RETURNING id
+        `;
+        broker.publishFrame(sessionId, { type: 'message_started', message_id: userMsg!.id, chat_id: chatId, role: 'user' } as WsFrame);
+        broker.publishFrame(sessionId, { type: 'delta', message_id: userMsg!.id, chat_id: chatId, content: userText } as WsFrame);
+        broker.publishFrame(sessionId, { type: 'message_complete', message_id: userMsg!.id, chat_id: chatId } as WsFrame);
+
+        const taskInput = `${body}\n\n---\n\n${userText}`;
+        const [task] = await sql<{ id: string; state: string }[]>`
+          INSERT INTO tasks (project_id, input, agent, model, mode_id, thinking_option_id, session_id)
+          VALUES (${sessionRows[0]!.project_id}, ${taskInput}, ${provider}, ${model ?? null}, ${mode_id ?? null}, ${thinking_option_id ?? null}, ${sessionId})
+          RETURNING id, state
+        `;
+        await sql`UPDATE chats SET updated_at = clock_timestamp() WHERE id = ${chatId}`;
+        reply.code(202);
+        return { user_message_id: userMsg!.id, task_id: task!.id, dispatched: true };
+      }
+
+      const { result, toolCall } = await runSkillInvokeTransaction(sql, {
+        sessionId,
+        chatId,
+        skillName: skill_name,
+        skillBody: body,
+        userText,
+      });
+
+      for (const frame of buildSkillInvokeSyntheticFrames(chatId, result, toolCall, body)) {
+        broker.publishFrame(sessionId, frame as WsFrame);
+      }
+      for (const frame of buildSkillInvokeUserFrames(chatId, result.user_message_id, userText)) {
+        broker.publishFrame(sessionId, frame as WsFrame);
+      }
+
+      inference.enqueue(sessionId, chatId, result.assistant_message_id, 'default');
+
+      reply.code(202);
+      return result;
+    },
+  );
+}
--- a/apps/coder/src/routes/stats.ts
+++ b/apps/coder/src/routes/stats.ts
@@ -0,0 +1,48 @@
+import type { FastifyInstance } from 'fastify';
+import { z } from 'zod';
+import type { Sql } from '../db.js';
+
+const CostQuery = z.object({
+  group_by: z.enum(['project', 'agent', 'day']).default('project'),
+});
+
+export function registerStatsRoutes(app: FastifyInstance, sql: Sql): void {
+  // GET /api/stats/costs — aggregate cost_tokens by project, agent, or day
+  app.get('/api/stats/costs', async (req, reply) => {
+    const parsed = CostQuery.safeParse(req.query);
+    if (!parsed.success) {
+      reply.code(400);
+      return { error: 'invalid query', details: parsed.error.flatten() };
+    }
+
+    const { group_by } = parsed.data;
+
+    switch (group_by) {
+      case 'project':
+        return sql`
+          SELECT project_id, COUNT(*)::int AS task_count, COALESCE(SUM(cost_tokens), 0)::int AS total_tokens
+          FROM tasks
+          WHERE cost_tokens IS NOT NULL
+          GROUP BY project_id
+          ORDER BY total_tokens DESC
+        `;
+      case 'agent':
+        return sql`
+          SELECT COALESCE(agent, 'native') AS agent, COUNT(*)::int AS task_count, COALESCE(SUM(cost_tokens), 0)::int AS total_tokens
+          FROM tasks
+          WHERE cost_tokens IS NOT NULL
+          GROUP BY agent
+          ORDER BY total_tokens DESC
+        `;
+      case 'day':
+        return sql`
+          SELECT DATE(created_at) AS day, COUNT(*)::int AS task_count, COALESCE(SUM(cost_tokens), 0)::int AS total_tokens
+          FROM tasks
+          WHERE cost_tokens IS NOT NULL
+          GROUP BY DATE(created_at)
+          ORDER BY day DESC
+          LIMIT 90
+        `;
+    }
+  });
+}
--- a/apps/coder/src/routes/tasks.ts
+++ b/apps/coder/src/routes/tasks.ts
@@ -0,0 +1,185 @@
+import type { FastifyInstance } from 'fastify';
+import { z } from 'zod';
+import type { Sql } from '../db.js';
+import { getPendingPermission, respondToPermission, cancelPendingPermission } from '../services/permission-waiter.js';
+import { getTaskCommands } from '../services/agent-commands-cache.js';
+
+interface InferenceApi {
+  cancel: (sessionId: string, chatId: string) => Promise<boolean>;
+}
+
+const CreateBody = z.object({
+  project_id: z.string().uuid(),
+  input: z.string().min(1).max(64_000),
+  agent: z.string().max(100).optional(),
+  model: z.string().max(200).optional(),
+  mode_id: z.string().max(200).optional(),
+  thinking_option_id: z.string().max(200).optional(),
+});
+
+const PermissionBody = z.object({
+  option_id: z.string().max(200).nullable(),
+  updated_input: z.record(z.unknown()).optional(),
+});
+
+const ListQuery = z.object({
+  state: z.enum(['pending', 'running', 'completed', 'failed', 'blocked', 'cancelled']).optional(),
+  project_id: z.string().uuid().optional(),
+});
+
+export function registerTaskRoutes(app: FastifyInstance, sql: Sql, inference: InferenceApi): void {
+  // POST /api/tasks — create a new task
+  app.post('/api/tasks', async (req, reply) => {
+    const parsed = CreateBody.safeParse(req.body);
+    if (!parsed.success) {
+      reply.code(400);
+      return { error: 'invalid body', details: parsed.error.flatten() };
+    }
+
+    const { project_id, input, agent, model, mode_id, thinking_option_id } = parsed.data;
+
+    const [task] = await sql<{ id: string; state: string }[]>`
+      INSERT INTO tasks (project_id, input, agent, model, mode_id, thinking_option_id)
+      VALUES (${project_id}, ${input}, ${agent ?? null}, ${model ?? null}, ${mode_id ?? null}, ${thinking_option_id ?? null})
+      RETURNING id, state
+    `;
+
+    reply.code(201);
+    return { id: task!.id, state: task!.state };
+  });
+
+  // GET /api/tasks — list tasks with optional filters
+  app.get('/api/tasks', async (req, _reply) => {
+    const parsed = ListQuery.safeParse(req.query);
+    if (!parsed.success) {
+      return { error: 'invalid query', details: parsed.error.flatten() };
+    }
+
+    const { state, project_id } = parsed.data;
+
+    // Build query with optional filters
+    if (state && project_id) {
+      return sql`
+        SELECT id, project_id, state, input, output_summary, agent, model, execution_path, session_id, started_at, ended_at, created_at
+        FROM tasks
+        WHERE state = ${state} AND project_id = ${project_id}
+        ORDER BY created_at DESC
+        LIMIT 100
+      `;
+    } else if (state) {
+      return sql`
+        SELECT id, project_id, state, input, output_summary, agent, model, execution_path, session_id, started_at, ended_at, created_at
+        FROM tasks
+        WHERE state = ${state}
+        ORDER BY created_at DESC
+        LIMIT 100
+      `;
+    } else if (project_id) {
+      return sql`
+        SELECT id, project_id, state, input, output_summary, agent, model, execution_path, session_id, started_at, ended_at, created_at
+        FROM tasks
+        WHERE project_id = ${project_id}
+        ORDER BY created_at DESC
+        LIMIT 100
+      `;
+    } else {
+      return sql`
+        SELECT id, project_id, state, input, output_summary, agent, model, execution_path, session_id, started_at, ended_at, created_at
+        FROM tasks
+        ORDER BY created_at DESC
+        LIMIT 100
+      `;
+    }
+  });
+
+  // GET /api/tasks/:id — single task detail
+  app.get<{ Params: { id: string } }>('/api/tasks/:id', async (req, reply) => {
+    const rows = await sql`
+      SELECT id, project_id, parent_task_id, state, input, output_summary, agent, model, execution_path, worktree_path, session_id, cost_tokens, started_at, ended_at, created_at
+      FROM tasks
+      WHERE id = ${req.params.id}
+    `;
+    if (rows.length === 0) {
+      reply.code(404);
+      return { error: 'task not found' };
+    }
+    return rows[0];
+  });
+
+  // POST /api/tasks/:id/cancel — cancel a pending or running task
+  app.post<{ Params: { id: string } }>('/api/tasks/:id/cancel', async (req, reply) => {
+    const taskId = req.params.id;
+
+    // Get current task state + session info
+    const rows = await sql<{ id: string; state: string; session_id: string | null }[]>`
+      SELECT id, state, session_id FROM tasks WHERE id = ${taskId}
+    `;
+    if (rows.length === 0) {
+      reply.code(404);
+      return { error: 'task not found' };
+    }
+
+    const task = rows[0]!;
+    if (task.state !== 'pending' && task.state !== 'running' && task.state !== 'blocked') {
+      reply.code(409);
+      return { error: `cannot cancel task in state '${task.state}'` };
+    }
+
+    cancelPendingPermission(taskId);
+
+    // If running, try to cancel inference
+    if ((task.state === 'running' || task.state === 'blocked') && task.session_id) {
+      // Find active chat in the task's session
+      const chats = await sql<{ id: string }[]>`
+        SELECT id FROM chats WHERE session_id = ${task.session_id} AND status = 'open'
+      `;
+      for (const chat of chats) {
+        await inference.cancel(task.session_id, chat.id);
+      }
+    }
+
+    await sql`
+      UPDATE tasks
+      SET state = 'cancelled', ended_at = clock_timestamp()
+      WHERE id = ${taskId} AND state IN ('pending', 'running', 'blocked')
+    `;
+
+    return { cancelled: true };
+  });
+
+  // GET /api/tasks/:id/permission — pending permission prompt (if any)
+  app.get<{ Params: { id: string } }>('/api/tasks/:id/permission', async (req, reply) => {
+    const prompt = getPendingPermission(req.params.id);
+    if (!prompt) {
+      reply.code(404);
+      return { error: 'no pending permission' };
+    }
+    return prompt;
+  });
+
+  // POST /api/tasks/:id/permission — respond to a pending permission prompt
+  app.post<{ Params: { id: string } }>('/api/tasks/:id/permission', async (req, reply) => {
+    const parsed = PermissionBody.safeParse(req.body);
+    if (!parsed.success) {
+      reply.code(400);
+      return { error: 'invalid body', details: parsed.error.flatten() };
+    }
+
+    const ok = respondToPermission(req.params.id, parsed.data.option_id, parsed.data.updated_input as Record<string, unknown> | undefined);
+    if (!ok) {
+      reply.code(404);
+      return { error: 'no pending permission' };
+    }
+    return { ok: true };
+  });
+
+  // GET /api/tasks/:id/commands — cached ACP slash commands (if any)
+  app.get<{ Params: { id: string } }>('/api/tasks/:id/commands', async (req, reply) => {
+    const commands = getTaskCommands(req.params.id);
+    if (!commands?.length) {
+      reply.code(404);
+      return { error: 'no commands cached' };
+    }
+    return { taskId: req.params.id, commands };
+  });
+}
--- a/apps/coder/src/routes/ws.ts
+++ b/apps/coder/src/routes/ws.ts
@@ -0,0 +1,51 @@
+import type { FastifyInstance } from 'fastify';
+import type { Sql } from '../db.js';
+import type { Broker } from '@boocode/server/broker';
+
+export function registerWebSocket(
+  app: FastifyInstance,
+  sql: Sql,
+  broker: Broker,
+): void {
+  // Per-session streaming WebSocket. Clients connect here to receive live
+  // inference frames (deltas, tool_calls, tool_results, message_complete).
+  app.get<{ Params: { sessionId: string } }>(
+    '/api/ws/sessions/:sessionId',
+    { websocket: true },
+    async (socket, req) => {
+      const sessionId = req.params.sessionId;
+
+      // Validate session exists
+      const session = await sql<{ id: string }[]>`SELECT id FROM sessions WHERE id = ${sessionId}`;
+      if (session.length === 0) {
+        socket.send(JSON.stringify({ type: 'error', error: 'session not found' }));
+        socket.close(1008, 'session not found');
+        return;
+      }
+
+      // Send snapshot of existing messages so client can hydrate
+      const messages = await sql<Record<string, unknown>[]>`
+        SELECT id, session_id, chat_id, role, content, kind, tool_calls, tool_results, reasoning_parts, status, last_seq,
+               tokens_used, ctx_used, ctx_max, started_at, finished_at, created_at, metadata,
+               summary, tail_start_id, compacted_at
+        FROM messages_with_parts
+        WHERE session_id = ${sessionId}
+        ORDER BY created_at ASC, id ASC
+      `;
+      socket.send(JSON.stringify({ type: 'snapshot', messages }));
+
+      // Subscribe to broker for live frames
+      const unsubscribe = broker.subscribe(sessionId, (frame) => {
+        if (socket.readyState !== socket.OPEN) return;
+        try {
+          socket.send(JSON.stringify(frame));
+        } catch (err) {
+          app.log.warn({ err, sessionId }, 'ws send failed');
+        }
+      });
+
+      socket.on('close', () => unsubscribe());
+      socket.on('error', () => unsubscribe());
+    },
+  );
+}
--- a/apps/coder/src/schema.sql
+++ b/apps/coder/src/schema.sql
@@ -0,0 +1,122 @@
+-- v2.0.0: BooCoder schema — pending changes, tasks, agent registry.
+-- Applied on startup by apps/coder/src/db.ts:applySchema().
+-- Lives in the same 'boochat' database as BooChat's tables.
+
+CREATE TABLE IF NOT EXISTS pending_changes (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  session_id UUID NOT NULL,
+  task_id UUID,
+  file_path TEXT NOT NULL,
+  operation TEXT NOT NULL,
+  diff TEXT NOT NULL,
+  status TEXT NOT NULL DEFAULT 'pending',
+  created_at TIMESTAMPTZ NOT NULL DEFAULT clock_timestamp(),
+  CONSTRAINT pending_changes_operation_chk CHECK (operation IN ('create', 'edit', 'delete')),
+  CONSTRAINT pending_changes_status_chk CHECK (status IN ('pending', 'applied', 'rejected', 'reverted'))
+);
+
+CREATE TABLE IF NOT EXISTS tasks (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  project_id UUID NOT NULL,
+  parent_task_id UUID REFERENCES tasks(id),
+  state TEXT NOT NULL DEFAULT 'pending',
+  input TEXT NOT NULL,
+  output_summary TEXT,
+  agent TEXT,
+  model TEXT,
+  execution_path TEXT,
+  worktree_path TEXT,
+  cost_tokens INTEGER,
+  started_at TIMESTAMPTZ,
+  ended_at TIMESTAMPTZ,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT clock_timestamp(),
+  CONSTRAINT tasks_state_chk CHECK (state IN ('pending', 'running', 'completed', 'failed', 'blocked', 'cancelled')),
+  CONSTRAINT tasks_execution_path_chk CHECK (execution_path IS NULL OR execution_path IN ('native', 'acp', 'pty', 'qwen'))
+);
+
+CREATE TABLE IF NOT EXISTS available_agents (
+  name TEXT PRIMARY KEY,
+  install_path TEXT,
+  version TEXT,
+  supports_acp BOOLEAN NOT NULL DEFAULT false,
+  supports_mcp_client BOOLEAN NOT NULL DEFAULT false,
+  last_probed_at TIMESTAMPTZ
+);
+
+-- v2.0.0 Phase 4: link tasks to their inference sessions.
+ALTER TABLE tasks ADD COLUMN IF NOT EXISTS session_id UUID REFERENCES sessions(id);
+
+-- v2.0.5: add 'qwen' to execution_path CHECK + arena_id column.
+ALTER TABLE tasks DROP CONSTRAINT IF EXISTS tasks_execution_path_chk;
+DO $$ BEGIN
+  IF NOT EXISTS (SELECT 1 FROM pg_constraint WHERE conname = 'tasks_execution_path_chk') THEN
+    ALTER TABLE tasks ADD CONSTRAINT tasks_execution_path_chk
+      CHECK (execution_path IS NULL OR execution_path IN ('native', 'acp', 'pty', 'qwen'));
+  END IF;
+END $$;
+
+-- v2.0.5: arena support — group tasks into competitive arenas.
+ALTER TABLE tasks ADD COLUMN IF NOT EXISTS arena_id UUID;
+
+-- Human inbox: tasks needing attention
+CREATE OR REPLACE VIEW human_inbox AS
+  SELECT * FROM tasks WHERE state IN ('blocked', 'failed');
+
+-- v2.1.0: provider picker — extend available_agents with model discovery.
+ALTER TABLE available_agents ADD COLUMN IF NOT EXISTS models JSONB DEFAULT '[]'::jsonb;
+ALTER TABLE available_agents ADD COLUMN IF NOT EXISTS label TEXT;
+ALTER TABLE available_agents ADD COLUMN IF NOT EXISTS transport TEXT DEFAULT 'pty';
+-- v2.5.10: persisted ACP available_commands (captured during the cold probe), so
+-- an agent's live command set survives the tier-2 probe skip and shows without a
+-- dispatch.
+ALTER TABLE available_agents ADD COLUMN IF NOT EXISTS commands JSONB DEFAULT '[]'::jsonb;
+
+-- v2.2.0: Paseo-style session config on tasks.
+ALTER TABLE tasks ADD COLUMN IF NOT EXISTS mode_id TEXT;
+ALTER TABLE tasks ADD COLUMN IF NOT EXISTS thinking_option_id TEXT;
+ALTER TABLE tasks ADD COLUMN IF NOT EXISTS feature_values JSONB;
+
+-- v2.6: one shared worktree per session (all agents/panes in the session operate in it).
+CREATE TABLE IF NOT EXISTS session_worktrees (
+  session_id UUID PRIMARY KEY REFERENCES sessions(id),
+  worktree_path TEXT NOT NULL,
+  base_commit TEXT,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT clock_timestamp()
+);
+
+-- v2.6: one backend session per (session, agent); resumed on switch-back.
+CREATE TABLE IF NOT EXISTS agent_sessions (
+  session_id UUID NOT NULL REFERENCES sessions(id),
+  agent TEXT NOT NULL,
+  backend TEXT NOT NULL,
+  agent_session_id TEXT,
+  server_port INTEGER,
+  status TEXT NOT NULL DEFAULT 'idle',
+  last_active_at TIMESTAMPTZ,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT clock_timestamp(),
+  PRIMARY KEY (session_id, agent),
+  CONSTRAINT agent_sessions_backend_chk CHECK (backend IN ('opencode_server', 'acp_warm')),
+  CONSTRAINT agent_sessions_status_chk CHECK (status IN ('idle', 'active', 'crashed', 'closed'))
+);
+
+-- v2.6: attribution for DiffPanel badges (Phase 1 UX reads this).
+ALTER TABLE pending_changes ADD COLUMN IF NOT EXISTS agent TEXT;
+
+-- LISTEN/NOTIFY fast path: every tasks INSERT (from any call site — routes,
+-- new_task tool, arena, MCP server) fires pg_notify('tasks_new') in the same
+-- transaction, so the dispatcher reacts immediately instead of waiting for the
+-- fallback poll. Postgres holds the notification until COMMIT, so the listener
+-- always sees the committed row. A trigger covers all insert paths with no
+-- app-code drift. Idempotent: re-applied on every startup.
+CREATE OR REPLACE FUNCTION notify_tasks_new() RETURNS trigger AS $$
+BEGIN
+  PERFORM pg_notify('tasks_new', '');
+  RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+DROP TRIGGER IF EXISTS tasks_notify_new ON tasks;
+CREATE TRIGGER tasks_notify_new
+  AFTER INSERT ON tasks
+  FOR EACH ROW
+  EXECUTE FUNCTION notify_tasks_new();
--- a/apps/coder/src/services/tests/acp-client-fs.test.ts
+++ b/apps/coder/src/services/tests/acp-client-fs.test.ts
@@ -0,0 +1,50 @@
+import { describe, it, expect, afterEach } from 'vitest';
+import { mkdtempSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { readWorktreeTextFile, writeWorktreeTextFile } from '../acp-client-fs.js';
+
+const created: string[] = [];
+function freshWorktree(): string {
+  const wt = mkdtempSync(join(tmpdir(), 'acp-wt-'));
+  created.push(wt);
+  return wt;
+}
+afterEach(() => {
+  for (const d of created.splice(0)) {
+    try {
+      rmSync(d, { recursive: true, force: true });
+      rmSync(`${d}-evil`, { recursive: true, force: true });
+    } catch {
+      /* ignore */
+    }
+  }
+});
+
+describe('acp-client-fs worktree scoping', () => {
+  it('writes then reads a file inside the worktree', async () => {
+    const wt = freshWorktree();
+    await writeWorktreeTextFile(wt, 'sub/dir/note.txt', 'hello');
+    expect(await readWorktreeTextFile(wt, 'sub/dir/note.txt')).toBe('hello');
+  });
+
+  it('rejects ../ traversal on read', async () => {
+    const wt = freshWorktree();
+    await expect(readWorktreeTextFile(wt, '../../etc/passwd')).rejects.toThrow(/escapes worktree/);
+  });
+
+  it('rejects ../ traversal on write', async () => {
+    const wt = freshWorktree();
+    await expect(writeWorktreeTextFile(wt, '../escape.txt', 'x')).rejects.toThrow(/escapes worktree/);
+  });
+
+  it('rejects a sibling-prefix path (the unbounded-startsWith bug)', async () => {
+    const wt = freshWorktree();
+    // Absolute path that shares the worktree as a STRING prefix but is a sibling
+    // dir: `<wt>-evil/...`. A bare `startsWith(<wt>)` wrongly admits it.
+    await expect(readWorktreeTextFile(wt, `${wt}-evil/secret.txt`)).rejects.toThrow(/escapes worktree/);
+    await expect(writeWorktreeTextFile(wt, `${wt}-evil/secret.txt`, 'x')).rejects.toThrow(
+      /escapes worktree/,
+    );
+  });
+});
--- a/apps/coder/src/services/tests/acp-derive.test.ts
+++ b/apps/coder/src/services/tests/acp-derive.test.ts
@@ -0,0 +1,154 @@
+import { describe, it, expect } from 'vitest';
+import type { SessionConfigOption } from '@agentclientprotocol/sdk';
+import {
+  deriveModesFromACP,
+  deriveModelDefinitionsFromACP,
+  findThoughtLevelConfigId,
+} from '../acp-derive.js';
+
+describe('deriveModesFromACP', () => {
+  it('prefers modeState.availableModes when present', () => {
+    const { modes, currentModeId } = deriveModesFromACP(
+      [{ id: 'fallback', label: 'Fallback' }],
+      {
+        currentModeId: 'plan',
+        availableModes: [
+          { id: 'plan', name: 'Plan', description: 'Read-only planning' },
+          { id: 'code', name: 'Code' },
+        ],
+      },
+    );
+
+    expect(modes).toEqual([
+      { id: 'plan', label: 'Plan', description: 'Read-only planning' },
+      { id: 'code', label: 'Code', description: undefined },
+    ]);
+    expect(currentModeId).toBe('plan');
+  });
+
+  it('falls back to configOptions mode select', () => {
+    const configOptions: SessionConfigOption[] = [
+      {
+        type: 'select',
+        id: 'mode',
+        category: 'mode',
+        currentValue: 'auto',
+        options: [
+          { value: 'auto', name: 'Auto' },
+          { value: 'manual', name: 'Manual', description: 'Ask first' },
+        ],
+      },
+    ];
+
+    const { modes, currentModeId } = deriveModesFromACP([], null, configOptions);
+
+    expect(modes).toEqual([
+      { id: 'auto', label: 'Auto', description: undefined },
+      { id: 'manual', label: 'Manual', description: 'Ask first' },
+    ]);
+    expect(currentModeId).toBe('auto');
+  });
+
+  it('uses static fallback when no ACP mode data', () => {
+    const fallback = [{ id: 'default', label: 'Default' }];
+    const { modes, currentModeId } = deriveModesFromACP(fallback, null, null);
+
+    expect(modes).toEqual(fallback);
+    expect(currentModeId).toBeNull();
+  });
+});
+
+describe('deriveModelDefinitionsFromACP', () => {
+  it('maps availableModels with thought_level options', () => {
+    const configOptions: SessionConfigOption[] = [
+      {
+        type: 'select',
+        id: 'thought',
+        category: 'thought_level',
+        currentValue: 'medium',
+        options: [
+          { value: 'low', name: 'Low' },
+          { value: 'medium', name: 'Medium' },
+        ],
+      },
+    ];
+
+    const models = deriveModelDefinitionsFromACP(
+      {
+        currentModelId: 'gpt-4',
+        availableModels: [
+          { modelId: 'gpt-4', name: 'GPT-4' },
+          { modelId: 'gpt-4-mini', name: 'Mini', description: 'Cheaper' },
+        ],
+      },
+      configOptions,
+    );
+
+    expect(models).toEqual([
+      {
+        id: 'gpt-4',
+        label: 'GPT-4',
+        description: undefined,
+        isDefault: true,
+        thinkingOptions: [
+          { id: 'low', label: 'Low', isDefault: false },
+          { id: 'medium', label: 'Medium', isDefault: true },
+        ],
+        defaultThinkingOptionId: 'medium',
+      },
+      {
+        id: 'gpt-4-mini',
+        label: 'Mini',
+        description: 'Cheaper',
+        isDefault: false,
+        thinkingOptions: [
+          { id: 'low', label: 'Low', isDefault: false },
+          { id: 'medium', label: 'Medium', isDefault: true },
+        ],
+        defaultThinkingOptionId: 'medium',
+      },
+    ]);
+  });
+
+  it('falls back to model select config when no availableModels', () => {
+    const configOptions: SessionConfigOption[] = [
+      {
+        type: 'select',
+        id: 'model',
+        category: 'model',
+        currentValue: 'sonnet',
+        options: [
+          { value: 'sonnet', name: 'Sonnet' },
+          { value: 'opus', name: 'Opus' },
+        ],
+      },
+    ];
+
+    const models = deriveModelDefinitionsFromACP(null, configOptions);
+
+    expect(models).toEqual([
+      { id: 'sonnet', label: 'Sonnet', isDefault: true, defaultThinkingOptionId: undefined },
+      { id: 'opus', label: 'Opus', isDefault: false, defaultThinkingOptionId: undefined },
+    ]);
+  });
+});
+
+describe('findThoughtLevelConfigId', () => {
+  it('returns thought_level select id', () => {
+    const configOptions: SessionConfigOption[] = [
+      {
+        type: 'select',
+        id: 'effort',
+        category: 'thought_level',
+        currentValue: 'high',
+        options: [{ value: 'high', name: 'High' }],
+      },
+    ];
+
+    expect(findThoughtLevelConfigId(configOptions)).toBe('effort');
+  });
+
+  it('returns null when missing', () => {
+    expect(findThoughtLevelConfigId(null)).toBeNull();
+  });
+});
--- a/apps/coder/src/services/tests/acp-spawn.test.ts
+++ b/apps/coder/src/services/tests/acp-spawn.test.ts
@@ -0,0 +1,73 @@
+import { describe, it, expect } from 'vitest';
+import { resolveLaunchSpec, resolveAcpSpawnArgs } from '../acp-spawn.js';
+import { buildResolvedRegistry } from '../provider-config-registry.js';
+import type { CoderProvidersFile } from '../provider-config.js';
+import { PROVIDERS } from '../provider-registry.js';
+
+/** Resolved def for a provider id under the given config (default: no override). */
+function builtin(name: string, providers: CoderProvidersFile['providers'] = {}) {
+  const def = buildResolvedRegistry(PROVIDERS, { providers }).get(name);
+  if (!def) throw new Error(`no resolved def for ${name}`);
+  return def;
+}
+
+describe('resolveLaunchSpec', () => {
+  // --- byte-identical built-in regression (the HARD CONSTRAINT) ---------------
+  // These argv values are the pre-v2.3 resolveAcpSpawnArgs switch outputs and
+  // MUST NOT change. spawn() is `spawn(spec.binary, spec.args, ...)`, so argv
+  // parity here is dispatch parity.
+  it('opencode (no override) → byte-identical argv ["acp"], binary = installPath', () => {
+    const spec = resolveLaunchSpec(builtin('opencode'), '/usr/bin/opencode');
+    expect(spec).not.toBeNull();
+    expect(spec!.args).toEqual(['acp']); // pre-v2.3 value
+    expect(spec!.binary).toBe('/usr/bin/opencode');
+    expect(spec!.env).toBeUndefined();
+    // cross-check against the switch source-of-truth
+    expect(spec!.args).toEqual(resolveAcpSpawnArgs('opencode'));
+  });
+
+  it('goose → ["acp"], qwen → ["--acp"] (byte-identical)', () => {
+    expect(resolveLaunchSpec(builtin('goose'), '/usr/bin/goose')!.args).toEqual(['acp']);
+    expect(resolveLaunchSpec(builtin('qwen'), '/usr/bin/qwen')!.args).toEqual(['--acp']);
+  });
+
+  it('built-in with null installPath falls back to the bare id (pre-v2.3 `installPath ?? agent`)', () => {
+    const spec = resolveLaunchSpec(builtin('opencode'), null);
+    expect(spec!.binary).toBe('opencode');
+    expect(spec!.args).toEqual(['acp']);
+  });
+
+  it('non-ACP / unknown provider → null (claude has no ACP argv)', () => {
+    expect(resolveLaunchSpec(builtin('claude'), '/usr/bin/claude')).toBeNull();
+    expect(resolveLaunchSpec(builtin('boocode'), null)).toBeNull();
+  });
+
+  // --- config-driven launch (the new capability) ------------------------------
+  it('custom ACP entry → configured command + env reach the spec', () => {
+    const def = builtin('amp-acp', {
+      'amp-acp': { extends: 'acp', label: 'Amp', command: ['amp-acp', '--acp'], env: { AMP_KEY: 'x' } },
+    });
+    const spec = resolveLaunchSpec(def, '/usr/local/bin/amp-acp');
+    expect(spec).not.toBeNull();
+    expect(spec!.binary).toBe('amp-acp'); // command[0], not the resolved install path
+    expect(spec!.args).toEqual(['--acp']); // command.slice(1)
+    expect(spec!.env).toEqual({ AMP_KEY: 'x' });
+  });
+
+  it('built-in WITH a config command override uses the override, not the switch default', () => {
+    const def = builtin('opencode', { opencode: { command: ['opencode', 'acp', '--verbose'], env: { DEBUG: '1' } } });
+    const spec = resolveLaunchSpec(def, '/usr/bin/opencode');
+    expect(spec!.binary).toBe('opencode');
+    expect(spec!.args).toEqual(['acp', '--verbose']);
+    expect(spec!.env).toEqual({ DEBUG: '1' });
+  });
+});
+
+describe('acp-dispatch spawn wiring (documented pass-through)', () => {
+  // dispatchViaAcp spawns `spawn(spec.binary, spec.args, { env: { ...process.env, ...spec.env } })`.
+  // The env merge layers config env over process.env; for a built-in with no
+  // config env, spec.env is undefined → { ...process.env } (byte-identical).
+  it('built-in with no config env yields an undefined spec.env (→ plain process.env at spawn)', () => {
+    expect(resolveLaunchSpec(builtin('opencode'), '/usr/bin/opencode')!.env).toBeUndefined();
+  });
+});
--- a/apps/coder/src/services/tests/acp-tool-snapshot.test.ts
+++ b/apps/coder/src/services/tests/acp-tool-snapshot.test.ts
@@ -0,0 +1,66 @@
+import { describe, it, expect } from 'vitest';
+import {
+  mergeToolSnapshot,
+  mapToolLifecycleStatus,
+  snapshotToWireToolCall,
+  synthesizeCanceledSnapshots,
+} from '../acp-tool-snapshot.js';
+
+describe('mergeToolSnapshot', () => {
+  it('preserves stable toolCallId across updates', () => {
+    const first = mergeToolSnapshot('tc-1', {
+      toolCallId: 'tc-1',
+      title: 'Read file',
+      kind: 'read',
+      status: 'in_progress',
+      rawInput: { path: 'foo.ts' },
+    });
+    const merged = mergeToolSnapshot(
+      'tc-1',
+      {
+        toolCallId: 'tc-1',
+        title: 'Read file',
+        status: 'completed',
+        rawOutput: { content: 'hello' },
+      },
+      first,
+    );
+    expect(merged.toolCallId).toBe('tc-1');
+    expect(merged.rawInput).toEqual({ path: 'foo.ts' });
+    expect(merged.status).toBe('completed');
+    expect(merged.rawOutput).toEqual({ content: 'hello' });
+  });
+});
+
+describe('snapshotToWireToolCall', () => {
+  it('embeds ACP lifecycle meta for UI merge', () => {
+    const wire = snapshotToWireToolCall({
+      toolCallId: 'tc-42',
+      title: 'Edit',
+      kind: 'edit',
+      status: 'completed',
+      rawInput: { path: 'a.ts' },
+      rawOutput: 'ok',
+    });
+    expect(wire.id).toBe('tc-42');
+    expect(wire.name).toBe('edit');
+    expect(wire.args._acp).toMatchObject({ status: 'completed', title: 'Edit', output: 'ok' });
+  });
+
+  it('maps synthesized cancel to canceled lifecycle', () => {
+    const [canceled] = synthesizeCanceledSnapshots([
+      { toolCallId: 'tc-1', title: 'Run', status: 'in_progress' },
+    ]);
+    const wire = snapshotToWireToolCall(canceled!);
+    expect(wire.args._acp).toMatchObject({ status: 'canceled' });
+  });
+});
+
+describe('mapToolLifecycleStatus', () => {
+  it('maps ACP statuses to UI lifecycle', () => {
+    expect(mapToolLifecycleStatus('completed')).toBe('completed');
+    expect(mapToolLifecycleStatus('failed')).toBe('failed');
+    expect(mapToolLifecycleStatus('in_progress')).toBe('running');
+    expect(mapToolLifecycleStatus(undefined, 'canceled')).toBe('canceled');
+  });
+});
--- a/apps/coder/src/services/tests/pending_changes_integration.test.ts
+++ b/apps/coder/src/services/tests/pending_changes_integration.test.ts
@@ -0,0 +1,96 @@
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import { readFileSync, existsSync } from 'node:fs';
+import { readFile, rm, mkdir } from 'node:fs/promises';
+import { resolve } from 'node:path';
+import postgres from 'postgres';
+import { queueCreate, queueEdit, queueDelete, applyOne, rewindOne, listPending } from '../pending_changes.js';
+
+/**
+ * Integration test for the full pending-changes lifecycle.
+ * Requires DATABASE_URL env var pointing to a running postgres instance.
+ * Skips cleanly when DATABASE_URL is not set.
+ *
+ * Run with:
+ *   DATABASE_URL='postgres://boocode:devpass@localhost:5500/boocode' pnpm -C apps/coder test
+ */
+describe.runIf(!!process.env.DATABASE_URL)('pending_changes integration', () => {
+  let sql: ReturnType<typeof postgres>;
+  const testDir = '/tmp/boocode-pending-changes-test-' + Date.now();
+  const projectRoot = testDir;
+  const testSessionId = '00000000-0000-0000-0000-000000000001';
+
+  beforeAll(async () => {
+    sql = postgres(process.env.DATABASE_URL!, { max: 3 });
+
+    // Apply schema
+    const schemaPath = resolve(__dirname, '../../schema.sql');
+    const ddl = readFileSync(schemaPath, 'utf8');
+    await sql.unsafe(ddl);
+
+    // Create temp project directory
+    await mkdir(testDir, { recursive: true });
+  });
+
+  afterAll(async () => {
+    // Cleanup test data
+    await sql`DELETE FROM pending_changes WHERE session_id = ${testSessionId}`;
+    await sql.end({ timeout: 5 });
+    // Remove temp directory
+    await rm(testDir, { recursive: true, force: true });
+  });
+
+  it('queueCreate → listPending → applyOne → verify file exists', async () => {
+    const change = await queueCreate(sql, testSessionId, null, 'hello.txt', 'hello world', projectRoot);
+    expect(change.status).toBe('pending');
+    expect(change.operation).toBe('create');
+
+    const pending = await listPending(sql, testSessionId);
+    expect(pending.some((p) => p.id === change.id)).toBe(true);
+
+    const result = await applyOne(sql, change.id, projectRoot);
+    expect(result.success).toBe(true);
+
+    const content = await readFile(resolve(testDir, 'hello.txt'), 'utf8');
+    expect(content).toBe('hello world');
+  });
+
+  it('queueEdit → apply → verify content changed', async () => {
+    // Setup: create a file first
+    const createChange = await queueCreate(sql, testSessionId, null, 'editable.txt', 'original content here', projectRoot);
+    await applyOne(sql, createChange.id, projectRoot);
+
+    // Queue an edit
+    const editChange = await queueEdit(sql, testSessionId, null, 'editable.txt', 'original', 'modified', projectRoot);
+    expect(editChange.operation).toBe('edit');
+
+    const result = await applyOne(sql, editChange.id, projectRoot);
+    expect(result.success).toBe(true);
+
+    const content = await readFile(resolve(testDir, 'editable.txt'), 'utf8');
+    expect(content).toBe('modified content here');
+  });
+
+  it('queueDelete → apply → verify file gone', async () => {
+    // Setup: create a file
+    const createChange = await queueCreate(sql, testSessionId, null, 'deleteme.txt', 'goodbye', projectRoot);
+    await applyOne(sql, createChange.id, projectRoot);
+    expect(existsSync(resolve(testDir, 'deleteme.txt'))).toBe(true);
+
+    // Queue a delete
+    const deleteChange = await queueDelete(sql, testSessionId, null, 'deleteme.txt', projectRoot);
+    const result = await applyOne(sql, deleteChange.id, projectRoot);
+    expect(result.success).toBe(true);
+    expect(existsSync(resolve(testDir, 'deleteme.txt'))).toBe(false);
+  });
+
+  it('rewindOne → verify reverted', async () => {
+    // Setup: create and apply a file
+    const createChange = await queueCreate(sql, testSessionId, null, 'rewindable.txt', 'initial', projectRoot);
+    await applyOne(sql, createChange.id, projectRoot);
+
+    // Rewind the create (should delete the file)
+    const result = await rewindOne(sql, createChange.id, projectRoot);
+    expect(result.success).toBe(true);
+    expect(existsSync(resolve(testDir, 'rewindable.txt'))).toBe(false);
+  });
+});
--- a/apps/coder/src/services/tests/provider-commands.test.ts
+++ b/apps/coder/src/services/tests/provider-commands.test.ts
@@ -0,0 +1,26 @@
+import { describe, it, expect } from 'vitest';
+import { getManifestCommands, mergeCommands, PROVIDER_COMMANDS } from '../provider-commands.js';
+
+describe('provider-commands', () => {
+  it('defines commands for every external harness', () => {
+    for (const name of ['claude', 'opencode', 'goose', 'qwen']) {
+      expect(getManifestCommands(name).length, name).toBeGreaterThan(0);
+    }
+  });
+
+  it('boocode uses frontend skills — empty manifest', () => {
+    expect(getManifestCommands('boocode')).toEqual([]);
+    expect(PROVIDER_COMMANDS.boocode).toEqual([]);
+  });
+
+  it('mergeCommands dedupes by name with later override', () => {
+    const merged = mergeCommands(
+      [{ name: 'help', description: 'a' }],
+      [{ name: 'help', description: 'b' }, { name: 'clear' }],
+    );
+    expect(merged).toEqual([
+      { name: 'clear' },
+      { name: 'help', description: 'b' },
+    ]);
+  });
+});
--- a/apps/coder/src/services/tests/provider-config-registry.test.ts
+++ b/apps/coder/src/services/tests/provider-config-registry.test.ts
@@ -0,0 +1,93 @@
+import { describe, it, expect, vi } from 'vitest';
+import { buildResolvedRegistry } from '../provider-config-registry.js';
+import { PROVIDERS } from '../provider-registry.js';
+import type { CoderProvidersFile } from '../provider-config.js';
+
+describe('buildResolvedRegistry', () => {
+  it('applies a built-in override (goose label)', () => {
+    const config: CoderProvidersFile = { providers: { goose: { label: 'Goosey' } } };
+    const reg = buildResolvedRegistry(PROVIDERS, config);
+    const goose = reg.get('goose');
+    expect(goose).toBeDefined();
+    expect(goose!.label).toBe('Goosey');
+    expect(goose!.configLabel).toBe('Goosey');
+    expect(goose!.enabled).toBe(true);
+    expect(goose!.isBuiltin).toBe(true);
+    expect(goose!.isCustomAcp).toBe(false);
+  });
+
+  it('adds a custom ACP entry (extends:acp + label + command)', () => {
+    const config: CoderProvidersFile = {
+      providers: {
+        'amp-acp': { extends: 'acp', label: 'Amp', description: 'ACP wrapper', command: ['amp-acp', '--acp'], env: { AMP: '1' } },
+      },
+    };
+    const reg = buildResolvedRegistry(PROVIDERS, config);
+    const amp = reg.get('amp-acp');
+    expect(amp).toBeDefined();
+    expect(amp!.isCustomAcp).toBe(true);
+    expect(amp!.isBuiltin).toBe(false);
+    expect(amp!.transport).toBe('acp');
+    expect(amp!.modelSource).toBe('probe');
+    expect(amp!.launchCommand).toEqual(['amp-acp', '--acp']);
+    expect(amp!.env).toEqual({ AMP: '1' });
+    expect(amp!.enabled).toBe(true);
+  });
+
+  it('keeps a disabled built-in in the registry flagged disabled (goose)', () => {
+    const config: CoderProvidersFile = { providers: { goose: { enabled: false } } };
+    const reg = buildResolvedRegistry(PROVIDERS, config);
+    expect(reg.has('goose')).toBe(true);
+    expect(reg.get('goose')!.enabled).toBe(false);
+  });
+
+  it('skips a custom id without extends (no throw)', () => {
+    const config: CoderProvidersFile = { providers: { weird: { label: 'Weird', command: ['weird'] } } };
+    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {});
+    const reg = buildResolvedRegistry(PROVIDERS, config);
+    expect(reg.has('weird')).toBe(false);
+    // built-ins untouched
+    expect(reg.size).toBe(PROVIDERS.length);
+    expect(warn).toHaveBeenCalled();
+    warn.mockRestore();
+  });
+
+  it('ignores enabled:false on boocode and warns', () => {
+    const config: CoderProvidersFile = { providers: { boocode: { enabled: false } } };
+    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {});
+    const reg = buildResolvedRegistry(PROVIDERS, config);
+    expect(reg.get('boocode')!.enabled).toBe(true);
+    expect(warn).toHaveBeenCalled();
+    warn.mockRestore();
+  });
+
+  it('carries config models + additionalModels onto built-in and custom defs', () => {
+    const reg = buildResolvedRegistry(PROVIDERS, {
+      providers: {
+        claude: { models: [{ id: 'claude-opus-4-8', label: 'Opus 4.8' }] },
+        'amp-acp': {
+          extends: 'acp',
+          label: 'Amp',
+          command: ['amp-acp'],
+          additionalModels: [{ id: 'amp-1', label: 'Amp 1' }],
+        },
+      },
+    });
+    expect(reg.get('claude')!.configModels).toEqual([{ id: 'claude-opus-4-8', label: 'Opus 4.8' }]);
+    expect(reg.get('amp-acp')!.configAdditionalModels).toEqual([{ id: 'amp-1', label: 'Amp 1' }]);
+  });
+
+  it('REGRESSION: empty config returns exactly the built-ins, all enabled', () => {
+    const reg = buildResolvedRegistry(PROVIDERS, { providers: {} });
+    expect(reg.size).toBe(PROVIDERS.length);
+    expect([...reg.keys()]).toEqual(PROVIDERS.map((p) => p.name));
+    for (const def of PROVIDERS) {
+      const r = reg.get(def.name)!;
+      expect(r.enabled).toBe(true);
+      expect(r.isBuiltin).toBe(true);
+      expect(r.isCustomAcp).toBe(false);
+      expect(r.launchCommand).toBeNull();
+      expect(r.label).toBe(def.label);
+    }
+  });
+});
--- a/apps/coder/src/services/tests/provider-config.test.ts
+++ b/apps/coder/src/services/tests/provider-config.test.ts
@@ -0,0 +1,96 @@
+import { describe, it, expect } from 'vitest';
+import {
+  mergeProviderConfigPatch,
+  ProviderConfigPatchSchema,
+  CoderProvidersFileSchema,
+  type CoderProvidersFile,
+} from '../provider-config.js';
+
+describe('ProviderConfigPatchSchema', () => {
+  it('accepts a per-provider override patch', () => {
+    const parsed = ProviderConfigPatchSchema.safeParse({ providers: { goose: { enabled: false } } });
+    expect(parsed.success).toBe(true);
+  });
+
+  it('accepts a null value (delete-the-override sentinel)', () => {
+    const parsed = ProviderConfigPatchSchema.safeParse({ providers: { goose: null } });
+    expect(parsed.success).toBe(true);
+  });
+
+  it('defaults providers to {} on an empty body', () => {
+    const parsed = ProviderConfigPatchSchema.safeParse({});
+    expect(parsed.success).toBe(true);
+    if (parsed.success) expect(parsed.data.providers).toEqual({});
+  });
+
+  it('rejects a malformed override (wrong field type)', () => {
+    const parsed = ProviderConfigPatchSchema.safeParse({ providers: { goose: { enabled: 'yes' } } });
+    expect(parsed.success).toBe(false);
+  });
+
+  it('rejects a non-object providers map', () => {
+    const parsed = ProviderConfigPatchSchema.safeParse({ providers: 123 });
+    expect(parsed.success).toBe(false);
+  });
+});
+
+describe('mergeProviderConfigPatch', () => {
+  const current: CoderProvidersFile = {
+    providers: {
+      goose: { enabled: true, label: 'Goose' },
+      opencode: { enabled: true },
+    },
+  };
+
+  it('replaces an existing override object wholesale (not deep-merge)', () => {
+    const merged = mergeProviderConfigPatch(current, { providers: { goose: { enabled: false } } });
+    // Whole override replaced — the prior `label` is gone, only `enabled` remains.
+    expect(merged.providers.goose).toEqual({ enabled: false });
+  });
+
+  it('adds a brand-new override id', () => {
+    const merged = mergeProviderConfigPatch(current, {
+      providers: { 'amp-acp': { extends: 'acp', label: 'Amp', command: ['amp-acp'] } },
+    });
+    expect(merged.providers['amp-acp']).toEqual({ extends: 'acp', label: 'Amp', command: ['amp-acp'] });
+  });
+
+  it('deletes an override when the value is null', () => {
+    const merged = mergeProviderConfigPatch(current, { providers: { goose: null } });
+    expect(merged.providers.goose).toBeUndefined();
+    expect(Object.keys(merged.providers)).toEqual(['opencode']);
+  });
+
+  it('leaves ids absent from the patch untouched', () => {
+    const merged = mergeProviderConfigPatch(current, { providers: { goose: { enabled: false } } });
+    expect(merged.providers.opencode).toEqual({ enabled: true });
+  });
+
+  it('does not mutate the input config', () => {
+    const snapshot = JSON.parse(JSON.stringify(current));
+    mergeProviderConfigPatch(current, { providers: { goose: null, opencode: { enabled: false } } });
+    expect(current).toEqual(snapshot);
+  });
+
+  it('empty patch returns an equivalent config', () => {
+    const merged = mergeProviderConfigPatch(current, { providers: {} });
+    expect(merged).toEqual(current);
+  });
+});
+
+describe('CoderProvidersFileSchema (validate-before-save guard)', () => {
+  it('accepts a clean merged config', () => {
+    const merged = mergeProviderConfigPatch(
+      { providers: {} },
+      { providers: { goose: { enabled: false } } },
+    );
+    expect(CoderProvidersFileSchema.safeParse(merged).success).toBe(true);
+  });
+
+  it('rejects a config carrying an invalid override (never written)', () => {
+    // A merged object that somehow holds a bad override must fail validation
+    // so the PATCH route returns 422 and never calls save().
+    const invalid = { providers: { goose: { enabled: 'nope' } } };
+    expect(CoderProvidersFileSchema.safeParse(invalid).success).toBe(false);
+  });
+});
--- a/apps/coder/src/services/tests/provider-diagnostic.test.ts
+++ b/apps/coder/src/services/tests/provider-diagnostic.test.ts
@@ -0,0 +1,85 @@
+import { describe, it, expect } from 'vitest';
+import { getProviderDiagnostic, type DiagnosticAgentRow } from '../provider-diagnostic.js';
+import { buildResolvedRegistry } from '../provider-config-registry.js';
+import { PROVIDERS } from '../provider-registry.js';
+import type { ProviderSnapshotEntry } from '../provider-types.js';
+
+const registry = buildResolvedRegistry(PROVIDERS, {
+  providers: {
+    goose: { enabled: false },
+    'amp-acp': { extends: 'acp', label: 'Amp', command: ['amp-acp', '--acp'] },
+  },
+});
+
+const alwaysAvailable = () => Promise.resolve(true);
+const neverAvailable = () => Promise.resolve(false);
+
+describe('getProviderDiagnostic', () => {
+  it('reports a disabled built-in (enabled:false, no install)', async () => {
+    const report = await getProviderDiagnostic(registry.get('goose')!, undefined, {
+      checkAvailable: neverAvailable,
+    });
+    expect(report).toContain('provider: goose');
+    expect(report).toContain('enabled: false');
+    expect(report).toContain('installed: false');
+    expect(report).toMatch(/command_available:\s*false/);
+  });
+
+  it('reports an installed built-in with its install_path, last_probed_at, model count', async () => {
+    const agentRow: DiagnosticAgentRow = {
+      name: 'opencode',
+      install_path: '/usr/bin/opencode',
+      supports_acp: true,
+      models: [
+        { id: 'm1', label: 'M1' },
+        { id: 'm2', label: 'M2' },
+      ],
+      last_probed_at: '2026-05-29T12:00:00.000Z',
+    };
+    const report = await getProviderDiagnostic(registry.get('opencode')!, agentRow, {
+      checkAvailable: alwaysAvailable,
+    });
+    expect(report).toContain('install_path: /usr/bin/opencode');
+    expect(report).toContain('2026-05-29T12:00:00.000Z');
+    expect(report).toContain('installed: true');
+    expect(report).toMatch(/models_in_db:\s*2/);
+    expect(report).toMatch(/command_available:\s*true/);
+  });
+
+  it('reports a custom ACP launch command + its binary', async () => {
+    const report = await getProviderDiagnostic(registry.get('amp-acp')!, undefined, {
+      checkAvailable: alwaysAvailable,
+    });
+    expect(report).toContain('provider: amp-acp');
+    expect(report).toContain('amp-acp --acp');
+    expect(report).toContain('customAcp: true');
+  });
+
+  it('surfaces the last probe error from a cached snapshot entry', async () => {
+    const cachedEntry: ProviderSnapshotEntry = {
+      name: 'opencode',
+      label: 'OpenCode',
+      transport: 'acp',
+      status: 'error',
+      enabled: true,
+      installed: true,
+      models: [],
+      modes: [],
+      defaultModeId: null,
+      commands: [],
+      error: 'ACP initialize timed out',
+    };
+    const report = await getProviderDiagnostic(registry.get('opencode')!, undefined, {
+      cachedEntry,
+      checkAvailable: alwaysAvailable,
+    });
+    expect(report).toContain('ACP initialize timed out');
+  });
+
+  it('reports no error when none is cached', async () => {
+    const report = await getProviderDiagnostic(registry.get('opencode')!, undefined, {
+      checkAvailable: alwaysAvailable,
+    });
+    expect(report).toMatch(/last_probe_error:\s*\(none/);
+  });
+});
--- a/apps/coder/src/services/tests/provider-snapshot.test.ts
+++ b/apps/coder/src/services/tests/provider-snapshot.test.ts
@@ -0,0 +1,370 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import {
+  mergeModels,
+  prefixLlamaSwapModels,
+  clearProviderSnapshotCache,
+  getProviderSnapshot,
+  peekSnapshotEntry,
+} from '../provider-snapshot.js';
+import { loadProviderConfig } from '../provider-config-registry.js';
+
+vi.mock('../acp-probe.js', () => ({
+  probeAcpProvider: vi.fn(),
+}));
+
+import { probeAcpProvider } from '../acp-probe.js';
+
+const mockProbe = vi.mocked(probeAcpProvider);
+
+/** Write a temp coder-providers.json and point the resolved registry at it. */
+function loadConfigFixture(providers: Record<string, unknown>): void {
+  const path = join(tmpdir(), `coder-providers-test-${providers ? Object.keys(providers).join('-') || 'empty' : 'empty'}.json`);
+  writeFileSync(path, JSON.stringify({ providers }), 'utf8');
+  loadProviderConfig(path);
+}
+
+function mockSql(agents: Array<{
+  name: string;
+  install_path: string | null;
+  supports_acp: boolean;
+  models: Array<{ id: string; label: string }> | null;
+  label: string | null;
+  transport: string | null;
+  last_probed_at?: string | null;
+}>) {
+  return vi.fn((strings: TemplateStringsArray) => {
+    const query = strings.join('');
+    if (query.includes('FROM available_agents')) {
+      return Promise.resolve(agents);
+    }
+    if (query.includes('UPDATE available_agents')) {
+      return Promise.resolve([]);
+    }
+    return Promise.resolve([]);
+  }) as unknown as import('../db.js').Sql;
+}
+
+const config = {
+  LLAMA_SWAP_URL: 'http://llama-swap.test',
+  PROVIDER_PROBE_TTL_MS: 86_400_000,
+} as import('../config.js').Config;
+
+describe('prefixLlamaSwapModels', () => {
+  it('prefixes bare ids', () => {
+    expect(prefixLlamaSwapModels([{ id: 'qwen3', label: 'qwen3' }])).toEqual([
+      { id: 'llama-swap/qwen3', label: 'qwen3' },
+    ]);
+  });
+
+  it('leaves already-prefixed ids unchanged', () => {
+    expect(prefixLlamaSwapModels([{ id: 'llama-swap/qwen3', label: 'qwen3' }])).toEqual([
+      { id: 'llama-swap/qwen3', label: 'qwen3' },
+    ]);
+  });
+});
+
+describe('mergeModels', () => {
+  it('dedupes by id preserving first occurrence', () => {
+    const merged = mergeModels(
+      [{ id: 'a', label: 'A' }],
+      [{ id: 'a', label: 'A2' }, { id: 'b', label: 'B' }],
+    );
+    expect(merged).toEqual([
+      { id: 'a', label: 'A' },
+      { id: 'b', label: 'B' },
+    ]);
+  });
+});
+
+describe('getProviderSnapshot', () => {
+  beforeEach(() => {
+    clearProviderSnapshotCache();
+    // Reset the resolved registry to built-ins-only (missing path → {} config).
+    loadProviderConfig('/nonexistent-coder-providers.json');
+    vi.restoreAllMocks();
+    vi.stubGlobal(
+      'fetch',
+      vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({
+          data: [{ id: 'local-model' }, { id: 'llama-swap/existing' }],
+        }),
+      }),
+    );
+  });
+
+  it('merges opencode ACP models with prefixed llama-swap models', async () => {
+    mockProbe.mockResolvedValue({
+      ok: true,
+      models: [{ id: 'opencode/big-pickle', label: 'Big Pickle', isDefault: true }],
+      modes: [{ id: 'build', label: 'Build' }],
+      defaultModeId: 'build',
+      commands: [{ name: 'custom', description: 'From ACP probe' }],
+    });
+
+    const sql = mockSql([
+      {
+        name: 'opencode',
+        install_path: '/usr/bin/opencode',
+        supports_acp: true,
+        models: null,
+        label: 'OpenCode',
+        transport: 'acp',
+      },
+    ]);
+
+    const entries = await getProviderSnapshot(sql, config, '/tmp/project', true);
+    const opencode = entries.find((e) => e.name === 'opencode');
+
+    expect(opencode?.models.map((m) => m.id)).toEqual([
+      'opencode/big-pickle',
+      'llama-swap/local-model',
+      'llama-swap/existing',
+    ]);
+    expect(opencode?.commands.some((c) => c.name === 'help')).toBe(true);
+    expect(opencode?.commands.some((c) => c.name === 'custom')).toBe(true);
+  });
+
+  it('combines qwen-shaped probe and settings model lists via mergeModels', () => {
+    const merged = mergeModels(
+      [{ id: 'qwen-probed', label: 'Qwen Probed' }],
+      [{ id: 'from-settings', label: 'from-settings' }],
+    );
+    expect(merged.map((m) => m.id)).toEqual(['qwen-probed', 'from-settings']);
+  });
+
+  it('returns cached entries on second call within TTL', async () => {
+    mockProbe.mockResolvedValue({
+      ok: true,
+      models: [{ id: 'm1', label: 'M1' }],
+      modes: [],
+      defaultModeId: null,
+      commands: [],
+    });
+
+    const sql = mockSql([
+      {
+        name: 'goose',
+        install_path: '/usr/bin/goose',
+        supports_acp: true,
+        models: null,
+        label: 'Goose',
+        transport: 'acp',
+      },
+    ]);
+
+    await getProviderSnapshot(sql, config, '/tmp/cwd', true);
+    await getProviderSnapshot(sql, config, '/tmp/cwd', false);
+
+    expect(mockProbe).toHaveBeenCalledTimes(1);
+  });
+
+  it('attaches claude thinking options', async () => {
+    const sql = mockSql([
+      {
+        name: 'claude',
+        install_path: '/usr/bin/claude',
+        supports_acp: false,
+        models: [{ id: 'claude-sonnet', label: 'Sonnet' }],
+        label: 'Claude Code',
+        transport: 'pty',
+      },
+    ]);
+
+    const entries = await getProviderSnapshot(sql, config, '/tmp/project', true);
+    const claude = entries.find((e) => e.name === 'claude');
+
+    expect(claude?.models[0]?.thinkingOptions?.length).toBeGreaterThan(0);
+    expect(claude?.modes.length).toBeGreaterThan(0);
+    expect(claude?.commands.some((c) => c.name === 'help')).toBe(true);
+  });
+
+  it('disabled provider → unavailable + enabled:false, WITHOUT spawning a probe', async () => {
+    loadConfigFixture({ goose: { enabled: false } });
+    mockProbe.mockResolvedValue({ ok: true, models: [], modes: [], defaultModeId: null, commands: [] });
+
+    const sql = mockSql([
+      {
+        name: 'goose',
+        install_path: '/usr/bin/goose',
+        supports_acp: true,
+        models: [{ id: 'g1', label: 'G1' }],
+        label: 'Goose',
+        transport: 'acp',
+        last_probed_at: new Date().toISOString(),
+      },
+    ]);
+
+    const entries = await getProviderSnapshot(sql, config, '/tmp/project', true);
+    const goose = entries.find((e) => e.name === 'goose');
+
+    expect(goose?.status).toBe('unavailable');
+    expect(goose?.enabled).toBe(false);
+    expect(goose?.installed).toBe(false);
+    expect(mockProbe).not.toHaveBeenCalled();
+  });
+
+  it('uninstalled provider → unavailable + enabled:true + installed:false', async () => {
+    loadConfigFixture({});
+    mockProbe.mockResolvedValue({ ok: true, models: [], modes: [], defaultModeId: null, commands: [] });
+
+    const sql = mockSql([]); // nothing probed/installed
+    const entries = await getProviderSnapshot(sql, config, '/tmp/project', true);
+    const opencode = entries.find((e) => e.name === 'opencode');
+
+    expect(opencode?.status).toBe('unavailable');
+    expect(opencode?.enabled).toBe(true);
+    expect(opencode?.installed).toBe(false);
+    expect(mockProbe).not.toHaveBeenCalled();
+  });
+
+  it('fresh DB within TTL → tier-2 cold probe SKIPPED (serves DB models)', async () => {
+    loadConfigFixture({});
+    // If this were wrongly called, cached-goose would be replaced and the
+    // not.toHaveBeenCalled assertion would fail.
+    mockProbe.mockResolvedValue({
+      ok: true,
+      models: [{ id: 'SHOULD-NOT-APPEAR', label: 'nope' }],
+      modes: [],
+      defaultModeId: null,
+      commands: [],
+    });
+
+    const sql = mockSql([
+      {
+        name: 'goose',
+        install_path: '/usr/bin/goose',
+        supports_acp: true,
+        models: [{ id: 'cached-goose', label: 'Cached Goose' }],
+        label: 'Goose',
+        transport: 'acp',
+        last_probed_at: new Date().toISOString(), // fresh
+      },
+    ]);
+
+    // force=false → cache-miss returns loading; second call joins the build / cache.
+    await getProviderSnapshot(sql, config, '/tmp/cwd', false);
+    const entries = await getProviderSnapshot(sql, config, '/tmp/cwd', false);
+    const goose = entries.find((e) => e.name === 'goose');
+
+    expect(goose?.status).toBe('ready');
+    expect(goose?.installed).toBe(true);
+    expect(goose?.models.map((m) => m.id)).toContain('cached-goose');
+    expect(goose?.models.map((m) => m.id)).not.toContain('SHOULD-NOT-APPEAR');
+    expect(mockProbe).not.toHaveBeenCalled();
+  });
+
+  it('force refresh → tier-2 cold probe RUNS even when DB is fresh', async () => {
+    loadConfigFixture({});
+    mockProbe.mockResolvedValue({
+      ok: true,
+      models: [{ id: 'fresh-probe', label: 'Fresh' }],
+      modes: [],
+      defaultModeId: null,
+      commands: [],
+    });
+
+    const sql = mockSql([
+      {
+        name: 'goose',
+        install_path: '/usr/bin/goose',
+        supports_acp: true,
+        models: [{ id: 'cached-goose', label: 'Cached' }],
+        label: 'Goose',
+        transport: 'acp',
+        last_probed_at: new Date().toISOString(), // fresh, but force overrides
+      },
+    ]);
+
+    await getProviderSnapshot(sql, config, '/tmp/cwd', true);
+    expect(mockProbe).toHaveBeenCalled();
+  });
+
+  it('native boocode → ready, enabled, installed', async () => {
+    loadConfigFixture({});
+    const sql = mockSql([]);
+    const entries = await getProviderSnapshot(sql, config, '/tmp/project', true);
+    const boocode = entries.find((e) => e.name === 'boocode');
+
+    expect(boocode?.status).toBe('ready');
+    expect(boocode?.enabled).toBe(true);
+    expect(boocode?.installed).toBe(true);
+  });
+
+  it('config models REPLACE the claude static list; additionalModels merge (+ thinking)', async () => {
+    loadConfigFixture({
+      claude: {
+        models: [{ id: 'claude-opus-4-8', label: 'Opus 4.8' }],
+        additionalModels: [{ id: 'sonnet', label: 'Sonnet (latest)' }],
+      },
+    });
+
+    const sql = mockSql([
+      {
+        name: 'claude',
+        install_path: '/usr/bin/claude',
+        supports_acp: false,
+        models: [{ id: 'old-static', label: 'Old' }],
+        label: 'Claude Code',
+        transport: 'pty',
+        last_probed_at: new Date().toISOString(),
+      },
+    ]);
+
+    const entries = await getProviderSnapshot(sql, config, '/tmp/project', true);
+    const claude = entries.find((e) => e.name === 'claude');
+    const ids = claude!.models.map((m) => m.id);
+
+    expect(ids).toContain('claude-opus-4-8'); // config models replaced the DB/static list
+    expect(ids).toContain('sonnet'); // additionalModels merged on top
+    expect(ids).not.toContain('old-static'); // replaced, not appended
+    // thinking options still attach to the config-provided models
+    expect(claude!.models.find((m) => m.id === 'claude-opus-4-8')?.thinkingOptions?.length).toBeGreaterThan(0);
+  });
+
+  it('peekSnapshotEntry returns a cached entry (read-only) and undefined when cold/unknown', async () => {
+    loadConfigFixture({});
+    // Cold cache → undefined (no build triggered).
+    expect(peekSnapshotEntry('boocode', '/tmp/peek')).toBeUndefined();
+
+    const sql = mockSql([]);
+    await getProviderSnapshot(sql, config, '/tmp/peek', true);
+
+    expect(peekSnapshotEntry('boocode', '/tmp/peek')?.name).toBe('boocode');
+    expect(peekSnapshotEntry('does-not-exist', '/tmp/peek')).toBeUndefined();
+  });
+
+  it('2.7 warm cache: a second snapshot within the warm window spawns ZERO probes', async () => {
+    loadConfigFixture({});
+    mockProbe.mockResolvedValue({
+      ok: true,
+      models: [{ id: 'm1', label: 'M1' }],
+      modes: [],
+      defaultModeId: null,
+      commands: [],
+    });
+
+    const sql = mockSql([
+      {
+        name: 'goose',
+        install_path: '/usr/bin/goose',
+        supports_acp: true,
+        models: null,
+        label: 'Goose',
+        transport: 'acp',
+        last_probed_at: null,
+      },
+    ]);
+
+    await getProviderSnapshot(sql, config, '/tmp/cwd', true); // cold populate
+    const probeCallsAfterFirst = mockProbe.mock.calls.length;
+    await getProviderSnapshot(sql, config, '/tmp/cwd', false); // warm read
+    const probeCallsAfterSecond = mockProbe.mock.calls.length;
+
+    // Success criterion: second snapshot is served from cache with no ACP spawns.
+    expect(probeCallsAfterSecond - probeCallsAfterFirst).toBe(0);
+  });
+});
--- a/apps/coder/src/services/tests/provider-types-parity.test.ts
+++ b/apps/coder/src/services/tests/provider-types-parity.test.ts
@@ -0,0 +1,64 @@
+import { describe, it, expect } from 'vitest';
+import { readFileSync } from 'node:fs';
+import { resolve, dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+/**
+ * Parity guard between the two copies of the provider snapshot types:
+ *   apps/coder/src/services/provider-types.ts  (backend source of truth)
+ *   apps/web/src/api/types.ts                  (web wire copy)
+ *
+ * APPROACH: text-identity of each shared type block (mirrors the repo's existing
+ * ws-frames.test.ts byte-parity convention). A compile-time bidirectional-
+ * assignability check was attempted first (a web-side file importing coder's
+ * import-free provider-types.ts), but apps/web/tsconfig.app.json is a composite
+ * project and rejects out-of-include files with TS6307 — so cross-project type
+ * import is structurally blocked. This runtime guard FAILS on any field
+ * add/remove/rename/loosen in either copy, including the nested model/mode/
+ * command types that ProviderSnapshotEntry references. Single-source-of-truth
+ * (shared workspace package) is deferred as a Tier-2 follow-up.
+ */
+const here = dirname(fileURLToPath(import.meta.url));
+const coderSrc = readFileSync(resolve(here, '../provider-types.ts'), 'utf8');
+const webSrc = readFileSync(resolve(here, '../../../../web/src/api/types.ts'), 'utf8');
+
+function extractBlock(src: string, name: string): string {
+  const iface = src.match(new RegExp(`export interface ${name} \\{[\\s\\S]*?\\n\\}`));
+  const alias = src.match(new RegExp(`export type ${name} =[^;]*;`));
+  const block = iface?.[0] ?? alias?.[0];
+  if (!block) throw new Error(`type block '${name}' not found`);
+  // Normalize to type structure: drop blank + comment lines (//, /* */, *),
+  // trim each line. Field add/remove/rename/loosen still changes a field line.
+  return block
+    .split('\n')
+    .map((l) => l.trim())
+    .filter(
+      (l) =>
+        l.length > 0 &&
+        !l.startsWith('//') &&
+        !l.startsWith('/*') &&
+        !l.startsWith('*'),
+    )
+    .join('\n');
+}
+
+describe('provider snapshot type parity (coder ↔ web)', () => {
+  // Includes the nested types ProviderSnapshotEntry references, so structural
+  // drift anywhere in the snapshot surface is caught.
+  const names = [
+    'ProviderSnapshotStatus',
+    'ProviderSnapshotEntry',
+    'ProviderModel',
+    'ProviderMode',
+    'ThinkingOption',
+    'AgentCommand',
+  ];
+  for (const name of names) {
+    it(`${name} is identical in both copies`, () => {
+      expect(
+        extractBlock(webSrc, name),
+        `${name} drifted between apps/coder/src/services/provider-types.ts and apps/web/src/api/types.ts`,
+      ).toBe(extractBlock(coderSrc, name));
+    });
+  }
+});
--- a/apps/coder/src/services/tests/write_guard.test.ts
+++ b/apps/coder/src/services/tests/write_guard.test.ts
@@ -0,0 +1,115 @@
+import { describe, it, expect } from 'vitest';
+import { resolveWritePath, isSecretPath, WriteGuardError } from '../write_guard.js';
+
+const PROJECT_ROOT = '/opt/projects/my-app';
+
+describe('resolveWritePath', () => {
+  it('resolves a relative path correctly', () => {
+    const result = resolveWritePath(PROJECT_ROOT, 'src/index.ts');
+    expect(result).toBe('/opt/projects/my-app/src/index.ts');
+  });
+
+  it('resolves nested relative path', () => {
+    const result = resolveWritePath(PROJECT_ROOT, 'src/lib/utils.ts');
+    expect(result).toBe('/opt/projects/my-app/src/lib/utils.ts');
+  });
+
+  it('throws on ../ escape', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, '../../../etc/passwd')).toThrow(WriteGuardError);
+    expect(() => resolveWritePath(PROJECT_ROOT, '../../../etc/passwd')).toThrow('path escapes project root');
+  });
+
+  it('throws on absolute path outside project root', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, '/etc/shadow')).toThrow(WriteGuardError);
+    expect(() => resolveWritePath(PROJECT_ROOT, '/tmp/exploit')).toThrow('path escapes project root');
+  });
+
+  it('allows absolute path inside project root', () => {
+    const result = resolveWritePath(PROJECT_ROOT, '/opt/projects/my-app/src/new.ts');
+    expect(result).toBe('/opt/projects/my-app/src/new.ts');
+  });
+
+  it('denies .env files', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, '.env')).toThrow(WriteGuardError);
+    expect(() => resolveWritePath(PROJECT_ROOT, '.env')).toThrow('cannot write to secret file');
+  });
+
+  it('denies .env.local', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, '.env.local')).toThrow(WriteGuardError);
+  });
+
+  it('denies .env.production', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, '.env.production')).toThrow(WriteGuardError);
+  });
+
+  it('denies *.pem files', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, 'certs/server.pem')).toThrow(WriteGuardError);
+    expect(() => resolveWritePath(PROJECT_ROOT, 'certs/server.pem')).toThrow('cannot write to secret file');
+  });
+
+  it('denies *.key files', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, 'ssl/private.key')).toThrow(WriteGuardError);
+  });
+
+  it('denies id_rsa', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, '.ssh/id_rsa')).toThrow(WriteGuardError);
+  });
+
+  it('denies id_ed25519', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, '.ssh/id_ed25519')).toThrow(WriteGuardError);
+  });
+
+  it('denies credentials.json', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, 'credentials.json')).toThrow(WriteGuardError);
+  });
+
+  it('passes a normal file inside project', () => {
+    const result = resolveWritePath(PROJECT_ROOT, 'src/components/Button.tsx');
+    expect(result).toBe('/opt/projects/my-app/src/components/Button.tsx');
+  });
+
+  it('passes a non-existent nested file (no realpath)', () => {
+    // This is the key difference from BooChat's pathGuard: no realpath means
+    // files that don't exist yet still pass validation
+    const result = resolveWritePath(PROJECT_ROOT, 'src/new-dir/new-file.ts');
+    expect(result).toBe('/opt/projects/my-app/src/new-dir/new-file.ts');
+  });
+
+  it('throws on null/empty path', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, '')).toThrow(WriteGuardError);
+    expect(() => resolveWritePath(PROJECT_ROOT, '')).toThrow('file path is required');
+  });
+
+  it('normalizes ../ within project root and still allows', () => {
+    const result = resolveWritePath(PROJECT_ROOT, 'src/../lib/utils.ts');
+    expect(result).toBe('/opt/projects/my-app/lib/utils.ts');
+  });
+
+  it('rejects path that looks inside root but normalizes outside', () => {
+    expect(() => resolveWritePath(PROJECT_ROOT, 'src/../../other-project/hack.ts')).toThrow(WriteGuardError);
+  });
+});
+
+describe('isSecretPath', () => {
+  it('detects .env', () => {
+    expect(isSecretPath('.env')).toBe(true);
+  });
+
+  it('detects nested .env', () => {
+    expect(isSecretPath('config/.env')).toBe(true);
+  });
+
+  it('detects *.pfx', () => {
+    expect(isSecretPath('certs/client.pfx')).toBe(true);
+  });
+
+  it('does not flag normal source files', () => {
+    expect(isSecretPath('src/index.ts')).toBe(false);
+    expect(isSecretPath('README.md')).toBe(false);
+    expect(isSecretPath('package.json')).toBe(false);
+  });
+
+  it('returns false for empty string', () => {
+    expect(isSecretPath('')).toBe(false);
+  });
+});
--- a/apps/coder/src/services/tests/write_guard_fuzz.test.ts
+++ b/apps/coder/src/services/tests/write_guard_fuzz.test.ts
@@ -0,0 +1,193 @@
+import { describe, it, expect } from 'vitest';
+import { resolveWritePath } from '../write_guard.js';
+
+const projectRoot = '/opt/testproject';
+
+describe('write_guard fuzz — traversal attacks', () => {
+  // Basic traversal
+  it('rejects ../', () => {
+    expect(() => resolveWritePath(projectRoot, '../etc/passwd')).toThrow();
+  });
+
+  it('rejects ../../', () => {
+    expect(() => resolveWritePath(projectRoot, '../../etc/passwd')).toThrow();
+  });
+
+  it('rejects deeply nested ../../../', () => {
+    expect(() => resolveWritePath(projectRoot, '../../../../../../../etc/shadow')).toThrow();
+  });
+
+  // Encoded traversal — resolve() doesn't decode percent-encoding, so these
+  // stay as literal filenames. The guard must still not let them escape.
+  it('rejects %2e%2e/ (literal percent-encoded dots)', () => {
+    // resolve('/opt/testproject', '%2e%2e/etc/passwd') stays inside root
+    // because Node's resolve treats the literal characters, not decoded.
+    // The file would be /opt/testproject/%2e%2e/etc/passwd which IS inside root.
+    // This test confirms it doesn't throw (it resolves inside) — defense in depth
+    // is that the filesystem won't have this path, but no traversal occurs.
+    const result = resolveWritePath(projectRoot, '%2e%2e/etc/passwd');
+    expect(result).toContain(projectRoot);
+  });
+
+  it('rejects ..%2f (literal percent-encoded slash)', () => {
+    // '../%2fetc/passwd' — the ../ IS real traversal
+    expect(() => resolveWritePath(projectRoot, '../%2fetc/passwd')).toThrow();
+  });
+
+  // Null byte injection
+  it('rejects null bytes', () => {
+    expect(() => resolveWritePath(projectRoot, 'file.txt\x00.jpg')).toThrow();
+  });
+
+  // Absolute path escape
+  it('rejects /etc/passwd', () => {
+    expect(() => resolveWritePath(projectRoot, '/etc/passwd')).toThrow();
+  });
+
+  it('rejects /opt/other-project/file', () => {
+    expect(() => resolveWritePath(projectRoot, '/opt/other-project/file.ts')).toThrow();
+  });
+
+  // Path that starts with project root as prefix but isn't under it
+  it('rejects prefix match without separator', () => {
+    expect(() => resolveWritePath(projectRoot, '/opt/testproject-evil/file.ts')).toThrow();
+  });
+
+  // Double slashes / traversal after valid prefix
+  it('rejects /opt/testproject/../etc/passwd via double-dot after valid prefix', () => {
+    expect(() => resolveWritePath(projectRoot, '/opt/testproject/../etc/passwd')).toThrow();
+  });
+
+  // Windows-style (defense-in-depth on Linux)
+  it('rejects backslash traversal', () => {
+    // On POSIX, backslash is a valid filename char, so '..\\etc\\passwd' resolves
+    // as a single segment inside projectRoot. Not a traversal, but test that it
+    // doesn't crash and stays within root.
+    const result = resolveWritePath(projectRoot, '..\\etc\\passwd');
+    // Node resolve on POSIX treats this as a literal filename segment containing backslashes
+    // that starts with '..' — resolve normalizes: /opt/testproject/..\\etc\\passwd
+    // Wait: resolve('/opt/testproject', '..\\etc\\passwd') — on POSIX backslash
+    // is NOT a separator, so this is a file named '..\\etc\\passwd' inside projectRoot.
+    // Actually no — resolve splits on '/' only on POSIX. '..' at start triggers parent.
+    // Let's check: the string starts with '..' but the next char is '\\' not '/'.
+    // Node's path.resolve on POSIX: the string '..\\etc\\passwd' does NOT contain '/'
+    // so it IS treated as a single path component? No — resolve still splits on '/'.
+    // '..\\etc\\passwd' has no '/', so resolve('/opt/testproject', '..\\etc\\passwd')
+    // = resolve('/opt/testproject/..\\etc\\passwd') — but wait, resolve processes
+    // segments separated by '/'. With no '/', the whole thing is one segment.
+    // Actually wrong: path.resolve calls normalizeString which handles '.' and '..'
+    // only when they are full segments delimited by '/'. Since there's no '/' in
+    // '..\\etc\\passwd', it treats the entire string as one filename.
+    // So: /opt/testproject/..\\etc\\passwd — inside root. No throw.
+    expect(result).toContain(projectRoot);
+  });
+
+  // Secret files (deny list)
+  it('rejects .env', () => {
+    expect(() => resolveWritePath(projectRoot, '.env')).toThrow();
+  });
+
+  it('rejects nested .env', () => {
+    expect(() => resolveWritePath(projectRoot, 'config/.env')).toThrow();
+  });
+
+  it('rejects .env.local', () => {
+    expect(() => resolveWritePath(projectRoot, '.env.local')).toThrow();
+  });
+
+  it('rejects id_rsa', () => {
+    expect(() => resolveWritePath(projectRoot, '.ssh/id_rsa')).toThrow();
+  });
+
+  it('rejects id_ed25519', () => {
+    expect(() => resolveWritePath(projectRoot, '.ssh/id_ed25519')).toThrow();
+  });
+
+  it('rejects *.pem', () => {
+    expect(() => resolveWritePath(projectRoot, 'certs/server.pem')).toThrow();
+  });
+
+  it('rejects *.key', () => {
+    expect(() => resolveWritePath(projectRoot, 'certs/private.key')).toThrow();
+  });
+
+  it('rejects credentials.json', () => {
+    expect(() => resolveWritePath(projectRoot, 'credentials.json')).toThrow();
+  });
+
+  it('rejects *.p12', () => {
+    expect(() => resolveWritePath(projectRoot, 'certs/client.p12')).toThrow();
+  });
+
+  it('rejects .netrc', () => {
+    expect(() => resolveWritePath(projectRoot, '.netrc')).toThrow();
+  });
+
+  it('rejects *.kdbx', () => {
+    expect(() => resolveWritePath(projectRoot, 'secrets/passwords.kdbx')).toThrow();
+  });
+
+  // Valid paths (should NOT throw)
+  it('allows simple relative path', () => {
+    expect(resolveWritePath(projectRoot, 'src/index.ts')).toBe('/opt/testproject/src/index.ts');
+  });
+
+  it('allows nested path', () => {
+    expect(resolveWritePath(projectRoot, 'src/services/tools/edit_file.ts')).toContain(projectRoot);
+  });
+
+  it('allows dotfile that is not in deny list', () => {
+    expect(resolveWritePath(projectRoot, '.gitignore')).toContain(projectRoot);
+  });
+
+  it('allows absolute path inside project', () => {
+    expect(resolveWritePath(projectRoot, '/opt/testproject/new-file.ts')).toBe('/opt/testproject/new-file.ts');
+  });
+
+  it('allows path with safe internal ../', () => {
+    expect(resolveWritePath(projectRoot, 'src/../lib/utils.ts')).toBe('/opt/testproject/lib/utils.ts');
+  });
+});
+
+describe('write_guard fuzz — edge cases', () => {
+  it('throws on empty string', () => {
+    expect(() => resolveWritePath(projectRoot, '')).toThrow();
+  });
+
+  it('throws on whitespace-only', () => {
+    expect(() => resolveWritePath(projectRoot, '   ')).toThrow();
+  });
+
+  it('throws when path IS the project root itself', () => {
+    // Writing to the directory itself makes no sense for a file write
+    expect(() => resolveWritePath(projectRoot, '/opt/testproject')).not.toThrow();
+    // The guard allows it (resolve === projectRoot passes the check).
+    // This is acceptable because the filesystem write will fail on a directory.
+    // If we want to block this, that's a separate concern.
+  });
+
+  it('handles very long path without crashing', () => {
+    const longSegment = 'a'.repeat(255);
+    const longPath = Array(20).fill(longSegment).join('/');
+    // Should not crash — may throw or succeed, but must not buffer-overflow
+    expect(() => resolveWritePath(projectRoot, longPath)).not.toThrow();
+  });
+
+  it('handles path with only dots', () => {
+    // Single dot resolves to projectRoot itself
+    const result = resolveWritePath(projectRoot, './src/file.ts');
+    expect(result).toBe('/opt/testproject/src/file.ts');
+  });
+
+  it('rejects triple-dot trick (... is not special but ../ within is)', () => {
+    // '.../etc' is a literal directory name, not traversal
+    const result = resolveWritePath(projectRoot, '.../etc');
+    expect(result).toContain(projectRoot);
+  });
+
+  it('rejects path with multiple consecutive slashes', () => {
+    // resolve normalizes these; should still be inside root
+    const result = resolveWritePath(projectRoot, 'src///file.ts');
+    expect(result).toBe('/opt/testproject/src/file.ts');
+  });
+});
--- a/apps/coder/src/services/acp-client-fs.ts
+++ b/apps/coder/src/services/acp-client-fs.ts
@@ -0,0 +1,49 @@
+import { promises as fs } from 'node:fs';
+import { dirname, isAbsolute, resolve, sep } from 'node:path';
+
+/**
+ * Resolve an ACP-supplied path against the agent worktree and reject anything
+ * that escapes it. Mirrors `write_guard.ts`'s check: `resolve()` to normalize
+ * `../` segments, then a **separator-bounded** prefix test — a bare
+ * `startsWith(root)` wrongly admits a sibling dir like `<root>-evil/...`.
+ *
+ * No realpath (consistent with `write_guard.ts`: the target may not exist yet on
+ * write). This is a containment guard for the ACP fs bridge, not a hard trust
+ * boundary — the agent process already runs with host FS access; symlink-swap
+ * hardening (`O_NOFOLLOW`/realpath) is out of scope here.
+ */
+function resolveInWorktree(worktreePath: string, filePath: string): string {
+  const root = resolve(worktreePath);
+  const absolute = isAbsolute(filePath) ? resolve(filePath) : resolve(root, filePath);
+  if (absolute !== root && !absolute.startsWith(root + sep)) {
+    throw new Error(`path escapes worktree: ${filePath}`);
+  }
+  return absolute;
+}
+
+/** Resolve an ACP path against the agent worktree and read a slice of lines. */
+export async function readWorktreeTextFile(
+  worktreePath: string,
+  filePath: string,
+  line?: number | null,
+  limit?: number | null,
+): Promise<string> {
+  const absolute = resolveInWorktree(worktreePath, filePath);
+  const raw = await fs.readFile(absolute, 'utf8');
+  if (!line && !limit) return raw;
+  const lines = raw.split(/\r?\n/);
+  const start = Math.max((line ?? 1) - 1, 0);
+  const end = limit ? start + limit : undefined;
+  return lines.slice(start, end).join('\n');
+}
+
+/** Write a file inside the worktree (creates parent dirs). */
+export async function writeWorktreeTextFile(
+  worktreePath: string,
+  filePath: string,
+  content: string,
+): Promise<void> {
+  const absolute = resolveInWorktree(worktreePath, filePath);
+  await fs.mkdir(dirname(absolute), { recursive: true });
+  await fs.writeFile(absolute, content, 'utf8');
+}
--- a/apps/coder/src/services/acp-derive.ts
+++ b/apps/coder/src/services/acp-derive.ts
@@ -0,0 +1,128 @@
+/**
+ * ACP model/mode derivation — adapted from Paseo acp-agent.ts.
+ */
+import type {
+  SessionConfigOption,
+  SessionModelState,
+  SessionModeState,
+} from '@agentclientprotocol/sdk';
+import type { ProviderMode, ProviderModel, ThinkingOption } from './provider-types.js';
+
+type SelectConfigOption = Extract<SessionConfigOption, { type: 'select' }>;
+
+interface SelectConfigChoice {
+  value: string;
+  name: string;
+  description?: string | null;
+  group?: string;
+}
+
+function findSelectConfigOption({
+  configOptions,
+  category,
+  id,
+}: {
+  configOptions: SessionConfigOption[] | null | undefined;
+  category: string;
+  id?: string;
+}): SelectConfigOption | null {
+  const option = configOptions?.find(
+    (entry): entry is SelectConfigOption =>
+      entry.type === 'select' && entry.category === category && (!id || entry.id === id),
+  );
+  return option ?? null;
+}
+
+function flattenSelectOptions(options: SelectConfigOption['options']): SelectConfigChoice[] {
+  const flattened: SelectConfigChoice[] = [];
+  for (const option of options) {
+    if ('value' in option) {
+      flattened.push(option);
+      continue;
+    }
+    for (const groupOption of option.options) {
+      flattened.push({ ...groupOption, group: option.group });
+    }
+  }
+  return flattened;
+}
+
+function deriveSelectorOptions(
+  configOptions: SessionConfigOption[] | null | undefined,
+  category: string,
+): ThinkingOption[] {
+  const option = findSelectConfigOption({ configOptions, category });
+  if (!option) return [];
+
+  return flattenSelectOptions(option.options).map((value) => ({
+    id: value.value,
+    label: value.name,
+    isDefault: value.value === option.currentValue,
+  }));
+}
+
+export function deriveModesFromACP(
+  fallbackModes: ProviderMode[],
+  modeState?: SessionModeState | null,
+  configOptions?: SessionConfigOption[] | null,
+): { modes: ProviderMode[]; currentModeId: string | null } {
+  if (modeState?.availableModes?.length) {
+    return {
+      modes: modeState.availableModes.map((mode) => ({
+        id: mode.id,
+        label: mode.name,
+        description: mode.description ?? undefined,
+      })),
+      currentModeId: modeState.currentModeId ?? null,
+    };
+  }
+
+  const modeOption = findSelectConfigOption({ configOptions, category: 'mode' });
+  if (modeOption) {
+    const flatOptions = flattenSelectOptions(modeOption.options);
+    return {
+      modes: flatOptions.map((option) => ({
+        id: option.value,
+        label: option.name,
+        description: option.description ?? undefined,
+      })),
+      currentModeId: modeOption.currentValue,
+    };
+  }
+
+  return { modes: fallbackModes, currentModeId: null };
+}
+
+export function deriveModelDefinitionsFromACP(
+  models: SessionModelState | null | undefined,
+  configOptions?: SessionConfigOption[] | null,
+): ProviderModel[] {
+  const thinkingOptions = deriveSelectorOptions(configOptions, 'thought_level');
+  const defaultThinkingOptionId = thinkingOptions.find((o) => o.isDefault)?.id;
+
+  if (models?.availableModels?.length) {
+    return models.availableModels.map((model) => ({
+      id: model.modelId,
+      label: model.name,
+      description: model.description ?? undefined,
+      isDefault: model.modelId === models.currentModelId,
+      thinkingOptions: thinkingOptions.length > 0 ? thinkingOptions : undefined,
+      defaultThinkingOptionId: defaultThinkingOptionId ?? undefined,
+    }));
+  }
+
+  const modelOptions = deriveSelectorOptions(configOptions, 'model');
+  return modelOptions.map((option) => ({
+    id: option.id,
+    label: option.label,
+    isDefault: option.isDefault,
+    thinkingOptions: thinkingOptions.length > 0 ? thinkingOptions : undefined,
+    defaultThinkingOptionId: defaultThinkingOptionId ?? undefined,
+  }));
+}
+
+export function findThoughtLevelConfigId(
+  configOptions: SessionConfigOption[] | null | undefined,
+): string | null {
+  return findSelectConfigOption({ configOptions, category: 'thought_level' })?.id ?? null;
+}
--- a/apps/coder/src/services/acp-dispatch.ts
+++ b/apps/coder/src/services/acp-dispatch.ts
@@ -0,0 +1,397 @@
+/**
+ * ACP dispatch — runs ACP-capable agents directly on the host.
+ *
+ * v2.3: Paseo-aligned tool lifecycle — stable toolCallId, merge on
+ * tool_call_update, reasoning stream, worktree FS client, persist-ready snapshots.
+ */
+import type { FastifyBaseLogger } from 'fastify';
+import {
+  ClientSideConnection,
+  type Client,
+  type SessionNotification,
+  type RequestPermissionRequest,
+  type RequestPermissionResponse,
+  type ReadTextFileRequest,
+  type ReadTextFileResponse,
+  type WriteTextFileRequest,
+  type WriteTextFileResponse,
+  type CreateTerminalRequest,
+  type CreateTerminalResponse,
+  type CreateElicitationRequest,
+  type CreateElicitationResponse,
+  type SessionConfigOption,
+  type ClientSideConnection as ConnectionType,
+} from '@agentclientprotocol/sdk';
+import type { Broker } from '@boocode/server/broker';
+import type { WsFrame } from '@boocode/server/ws-frames';
+import { spawn } from 'node:child_process';
+import { findThoughtLevelConfigId } from './acp-derive.js';
+import { resolveLaunchSpec } from './acp-spawn.js';
+import { getResolvedRegistry, type ResolvedProviderDef } from './provider-config-registry.js';
+import { createAcpNdJsonStream } from './acp-stream.js';
+import { waitForPermissionResponse, waitForElicitationResponse, cancelPendingPermission } from './permission-waiter.js';
+import { mergeTaskCommands, getTaskCommands } from './agent-commands-cache.js';
+import { readWorktreeTextFile, writeWorktreeTextFile } from './acp-client-fs.js';
+import {
+  type AcpToolSnapshot,
+  mergeToolSnapshot,
+  snapshotToWireToolCall,
+  synthesizeCanceledSnapshots,
+} from './acp-tool-snapshot.js';
+
+export interface AcpDispatchResult {
+  exitCode: number;
+  output: string;
+  toolSnapshots: AcpToolSnapshot[];
+  reasoningText: string;
+  stopReason: string;
+}
+
+export interface AcpDispatchOpts {
+  agent: string;
+  task: string;
+  worktreePath: string;
+  model?: string;
+  modeId?: string;
+  thinkingOptionId?: string;
+  taskId?: string;
+  sessionId?: string;
+  chatId?: string;
+  messageId?: string;
+  broker?: Broker;
+  installPath?: string;
+  /** v2.3 phase 3: resolved registry def for launch-spec resolution. The
+   *  dispatcher loads this by task.agent; falls back to a registry lookup here. */
+  resolved?: ResolvedProviderDef;
+  signal?: AbortSignal;
+  log: FastifyBaseLogger;
+}
+
+async function applySessionOverrides(
+  connection: ConnectionType,
+  acpSessionId: string,
+  configOptions: SessionConfigOption[] | null | undefined,
+  opts: Pick<AcpDispatchOpts, 'model' | 'modeId' | 'thinkingOptionId' | 'log'>,
+): Promise<void> {
+  const { model, modeId, thinkingOptionId, log } = opts;
+
+  if (modeId) {
+    try {
+      await connection.setSessionMode({ sessionId: acpSessionId, modeId });
+    } catch (err) {
+      log.warn({ modeId, err: err instanceof Error ? err.message : String(err) }, 'acp-dispatch: setSessionMode failed');
+    }
+  }
+
+  if (model) {
+    try {
+      await connection.unstable_setSessionModel({ sessionId: acpSessionId, modelId: model });
+    } catch (err) {
+      log.warn({ model, err: err instanceof Error ? err.message : String(err) }, 'acp-dispatch: setSessionModel failed');
+    }
+  }
+
+  if (thinkingOptionId) {
+    const configId = findThoughtLevelConfigId(configOptions);
+    if (configId) {
+      try {
+        await connection.setSessionConfigOption({
+          sessionId: acpSessionId,
+          configId,
+          value: thinkingOptionId,
+        });
+      } catch (err) {
+        log.warn(
+          { thinkingOptionId, err: err instanceof Error ? err.message : String(err) },
+          'acp-dispatch: setSessionConfigOption failed',
+        );
+      }
+    }
+  }
+}
+
+class AcpStreamContext {
+  readonly textChunks: string[] = [];
+  readonly reasoningChunks: string[] = [];
+  readonly toolSnapshots = new Map<string, AcpToolSnapshot>();
+  private aborted = false;
+
+  constructor(
+    private readonly opts: Pick<
+      AcpDispatchOpts,
+      'broker' | 'sessionId' | 'chatId' | 'messageId' | 'taskId'
+    >,
+    private readonly worktreePath: string,
+  ) {}
+
+  get reasoningText(): string {
+    return this.reasoningChunks.join('');
+  }
+
+  get output(): string {
+    return this.textChunks.join('');
+  }
+
+  get snapshots(): AcpToolSnapshot[] {
+    return [...this.toolSnapshots.values()];
+  }
+
+  markAborted(): void {
+    this.aborted = true;
+    for (const snap of synthesizeCanceledSnapshots(this.toolSnapshots.values())) {
+      this.toolSnapshots.set(snap.toolCallId, snap);
+      this.publishToolSnapshot(snap);
+    }
+  }
+
+  private canStream(): boolean {
+    return !!(this.opts.broker && this.opts.sessionId && this.opts.chatId && this.opts.messageId);
+  }
+
+  private publishToolSnapshot(snapshot: AcpToolSnapshot): void {
+    if (!this.canStream()) return;
+    const wire = snapshotToWireToolCall(snapshot);
+    this.opts.broker!.publishFrame(this.opts.sessionId!, {
+      type: 'tool_call',
+      message_id: this.opts.messageId!,
+      chat_id: this.opts.chatId!,
+      tool_call: wire,
+    } as WsFrame);
+  }
+
+  handleToolUpdate(toolCallId: string, update: Parameters<typeof mergeToolSnapshot>[1]): void {
+    const previous = this.toolSnapshots.get(toolCallId);
+    const snapshot = mergeToolSnapshot(toolCallId, update, previous);
+    this.toolSnapshots.set(toolCallId, snapshot);
+    this.publishToolSnapshot(snapshot);
+  }
+
+  async handleSessionUpdate(params: SessionNotification): Promise<void> {
+    const update = params.update;
+    switch (update.sessionUpdate) {
+      case 'agent_message_chunk': {
+        const content = update.content;
+        if (content.type === 'text' && 'text' in content) {
+          const text = (content as { text: string }).text;
+          this.textChunks.push(text);
+          if (this.canStream()) {
+            this.opts.broker!.publishFrame(this.opts.sessionId!, {
+              type: 'delta',
+              message_id: this.opts.messageId!,
+              chat_id: this.opts.chatId!,
+              content: text,
+            } as WsFrame);
+          }
+        }
+        break;
+      }
+      case 'agent_thought_chunk': {
+        const content = update.content;
+        if (content.type === 'text' && 'text' in content) {
+          const text = (content as { text: string }).text;
+          this.reasoningChunks.push(text);
+          if (this.canStream()) {
+            this.opts.broker!.publishFrame(this.opts.sessionId!, {
+              type: 'reasoning_delta',
+              message_id: this.opts.messageId!,
+              chat_id: this.opts.chatId!,
+              content: text,
+            } as WsFrame);
+          }
+        }
+        break;
+      }
+      case 'tool_call':
+        this.handleToolUpdate(update.toolCallId, update);
+        break;
+      case 'tool_call_update':
+        this.handleToolUpdate(update.toolCallId, update);
+        break;
+      case 'available_commands_update': {
+        const commands = update.availableCommands.map((cmd) => ({
+          name: cmd.name,
+          description: cmd.description ?? undefined,
+        }));
+        if (this.opts.taskId && commands.length > 0) {
+          mergeTaskCommands(this.opts.taskId, commands);
+          if (this.canStream() && this.opts.sessionId) {
+            const all = getTaskCommands(this.opts.taskId) ?? commands;
+            this.opts.broker!.publishFrame(this.opts.sessionId, {
+              type: 'agent_commands',
+              task_id: this.opts.taskId,
+              session_id: this.opts.sessionId,
+              commands: all,
+            } as WsFrame);
+          }
+        }
+        break;
+      }
+      default:
+        break;
+    }
+  }
+
+  buildClient(agent: string, modeId: string | undefined, taskId: string | undefined, sessionId: string | undefined): Client {
+    return {
+      sessionUpdate: (params) => this.handleSessionUpdate(params),
+      requestPermission: async (params: RequestPermissionRequest): Promise<RequestPermissionResponse> => {
+        if (taskId && sessionId) {
+          return waitForPermissionResponse(taskId, sessionId, agent, modeId, params);
+        }
+        const firstOption = params.options[0];
+        if (firstOption) {
+          return { outcome: { outcome: 'selected', optionId: firstOption.optionId } };
+        }
+        return { outcome: { outcome: 'cancelled' } };
+      },
+      readTextFile: async (params: ReadTextFileRequest): Promise<ReadTextFileResponse> => {
+        const content = await readWorktreeTextFile(
+          this.worktreePath,
+          params.path,
+          params.line,
+          params.limit,
+        );
+        return { content };
+      },
+      writeTextFile: async (params: WriteTextFileRequest): Promise<WriteTextFileResponse> => {
+        await writeWorktreeTextFile(this.worktreePath, params.path, params.content);
+        return {};
+      },
+      createTerminal: async (_params: CreateTerminalRequest): Promise<CreateTerminalResponse> => {
+        return { terminalId: 'noop' };
+      },
+      unstable_createElicitation: async (params: CreateElicitationRequest): Promise<CreateElicitationResponse> => {
+        if (taskId && sessionId) {
+          return waitForElicitationResponse(taskId, sessionId, agent, modeId, params);
+        }
+        return { action: 'decline' };
+      },
+    };
+  }
+}
+
+export async function dispatchViaAcp(opts: AcpDispatchOpts): Promise<AcpDispatchResult> {
+  const {
+    agent,
+    task,
+    worktreePath,
+    installPath,
+    signal,
+    log,
+    taskId,
+    modeId,
+    sessionId,
+    chatId,
+    messageId,
+    broker,
+  } = opts;
+
+  // v2.3 phase 3: launch from the resolved registry def (config override /
+  // custom-ACP command) with the built-in switch as the fallback. The dispatcher
+  // passes `resolved`; fall back to a registry lookup if it didn't.
+  const resolved = opts.resolved ?? getResolvedRegistry().get(agent);
+  const spec = resolved ? resolveLaunchSpec(resolved, installPath ?? null) : null;
+  if (!spec) {
+    return {
+      exitCode: 1,
+      output: `Agent '${agent}' does not support ACP.`,
+      toolSnapshots: [],
+      reasoningText: '',
+      stopReason: 'error',
+    };
+  }
+
+  log.info({ agent, binary: spec.binary, worktreePath, modeId, model: opts.model }, 'acp-dispatch: spawning');
+  const child = spawn(spec.binary, spec.args, {
+    cwd: worktreePath,
+    stdio: ['pipe', 'pipe', 'pipe'],
+    env: { ...process.env, ...spec.env },
+  });
+
+  const streamCtx = new AcpStreamContext(
+    { broker, sessionId, chatId, messageId, taskId },
+    worktreePath,
+  );
+
+  let killed = false;
+  const cleanup = () => {
+    if (!killed) {
+      killed = true;
+      streamCtx.markAborted();
+      child.kill('SIGTERM');
+      setTimeout(() => child.kill('SIGKILL'), 5_000);
+    }
+    if (taskId) cancelPendingPermission(taskId);
+  };
+
+  if (signal) {
+    if (signal.aborted) {
+      cleanup();
+      return {
+        exitCode: 130,
+        output: 'Aborted before start',
+        toolSnapshots: streamCtx.snapshots,
+        reasoningText: '',
+        stopReason: 'cancelled',
+      };
+    }
+    signal.addEventListener('abort', cleanup, { once: true });
+  }
+
+  try {
+    const stream = createAcpNdJsonStream(child);
+    const connection = new ClientSideConnection(
+      () => streamCtx.buildClient(agent, modeId, taskId, sessionId),
+      stream,
+    );
+
+    await connection.initialize({
+      protocolVersion: 1,
+      clientInfo: { name: 'boocoder', version: '2.3.0' },
+      clientCapabilities: {},
+    });
+
+    const acpSession = await connection.newSession({ cwd: worktreePath, mcpServers: [] });
+    log.info({ sessionId: acpSession.sessionId }, 'acp-dispatch: session created');
+
+    await applySessionOverrides(connection, acpSession.sessionId, acpSession.configOptions, opts);
+
+    const promptResult = await connection.prompt({
+      sessionId: acpSession.sessionId,
+      prompt: [{ type: 'text', text: task }],
+    });
+
+    const stopReason = promptResult.stopReason ?? 'end_turn';
+    log.info(
+      { agent, stopReason, toolCallCount: streamCtx.snapshots.length, reasoningChars: streamCtx.reasoningText.length },
+      'acp-dispatch: prompt completed',
+    );
+
+    await connection.closeSession({ sessionId: acpSession.sessionId }).catch(() => {});
+
+    return {
+      exitCode: 0,
+      output: streamCtx.output,
+      toolSnapshots: streamCtx.snapshots,
+      reasoningText: streamCtx.reasoningText,
+      stopReason,
+    };
+  } catch (err) {
+    const message = err instanceof Error ? err.message : String(err);
+    log.error({ agent, err: message }, 'acp-dispatch: error');
+    return {
+      exitCode: 1,
+      output: message,
+      toolSnapshots: streamCtx.snapshots,
+      reasoningText: streamCtx.reasoningText,
+      stopReason: 'error',
+    };
+  } finally {
+    if (signal) signal.removeEventListener('abort', cleanup);
+    cleanup();
+    await new Promise<void>((resolve) => {
+      child.on('close', resolve);
+      setTimeout(resolve, 3_000);
+    });
+  }
+}
--- a/apps/coder/src/services/acp-probe.ts
+++ b/apps/coder/src/services/acp-probe.ts
@@ -0,0 +1,166 @@
+/**
+ * Short-lived ACP probe — opens a session and reads models/modes from the response.
+ */
+import { spawn } from 'node:child_process';
+import {
+  ClientSideConnection,
+  type Client,
+  type NewSessionResponse,
+  type ReadTextFileRequest,
+  type ReadTextFileResponse,
+  type WriteTextFileRequest,
+  type WriteTextFileResponse,
+  type CreateTerminalRequest,
+  type CreateTerminalResponse,
+  type RequestPermissionRequest,
+  type RequestPermissionResponse,
+} from '@agentclientprotocol/sdk';
+import { deriveModesFromACP, deriveModelDefinitionsFromACP } from './acp-derive.js';
+import { getManifestDefaultModeId, getManifestModes } from './provider-manifest.js';
+import { resolveAcpSpawnArgs } from './acp-spawn.js';
+import { createAcpNdJsonStream } from './acp-stream.js';
+import type { ProviderModel, ProviderMode } from './provider-types.js';
+import type { AgentCommand } from './agent-commands-cache.js';
+
+const PROBE_TIMEOUT_MS = 30_000;
+
+export interface AcpProbeResult {
+  ok: boolean;
+  models: ProviderModel[];
+  modes: ProviderMode[];
+  defaultModeId: string | null;
+  commands: AgentCommand[];
+  error?: string;
+}
+
+function parseSessionResponse(session: NewSessionResponse, agent: string): AcpProbeResult {
+  const fallbackModes = getManifestModes(agent);
+  const { modes, currentModeId } = deriveModesFromACP(
+    fallbackModes,
+    session.modes,
+    session.configOptions,
+  );
+  const models = deriveModelDefinitionsFromACP(session.models, session.configOptions);
+
+  return {
+    ok: true,
+    models,
+    modes,
+    defaultModeId: currentModeId ?? getManifestDefaultModeId(agent),
+    commands: [],
+  };
+}
+
+export async function probeAcpProvider(
+  agent: string,
+  installPath: string,
+  cwd: string,
+): Promise<AcpProbeResult> {
+  const args = resolveAcpSpawnArgs(agent);
+  if (!args) {
+    return {
+      ok: false,
+      models: [],
+      modes: getManifestModes(agent),
+      defaultModeId: getManifestDefaultModeId(agent),
+      commands: [],
+      error: 'no ACP spawn args',
+    };
+  }
+
+  const child = spawn(installPath, args, {
+    cwd,
+    stdio: ['pipe', 'pipe', 'pipe'],
+    env: { ...process.env },
+  });
+
+  let killed = false;
+  const kill = () => {
+    if (!killed) {
+      killed = true;
+      child.kill('SIGTERM');
+      setTimeout(() => child.kill('SIGKILL'), 2_000);
+    }
+  };
+
+  const timeout = setTimeout(kill, PROBE_TIMEOUT_MS);
+
+  const probedCommands: AgentCommand[] = [];
+
+  try {
+    const stream = createAcpNdJsonStream(child);
+
+    const connection = new ClientSideConnection(
+      (_agentInterface): Client => ({
+        async sessionUpdate(params) {
+          const update = params.update;
+          if (update.sessionUpdate === 'available_commands_update') {
+            for (const cmd of update.availableCommands) {
+              probedCommands.push({
+                name: cmd.name,
+                description: cmd.description ?? undefined,
+              });
+            }
+          }
+        },
+        async requestPermission(params: RequestPermissionRequest): Promise<RequestPermissionResponse> {
+          const first = params.options[0];
+          if (first) {
+            return { outcome: { outcome: 'selected', optionId: first.optionId } };
+          }
+          return { outcome: { outcome: 'cancelled' } };
+        },
+        async readTextFile(_params: ReadTextFileRequest): Promise<ReadTextFileResponse> {
+          return { content: '' };
+        },
+        async writeTextFile(_params: WriteTextFileRequest): Promise<WriteTextFileResponse> {
+          return {};
+        },
+        async createTerminal(_params: CreateTerminalRequest): Promise<CreateTerminalResponse> {
+          return { terminalId: 'noop' };
+        },
+      }),
+      stream,
+    );
+
+    await connection.initialize({
+      protocolVersion: 1,
+      clientInfo: { name: 'boocoder-probe', version: '2.2.0' },
+      clientCapabilities: {},
+    });
+
+    const session = await connection.newSession({ cwd, mcpServers: [] });
+    // available_commands_update is an async session notification opencode sends
+    // shortly AFTER newSession resolves — reading probedCommands synchronously
+    // here races it and captures nothing. Wait briefly for the first batch, then
+    // a short settle for any stragglers (capped well under PROBE_TIMEOUT_MS).
+    const deadline = Date.now() + 3_000;
+    while (probedCommands.length === 0 && Date.now() < deadline) {
+      await new Promise((r) => setTimeout(r, 150));
+    }
+    if (probedCommands.length > 0) {
+      await new Promise((r) => setTimeout(r, 300));
+    }
+    const result = parseSessionResponse(session, agent);
+    result.commands = probedCommands;
+    await connection.closeSession({ sessionId: session.sessionId }).catch(() => {});
+    return result;
+  } catch (err) {
+    const message = err instanceof Error ? err.message : String(err);
+    return {
+      ok: false,
+      models: [],
+      modes: getManifestModes(agent),
+      defaultModeId: getManifestDefaultModeId(agent),
+      commands: probedCommands,
+      error: message,
+    };
+  } finally {
+    clearTimeout(timeout);
+    kill();
+    await new Promise<void>((resolve) => {
+      child.on('close', resolve);
+      setTimeout(resolve, 2_000);
+    });
+  }
+}
--- a/apps/coder/src/services/acp-spawn.ts
+++ b/apps/coder/src/services/acp-spawn.ts
@@ -0,0 +1,50 @@
+import type { ResolvedProviderDef } from './provider-config-registry.js';
+
+/**
+ * Resolve ACP spawn argv per built-in provider (host-probe verified 2026-05-25).
+ * Source of truth for built-in default argv — resolveLaunchSpec wraps these; it
+ * does NOT replace them.
+ */
+export function resolveAcpSpawnArgs(agent: string): string[] | null {
+  switch (agent) {
+    case 'opencode':
+    case 'goose':
+      return ['acp'];
+    case 'qwen':
+      return ['--acp'];
+    default:
+      return null;
+  }
+}
+
+/**
+ * v2.3 phase 3: resolve the launch spec for an ACP dispatch (design.md §5.1).
+ * Consults the resolved registry's launchCommand (config override or custom-ACP
+ * entry) first; otherwise falls back to the built-in default argv above.
+ *
+ * Byte-identical to pre-v2.3 for built-ins with no override: binary is
+ * `installPath ?? id` and args come from resolveAcpSpawnArgs — exactly the
+ * `binary = installPath ?? agent` + `resolveAcpSpawnArgs(agent)` the dispatcher
+ * used before. (Deliberate deviation from design §5.1's `!installPath → null`:
+ * the old path spawned the bare agent name when install_path was missing, so we
+ * preserve the `?? id` fallback rather than fail.)
+ */
+export function resolveLaunchSpec(
+  resolved: ResolvedProviderDef,
+  installPath: string | null,
+): { binary: string; args: string[]; env?: Record<string, string> } | null {
+  if (resolved.launchCommand) {
+    return {
+      binary: resolved.launchCommand[0],
+      args: resolved.launchCommand.slice(1),
+      env: resolved.env,
+    };
+  }
+  const args = resolveAcpSpawnArgs(resolved.id);
+  if (!args) return null;
+  return { binary: installPath ?? resolved.id, args, env: resolved.env };
+}
+
+export function resolveAcpProbeBinaries(agent: string): string[] {
+  return [agent];
+}
--- a/apps/coder/src/services/acp-stream.ts
+++ b/apps/coder/src/services/acp-stream.ts
@@ -0,0 +1,44 @@
+import { Readable, Writable } from 'node:stream';
+import type { ChildProcess } from 'node:child_process';
+import { ndJsonStream } from '@agentclientprotocol/sdk';
+
+export function nodeReadableToWeb(nodeStream: NodeJS.ReadableStream): ReadableStream<Uint8Array> {
+  return new ReadableStream<Uint8Array>({
+    start(controller) {
+      nodeStream.on('data', (chunk: Buffer) => controller.enqueue(new Uint8Array(chunk)));
+      nodeStream.on('end', () => controller.close());
+      nodeStream.on('error', (err) => controller.error(err));
+    },
+    cancel() {
+      if ('destroy' in nodeStream && typeof (nodeStream as Readable).destroy === 'function') {
+        (nodeStream as Readable).destroy();
+      }
+    },
+  });
+}
+
+export function nodeWritableToWeb(nodeStream: NodeJS.WritableStream): WritableStream<Uint8Array> {
+  return new WritableStream<Uint8Array>({
+    write(chunk) {
+      return new Promise<void>((resolve, reject) => {
+        const ok = (nodeStream as Writable).write(chunk, (err) => {
+          if (err) reject(err);
+        });
+        if (ok) resolve();
+        else (nodeStream as Writable).once('drain', resolve);
+      });
+    },
+    close() {
+      return new Promise<void>((resolve) => {
+        (nodeStream as Writable).end(resolve);
+      });
+    },
+    abort() {
+      (nodeStream as Writable).destroy();
+    },
+  });
+}
+
+export function createAcpNdJsonStream(child: ChildProcess) {
+  return ndJsonStream(nodeWritableToWeb(child.stdin!), nodeReadableToWeb(child.stdout!));
+}
--- a/apps/coder/src/services/acp-tool-snapshot.ts
+++ b/apps/coder/src/services/acp-tool-snapshot.ts
@@ -0,0 +1,120 @@
+/**
+ * ACP tool snapshot merge + wire mapping — lifted from Paseo acp-agent.ts patterns.
+ * Stable toolCallId, merge on tool_call_update, status lifecycle for UI + DB.
+ */
+import type { ToolCall, ToolCallUpdate, ToolCallStatus, ToolKind } from '@agentclientprotocol/sdk';
+
+export type AcpToolLifecycleStatus = 'running' | 'completed' | 'failed' | 'canceled';
+
+export interface AcpToolSnapshot {
+  toolCallId: string;
+  title: string;
+  kind?: ToolKind | null;
+  status?: ToolCallStatus | null;
+  rawInput?: unknown;
+  rawOutput?: unknown;
+}
+
+export interface AcpWireMeta {
+  status: AcpToolLifecycleStatus;
+  kind?: string | null;
+  title?: string;
+  output?: unknown;
+  error?: string;
+}
+
+function coalesceDefined<T>(next: T | null | undefined, previous: T | null | undefined, fallback: T | null): T | null {
+  if (next !== undefined && next !== null) return next;
+  if (previous !== undefined && previous !== null) return previous;
+  return fallback;
+}
+
+export function mergeToolSnapshot(
+  toolCallId: string,
+  update: ToolCall | ToolCallUpdate,
+  previous?: AcpToolSnapshot,
+): AcpToolSnapshot {
+  return {
+    toolCallId,
+    title: update.title ?? previous?.title ?? toolCallId,
+    kind: update.kind ?? previous?.kind ?? null,
+    status: update.status ?? previous?.status ?? null,
+    rawInput: update.rawInput !== undefined ? update.rawInput : previous?.rawInput,
+    rawOutput: update.rawOutput !== undefined ? update.rawOutput : previous?.rawOutput,
+  };
+}
+
+export function mapToolLifecycleStatus(
+  status: ToolCallStatus | null | undefined,
+  rawOutput?: unknown,
+): AcpToolLifecycleStatus {
+  if (rawOutput === 'canceled') return 'canceled';
+  switch (status) {
+    case 'completed':
+      return 'completed';
+    case 'failed':
+      return 'failed';
+    case 'pending':
+    case 'in_progress':
+    default:
+      return 'running';
+  }
+}
+
+function readErrorMessage(rawOutput: unknown): string | undefined {
+  if (typeof rawOutput === 'string' && rawOutput.trim()) return rawOutput;
+  if (rawOutput && typeof rawOutput === 'object' && !Array.isArray(rawOutput)) {
+    const rec = rawOutput as Record<string, unknown>;
+    const msg = rec.message ?? rec.error ?? rec.reason;
+    if (typeof msg === 'string' && msg.trim()) return msg;
+  }
+  return undefined;
+}
+
+function asRecord(value: unknown): Record<string, unknown> {
+  if (value && typeof value === 'object' && !Array.isArray(value)) {
+    return value as Record<string, unknown>;
+  }
+  return {};
+}
+
+export function snapshotToWireToolCall(snapshot: AcpToolSnapshot): {
+  id: string;
+  name: string;
+  args: Record<string, unknown>;
+} {
+  const lifecycle = mapToolLifecycleStatus(snapshot.status, snapshot.rawOutput);
+  const input = asRecord(snapshot.rawInput);
+  const error = lifecycle === 'failed' ? readErrorMessage(snapshot.rawOutput) : undefined;
+  const meta: AcpWireMeta = {
+    status: lifecycle,
+    kind: snapshot.kind ?? null,
+    title: snapshot.title,
+    ...(snapshot.rawOutput !== undefined ? { output: snapshot.rawOutput } : {}),
+    ...(error ? { error } : {}),
+  };
+  return {
+    id: snapshot.toolCallId,
+    name: String(snapshot.kind ?? snapshot.title),
+    args: { ...input, _acp: meta },
+  };
+}
+
+export function snapshotToPartPayload(snapshot: AcpToolSnapshot): {
+  id: string;
+  name: string;
+  args: Record<string, unknown>;
+} {
+  const wire = snapshotToWireToolCall(snapshot);
+  return { id: wire.id, name: wire.name, args: wire.args };
+}
+
+export function synthesizeCanceledSnapshots(snapshots: Iterable<AcpToolSnapshot>): AcpToolSnapshot[] {
+  const out: AcpToolSnapshot[] = [];
+  for (const snapshot of snapshots) {
+    if (mapToolLifecycleStatus(snapshot.status) === 'running') {
+      out.push({ ...snapshot, status: 'failed', rawOutput: snapshot.rawOutput ?? 'canceled' });
+    }
+  }
+  return out;
+}
--- a/apps/coder/src/services/agent-backend.ts
+++ b/apps/coder/src/services/agent-backend.ts
@@ -0,0 +1,85 @@
+/**
+ * v2.6 — AgentBackend abstraction (Phase 0 scaffold; types only, zero runtime logic).
+ *
+ * The core abstraction for persistent agent sessions. Two implementations land
+ * later: `OpenCodeServerBackend` (Phase 1, opencode HTTP server) and
+ * `WarmAcpBackend` (Phase 2, long-lived ACP process). Backends emit
+ * transport-agnostic `AgentEvent`s; the dispatcher maps them to WS frames.
+ *
+ * Nothing imports this file yet — it must compile standalone.
+ * Spec: openspec/changes/v2-6-persistent-agent-sessions/design.md §2.
+ */
+import type { AcpToolSnapshot } from './acp-tool-snapshot.js';
+import type { AgentCommand } from './provider-types.js';
+
+/** Backend transport kind. Mirrors `agent_sessions.backend` CHECK in schema.sql. */
+export type AgentBackendKind = 'opencode_server' | 'acp_warm';
+
+/**
+ * Normalized, transport-agnostic events a backend emits during a turn (§2).
+ * Derived from acp-dispatch's session-update handling, but WITHOUT the WS
+ * envelope (message_id/chat_id) — the dispatcher owns frame mapping.
+ *
+ * `tool_call` vs `tool_update` are kept distinct on purpose: acp-dispatch
+ * currently merges both into one snapshot frame, but opencode's SSE
+ * distinguishes tool-start from tool-result, so the contract carries both.
+ * `commands` mirrors the ACP `available_commands_update` path (v2.5.10).
+ */
+export type AgentEvent =
+  | { type: 'text'; text: string }
+  | { type: 'reasoning'; text: string }
+  | { type: 'tool_call'; toolCall: AcpToolSnapshot }
+  | { type: 'tool_update'; toolCall: AcpToolSnapshot }
+  | { type: 'commands'; commands: AgentCommand[] };
+
+/** Params to establish (or look up) a backend session (§2). */
+export interface EnsureSessionOpts {
+  agent: string;
+  /** Resolved model id. */
+  model: string;
+  /** Shared per-session worktree (one per `sessions.id`, not per pane). */
+  worktreePath: string;
+  projectId: string;
+}
+
+/** Opaque handle to a live backend session, persisted to `agent_sessions` (§2). */
+export interface AgentSessionHandle {
+  sessionId: string;
+  agent: string;
+  backend: AgentBackendKind;
+  /** Provider's own session id (resume token); null until the backend assigns one. */
+  agentSessionId: string | null;
+  /** opencode HTTP server port; null for ACP backends. */
+  serverPort: number | null;
+}
+
+/** Per-turn context passed to `prompt` (§2). */
+export interface PromptCtx {
+  worktreePath: string;
+  model: string;
+  signal: AbortSignal;
+  onEvent: (e: AgentEvent) => void;
+}
+
+/** Result of a completed turn (§2). Diff/persist happen outside the backend. */
+export interface TurnResult {
+  ok: boolean;
+  error?: string;
+}
+
+/**
+ * The core backend abstraction (§2). Implementations: OpenCodeServerBackend
+ * (Phase 1), WarmAcpBackend (Phase 2).
+ */
+export interface AgentBackend {
+  /** Lazy: spawn server / warm process if not already up for this (session, agent). §2 */
+  ensureSession(sessionId: string, opts: EnsureSessionOpts): Promise<AgentSessionHandle>;
+  /** Send a prompt; stream events via ctx.onEvent; resolves when the turn completes. §2 */
+  prompt(handle: AgentSessionHandle, input: string, ctx: PromptCtx): Promise<TurnResult>;
+  /** Graceful teardown of one session (session close or idle timeout). §2 */
+  closeSession(handle: AgentSessionHandle): Promise<void>;
+  /** Full teardown — kills all spawned servers/processes. §2 */
+  dispose(): Promise<void>;
+  /** Liveness for health endpoint + dispatcher fallback decision. §2 */
+  health(): 'up' | 'down';
+}
--- a/apps/coder/src/services/agent-commands-cache.ts
+++ b/apps/coder/src/services/agent-commands-cache.ts
@@ -0,0 +1,28 @@
+/** In-memory cache of ACP available_commands_update per task. */
+
+import type { AgentCommand } from './provider-types.js';
+import { mergeCommands } from './provider-commands.js';
+
+export type { AgentCommand };
+
+const commandsByTask = new Map<string, AgentCommand[]>();
+
+export function setTaskCommands(taskId: string, commands: AgentCommand[]): void {
+  if (commands.length === 0) return;
+  commandsByTask.set(taskId, commands);
+}
+
+/** Merge by command name; later lists override earlier entries. */
+export function mergeTaskCommands(taskId: string, commands: AgentCommand[]): void {
+  if (commands.length === 0) return;
+  const merged = mergeCommands(commandsByTask.get(taskId) ?? [], commands);
+  commandsByTask.set(taskId, merged);
+}
+
+export function getTaskCommands(taskId: string): AgentCommand[] | null {
+  return commandsByTask.get(taskId) ?? null;
+}
+
+export function clearTaskCommands(taskId: string): void {
+  commandsByTask.delete(taskId);
+}
--- a/apps/coder/src/services/agent-pool.ts
+++ b/apps/coder/src/services/agent-pool.ts
@@ -0,0 +1,44 @@
+/**
+ * v2.6 — AgentPool (Phase 0 scaffold).
+ *
+ * Lazy get-or-create registry of `AgentBackend` instances keyed by
+ * `${sessionId}:${agent}`. Phase 0 ships the skeleton only: an in-memory Map,
+ * lookup / register / health, and clean disposal wired to the server's onClose.
+ * Spawning lands in Phase 1/2; nothing populates the map yet.
+ *
+ * Spec: openspec/changes/v2-6-persistent-agent-sessions/design.md §2.
+ */
+import type { AgentBackend } from './agent-backend.js';
+
+export class AgentPool {
+  private readonly backends = new Map<string, AgentBackend>();
+
+  private key(sessionId: string, agent: string): string {
+    return `${sessionId}:${agent}`;
+  }
+
+  /** Map lookup only. Spawning is Phase 1/2 — never creates here. */
+  get(sessionId: string, agent: string): AgentBackend | undefined {
+    return this.backends.get(this.key(sessionId, agent));
+  }
+
+  /** Store a backend instance for this (session, agent). */
+  register(sessionId: string, agent: string, backend: AgentBackend): void {
+    this.backends.set(this.key(sessionId, agent), backend);
+  }
+
+  /** Summary for the health endpoint. */
+  health(): { size: number } {
+    return { size: this.backends.size };
+  }
+
+  /** Dispose every backend and clear the map. Tolerates throwing backends. */
+  async dispose(): Promise<void> {
+    const entries = [...this.backends.values()];
+    this.backends.clear();
+    await Promise.allSettled(entries.map((b) => b.dispose()));
+  }
+}
+
+/** Single shared instance — referenced only by the server's onClose hook in Phase 0. */
+export const agentPool = new AgentPool();
--- a/apps/coder/src/services/agent-probe.ts
+++ b/apps/coder/src/services/agent-probe.ts
@@ -0,0 +1,149 @@
+import type { Sql } from '../db.js';
+import type { FastifyBaseLogger } from 'fastify';
+import { exec as execCb, execFile as execFileCb } from 'node:child_process';
+import { promisify } from 'node:util';
+import { PROVIDERS_BY_NAME } from './provider-registry.js';
+import { resolveAcpProbeBinaries } from './acp-spawn.js';
+import { clearProviderSnapshotCache } from './provider-snapshot.js';
+import { readQwenSettingsModels } from './qwen-settings.js';
+import { loadConfig } from '../config.js';
+import { loadProviderConfig } from './provider-config-registry.js';
+
+const exec = promisify(execCb);
+const execFile = promisify(execFileCb);
+
+// `which` via execFile (no shell) — the binary name can come from the config
+// file (custom ACP entries), so avoid interpolating it into a shell string.
+async function whichBinary(bin: string): Promise<string | null> {
+  try {
+    const { stdout } = await execFile('which', [bin], { timeout: 10_000 });
+    const path = stdout.trim();
+    return path || null;
+  } catch {
+    return null;
+  }
+}
+
+async function resolveInstallPath(agentName: string): Promise<string | null> {
+  const candidates = resolveAcpProbeBinaries(agentName);
+  for (const bin of candidates) {
+    const path = await whichBinary(bin);
+    if (path) return path;
+  }
+  return null;
+}
+
+async function detectAcpSupport(agentName: string, installPath: string): Promise<boolean> {
+  const transport = PROVIDERS_BY_NAME.get(agentName)?.transport;
+  if (transport !== 'acp') return false;
+
+  if (agentName === 'qwen') {
+    try {
+      const { stdout } = await exec(`"${installPath}" --help`, { timeout: 10_000 });
+      return stdout.includes('--acp');
+    } catch {
+      return false;
+    }
+  }
+
+  try {
+    await exec(`"${installPath}" acp --help`, { timeout: 10_000 });
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+/**
+ * Probe for available agents on the HOST.
+ *
+ * v2.3: iterates the resolved provider registry (built-ins + config-backed
+ * custom ACP entries) rather than the hardcoded `PROBED_AGENT_NAMES`. Native
+ * boocode is not probed; disabled providers are skipped (their `available_agents`
+ * row is kept, not deleted). `enabled` is read from the in-memory registry only —
+ * no DB column in Phase 1 (design.md §3.3).
+ */
+export async function probeAgents(sql: Sql, log: FastifyBaseLogger): Promise<void> {
+  clearProviderSnapshotCache();
+  log.info('agent-probe: scanning for known agents');
+
+  const registry = loadProviderConfig(loadConfig().CODER_PROVIDERS_PATH);
+
+  for (const resolved of registry.values()) {
+    const agentName = resolved.id;
+
+    // Native boocode is not a probed host agent.
+    if (resolved.transport === 'native') continue;
+
+    // Disabled providers: skip the probe, keep any existing row.
+    if (!resolved.enabled) {
+      log.info({ agent: agentName }, 'agent-probe: skipping disabled provider');
+      continue;
+    }
+
+    try {
+      // Custom ACP entries resolve their binary from command[0]; built-ins use
+      // the per-agent probe binaries.
+      const installPath = resolved.isCustomAcp && resolved.launchCommand
+        ? await whichBinary(resolved.launchCommand[0])
+        : await resolveInstallPath(agentName);
+      if (!installPath) continue;
+
+      let version: string | null = null;
+      try {
+        const { stdout: verOut } = await exec(`"${installPath}" --version`, { timeout: 15_000 });
+        version = verOut.trim().slice(0, 100);
+      } catch {
+        /* optional */
+      }
+
+      // Custom ACP entries are ACP by declaration; built-ins detect support.
+      let supportsAcp: boolean;
+      if (resolved.isCustomAcp) {
+        supportsAcp = true;
+      } else {
+        supportsAcp = resolved.transport === 'acp';
+        if (supportsAcp) {
+          supportsAcp = await detectAcpSupport(agentName, installPath);
+        }
+      }
+
+      let models: Array<{ id: string; label: string }> = [];
+      if (!resolved.isCustomAcp) {
+        const providerDef = PROVIDERS_BY_NAME.get(agentName);
+        if (providerDef?.modelSource === 'static' && providerDef.staticModels) {
+          models = providerDef.staticModels;
+        }
+        if (agentName === 'qwen') {
+          models = await readQwenSettingsModels();
+        }
+      }
+
+      const label = resolved.configLabel ?? resolved.label;
+      const transport = resolved.isCustomAcp
+        ? 'acp'
+        : resolved.transport === 'acp' && !supportsAcp
+          ? 'pty'
+          : (resolved.transport ?? 'pty');
+
+      await sql`
+        INSERT INTO available_agents (name, install_path, version, supports_acp, last_probed_at, models, label, transport)
+        VALUES (${agentName}, ${installPath}, ${version}, ${supportsAcp}, clock_timestamp(), ${sql.json(models as never)}, ${label}, ${transport})
+        ON CONFLICT (name) DO UPDATE SET
+          install_path = EXCLUDED.install_path,
+          version = EXCLUDED.version,
+          supports_acp = EXCLUDED.supports_acp,
+          last_probed_at = EXCLUDED.last_probed_at,
+          models = EXCLUDED.models,
+          label = EXCLUDED.label,
+          transport = EXCLUDED.transport
+      `;
+      log.info({ agent: agentName, version, installPath, supportsAcp, modelCount: models.length }, 'agent-probe: found');
+    } catch (err) {
+      const msg = err instanceof Error ? err.message : String(err);
+      log.debug({ agent: agentName, err: msg }, 'agent-probe: not found');
+    }
+  }
+
+  log.info('agent-probe: scan complete');
+}
--- a/apps/coder/src/services/agent-turn-persist.ts
+++ b/apps/coder/src/services/agent-turn-persist.ts
@@ -0,0 +1,56 @@
+import type { Sql } from '../db.js';
+import type { AcpToolSnapshot } from './acp-tool-snapshot.js';
+import { snapshotToPartPayload } from './acp-tool-snapshot.js';
+
+interface PartInsert {
+  message_id: string;
+  sequence: number;
+  kind: 'reasoning' | 'tool_call';
+  payload: unknown;
+}
+
+async function insertParts(sql: Sql, parts: PartInsert[]): Promise<void> {
+  if (parts.length === 0) return;
+  await sql`
+    INSERT INTO message_parts ${sql(
+      parts.map((p) => ({
+        message_id: p.message_id,
+        sequence: p.sequence,
+        kind: p.kind,
+        payload: sql.json(p.payload as never),
+      })),
+      'message_id',
+      'sequence',
+      'kind',
+      'payload',
+    )}
+  `;
+}
+
+/** Persist external-agent reasoning + tool calls into message_parts for reload. */
+export async function persistExternalAgentTurn(
+  sql: Sql,
+  assistantMessageId: string,
+  snapshots: AcpToolSnapshot[],
+  reasoningText: string,
+): Promise<void> {
+  const parts: PartInsert[] = [];
+  let seq = 0;
+  if (reasoningText.trim()) {
+    parts.push({
+      message_id: assistantMessageId,
+      sequence: seq++,
+      kind: 'reasoning',
+      payload: { text: reasoningText },
+    });
+  }
+  for (const snapshot of snapshots) {
+    parts.push({
+      message_id: assistantMessageId,
+      sequence: seq++,
+      kind: 'tool_call',
+      payload: snapshotToPartPayload(snapshot),
+    });
+  }
+  await insertParts(sql, parts);
+}
--- a/apps/coder/src/services/claude-command-discovery.ts
+++ b/apps/coder/src/services/claude-command-discovery.ts
@@ -0,0 +1,108 @@
+/**
+ * v2.5.11: discover Claude Code's real, enabled commands + plugin skills from
+ * disk so the coder slash menu shows them (claude is PTY — no ACP discovery).
+ *
+ * Scope (v1): user-global only — `~/.claude/commands/*.md` plus the enabled
+ * plugins listed in `~/.claude/settings.json:enabledPlugins` (user-scope install
+ * paths from `~/.claude/plugins/.../installed_plugins.json`). Project-local
+ * plugins and `<cwd>/.claude/commands` are deferred. Names are bare.
+ */
+import { readFileSync, readdirSync, existsSync } from 'node:fs';
+import { homedir } from 'node:os';
+import { join } from 'node:path';
+import type { AgentCommand } from './provider-types.js';
+
+/** Minimal frontmatter reader — single-line `key: value` between `---` fences. */
+function frontmatterField(content: string, field: string): string | undefined {
+  const block = content.match(/^---\r?\n([\s\S]*?)\r?\n---/);
+  if (!block?.[1]) return undefined;
+  const m = block[1].match(new RegExp(`^${field}:\\s*(.+)$`, 'm'));
+  return m?.[1]?.trim().replace(/^["']|["']$/g, '') || undefined;
+}
+
+function readCommandDir(dir: string): AgentCommand[] {
+  if (!existsSync(dir)) return [];
+  let files: string[];
+  try {
+    files = readdirSync(dir);
+  } catch {
+    return [];
+  }
+  const out: AgentCommand[] = [];
+  for (const f of files) {
+    if (!f.endsWith('.md')) continue;
+    let description: string | undefined;
+    try {
+      description = frontmatterField(readFileSync(join(dir, f), 'utf8'), 'description');
+    } catch {
+      /* unreadable — still list the command by name */
+    }
+    out.push({ name: f.slice(0, -3), kind: 'command', ...(description ? { description } : {}) });
+  }
+  return out;
+}
+
+function readSkillDir(dir: string): AgentCommand[] {
+  if (!existsSync(dir)) return [];
+  let entries: string[];
+  try {
+    entries = readdirSync(dir);
+  } catch {
+    return [];
+  }
+  const out: AgentCommand[] = [];
+  for (const sub of entries) {
+    const skillMd = join(dir, sub, 'SKILL.md');
+    if (!existsSync(skillMd)) continue;
+    let content: string;
+    try {
+      content = readFileSync(skillMd, 'utf8');
+    } catch {
+      continue;
+    }
+    out.push({
+      name: frontmatterField(content, 'name') ?? sub,
+      kind: 'skill',
+      ...(() => {
+        const d = frontmatterField(content, 'description');
+        return d ? { description: d } : {};
+      })(),
+    });
+  }
+  return out;
+}
+
+export function discoverClaudeCommands(): AgentCommand[] {
+  const root = join(homedir(), '.claude');
+  const out: AgentCommand[] = [];
+
+  // User custom commands.
+  out.push(...readCommandDir(join(root, 'commands')));
+
+  // Enabled plugins (user-scope installs).
+  try {
+    const settings = JSON.parse(readFileSync(join(root, 'settings.json'), 'utf8')) as {
+      enabledPlugins?: Record<string, boolean>;
+    };
+    const installed = JSON.parse(
+      readFileSync(join(root, 'plugins', 'installed_plugins.json'), 'utf8'),
+    ) as { plugins?: Record<string, Array<{ scope?: string; installPath?: string }>> };
+
+    const enabled = settings.enabledPlugins ?? {};
+    const plugins = installed.plugins ?? {};
+    for (const [key, on] of Object.entries(enabled)) {
+      if (!on) continue;
+      const installs = plugins[key] ?? [];
+      const installPath = (installs.find((i) => i.scope === 'user') ?? installs[0])?.installPath;
+      if (!installPath || !existsSync(installPath)) continue;
+      out.push(...readSkillDir(join(installPath, 'skills')));
+      out.push(...readCommandDir(join(installPath, 'commands')));
+    }
+  } catch {
+    /* missing/unreadable plugin config → user commands only */
+  }
+
+  // Dedupe by name (first wins).
+  const seen = new Set<string>();
+  return out.filter((c) => (seen.has(c.name) ? false : (seen.add(c.name), true)));
+}
--- a/apps/coder/src/services/command-availability.ts
+++ b/apps/coder/src/services/command-availability.ts
@@ -0,0 +1,22 @@
+/**
+ * v2.3 phase 2: tier-1 fast availability check — is a binary on PATH?
+ *
+ * Uses execFile (NO shell) because the binary name can come from the provider
+ * config file (custom ACP entries) — mirrors the Phase 1 agent-probe hardening.
+ * Note: agent-probe's `whichBinary` returns the resolved path (it needs it for
+ * `install_path`); this returns a boolean. Kept separate rather than over-
+ * refactored into one helper — different return contracts, two short call sites.
+ */
+import { execFile as execFileCb } from 'node:child_process';
+import { promisify } from 'node:util';
+
+const execFile = promisify(execFileCb);
+
+export async function isCommandAvailable(binary: string): Promise<boolean> {
+  try {
+    const { stdout } = await execFile('which', [binary], { timeout: 10_000 });
+    return stdout.trim().length > 0;
+  } catch {
+    return false;
+  }
+}
--- a/apps/coder/src/services/dispatcher.ts
+++ b/apps/coder/src/services/dispatcher.ts
@@ -0,0 +1,524 @@
+import type { Sql } from '../db.js';
+import type { FastifyBaseLogger } from 'fastify';
+import type { Broker } from '@boocode/server/broker';
+import type { WsFrame } from '@boocode/server/ws-frames';
+import type { Config } from '../config.js';
+import { createWorktree, diffWorktree, cleanupWorktree } from './worktrees.js';
+import { dispatchViaAcp } from './acp-dispatch.js';
+import { getResolvedRegistry } from './provider-config-registry.js';
+import { dispatchViaPty } from './pty-dispatch.js';
+import { clearTaskCommands, setTaskCommands } from './agent-commands-cache.js';
+import { getManifestCommands } from './provider-commands.js';
+import { persistExternalAgentTurn } from './agent-turn-persist.js';
+
+interface InferenceRunner {
+  enqueue: (sessionId: string, chatId: string, assistantId: string, user: string) => void;
+  cancel: (sessionId: string, chatId: string) => Promise<boolean>;
+  hasActive: (chatId: string) => boolean;
+}
+
+interface Deps {
+  sql: Sql;
+  inference: InferenceRunner;
+  broker: Broker;
+  log: FastifyBaseLogger;
+  config: Config;
+}
+
+// LISTEN/NOTIFY ('tasks_new') is the fast path — the dispatcher reacts to new
+// tasks immediately. The poll is only a safety net for notifications missed
+// during a listen-connection drop (porsager auto-reconnects), so it can stay slow.
+const POLL_INTERVAL_MS = 2_000;
+const COMPLETION_POLL_MS = 2_000;
+
+export function createDispatcher(deps: Deps): { start(): void; stop(): Promise<void> } {
+  const { sql, inference, broker, log, config } = deps;
+  let timer: ReturnType<typeof setInterval> | null = null;
+  let listener: { unlisten: () => Promise<void> } | null = null;
+  let running = false;
+  let stopping = false;
+  let inflightPromise: Promise<void> | null = null;
+
+  // Shared entry point for both the poll timer and the NOTIFY listener. poll()'s
+  // `running`/`stopping` guard makes this safe to call concurrently — a notify
+  // arriving mid-task returns immediately and never double-dispatches.
+  function triggerPoll(reason: string): void {
+    poll().catch((err) => {
+      log.error({ err, reason }, 'dispatcher: poll error');
+    });
+  }
+
+  async function poll(): Promise<void> {
+    if (running || stopping) return;
+
+    // Grab one pending task
+    const rows = await sql<{
+      id: string;
+      project_id: string;
+      input: string;
+      agent: string | null;
+      model: string | null;
+      mode_id: string | null;
+      thinking_option_id: string | null;
+      session_id: string | null;
+    }[]>`
+      SELECT id, project_id, input, agent, model, mode_id, thinking_option_id, session_id
+      FROM tasks
+      WHERE state = 'pending'
+      ORDER BY created_at
+      LIMIT 1
+    `;
+    if (rows.length === 0) return;
+
+    const task = rows[0]!;
+    running = true;
+    inflightPromise = runTask(task).finally(() => {
+      running = false;
+      inflightPromise = null;
+    });
+  }
+
+  async function runTask(task: {
+    id: string;
+    project_id: string;
+    input: string;
+    agent: string | null;
+    model: string | null;
+    mode_id: string | null;
+    thinking_option_id: string | null;
+    session_id: string | null;
+  }): Promise<void> {
+    const taskId = task.id;
+
+    // Determine execution path: if agent is specified AND exists in available_agents → Path B
+    if (task.agent) {
+      const [agentRow] = await sql<{ name: string; supports_acp: boolean; install_path: string | null }[]>`
+        SELECT name, supports_acp, install_path FROM available_agents WHERE name = ${task.agent}
+      `;
+      if (agentRow) {
+        await runExternalAgent(task, agentRow.supports_acp, agentRow.install_path);
+        return;
+      }
+      // Agent specified but not available — fall through to Path A with a warning
+      log.warn({ taskId, agent: task.agent }, 'dispatcher: specified agent not available, falling back to native');
+    }
+
+    // Path A — native inference (existing behavior)
+    await runNativeInference(task);
+  }
+
+  // ─── Path A: Native Inference ───────────────────────────────────────────────
+
+  async function runNativeInference(task: { id: string; project_id: string; input: string; agent: string | null; model: string | null; session_id: string | null }): Promise<void> {
+    const taskId = task.id;
+    log.info({ taskId }, 'dispatcher: starting task (path A — native)');
+
+    try {
+      // Mark running
+      await sql`
+        UPDATE tasks
+        SET state = 'running', started_at = clock_timestamp(), execution_path = 'native'
+        WHERE id = ${taskId}
+      `;
+
+      // Create session + chat for this task
+      const model = task.model ?? config.DEFAULT_MODEL;
+      const sessionName = 'Task: ' + task.input.slice(0, 40);
+
+      const [session] = await sql<{ id: string }[]>`
+        INSERT INTO sessions (project_id, name, model, status)
+        VALUES (${task.project_id}, ${sessionName}, ${model}, 'open')
+        RETURNING id
+      `;
+      const sessionId = session!.id;
+
+      const [chat] = await sql<{ id: string }[]>`
+        INSERT INTO chats (session_id, name, status)
+        VALUES (${sessionId}, 'Task execution', 'open')
+        RETURNING id
+      `;
+      const chatId = chat!.id;
+
+      // Link task to session
+      await sql`UPDATE tasks SET session_id = ${sessionId} WHERE id = ${taskId}`;
+
+      // Create user message + streaming assistant
+      await sql<{ id: string }[]>`
+        INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+        VALUES (${sessionId}, ${chatId}, 'user', ${task.input}, 'complete', clock_timestamp())
+        RETURNING id
+      `;
+      const [assistantMsg] = await sql<{ id: string }[]>`
+        INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+        VALUES (${sessionId}, ${chatId}, 'assistant', '', 'streaming', clock_timestamp())
+        RETURNING id
+      `;
+      const assistantId = assistantMsg!.id;
+
+      // Enqueue inference
+      inference.enqueue(sessionId, chatId, assistantId, 'default');
+
+      // Wait for inference to complete (poll message status)
+      const finalStatus = await waitForCompletion(assistantId);
+
+      if (stopping) {
+        await sql`
+          UPDATE tasks
+          SET state = 'cancelled', ended_at = clock_timestamp()
+          WHERE id = ${taskId}
+        `;
+        return;
+      }
+
+      // Aggregate token cost for the task's session
+      const [costRow] = await sql<{ total: number | null }[]>`
+        SELECT SUM(tokens_used)::int AS total
+        FROM messages
+        WHERE session_id = ${sessionId} AND tokens_used IS NOT NULL
+      `;
+      const costTokens = costRow?.total ?? null;
+
+      if (finalStatus === 'complete') {
+        const [msg] = await sql<{ content: string | null }[]>`
+          SELECT content FROM messages WHERE id = ${assistantId}
+        `;
+        const summary = (msg?.content ?? '').slice(0, 500);
+        await sql`
+          UPDATE tasks
+          SET state = 'completed', ended_at = clock_timestamp(), output_summary = ${summary}, cost_tokens = ${costTokens}
+          WHERE id = ${taskId}
+        `;
+        log.info({ taskId, costTokens }, 'dispatcher: task completed (native)');
+      } else {
+        const [msg] = await sql<{ content: string | null }[]>`
+          SELECT content FROM messages WHERE id = ${assistantId}
+        `;
+        const summary = (msg?.content ?? 'Inference failed').slice(0, 500);
+        await sql`
+          UPDATE tasks
+          SET state = 'failed', ended_at = clock_timestamp(), output_summary = ${summary}, cost_tokens = ${costTokens}
+          WHERE id = ${taskId}
+        `;
+        log.warn({ taskId, finalStatus }, 'dispatcher: task failed (native)');
+      }
+    } catch (err) {
+      const errMsg = err instanceof Error ? err.message : String(err);
+      log.error({ taskId, err: errMsg }, 'dispatcher: task error (native)');
+      await sql`
+        UPDATE tasks
+        SET state = 'failed', ended_at = clock_timestamp(), output_summary = ${errMsg.slice(0, 500)}
+        WHERE id = ${taskId}
+      `.catch(() => {});
+    }
+  }
+
+  // ─── Path B: External Agent Dispatch ──────<E29480><E29480><EFBFBD>─────────────────────────────────
+
+  async function runExternalAgent(
+    task: {
+      id: string;
+      project_id: string;
+      input: string;
+      agent: string | null;
+      model: string | null;
+      mode_id: string | null;
+      thinking_option_id: string | null;
+      session_id: string | null;
+    },
+    supportsAcp: boolean,
+    installPath: string | null,
+  ): Promise<void> {
+    const taskId = task.id;
+    const agent = task.agent!;
+    const executionPath = supportsAcp ? 'acp' : 'pty';
+
+    log.info({ taskId, agent, executionPath }, 'dispatcher: starting task (path B — external)');
+
+    // Resolve the project's root path
+    const [project] = await sql<{ path: string | null }[]>`
+      SELECT path FROM projects WHERE id = ${task.project_id}
+    `;
+    const projectPath = project?.path;
+    if (!projectPath) {
+      await sql`
+        UPDATE tasks
+        SET state = 'failed', ended_at = clock_timestamp(), output_summary = 'Project has no path — cannot create worktree'
+        WHERE id = ${taskId}
+      `;
+      return;
+    }
+
+    // Create an abort controller for this task
+    const ac = new AbortController();
+
+    try {
+      // Mark running
+      await sql`
+        UPDATE tasks
+        SET state = 'running', started_at = clock_timestamp(), execution_path = ${executionPath}
+        WHERE id = ${taskId}
+      `;
+
+      let sessionId: string;
+      let chatId: string;
+
+      if (task.session_id) {
+        sessionId = task.session_id;
+        const chats = await sql<{ id: string }[]>`
+          SELECT id FROM chats WHERE session_id = ${sessionId} AND status = 'open' ORDER BY created_at DESC LIMIT 1
+        `;
+        if (chats.length === 0) {
+          const [chat] = await sql<{ id: string }[]>`
+            INSERT INTO chats (session_id, name, status)
+            VALUES (${sessionId}, 'External agent execution', 'open')
+            RETURNING id
+          `;
+          chatId = chat!.id;
+        } else {
+          chatId = chats[0]!.id;
+        }
+      } else {
+        const sessionName = `Task [${agent}]: ${task.input.slice(0, 30)}`;
+        const [session] = await sql<{ id: string }[]>`
+          INSERT INTO sessions (project_id, name, model, status)
+          VALUES (${task.project_id}, ${sessionName}, ${task.model ?? config.DEFAULT_MODEL}, 'open')
+          RETURNING id
+        `;
+        sessionId = session!.id;
+
+        const [chat] = await sql<{ id: string }[]>`
+          INSERT INTO chats (session_id, name, status)
+          VALUES (${sessionId}, 'External agent execution', 'open')
+          RETURNING id
+        `;
+        chatId = chat!.id;
+
+        await sql`UPDATE tasks SET session_id = ${sessionId} WHERE id = ${taskId}`;
+      }
+
+      if (!task.session_id) {
+        await sql`
+          INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+          VALUES (${sessionId}, ${chatId}, 'user', ${task.input}, 'complete', clock_timestamp())
+        `;
+      }
+
+      // Step 1: Create worktree
+      log.info({ taskId, projectPath }, 'dispatcher: creating worktree');
+      const worktreePath = await createWorktree(projectPath, taskId, { signal: ac.signal });
+      log.info({ taskId, worktreePath }, 'dispatcher: worktree created');
+
+      // Step 2: Dispatch to agent
+      let outputSummary: string;
+      let assistantContent = '';
+      let acpReasoning = '';
+
+      const [assistantMsg] = await sql<{ id: string }[]>`
+        INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
+        VALUES (${sessionId}, ${chatId}, 'assistant', '', 'streaming', clock_timestamp())
+        RETURNING id
+      `;
+      const assistantId = assistantMsg!.id;
+
+      broker.publishFrame(sessionId, {
+        type: 'message_started',
+        message_id: assistantId,
+        chat_id: chatId,
+        role: 'assistant',
+      } as WsFrame);
+
+      const manifestCommands = getManifestCommands(agent);
+      if (manifestCommands.length > 0) {
+        setTaskCommands(taskId, manifestCommands);
+        broker.publishFrame(sessionId, {
+          type: 'agent_commands',
+          task_id: taskId,
+          session_id: sessionId,
+          commands: manifestCommands,
+        } as WsFrame);
+      }
+
+      if (supportsAcp) {
+        const result = await dispatchViaAcp({
+          agent,
+          resolved: getResolvedRegistry().get(agent),
+          task: task.input,
+          worktreePath,
+          installPath: installPath ?? undefined,
+          model: task.model ?? undefined,
+          modeId: task.mode_id ?? undefined,
+          thinkingOptionId: task.thinking_option_id ?? undefined,
+          taskId,
+          sessionId,
+          chatId,
+          messageId: assistantId,
+          broker,
+          signal: ac.signal,
+          log,
+        });
+        assistantContent = result.output.slice(0, 50_000);
+        acpReasoning = result.reasoningText.slice(0, 200_000);
+        outputSummary = result.output.slice(0, 500);
+        await persistExternalAgentTurn(sql, assistantId, result.toolSnapshots, acpReasoning);
+      } else {
+        const result = await dispatchViaPty({
+          agent,
+          task: task.input,
+          worktreePath,
+          installPath: installPath ?? undefined,
+          model: task.model ?? undefined,
+          modeId: task.mode_id ?? undefined,
+          thinkingOptionId: task.thinking_option_id ?? undefined,
+          signal: ac.signal,
+          log,
+        });
+        assistantContent = (result.stdout || result.stderr || '(no output)').slice(0, 50_000);
+        outputSummary = (result.stdout || result.stderr).slice(0, 500);
+
+        if (assistantContent) {
+          broker.publishFrame(sessionId, {
+            type: 'delta',
+            message_id: assistantId,
+            chat_id: chatId,
+            content: assistantContent,
+          } as WsFrame);
+        }
+      }
+
+      await sql`
+        UPDATE messages
+        SET content = ${assistantContent}, status = 'complete', finished_at = clock_timestamp()
+        WHERE id = ${assistantId}
+      `;
+
+      broker.publishFrame(sessionId, {
+        type: 'message_complete',
+        message_id: assistantId,
+        chat_id: chatId,
+      } as WsFrame);
+
+      if (stopping) {
+        await sql`
+          UPDATE tasks SET state = 'cancelled', ended_at = clock_timestamp() WHERE id = ${taskId}
+        `;
+        await cleanupWorktree(projectPath, taskId);
+        return;
+      }
+
+      // Step 3: Diff the worktree and queue pending changes
+      log.info({ taskId }, 'dispatcher: diffing worktree');
+      const diff = await diffWorktree(worktreePath, projectPath, { signal: ac.signal });
+
+      if (diff) {
+        // Queue a single pending_change entry with the full unified diff
+        await sql`
+          INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff)
+          VALUES (${sessionId}, ${taskId}, ${projectPath}, 'edit', ${diff})
+        `;
+        log.info({ taskId, diffLength: diff.length }, 'dispatcher: diff queued as pending change');
+      } else {
+        log.info({ taskId }, 'dispatcher: no changes detected in worktree');
+      }
+
+      // Step 4: Cleanup worktree
+      await cleanupWorktree(projectPath, taskId);
+
+      // Step 5: Aggregate token cost
+      const [extCostRow] = await sql<{ total: number | null }[]>`
+        SELECT SUM(tokens_used)::int AS total
+        FROM messages
+        WHERE session_id = ${sessionId} AND tokens_used IS NOT NULL
+      `;
+      const extCostTokens = extCostRow?.total ?? null;
+
+      // Step 6: Mark task completed
+      await sql`
+        UPDATE tasks
+        SET state = 'completed', ended_at = clock_timestamp(), output_summary = ${outputSummary}, cost_tokens = ${extCostTokens}
+        WHERE id = ${taskId}
+      `;
+      log.info({ taskId, agent, costTokens: extCostTokens }, 'dispatcher: task completed (external)');
+      clearTaskCommands(taskId);
+
+    } catch (err) {
+      const errMsg = err instanceof Error ? err.message : String(err);
+      log.error({ taskId, agent, err: errMsg }, 'dispatcher: external agent error');
+
+      await sql`
+        UPDATE tasks
+        SET state = 'failed', ended_at = clock_timestamp(), output_summary = ${errMsg.slice(0, 500)}
+        WHERE id = ${taskId}
+      `.catch(() => {});
+
+      // Best-effort cleanup
+      await cleanupWorktree(projectPath, taskId);
+      clearTaskCommands(taskId);
+    }
+  }
+
+  // ─── Helpers ────────────────────────────────────────────────────────────────
+
+  async function waitForCompletion(assistantId: string): Promise<string> {
+    for (;;) {
+      if (stopping) return 'cancelled';
+
+      const [row] = await sql<{ status: string }[]>`
+        SELECT status FROM messages WHERE id = ${assistantId}
+      `;
+      const status = row?.status ?? 'failed';
+      if (status !== 'streaming') return status;
+
+      await sleep(COMPLETION_POLL_MS);
+    }
+  }
+
+  function sleep(ms: number): Promise<void> {
+    return new Promise((resolve) => setTimeout(resolve, ms));
+  }
+
+  return {
+    start() {
+      log.info('dispatcher: starting poll loop + tasks_new listener');
+
+      // Fallback poll — catches notifications missed while the listen connection
+      // was down. The fast path is the NOTIFY listener below.
+      timer = setInterval(() => triggerPoll('interval'), POLL_INTERVAL_MS);
+
+      // Fast path: react immediately to new tasks. porsager reserves a dedicated
+      // connection and auto-resubscribes on reconnect; the onlisten callback
+      // fires on each (re)subscribe, so we kick a catch-up poll there too to
+      // sweep up anything inserted during a disconnect.
+      sql
+        .listen(
+          'tasks_new',
+          () => triggerPoll('notify'),
+          () => triggerPoll('listen-subscribed'),
+        )
+        .then((meta) => {
+          listener = meta;
+        })
+        .catch((err) => {
+          log.error({ err }, 'dispatcher: failed to LISTEN tasks_new — relying on poll fallback');
+        });
+    },
+
+    async stop() {
+      stopping = true;
+      if (timer) {
+        clearInterval(timer);
+        timer = null;
+      }
+      if (listener) {
+        await listener.unlisten().catch((err) => {
+          log.error({ err }, 'dispatcher: unlisten error');
+        });
+        listener = null;
+      }
+      if (inflightPromise) {
+        log.info('dispatcher: waiting for in-flight task');
+        await inflightPromise;
+      }
+      log.info('dispatcher: stopped');
+    },
+  };
+}
--- a/apps/coder/src/services/host-exec.ts
+++ b/apps/coder/src/services/host-exec.ts
@@ -0,0 +1,66 @@
+/**
+ * Local shell exec on the BooCoder host (replaces deprecated ssh.ts for worktrees).
+ */
+import { spawn } from 'node:child_process';
+
+export interface HostExecResult {
+  exitCode: number;
+  stdout: string;
+  stderr: string;
+}
+
+export async function hostExec(
+  command: string,
+  opts?: { signal?: AbortSignal; timeoutMs?: number },
+): Promise<HostExecResult> {
+  return new Promise<HostExecResult>((resolve, reject) => {
+    const child = spawn('bash', ['-lc', command], {
+      stdio: ['pipe', 'pipe', 'pipe'],
+    });
+
+    let stdout = '';
+    let stderr = '';
+    let killed = false;
+
+    child.stdout!.on('data', (chunk: Buffer) => { stdout += chunk.toString(); });
+    child.stderr!.on('data', (chunk: Buffer) => { stderr += chunk.toString(); });
+
+    const cleanup = () => {
+      if (!killed) {
+        killed = true;
+        child.kill('SIGTERM');
+      }
+    };
+
+    if (opts?.signal) {
+      if (opts.signal.aborted) {
+        cleanup();
+        reject(new Error('host exec aborted before start'));
+        return;
+      }
+      opts.signal.addEventListener('abort', cleanup, { once: true });
+    }
+
+    let timer: ReturnType<typeof setTimeout> | undefined;
+    if (opts?.timeoutMs) {
+      timer = setTimeout(() => {
+        cleanup();
+        reject(new Error(`host exec timed out after ${opts.timeoutMs}ms`));
+      }, opts.timeoutMs);
+    }
+
+    child.on('close', (code) => {
+      if (timer) clearTimeout(timer);
+      if (opts?.signal) opts.signal.removeEventListener('abort', cleanup);
+      resolve({ exitCode: code ?? 1, stdout, stderr });
+    });
+
+    child.on('error', (err) => {
+      if (timer) clearTimeout(timer);
+      if (opts?.signal) opts.signal.removeEventListener('abort', cleanup);
+      reject(err);
+    });
+
+    child.stdin!.end();
+  });
+}
--- a/apps/coder/src/services/mcp-server.ts
+++ b/apps/coder/src/services/mcp-server.ts
@@ -0,0 +1,232 @@
+/**
+ * BooCoder MCP Server — exposes task primitives as MCP tools.
+ *
+ * Started when `--mcp` flag is passed to the entry point. Runs stdio transport
+ * so external tools (opencode in Termius) can drive the task queue.
+ */
+import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
+import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
+import { z } from 'zod';
+import type { Sql } from '../db.js';
+import { applyOne, rejectOne } from './pending_changes.js';
+
+// --- Tool handlers -----------------------------------------------------------
+
+interface TaskRow {
+  id: string;
+  state: string;
+}
+
+interface PendingRow {
+  id: string;
+  file_path: string;
+  operation: string;
+  diff: string;
+  session_id: string;
+}
+
+interface WorktreeRow {
+  id: string;
+  worktree_path: string;
+  agent: string;
+  started_at: string;
+}
+
+interface ProjectPathRow {
+  path: string;
+}
+
+function textResult(data: unknown) {
+  return { content: [{ type: 'text' as const, text: JSON.stringify(data, null, 2) }] };
+}
+
+// --- Public entry ------------------------------------------------------------
+
+export async function startMcpServer(sql: Sql): Promise<void> {
+  const server = new McpServer(
+    { name: 'boocoder', version: '2.0.2' },
+    { capabilities: { tools: {} } },
+  );
+
+  // 1. boocoder.create_task
+  server.tool(
+    'boocoder.create_task',
+    'Create a new task in the BooCoder task queue',
+    {
+      project_id: z.string().describe('Project UUID'),
+      input: z.string().describe('Task description / prompt for the agent'),
+      agent: z.string().optional().describe('Agent name (optional — uses default if omitted)'),
+      model: z.string().optional().describe('Model override (optional)'),
+      mode_id: z.string().optional().describe('Permission/mode id (optional)'),
+      thinking_option_id: z.string().optional().describe('Thinking/effort option id (optional)'),
+    },
+    async (args) => {
+      const [row] = await sql<TaskRow[]>`
+        INSERT INTO tasks (project_id, input, agent, model, mode_id, thinking_option_id, state)
+        VALUES (
+          ${args.project_id},
+          ${args.input},
+          ${args.agent ?? null},
+          ${args.model ?? null},
+          ${args.mode_id ?? null},
+          ${args.thinking_option_id ?? null},
+          'pending'
+        )
+        RETURNING id, state
+      `;
+      return textResult({
+        task_id: row!.id,
+        state: row!.state,
+        mode_id: args.mode_id ?? null,
+        thinking_option_id: args.thinking_option_id ?? null,
+      });
+    },
+  );
+
+  // 2. boocoder.list_pending_changes
+  server.tool(
+    'boocoder.list_pending_changes',
+    'List pending changes awaiting review',
+    {
+      session_id: z.string().optional().describe('Optional session filter'),
+    },
+    async (args) => {
+      let rows: PendingRow[];
+      if (args.session_id) {
+        rows = await sql<PendingRow[]>`
+          SELECT id, file_path, operation, diff, session_id
+          FROM pending_changes
+          WHERE status = 'pending' AND session_id = ${args.session_id}
+          ORDER BY created_at ASC
+        `;
+      } else {
+        rows = await sql<PendingRow[]>`
+          SELECT id, file_path, operation, diff, session_id
+          FROM pending_changes
+          WHERE status = 'pending'
+          ORDER BY created_at ASC
+        `;
+      }
+      const items = rows.map((r) => ({
+        id: r.id,
+        file_path: r.file_path,
+        operation: r.operation,
+        diff_preview: r.diff.slice(0, 200),
+      }));
+      return textResult(items);
+    },
+  );
+
+  // 3. boocoder.apply
+  server.tool(
+    'boocoder.apply',
+    'Apply a pending change (write to disk)',
+    {
+      change_id: z.string().describe('Pending change UUID'),
+    },
+    async (args) => {
+      // Resolve projectRoot from the change's session → project path
+      const [proj] = await sql<ProjectPathRow[]>`
+        SELECT p.path FROM pending_changes pc
+        JOIN sessions s ON pc.session_id = s.id
+        JOIN projects p ON s.project_id = p.id
+        WHERE pc.id = ${args.change_id}
+      `;
+      if (!proj) {
+        return textResult({ success: false, file_path: '', error: 'change not found or project path unresolved' });
+      }
+      const result = await applyOne(sql, args.change_id, proj.path);
+      return textResult({ success: result.success, file_path: result.file_path, error: result.error });
+    },
+  );
+
+  // 4. boocoder.reject
+  server.tool(
+    'boocoder.reject',
+    'Reject a pending change (mark as rejected, no disk write)',
+    {
+      change_id: z.string().describe('Pending change UUID'),
+    },
+    async (args) => {
+      await rejectOne(sql, args.change_id);
+      return textResult({ success: true });
+    },
+  );
+
+  // 5. boocoder.dispatch_external_agent
+  server.tool(
+    'boocoder.dispatch_external_agent',
+    'Create a task targeting a specific external agent (ACP or PTY dispatch)',
+    {
+      project_id: z.string().describe('Project UUID'),
+      input: z.string().describe('Task prompt'),
+      agent: z.string().describe('Agent name (must match available_agents registry)'),
+      model: z.string().optional().describe('Model override (optional)'),
+      mode_id: z.string().optional().describe('Permission/mode id (optional)'),
+      thinking_option_id: z.string().optional().describe('Thinking/effort option id (optional)'),
+    },
+    async (args) => {
+      const [row] = await sql<TaskRow[]>`
+        INSERT INTO tasks (project_id, input, agent, model, mode_id, thinking_option_id, state)
+        VALUES (
+          ${args.project_id},
+          ${args.input},
+          ${args.agent},
+          ${args.model ?? null},
+          ${args.mode_id ?? null},
+          ${args.thinking_option_id ?? null},
+          'pending'
+        )
+        RETURNING id, state
+      `;
+
+      // Determine execution path from available_agents
+      const [agentRow] = await sql<{ supports_acp: boolean }[]>`
+        SELECT supports_acp FROM available_agents WHERE name = ${args.agent}
+      `;
+      const executionPath = agentRow?.supports_acp ? 'acp' : 'pty';
+
+      return textResult({
+        task_id: row!.id,
+        state: row!.state,
+        execution_path: executionPath,
+        mode_id: args.mode_id ?? null,
+        thinking_option_id: args.thinking_option_id ?? null,
+      });
+    },
+  );
+
+  // 6. boocoder.list_worktrees
+  server.tool(
+    'boocoder.list_worktrees',
+    'List active worktrees from running tasks',
+    {},
+    async () => {
+      const rows = await sql<WorktreeRow[]>`
+        SELECT id, worktree_path, agent, started_at
+        FROM tasks
+        WHERE worktree_path IS NOT NULL AND state = 'running'
+        ORDER BY started_at DESC
+      `;
+      const items = rows.map((r) => ({
+        task_id: r.id,
+        worktree_path: r.worktree_path,
+        agent: r.agent,
+        started_at: r.started_at,
+      }));
+      return textResult(items);
+    },
+  );
+
+  // Connect via stdio
+  const transport = new StdioServerTransport();
+  await server.connect(transport);
+
+  // Block until stdin closes (transport handles lifecycle)
+  await new Promise<void>((resolve) => {
+    process.stdin.on('end', resolve);
+    process.stdin.on('close', resolve);
+  });
+
+  await sql.end({ timeout: 5 });
+}
--- a/apps/coder/src/services/pending_changes.ts
+++ b/apps/coder/src/services/pending_changes.ts
@@ -0,0 +1,224 @@
+import { readFile, writeFile, unlink, mkdir } from 'node:fs/promises';
+import { dirname } from 'node:path';
+import type { Sql } from '../db.js';
+import { resolveWritePath } from './write_guard.js';
+
+// --- Types -------------------------------------------------------------------
+
+export interface PendingChange {
+  id: string;
+  session_id: string;
+  task_id: string | null;
+  file_path: string;
+  operation: 'create' | 'edit' | 'delete';
+  diff: string;
+  status: 'pending' | 'applied' | 'rejected' | 'reverted';
+  created_at: string;
+}
+
+export interface ApplyResult {
+  id: string;
+  file_path: string;
+  operation: string;
+  success: boolean;
+  error?: string;
+}
+
+// --- Queue functions ---------------------------------------------------------
+
+export async function queueEdit(
+  sql: Sql,
+  sessionId: string,
+  taskId: string | null,
+  filePath: string,
+  oldString: string,
+  newString: string,
+  projectRoot: string,
+): Promise<PendingChange> {
+  const resolved = resolveWritePath(projectRoot, filePath);
+  const diff = JSON.stringify({ old: oldString, new: newString });
+
+  const [row] = await sql<PendingChange[]>`
+    INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff)
+    VALUES (${sessionId}, ${taskId}, ${resolved}, 'edit', ${diff})
+    RETURNING *
+  `;
+  return row!;
+}
+
+export async function queueCreate(
+  sql: Sql,
+  sessionId: string,
+  taskId: string | null,
+  filePath: string,
+  content: string,
+  projectRoot: string,
+): Promise<PendingChange> {
+  const resolved = resolveWritePath(projectRoot, filePath);
+
+  const [row] = await sql<PendingChange[]>`
+    INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff)
+    VALUES (${sessionId}, ${taskId}, ${resolved}, 'create', ${content})
+    RETURNING *
+  `;
+  return row!;
+}
+
+export async function queueDelete(
+  sql: Sql,
+  sessionId: string,
+  taskId: string | null,
+  filePath: string,
+  projectRoot: string,
+): Promise<PendingChange> {
+  const resolved = resolveWritePath(projectRoot, filePath);
+
+  const [row] = await sql<PendingChange[]>`
+    INSERT INTO pending_changes (session_id, task_id, file_path, operation, diff)
+    VALUES (${sessionId}, ${taskId}, ${resolved}, 'delete', '')
+    RETURNING *
+  `;
+  return row!;
+}
+
+// --- Apply functions ---------------------------------------------------------
+
+export async function applyOne(
+  sql: Sql,
+  changeId: string,
+  projectRoot: string,
+): Promise<ApplyResult> {
+  const [change] = await sql<PendingChange[]>`
+    SELECT * FROM pending_changes WHERE id = ${changeId} AND status = 'pending'
+  `;
+  if (!change) {
+    return { id: changeId, file_path: '', operation: '', success: false, error: 'change not found or not pending' };
+  }
+
+  try {
+    // Re-validate path in case projectRoot has shifted
+    resolveWritePath(projectRoot, change.file_path);
+
+    switch (change.operation) {
+      case 'create': {
+        await mkdir(dirname(change.file_path), { recursive: true });
+        await writeFile(change.file_path, change.diff, 'utf8');
+        break;
+      }
+      case 'edit': {
+        const { old: oldStr, new: newStr } = JSON.parse(change.diff) as { old: string; new: string };
+        const content = await readFile(change.file_path, 'utf8');
+        if (!content.includes(oldStr)) {
+          throw new Error('old_string not found in file — file may have changed since the edit was queued');
+        }
+        const updated = content.replace(oldStr, newStr);
+        await writeFile(change.file_path, updated, 'utf8');
+        break;
+      }
+      case 'delete': {
+        // Stash current content in diff for potential rewind
+        try {
+          const existing = await readFile(change.file_path, 'utf8');
+          await sql`UPDATE pending_changes SET diff = ${existing} WHERE id = ${changeId}`;
+        } catch {
+          // File may already be gone — proceed with status update
+        }
+        await unlink(change.file_path);
+        break;
+      }
+    }
+
+    await sql`UPDATE pending_changes SET status = 'applied' WHERE id = ${changeId}`;
+    return { id: change.id, file_path: change.file_path, operation: change.operation, success: true };
+  } catch (err) {
+    const message = err instanceof Error ? err.message : String(err);
+    return { id: change.id, file_path: change.file_path, operation: change.operation, success: false, error: message };
+  }
+}
+
+export async function applyAll(
+  sql: Sql,
+  sessionId: string,
+  projectRoot: string,
+): Promise<ApplyResult[]> {
+  const pending = await sql<PendingChange[]>`
+    SELECT * FROM pending_changes
+    WHERE session_id = ${sessionId} AND status = 'pending'
+    ORDER BY created_at ASC
+  `;
+  const results: ApplyResult[] = [];
+  for (const change of pending) {
+    results.push(await applyOne(sql, change.id, projectRoot));
+  }
+  return results;
+}
+
+// --- Reject functions --------------------------------------------------------
+
+export async function rejectOne(sql: Sql, changeId: string): Promise<void> {
+  await sql`UPDATE pending_changes SET status = 'rejected' WHERE id = ${changeId} AND status = 'pending'`;
+}
+
+export async function rejectAll(sql: Sql, sessionId: string): Promise<void> {
+  await sql`UPDATE pending_changes SET status = 'rejected' WHERE session_id = ${sessionId} AND status = 'pending'`;
+}
+
+// --- Rewind functions --------------------------------------------------------
+
+export async function rewindOne(
+  sql: Sql,
+  changeId: string,
+  projectRoot: string,
+): Promise<ApplyResult> {
+  const [change] = await sql<PendingChange[]>`
+    SELECT * FROM pending_changes WHERE id = ${changeId} AND status = 'applied'
+  `;
+  if (!change) {
+    return { id: changeId, file_path: '', operation: '', success: false, error: 'change not found or not applied' };
+  }
+
+  try {
+    resolveWritePath(projectRoot, change.file_path);
+
+    switch (change.operation) {
+      case 'create': {
+        // Reverse a create: delete the file
+        await unlink(change.file_path);
+        break;
+      }
+      case 'edit': {
+        // Reverse an edit: swap old and new
+        const { old: oldStr, new: newStr } = JSON.parse(change.diff) as { old: string; new: string };
+        const content = await readFile(change.file_path, 'utf8');
+        if (!content.includes(newStr)) {
+          throw new Error('new_string not found in file — cannot rewind; file may have been modified since apply');
+        }
+        const reverted = content.replace(newStr, oldStr);
+        await writeFile(change.file_path, reverted, 'utf8');
+        break;
+      }
+      case 'delete': {
+        // Reverse a delete: recreate the file (diff holds the original content stashed at apply time)
+        await mkdir(dirname(change.file_path), { recursive: true });
+        await writeFile(change.file_path, change.diff, 'utf8');
+        break;
+      }
+    }
+
+    await sql`UPDATE pending_changes SET status = 'reverted' WHERE id = ${changeId}`;
+    return { id: change.id, file_path: change.file_path, operation: change.operation, success: true };
+  } catch (err) {
+    const message = err instanceof Error ? err.message : String(err);
+    return { id: change.id, file_path: change.file_path, operation: change.operation, success: false, error: message };
+  }
+}
+
+// --- Query functions ---------------------------------------------------------
+
+export async function listPending(sql: Sql, sessionId: string): Promise<PendingChange[]> {
+  return sql<PendingChange[]>`
+    SELECT * FROM pending_changes
+    WHERE session_id = ${sessionId} AND status = 'pending'
+    ORDER BY created_at ASC
+  `;
+}
--- a/apps/coder/src/services/permission-waiter.ts
+++ b/apps/coder/src/services/permission-waiter.ts
@@ -0,0 +1,207 @@
+/**
+ * Blocks ACP dispatch on permission/elicitation prompts until the user responds via API.
+ */
+import type { RequestPermissionRequest, RequestPermissionResponse, CreateElicitationRequest, CreateElicitationResponse } from '@agentclientprotocol/sdk';
+import { isUnattendedMode } from './provider-manifest.js';
+
+const DEFAULT_TIMEOUT_MS = 120_000;
+
+interface PendingPermission {
+  type: 'permission';
+  request: RequestPermissionRequest;
+  sessionId: string;
+  resolve: (response: RequestPermissionResponse) => void;
+  reject: (err: Error) => void;
+  timer: ReturnType<typeof setTimeout>;
+}
+
+interface PendingElicitation {
+  type: 'elicitation';
+  request: CreateElicitationRequest;
+  sessionId: string;
+  resolve: (response: CreateElicitationResponse) => void;
+  reject: (err: Error) => void;
+  timer: ReturnType<typeof setTimeout>;
+}
+
+type PendingEntry = PendingPermission | PendingElicitation;
+
+const pendingByTask = new Map<string, PendingEntry>();
+
+export type PermissionKind = 'tool' | 'question' | 'plan' | 'elicitation';
+
+export interface PermissionPrompt {
+  taskId: string;
+  kind: PermissionKind;
+  toolTitle?: string;
+  description?: string;
+  input?: Record<string, unknown>;
+  options: Array<{ optionId: string; label: string }>;
+}
+
+export interface PermissionHooks {
+  onPrompt?: (prompt: PermissionPrompt & { sessionId: string }) => void | Promise<void>;
+  onResolved?: (taskId: string, sessionId: string) => void | Promise<void>;
+}
+
+let hooks: PermissionHooks = {};
+
+export function setPermissionHooks(next: PermissionHooks): void {
+  hooks = next;
+}
+
+function resolveKind(params: RequestPermissionRequest): PermissionKind {
+  const input = params.toolCall?.rawInput;
+  if (input && typeof input === 'object' && !Array.isArray(input) && 'questions' in input && Array.isArray((input as Record<string, unknown>).questions)) {
+    return 'question';
+  }
+  return 'tool';
+}
+
+function toPrompt(taskId: string, params: RequestPermissionRequest): PermissionPrompt {
+  const kind = resolveKind(params);
+  const rawInput = params.toolCall?.rawInput;
+  const input = rawInput && typeof rawInput === 'object' && !Array.isArray(rawInput)
+    ? rawInput as Record<string, unknown>
+    : undefined;
+  return {
+    taskId,
+    kind,
+    toolTitle: params.toolCall?.title ?? undefined,
+    ...(input ? { input } : {}),
+    options: params.options.map((o) => ({
+      optionId: o.optionId,
+      label: o.name,
+    })),
+  };
+}
+
+export function waitForPermissionResponse(
+  taskId: string,
+  sessionId: string,
+  provider: string,
+  modeId: string | undefined,
+  params: RequestPermissionRequest,
+  timeoutMs = DEFAULT_TIMEOUT_MS,
+): Promise<RequestPermissionResponse> {
+  if (isUnattendedMode(provider, modeId)) {
+    const first = params.options[0];
+    if (first) {
+      return Promise.resolve({ outcome: { outcome: 'selected', optionId: first.optionId } });
+    }
+    return Promise.resolve({ outcome: { outcome: 'cancelled' } });
+  }
+
+  return new Promise((resolve, reject) => {
+    const existing = pendingByTask.get(taskId);
+    if (existing) {
+      clearTimeout(existing.timer);
+      existing.reject(new Error('superseded by newer permission request'));
+    }
+
+    const timer = setTimeout(() => {
+      pendingByTask.delete(taskId);
+      void hooks.onResolved?.(taskId, sessionId);
+      resolve({ outcome: { outcome: 'cancelled' } });
+    }, timeoutMs);
+
+    pendingByTask.set(taskId, { type: 'permission', request: params, sessionId, resolve, reject, timer });
+
+    const prompt = toPrompt(taskId, params);
+    void hooks.onPrompt?.({ ...prompt, sessionId });
+  });
+}
+
+export function respondToPermission(taskId: string, optionId: string | null, updatedInput?: Record<string, unknown>): boolean {
+  const pending = pendingByTask.get(taskId);
+  if (!pending) return false;
+
+  clearTimeout(pending.timer);
+  pendingByTask.delete(taskId);
+
+  if (pending.type === 'elicitation') {
+    if (updatedInput) {
+      const content = updatedInput as { [key: string]: string | number | boolean | string[] };
+      pending.resolve({ action: 'accept', content });
+    } else {
+      pending.resolve({ action: 'decline' });
+    }
+  } else {
+    if (optionId) {
+      pending.resolve({ outcome: { outcome: 'selected', optionId } });
+    } else {
+      pending.resolve({ outcome: { outcome: 'cancelled' } });
+    }
+  }
+
+  void hooks.onResolved?.(taskId, pending.sessionId);
+  return true;
+}
+
+export function getPendingPermission(taskId: string): PermissionPrompt | null {
+  const pending = pendingByTask.get(taskId);
+  if (!pending) return null;
+  if (pending.type === 'elicitation') {
+    return elicitationToPrompt(taskId, pending.request);
+  }
+  return toPrompt(taskId, pending.request);
+}
+
+function elicitationToPrompt(taskId: string, params: CreateElicitationRequest): PermissionPrompt {
+  const input: Record<string, unknown> = { message: params.message };
+  if ('requestedSchema' in params) {
+    input.requestedSchema = params.requestedSchema;
+  }
+  return {
+    taskId,
+    kind: 'elicitation',
+    toolTitle: params.message,
+    input,
+    options: [],
+  };
+}
+
+export function waitForElicitationResponse(
+  taskId: string,
+  sessionId: string,
+  provider: string,
+  modeId: string | undefined,
+  params: CreateElicitationRequest,
+  timeoutMs = DEFAULT_TIMEOUT_MS,
+): Promise<CreateElicitationResponse> {
+  if (isUnattendedMode(provider, modeId)) {
+    return Promise.resolve({ action: 'decline' });
+  }
+
+  return new Promise((resolve, reject) => {
+    const existing = pendingByTask.get(taskId);
+    if (existing) {
+      clearTimeout(existing.timer);
+      existing.reject(new Error('superseded by newer elicitation request'));
+    }
+
+    const timer = setTimeout(() => {
+      pendingByTask.delete(taskId);
+      void hooks.onResolved?.(taskId, sessionId);
+      resolve({ action: 'cancel' });
+    }, timeoutMs);
+
+    pendingByTask.set(taskId, { type: 'elicitation', request: params, sessionId, resolve, reject, timer });
+
+    const prompt = elicitationToPrompt(taskId, params);
+    void hooks.onPrompt?.({ ...prompt, sessionId });
+  });
+}
+
+export function cancelPendingPermission(taskId: string): void {
+  const pending = pendingByTask.get(taskId);
+  if (!pending) return;
+  clearTimeout(pending.timer);
+  pendingByTask.delete(taskId);
+  if (pending.type === 'elicitation') {
+    pending.resolve({ action: 'cancel' });
+  } else {
+    pending.resolve({ outcome: { outcome: 'cancelled' } });
+  }
+  void hooks.onResolved?.(taskId, pending.sessionId);
+}
--- a/apps/coder/src/services/provider-commands.ts
+++ b/apps/coder/src/services/provider-commands.ts
@@ -0,0 +1,66 @@
+/**
+ * Static slash-command hints per harness (interactive TUI / agent session).
+ * Live ACP `available_commands_update` merges on top during dispatch.
+ */
+import type { AgentCommand } from './provider-types.js';
+
+const CLAUDE_COMMANDS: AgentCommand[] = [
+  { name: 'help', description: 'Show available slash commands' },
+  { name: 'clear', description: 'Clear conversation history' },
+  { name: 'compact', description: 'Compact context window' },
+  { name: 'cost', description: 'Show session cost' },
+  { name: 'memory', description: 'Manage project memory' },
+  { name: 'model', description: 'Switch model' },
+  { name: 'permissions', description: 'View or change permission mode' },
+  { name: 'review', description: 'Review current changes' },
+  { name: 'status', description: 'Show session status' },
+  { name: 'vim', description: 'Toggle vim-style input' },
+];
+
+const OPENCODE_COMMANDS: AgentCommand[] = [
+  { name: 'help', description: 'Show available commands' },
+  { name: 'new', description: 'Start a new session' },
+  { name: 'models', description: 'List or switch models' },
+  { name: 'agents', description: 'List or switch agents' },
+  { name: 'compact', description: 'Compact context' },
+  { name: 'share', description: 'Share session' },
+  { name: 'export', description: 'Export session' },
+];
+
+const GOOSE_COMMANDS: AgentCommand[] = [
+  { name: 'help', description: 'Show available commands' },
+  { name: 'clear', description: 'Clear conversation' },
+  { name: 'compact', description: 'Compact context' },
+  { name: 'exit', description: 'Exit session' },
+];
+
+const QWEN_COMMANDS: AgentCommand[] = [
+  { name: 'help', description: 'Show available slash commands' },
+  { name: 'clear', description: 'Clear conversation' },
+  { name: 'memory', description: 'Manage memory' },
+  { name: 'hooks', description: 'Manage hooks' },
+  { name: 'review', description: 'Review changes' },
+];
+
+/** boocode harness uses /api/skills — merged on the frontend. */
+export const PROVIDER_COMMANDS: Record<string, AgentCommand[]> = {
+  claude: CLAUDE_COMMANDS,
+  opencode: OPENCODE_COMMANDS,
+  goose: GOOSE_COMMANDS,
+  qwen: QWEN_COMMANDS,
+  boocode: [],
+};
+
+export function getManifestCommands(provider: string): AgentCommand[] {
+  return PROVIDER_COMMANDS[provider] ?? [];
+}
+
+export function mergeCommands(...lists: AgentCommand[][]): AgentCommand[] {
+  const byName = new Map<string, AgentCommand>();
+  for (const list of lists) {
+    for (const cmd of list) {
+      byName.set(cmd.name, cmd);
+    }
+  }
+  return [...byName.values()].sort((a, b) => a.name.localeCompare(b.name));
+}
--- a/apps/coder/src/services/provider-config-registry.ts
+++ b/apps/coder/src/services/provider-config-registry.ts
@@ -0,0 +1,133 @@
+/**
+ * v2.3 resolved provider registry — single in-memory source of truth after
+ * merging the hardcoded built-ins (provider-registry.ts) with the config file
+ * (provider-config.ts). Mirrors Paseo's buildProviderRegistry/addDerivedProviders.
+ *
+ * Phase 1 scope: build + expose the resolved registry. `launchCommand` is null
+ * for built-ins (the default argv is resolved at dispatch time in Phase 3) and
+ * is the config `command` for custom ACP entries. No DB columns (design.md §3.3);
+ * `enabled` lives in memory only.
+ */
+import type { ProviderDef } from './provider-registry.js';
+import { PROVIDERS } from './provider-registry.js';
+import { load, type CoderProvidersFile } from './provider-config.js';
+
+export interface ResolvedProviderDef extends ProviderDef {
+  id: string;
+  enabled: boolean;
+  isBuiltin: boolean;
+  isCustomAcp: boolean;
+  /** Full argv for spawn: [binary, ...args]. Null for built-ins (resolved at dispatch). */
+  launchCommand: [string, ...string[]] | null;
+  env: Record<string, string> | undefined;
+  configLabel?: string;
+  configDescription?: string;
+  /** Config `models` — REPLACES the discovered/static model list when present. */
+  configModels?: Array<{ id: string; label: string }>;
+  /** Config `additionalModels` — MERGED on top of the resolved model list. */
+  configAdditionalModels?: Array<{ id: string; label: string }>;
+}
+
+/**
+ * Merge built-ins with config overrides into the resolved registry.
+ * Algorithm verbatim from design.md §3.1.
+ */
+export function buildResolvedRegistry(
+  builtins: ProviderDef[],
+  config: CoderProvidersFile,
+): Map<string, ResolvedProviderDef> {
+  const out = new Map<string, ResolvedProviderDef>();
+  const overrides = config.providers ?? {};
+  const builtinNames = new Set(builtins.map((b) => b.name));
+
+  // 1. Built-ins, applying a config override if one is present.
+  for (const def of builtins) {
+    const ov = overrides[def.name];
+    let enabled = ov?.enabled !== false;
+
+    // 3. boocode is always enabled; an enabled:false override is ignored + warned.
+    if (def.name === 'boocode' && ov?.enabled === false) {
+      console.warn("provider-config: ignoring enabled:false for built-in 'boocode' (always enabled)");
+      enabled = true;
+    }
+
+    const launchCommand =
+      ov?.command && ov.command.length > 0 ? (ov.command as [string, ...string[]]) : null;
+
+    out.set(def.name, {
+      ...def,
+      label: ov?.label ?? def.label,
+      id: def.name,
+      enabled,
+      isBuiltin: true,
+      isCustomAcp: false,
+      launchCommand,
+      env: ov?.env,
+      configLabel: ov?.label,
+      configDescription: ov?.description,
+      configModels: ov?.models,
+      configAdditionalModels: ov?.additionalModels,
+    });
+  }
+
+  // 2. Config ids that are not built-ins → custom ACP entries.
+  for (const [id, ov] of Object.entries(overrides)) {
+    if (builtinNames.has(id)) continue;
+    // §2.2 rules: "New id without extends → Reject at load with log."
+    if (ov.extends !== 'acp' || !ov.label || !ov.command || ov.command.length === 0) {
+      console.warn(
+        `provider-config: skipping custom provider '${id}' — requires extends:'acp', label, and command`,
+      );
+      continue;
+    }
+    out.set(id, {
+      name: id,
+      label: ov.label,
+      transport: 'acp',
+      modelSource: 'probe',
+      id,
+      enabled: ov.enabled !== false,
+      isBuiltin: false,
+      isCustomAcp: true,
+      launchCommand: ov.command as [string, ...string[]],
+      env: ov.env,
+      configLabel: ov.label,
+      configDescription: ov.description,
+      configModels: ov.models,
+      configAdditionalModels: ov.additionalModels,
+    });
+  }
+
+  return out;
+}
+
+// --- Module singleton ---------------------------------------------------------
+
+let cachedRegistry: Map<string, ResolvedProviderDef> | null = null;
+let cachedPath: string | null = null;
+
+/** Load the config file at `path`, rebuild, and cache the resolved registry. */
+export function loadProviderConfig(path: string): Map<string, ResolvedProviderDef> {
+  cachedPath = path;
+  cachedRegistry = buildResolvedRegistry(PROVIDERS, load(path));
+  return cachedRegistry;
+}
+
+/** Re-read the last-loaded config file and rebuild (Phase 4 calls this after PATCH). */
+export function reloadProviderConfig(): Map<string, ResolvedProviderDef> {
+  if (cachedPath == null) {
+    cachedRegistry = buildResolvedRegistry(PROVIDERS, { providers: {} });
+    return cachedRegistry;
+  }
+  return loadProviderConfig(cachedPath);
+}
+
+/** The cached resolved registry (built-ins only if nothing has been loaded yet). */
+export function getResolvedRegistry(): Map<string, ResolvedProviderDef> {
+  return cachedRegistry ?? buildResolvedRegistry(PROVIDERS, { providers: {} });
+}
+
+/** Resolved provider ids in registry order. */
+export function getResolvedProviderIds(): string[] {
+  return [...getResolvedRegistry().keys()];
+}
--- a/apps/coder/src/services/provider-config.ts
+++ b/apps/coder/src/services/provider-config.ts
@@ -0,0 +1,100 @@
+/**
+ * v2.3 provider config file (`/data/coder-providers.json`) — schema + loader.
+ *
+ * Layers config-backed overrides/custom-ACP entries over the hardcoded built-ins
+ * (see provider-config-registry.ts). Loading NEVER throws at startup (design.md
+ * §2.1): a missing file, invalid JSON, or schema mismatch all fall back to
+ * `{ providers: {} }` (built-ins only, all enabled).
+ */
+import { readFileSync, writeFileSync } from 'node:fs';
+import { z } from 'zod';
+
+// Schemas verbatim from design.md §2.2.
+export const ProviderOverrideSchema = z.object({
+  extends: z.enum(['acp']).optional(), // v2.3: only 'acp' for custom; built-ins omit extends
+  label: z.string().min(1).optional(),
+  description: z.string().optional(),
+  command: z.array(z.string().min(1)).min(1).optional(), // [binary, ...args]
+  env: z.record(z.string()).optional(),
+  enabled: z.boolean().optional(), // default true
+  order: z.number().int().optional(), // UI sort key
+  models: z.array(z.object({ id: z.string(), label: z.string() })).optional(),
+  additionalModels: z.array(z.object({ id: z.string(), label: z.string() })).optional(),
+});
+
+export const CoderProvidersFileSchema = z.object({
+  providers: z.record(ProviderOverrideSchema).default({}),
+});
+
+export type ProviderOverride = z.infer<typeof ProviderOverrideSchema>;
+export type CoderProvidersFile = z.infer<typeof CoderProvidersFileSchema>;
+
+/**
+ * PATCH body schema (design.md §6.2). A partial providers map where each value
+ * is either a full override object (REPLACES that id's override) or `null`
+ * (DELETES the override → revert to the built-in default). Ids absent from the
+ * patch are left untouched. The route validates the body against this first
+ * (malformed → 422) so a bad shape can never reach the merge/save step.
+ */
+export const ProviderConfigPatchSchema = z.object({
+  providers: z.record(ProviderOverrideSchema.nullable()).default({}),
+});
+
+export type ProviderConfigPatch = z.infer<typeof ProviderConfigPatchSchema>;
+
+/**
+ * Shallow per-id merge (design.md §6.2 / Paseo `patchConfig`). Each key in
+ * `patch.providers` REPLACES that id's override object wholesale (NOT a deep
+ * field merge); a `null` value DELETES the override. Returns a new object —
+ * never mutates `current`. The result is a plain CoderProvidersFile (no nulls),
+ * which the route re-validates against CoderProvidersFileSchema before save.
+ */
+export function mergeProviderConfigPatch(
+  current: CoderProvidersFile,
+  patch: ProviderConfigPatch,
+): CoderProvidersFile {
+  const providers: Record<string, ProviderOverride> = { ...current.providers };
+  for (const [id, override] of Object.entries(patch.providers)) {
+    if (override === null) {
+      delete providers[id];
+    } else {
+      providers[id] = override;
+    }
+  }
+  return { providers };
+}
+
+/** Read + parse + validate. Falls back to built-ins-only on any failure; never throws. */
+export function load(path: string): CoderProvidersFile {
+  let raw: string;
+  try {
+    raw = readFileSync(path, 'utf8');
+  } catch {
+    // Missing file → built-ins only. Expected, not an error.
+    return { providers: {} };
+  }
+
+  let json: unknown;
+  try {
+    json = JSON.parse(raw);
+  } catch (err) {
+    console.error(`provider-config: invalid JSON in ${path} — using built-ins only`, err);
+    return { providers: {} };
+  }
+
+  const parsed = CoderProvidersFileSchema.safeParse(json);
+  if (!parsed.success) {
+    console.error(
+      `provider-config: schema validation failed for ${path} — using built-ins only`,
+      parsed.error.flatten(),
+    );
+    return { providers: {} };
+  }
+
+  return parsed.data;
+}
+
+/** Write the config back to disk (used by the Phase 4 PATCH route). */
+export function save(path: string, config: CoderProvidersFile): void {
+  writeFileSync(path, `${JSON.stringify(config, null, 2)}\n`, 'utf8');
+}
--- a/apps/coder/src/services/provider-diagnostic.ts
+++ b/apps/coder/src/services/provider-diagnostic.ts
@@ -0,0 +1,71 @@
+/**
+ * v2.3 Phase 4 (design.md §8) — per-provider plaintext diagnostic report.
+ *
+ * Read-only by default: reports CACHED state (resolved registry def + the
+ * available_agents row + the warm snapshot-cache entry) plus a `which`-style
+ * PATH check for the launch binary. It does NOT spawn an ACP probe — §8 lists
+ * the live initialize probe as optional, and the route defaults to cached state.
+ *
+ * A template string is the whole formatter (no Paseo diagnostic-utils port).
+ */
+import type { ResolvedProviderDef } from './provider-config-registry.js';
+import type { ProviderSnapshotEntry, ProviderModel } from './provider-types.js';
+import { isCommandAvailable } from './command-availability.js';
+
+/** The subset of an `available_agents` row the diagnostic reads. */
+export interface DiagnosticAgentRow {
+  name: string;
+  install_path: string | null;
+  supports_acp?: boolean;
+  models?: ProviderModel[] | null;
+  last_probed_at?: string | Date | null;
+}
+
+interface DiagnosticOpts {
+  /** Warm snapshot-cache entry (read-only peek) — source of the last probe error. */
+  cachedEntry?: ProviderSnapshotEntry;
+  /** Injectable PATH check (defaults to the real `which`); stubbed in tests. */
+  checkAvailable?: (binary: string) => Promise<boolean>;
+}
+
+/** Resolve the binary the dispatcher would launch (for the PATH check + report). */
+function resolveBinary(resolved: ResolvedProviderDef, agentRow: DiagnosticAgentRow | undefined): string {
+  return resolved.launchCommand?.[0] ?? agentRow?.install_path ?? resolved.id;
+}
+
+export async function getProviderDiagnostic(
+  resolved: ResolvedProviderDef,
+  agentRow: DiagnosticAgentRow | undefined,
+  opts: DiagnosticOpts = {},
+): Promise<string> {
+  const checkAvailable = opts.checkAvailable ?? isCommandAvailable;
+  const installed = agentRow?.install_path != null;
+  const binary = resolveBinary(resolved, agentRow);
+  // boocode is native (no binary to launch) — short-circuit the PATH check.
+  const commandAvailable = resolved.transport === 'native' ? true : await checkAvailable(binary);
+  const lastProbedAt =
+    agentRow?.last_probed_at != null ? new Date(agentRow.last_probed_at).toISOString() : '(never)';
+  const modelCount = agentRow?.models?.length ?? 0;
+  const launchCommand = resolved.launchCommand
+    ? resolved.launchCommand.join(' ')
+    : '(built-in default, resolved at dispatch)';
+  const lastError = opts.cachedEntry?.error ?? '(none recorded)';
+
+  return [
+    `provider: ${resolved.id}`,
+    `label: ${resolved.configLabel ?? resolved.label}`,
+    `transport: ${resolved.transport}`,
+    `enabled: ${resolved.enabled}`,
+    `builtin: ${resolved.isBuiltin}`,
+    `customAcp: ${resolved.isCustomAcp}`,
+    `installed: ${installed}`,
+    `install_path: ${agentRow?.install_path ?? '(none)'}`,
+    `binary: ${binary}`,
+    `command_available: ${commandAvailable}`,
+    `launch_command: ${launchCommand}`,
+    `supports_acp: ${agentRow?.supports_acp ?? '(unknown)'}`,
+    `last_probed_at: ${lastProbedAt}`,
+    `models_in_db: ${modelCount}`,
+    `last_probe_error: ${lastError}`,
+  ].join('\n');
+}
--- a/apps/coder/src/services/provider-manifest.ts
+++ b/apps/coder/src/services/provider-manifest.ts
@@ -0,0 +1,75 @@
+/**
+ * Static provider mode metadata — lifted from Paseo provider-manifest.ts patterns.
+ */
+import type { ProviderMode } from './provider-types.js';
+
+export interface ProviderManifestEntry {
+  defaultModeId: string | null;
+  modes: ProviderMode[];
+  /** Claude effort levels exposed as thinking options on models. */
+  thinkingOptions?: Array<{ id: string; label: string }>;
+}
+
+const CLAUDE_MODES: ProviderMode[] = [
+  { id: 'default', label: 'Always Ask', description: 'Prompts for permission the first time a tool is used' },
+  { id: 'auto', label: 'Auto mode', description: 'Model classifier reviews permission prompts automatically' },
+  { id: 'acceptEdits', label: 'Accept File Edits', description: 'Automatically approves edit-focused tools' },
+  { id: 'plan', label: 'Plan Mode', description: 'Analyze without executing tools or edits' },
+  { id: 'bypassPermissions', label: 'Bypass', description: 'Skip all permission prompts', isUnattended: true },
+];
+
+const OPENCODE_MODES: ProviderMode[] = [
+  { id: 'build', label: 'Build', description: 'Allows edits and tool execution' },
+  { id: 'plan', label: 'Plan', description: 'Read-only planning mode' },
+  { id: 'full-access', label: 'Full Access', description: 'Auto-approves all tool prompts', isUnattended: true },
+];
+
+const QWEN_PTY_MODES: ProviderMode[] = [
+  { id: 'default', label: 'Default', description: 'Prompt for approval' },
+  { id: 'plan', label: 'Plan', description: 'Plan only — no edits' },
+  { id: 'auto-edit', label: 'Auto Edit', description: 'Auto-approve edit tools' },
+  { id: 'auto', label: 'Auto', description: 'LLM classifier auto-approves safe actions' },
+  { id: 'yolo', label: 'YOLO', description: 'Auto-approve all tools', isUnattended: true },
+];
+
+const CLAUDE_THINKING = [
+  { id: 'low', label: 'Low' },
+  { id: 'medium', label: 'Medium' },
+  { id: 'high', label: 'High' },
+  { id: 'xhigh', label: 'Extra High' },
+  { id: 'max', label: 'Max' },
+];
+
+export const PROVIDER_MANIFEST: Record<string, ProviderManifestEntry> = {
+  claude: {
+    defaultModeId: 'default',
+    modes: CLAUDE_MODES,
+    thinkingOptions: CLAUDE_THINKING,
+  },
+  opencode: {
+    defaultModeId: 'build',
+    modes: OPENCODE_MODES,
+  },
+  goose: {
+    defaultModeId: null,
+    modes: [],
+  },
+  qwen: {
+    defaultModeId: 'default',
+    modes: QWEN_PTY_MODES,
+  },
+};
+
+export function getManifestModes(provider: string): ProviderMode[] {
+  return PROVIDER_MANIFEST[provider]?.modes ?? [];
+}
+
+export function getManifestDefaultModeId(provider: string): string | null {
+  return PROVIDER_MANIFEST[provider]?.defaultModeId ?? null;
+}
+
+export function isUnattendedMode(provider: string, modeId: string | undefined): boolean {
+  if (!modeId) return false;
+  const modes = getManifestModes(provider);
+  return modes.some((m) => m.id === modeId && m.isUnattended);
+}
--- a/apps/coder/src/services/provider-registry.ts
+++ b/apps/coder/src/services/provider-registry.ts
@@ -0,0 +1,69 @@
+export interface ProviderDef {
+  name: string;
+  label: string;
+  transport: 'native' | 'acp' | 'pty';
+  modelSource: 'llama-swap' | 'static' | 'probe';
+  staticModels?: Array<{ id: string; label: string }>;
+  /** Merge llama-swap models into probed list (OpenCode). */
+  mergeLlamaSwap?: boolean;
+}
+
+/**
+ * Model discovery rules (see provider-snapshot.ts):
+ * - boocode: llama-swap only
+ * - opencode: ACP probe + mergeLlamaSwap (prefixed llama-swap/* ids)
+ * - qwen: ACP probe + merge ~/.qwen/settings.json; PTY fallback reads settings only
+ * - goose: ACP probe only
+ * - claude: static manifest models + thinking options
+ */
+export const PROVIDERS: ProviderDef[] = [
+  {
+    name: 'boocode',
+    label: 'BooCoder',
+    transport: 'native',
+    modelSource: 'llama-swap',
+  },
+  {
+    name: 'opencode',
+    label: 'OpenCode',
+    transport: 'acp',
+    modelSource: 'probe',
+    mergeLlamaSwap: true,
+  },
+  {
+    name: 'goose',
+    label: 'Goose',
+    transport: 'acp',
+    modelSource: 'probe',
+  },
+  {
+    name: 'claude',
+    label: 'Claude Code',
+    transport: 'pty',
+    modelSource: 'static',
+    // Passed verbatim to `claude --model <id>` (PTY dispatch). The CLI accepts a
+    // latest-alias ('opus'/'sonnet'/'haiku') or a pinned full name
+    // ('claude-opus-4-8'). Aliases never go stale; pinned IDs let you select an
+    // exact version. Extend/replace per-install via data/coder-providers.json
+    // (models / additionalModels) without a code change.
+    staticModels: [
+      { id: 'opus', label: 'Opus (latest)' },
+      { id: 'claude-opus-4-8', label: 'Opus 4.8' },
+      { id: 'sonnet', label: 'Sonnet (latest)' },
+      { id: 'claude-sonnet-4-6', label: 'Sonnet 4.6' },
+      { id: 'haiku', label: 'Haiku (latest)' },
+      { id: 'claude-haiku-4-5-20251001', label: 'Haiku 4.5' },
+    ],
+  },
+  {
+    name: 'qwen',
+    label: 'Qwen Code',
+    transport: 'acp',
+    modelSource: 'probe',
+  },
+];
+
+export const PROVIDERS_BY_NAME = new Map(PROVIDERS.map((p) => [p.name, p]));
+
+/** External agents probed on host (excludes native boocode). */
+export const PROBED_AGENT_NAMES = PROVIDERS.filter((p) => p.name !== 'boocode').map((p) => p.name);
--- a/apps/coder/src/services/provider-snapshot.ts
+++ b/apps/coder/src/services/provider-snapshot.ts
@@ -0,0 +1,334 @@
+/**
+ * Provider snapshot cache — cold ACP probe per provider + static manifest merge.
+ */
+import { homedir } from 'node:os';
+import type { FastifyBaseLogger } from 'fastify';
+import type { Sql } from '../db.js';
+import type { Config } from '../config.js';
+import {
+  getManifestDefaultModeId,
+  getManifestModes,
+  PROVIDER_MANIFEST,
+} from './provider-manifest.js';
+import { probeAcpProvider } from './acp-probe.js';
+import type { ProviderModel, ProviderSnapshotEntry, AgentCommand } from './provider-types.js';
+import { getManifestCommands, mergeCommands } from './provider-commands.js';
+import { readQwenSettingsModels } from './qwen-settings.js';
+import { getResolvedRegistry, type ResolvedProviderDef } from './provider-config-registry.js';
+import { isCommandAvailable } from './command-availability.js';
+import { discoverClaudeCommands } from './claude-command-discovery.js';
+
+interface AgentRow {
+  name: string;
+  install_path: string | null;
+  supports_acp: boolean;
+  models: ProviderModel[] | null;
+  commands: AgentCommand[] | null;
+  label: string | null;
+  transport: string | null;
+  last_probed_at: string | Date | null;
+}
+
+async function fetchLlamaSwapModels(config: Config): Promise<ProviderModel[]> {
+  try {
+    const res = await fetch(`${config.LLAMA_SWAP_URL}/v1/models`);
+    if (!res.ok) return [];
+    const parsed = (await res.json()) as { data?: Array<{ id: string }> };
+    return (parsed.data ?? []).map((m) => ({ id: m.id, label: m.id }));
+  } catch {
+    return [];
+  }
+}
+
+/** Prefix llama-swap model ids so they don't collide with provider-native models. */
+export function prefixLlamaSwapModels(models: ProviderModel[]): ProviderModel[] {
+  return models.map((m) => ({
+    ...m,
+    id: m.id.startsWith('llama-swap/') ? m.id : `llama-swap/${m.id}`,
+  }));
+}
+
+function attachClaudeThinking(models: ProviderModel[]): ProviderModel[] {
+  const thinking = PROVIDER_MANIFEST.claude?.thinkingOptions;
+  if (!thinking?.length) return models;
+  return models.map((m) => ({
+    ...m,
+    thinkingOptions: thinking,
+    defaultThinkingOptionId: 'medium',
+  }));
+}
+
+export function mergeModels(...lists: ProviderModel[][]): ProviderModel[] {
+  const seen = new Set<string>();
+  const out: ProviderModel[] = [];
+  for (const list of lists) {
+    for (const m of list) {
+      if (seen.has(m.id)) continue;
+      seen.add(m.id);
+      out.push(m);
+    }
+  }
+  return out;
+}
+
+async function buildProviderEntry(
+  resolved: ResolvedProviderDef,
+  agentRow: AgentRow | undefined,
+  llamaModels: ProviderModel[],
+  cwd: string,
+  ttlMs: number,
+  force: boolean,
+): Promise<ProviderSnapshotEntry> {
+  const name = resolved.id;
+  const isNative = resolved.transport === 'native';
+  const fallbackModes = getManifestModes(name);
+  const defaultModeId = getManifestDefaultModeId(name);
+  const manifestCommands = getManifestCommands(name);
+  // Manifest + persisted live ACP commands (captured on a prior cold probe), so
+  // the agent's discovered commands show even when the tier-2 probe is skipped.
+  const dbCommands = mergeCommands(manifestCommands, agentRow?.commands ?? []);
+  const label = agentRow?.label ?? resolved.configLabel ?? resolved.label;
+  const descr = resolved.configDescription ? { description: resolved.configDescription } : {};
+
+  // v2.3: config `models` REPLACES the discovered/static list; `additionalModels`
+  // MERGES on top. Applied to every ready/installed model list below.
+  const withConfigModels = (m: ProviderModel[]): ProviderModel[] => {
+    let out = resolved.configModels && resolved.configModels.length > 0 ? resolved.configModels : m;
+    if (resolved.configAdditionalModels && resolved.configAdditionalModels.length > 0) {
+      out = mergeModels(out, resolved.configAdditionalModels);
+    }
+    return out;
+  };
+
+  // ACP built-ins fall back to PTY transport when the installed binary lacks ACP.
+  let transport = resolved.transport;
+  if (agentRow && resolved.transport === 'acp' && !agentRow.supports_acp) {
+    transport = 'pty';
+  }
+
+  // 1. Disabled → unavailable, no probe.
+  if (!resolved.enabled) {
+    return {
+      name, label, ...descr, transport, status: 'unavailable',
+      enabled: false, installed: false, models: [], modes: fallbackModes,
+      defaultModeId, commands: manifestCommands,
+    };
+  }
+
+  // 2. Native boocode → always ready (llama-swap models).
+  if (isNative) {
+    return {
+      name, label: resolved.label, transport, status: 'ready',
+      enabled: true, installed: true, models: withConfigModels(llamaModels), modes: [],
+      defaultModeId: null, commands: manifestCommands,
+    };
+  }
+
+  // 3. Tier-1 fast availability: installed iff a probed install_path exists or
+  // the launch binary is on PATH. No spawn beyond a `which` for custom entries.
+  const fast =
+    agentRow?.install_path != null ||
+    (resolved.launchCommand ? await isCommandAvailable(resolved.launchCommand[0]) : false);
+
+  if (!fast) {
+    return {
+      name, label, ...descr, transport, status: 'unavailable',
+      enabled: true, installed: false, models: [], modes: fallbackModes,
+      defaultModeId, commands: manifestCommands,
+    };
+  }
+
+  // Baseline model precedence (used by claude + non-probe fallbacks).
+  let models: ProviderModel[] = [];
+  if (resolved.modelSource === 'llama-swap' && resolved.mergeLlamaSwap) {
+    models = llamaModels;
+  } else if (agentRow?.models?.length) {
+    models = agentRow.models;
+  } else if (resolved.staticModels) {
+    models = resolved.staticModels.map((m) => ({ id: m.id, label: m.label }));
+  }
+
+  // claude: static models + thinking options, no ACP probe (unchanged from v2.2).
+  if (name === 'claude') {
+    // claude is PTY (no ACP discovery) — read its enabled commands + plugin
+    // skills from disk live (the snapshot cache rate-limits the fs reads).
+    return {
+      name, label, transport, status: 'ready', enabled: true, installed: true,
+      models: attachClaudeThinking(withConfigModels(models)), modes: fallbackModes, defaultModeId,
+      commands: mergeCommands(manifestCommands, discoverClaudeCommands()),
+    };
+  }
+
+  const canProbeAcp =
+    transport === 'acp' &&
+    ((agentRow?.install_path != null && agentRow.supports_acp) ||
+      (resolved.isCustomAcp && resolved.launchCommand != null));
+
+  if (canProbeAcp) {
+    // Tier-2 gate (§4.3): cold ACP probe only on force, staleness, or empty DB
+    // models. Otherwise serve DB models + manifest modes/commands — no spawn.
+    const lastProbedMs =
+      agentRow?.last_probed_at != null ? new Date(agentRow.last_probed_at).getTime() : NaN;
+    const stale = Number.isNaN(lastProbedMs) || Date.now() - lastProbedMs > ttlMs;
+    const dbEmpty = !(agentRow?.models && agentRow.models.length > 0);
+    const runTier2 = force || stale || dbEmpty;
+
+    if (!runTier2) {
+      let skipModels = agentRow?.models ?? [];
+      if (resolved.mergeLlamaSwap && resolved.modelSource !== 'llama-swap') {
+        skipModels = mergeModels(skipModels, prefixLlamaSwapModels(llamaModels));
+      } else if (resolved.modelSource === 'llama-swap' && skipModels.length === 0) {
+        skipModels = llamaModels;
+      }
+      return {
+        name, label, transport, status: 'ready', enabled: true, installed: true,
+        models: withConfigModels(skipModels), modes: fallbackModes, defaultModeId, commands: dbCommands,
+      };
+    }
+
+    const probeTarget =
+      resolved.isCustomAcp && resolved.launchCommand
+        ? resolved.launchCommand[0]
+        : agentRow!.install_path!;
+    const probe = await probeAcpProvider(name, probeTarget, cwd);
+
+    let probeModels = probe.models.length > 0 ? probe.models : models;
+    if (name === 'qwen') {
+      probeModels = mergeModels(probeModels, await readQwenSettingsModels());
+    }
+    if (resolved.mergeLlamaSwap && resolved.modelSource !== 'llama-swap') {
+      const nativeModels = probe.models.length > 0 ? probe.models : probeModels;
+      probeModels = mergeModels(nativeModels, prefixLlamaSwapModels(llamaModels));
+    }
+
+    return {
+      name, label, transport,
+      status: probe.ok ? 'ready' : 'error',
+      enabled: true, installed: true,
+      models: withConfigModels(probeModels),
+      modes: probe.modes.length > 0 ? probe.modes : fallbackModes,
+      defaultModeId: probe.defaultModeId ?? defaultModeId,
+      commands: mergeCommands(manifestCommands, probe.commands),
+      ...(probe.error ? { error: probe.error } : {}),
+      fetchedAt: new Date().toISOString(),
+    };
+  }
+
+  // PTY-only fallback (e.g. qwen without ACP) — installed + ready.
+  if (name === 'qwen' && models.length === 0) {
+    models = await readQwenSettingsModels();
+  }
+  return {
+    name, label, transport, status: 'ready', enabled: true, installed: true,
+    models: withConfigModels(models), modes: fallbackModes, defaultModeId, commands: dbCommands,
+  };
+}
+
+const snapshotCache = new Map<string, { at: number; entries: ProviderSnapshotEntry[] }>();
+const snapshotInflight = new Map<string, Promise<ProviderSnapshotEntry[]>>();
+const CACHE_TTL_MS = 5 * 60_000;
+
+export async function getProviderSnapshot(
+  sql: Sql,
+  config: Config,
+  cwd?: string,
+  force = false,
+): Promise<ProviderSnapshotEntry[]> {
+  const resolvedCwd = cwd?.trim() || homedir();
+  const cacheKey = resolvedCwd;
+  const cached = snapshotCache.get(cacheKey);
+  if (!force && cached && Date.now() - cached.at < CACHE_TTL_MS) {
+    return cached.entries;
+  }
+
+  const inflight = snapshotInflight.get(cacheKey);
+  if (!force && inflight) {
+    return inflight;
+  }
+
+  const build = async (): Promise<ProviderSnapshotEntry[]> => {
+    const llamaModels = await fetchLlamaSwapModels(config);
+    const agents = await sql<AgentRow[]>`
+      SELECT name, install_path, supports_acp, models, commands, label, transport, last_probed_at FROM available_agents
+    `;
+    const agentMap = new Map(agents.map((a) => [a.name, a]));
+    const ttlMs = config.PROVIDER_PROBE_TTL_MS;
+
+    const entries = await Promise.all(
+      [...getResolvedRegistry().values()].map((resolved) =>
+        buildProviderEntry(resolved, agentMap.get(resolved.id), llamaModels, resolvedCwd, ttlMs, force),
+      ),
+    );
+
+    snapshotCache.set(cacheKey, { at: Date.now(), entries });
+    return entries;
+  };
+
+  const promise = build().finally(() => {
+    snapshotInflight.delete(cacheKey);
+  });
+  snapshotInflight.set(cacheKey, promise);
+
+  // Await the build (force or cache-miss) and return terminal entries. The sync
+  // `loading` return (design §4.4) is DEFERRED until Phase 5 ships the client
+  // poll that resolves it: without that poll, a single fetch lands on
+  // installed:false `loading` entries, which AgentComposerBar filters out
+  // (`e.installed && ...`) → empty picker. Builds stay fast via the tier-2 skip
+  // once available_agents.models is warm.
+  return promise;
+}
+
+export function clearProviderSnapshotCache(): void {
+  snapshotCache.clear();
+  snapshotInflight.clear();
+}
+
+/**
+ * Read-only peek into the warm snapshot cache for one provider (no build, no
+ * probe). Used by the diagnostic route to report the last computed probe error
+ * without spawning anything. Returns undefined on a cold cache / unknown name.
+ */
+export function peekSnapshotEntry(name: string, cwd?: string): ProviderSnapshotEntry | undefined {
+  const resolvedCwd = cwd?.trim() || homedir();
+  return snapshotCache.get(resolvedCwd)?.entries.find((e) => e.name === name);
+}
+
+/** Persist probed model lists back to available_agents for fast legacy reads. */
+export async function persistProbedModels(
+  sql: Sql,
+  entries: ProviderSnapshotEntry[],
+  log: FastifyBaseLogger,
+): Promise<void> {
+  let count = 0;
+  for (const entry of entries) {
+    if (entry.name === 'boocode') continue;
+    let persisted = false;
+    if (entry.models.length > 0) {
+      const flatModels = entry.models.map(({ id, label }) => ({ id, label }));
+      await sql`
+        UPDATE available_agents
+        SET models = ${sql.json(flatModels as never)}, last_probed_at = clock_timestamp()
+        WHERE name = ${entry.name}
+      `;
+      persisted = true;
+    }
+    // Persist captured ACP commands so they survive the tier-2 probe skip and
+    // show without a dispatch. Only when non-empty — never clobber a prior set.
+    if (entry.commands.length > 0) {
+      const flatCommands = entry.commands.map((c) => ({
+        name: c.name,
+        ...(c.description ? { description: c.description } : {}),
+      }));
+      await sql`
+        UPDATE available_agents
+        SET commands = ${sql.json(flatCommands as never)}, last_probed_at = clock_timestamp()
+        WHERE name = ${entry.name}
+      `;
+      persisted = true;
+    }
+    if (persisted) count++;
+  }
+  if (count > 0) {
+    log.info({ count }, 'provider-snapshot: persisted models/commands to available_agents');
+  }
+}
--- a/apps/coder/src/services/provider-types.ts
+++ b/apps/coder/src/services/provider-types.ts
@@ -0,0 +1,61 @@
+/** Shared provider / snapshot types (Paseo-shaped, BooCoder-native). */
+
+export interface ProviderMode {
+  id: string;
+  label: string;
+  description?: string;
+  /** Auto-approve tool permissions when this mode is selected. */
+  isUnattended?: boolean;
+}
+
+export interface ThinkingOption {
+  id: string;
+  label: string;
+  isDefault?: boolean;
+}
+
+export interface ProviderModel {
+  id: string;
+  label: string;
+  description?: string;
+  isDefault?: boolean;
+  thinkingOptions?: ThinkingOption[];
+  defaultThinkingOptionId?: string;
+}
+
+// v2.3 phase 2: 'loading' (cache-miss, probe in flight) + 'unavailable'
+// (disabled or not installed) restored alongside the terminal 'ready' | 'error'.
+export type ProviderSnapshotStatus = 'loading' | 'ready' | 'unavailable' | 'error';
+
+export interface AgentCommand {
+  name: string;
+  description?: string;
+  // v2.5.11: 'skill' (plugin skill) vs 'command' (native/CLI slash command).
+  // Drives the icon split in the coder slash menu. Undefined → command.
+  kind?: 'command' | 'skill';
+}
+
+// KEEP IN SYNC with apps/web/src/api/types.ts ProviderSnapshotEntry — parity is
+// enforced by __tests__/provider-types-parity.test.ts (fails on any field drift).
+export interface ProviderSnapshotEntry {
+  name: string;
+  label: string;
+  description?: string;
+  transport: string;
+  status: ProviderSnapshotStatus;
+  enabled: boolean;
+  installed: boolean;
+  models: ProviderModel[];
+  modes: ProviderMode[];
+  defaultModeId: string | null;
+  commands: AgentCommand[];
+  error?: string;
+  fetchedAt?: string;
+}
+
+export interface AgentSessionConfig {
+  provider: string;
+  model?: string;
+  modeId?: string;
+  thinkingOptionId?: string;
+}
--- a/apps/coder/src/services/pty-dispatch.ts
+++ b/apps/coder/src/services/pty-dispatch.ts
@@ -0,0 +1,137 @@
+/**
+ * PTY dispatch — runs external agents directly on the host.
+ */
+import type { FastifyBaseLogger } from 'fastify';
+import { spawn } from 'node:child_process';
+
+export interface DispatchResult {
+  exitCode: number;
+  stdout: string;
+  stderr: string;
+}
+
+export interface PtyDispatchOpts {
+  agent: string;
+  task: string;
+  worktreePath: string;
+  model?: string;
+  modeId?: string;
+  thinkingOptionId?: string;
+  installPath?: string;
+  signal?: AbortSignal;
+  log: FastifyBaseLogger;
+}
+
+interface PtySpawnSpec {
+  binary: string;
+  args: string[];
+  stdin?: string;
+}
+
+function buildPtySpawnSpec(
+  agent: string,
+  task: string,
+  model?: string,
+  modeId?: string,
+  thinkingOptionId?: string,
+  installPath?: string,
+): PtySpawnSpec | null {
+  const binary = installPath ?? agent;
+
+  switch (agent) {
+    case 'claude': {
+      const args = ['-p'];
+      if (model) args.push('--model', model);
+      if (modeId) args.push('--permission-mode', modeId);
+      if (thinkingOptionId) args.push('--effort', thinkingOptionId);
+      return { binary, args, stdin: task };
+    }
+
+    case 'qwen': {
+      const args = ['-p', task, '--output-format', 'stream-json'];
+      if (model) args.push('--model', model);
+      if (modeId) args.push('--approval-mode', modeId);
+      return { binary, args };
+    }
+
+    case 'opencode':
+      return {
+        binary,
+        args: model ? ['--model', model] : [],
+        stdin: task,
+      };
+
+    case 'goose':
+      return {
+        binary,
+        args: model ? ['run', '--text', task, '--model', model] : ['run', '--text', task],
+      };
+
+    default:
+      return null;
+  }
+}
+
+export async function dispatchViaPty(opts: PtyDispatchOpts): Promise<DispatchResult> {
+  const { agent, task, worktreePath, model, modeId, thinkingOptionId, installPath, signal, log } = opts;
+
+  const cmd = buildPtySpawnSpec(agent, task, model, modeId, thinkingOptionId, installPath);
+  if (!cmd) {
+    return {
+      exitCode: 1,
+      stdout: '',
+      stderr: `Agent '${agent}' is not yet supported for PTY dispatch.`,
+    };
+  }
+
+  log.info({ agent, binary: cmd.binary, worktreePath, modeId }, 'pty-dispatch: starting');
+
+  return new Promise<DispatchResult>((resolve, reject) => {
+    const child = spawn(cmd.binary, cmd.args, {
+      cwd: worktreePath,
+      stdio: ['pipe', 'pipe', 'pipe'],
+      env: { ...process.env },
+    });
+
+    if (cmd.stdin) {
+      child.stdin!.write(cmd.stdin);
+    }
+    child.stdin!.end();
+
+    let stdout = '';
+    let stderr = '';
+    let killed = false;
+
+    child.stdout!.on('data', (chunk: Buffer) => { stdout += chunk.toString(); });
+    child.stderr!.on('data', (chunk: Buffer) => { stderr += chunk.toString(); });
+
+    const cleanup = () => {
+      if (!killed) {
+        killed = true;
+        child.kill('SIGTERM');
+        setTimeout(() => child.kill('SIGKILL'), 5_000);
+      }
+    };
+
+    if (signal) {
+      if (signal.aborted) {
+        cleanup();
+        resolve({ exitCode: 130, stdout: '', stderr: 'Aborted before start' });
+        return;
+      }
+      signal.addEventListener('abort', cleanup, { once: true });
+    }
+
+    child.on('close', (code) => {
+      if (signal) signal.removeEventListener('abort', cleanup);
+      log.info({ agent, exitCode: code }, 'pty-dispatch: completed');
+      resolve({ exitCode: code ?? 1, stdout, stderr });
+    });
+
+    child.on('error', (err) => {
+      if (signal) signal.removeEventListener('abort', cleanup);
+      log.error({ agent, err: err.message }, 'pty-dispatch: spawn error');
+      reject(err);
+    });
+  });
+}
--- a/apps/coder/src/services/qwen-settings.ts
+++ b/apps/coder/src/services/qwen-settings.ts
@@ -0,0 +1,21 @@
+import { readFile } from 'node:fs/promises';
+import { join } from 'node:path';
+import { homedir } from 'node:os';
+import type { ProviderModel } from './provider-types.js';
+
+const QWEN_SETTINGS_PATH = join(homedir(), '.qwen', 'settings.json');
+
+export async function readQwenSettingsModels(): Promise<ProviderModel[]> {
+  try {
+    const raw = await readFile(QWEN_SETTINGS_PATH, 'utf8');
+    if (!raw.trim()) return [];
+    const settings = JSON.parse(raw) as {
+      modelProviders?: { openai?: Array<{ id: string }> };
+    };
+    const openaiModels = settings?.modelProviders?.openai;
+    if (!Array.isArray(openaiModels)) return [];
+    return openaiModels.map((m) => ({ id: m.id, label: m.id }));
+  } catch {
+    return [];
+  }
+}
--- a/apps/coder/src/services/tools/adapter.ts
+++ b/apps/coder/src/services/tools/adapter.ts
@@ -0,0 +1,30 @@
+/**
+ * Adapts BooCoder write tools (which take ToolContext) into BooChat's ToolDef
+ * interface (which takes `projectRoot, extraRoots?`).
+ *
+ * The adapter reads the module-level inference context at execute time, so the
+ * wrapping happens at boot (static) — no per-inference re-wrap needed.
+ */
+
+import type { ToolDef as ServerToolDef } from '@boocode/server/tools';
+import type { ToolDef, ToolContext } from './types.js';
+import { getInferenceContext } from './inference_context.js';
+
+/**
+ * Wrap a BooCoder write tool (execute takes ToolContext) into a BooChat
+ * ToolDef (execute takes projectRoot + optional extraRoots). The adapter
+ * builds the ToolContext from the module-level inference context at call time.
+ */
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export function adaptWriteTool(tool: ToolDef<any>): ServerToolDef<any> {
+  return {
+    name: tool.name,
+    description: tool.description,
+    inputSchema: tool.inputSchema,
+    jsonSchema: tool.jsonSchema,
+    async execute(input: unknown, projectRoot: string, _extraRoots?: readonly string[]): Promise<unknown> {
+      const ctx: ToolContext = getInferenceContext();
+      return tool.execute(input, projectRoot, ctx);
+    },
+  };
+}
--- a/apps/coder/src/services/tools/apply_pending.ts
+++ b/apps/coder/src/services/tools/apply_pending.ts
@@ -0,0 +1,44 @@
+import { z } from 'zod';
+import type { ToolDef, ToolContext } from './types.js';
+import { applyAll } from '../pending_changes.js';
+
+const ApplyPendingInput = z.object({});
+type ApplyPendingInputT = z.infer<typeof ApplyPendingInput>;
+
+export const applyPendingTool: ToolDef<ApplyPendingInputT> = {
+  name: 'apply_pending',
+  description:
+    'Apply all pending changes for the current session to disk. ' +
+    'Each queued create/edit/delete is executed in order.',
+  inputSchema: ApplyPendingInput,
+  jsonSchema: {
+    type: 'function',
+    function: {
+      name: 'apply_pending',
+      description:
+        'Apply all pending changes for the current session to disk. ' +
+        'Each queued create/edit/delete is executed in order.',
+      parameters: {
+        type: 'object',
+        properties: {},
+        required: [],
+      },
+    },
+  },
+  async execute(_input: ApplyPendingInputT, projectRoot: string, context: ToolContext): Promise<unknown> {
+    const results = await applyAll(context.sql, context.sessionId, projectRoot);
+    const succeeded = results.filter((r) => r.success).length;
+    const failed = results.filter((r) => !r.success).length;
+
+    return {
+      total: results.length,
+      succeeded,
+      failed,
+      results,
+      message:
+        results.length === 0
+          ? 'No pending changes to apply.'
+          : `Applied ${succeeded}/${results.length} changes.${failed > 0 ? ` ${failed} failed.` : ''}`,
+    };
+  },
+};
--- a/apps/coder/src/services/tools/check_task_status.ts
+++ b/apps/coder/src/services/tools/check_task_status.ts
@@ -0,0 +1,50 @@
+import { z } from 'zod';
+import type { ToolDef, ToolContext } from './types.js';
+
+const CheckTaskStatusInput = z.object({
+  task_id: z.string().uuid().describe('ID of the task to check'),
+});
+
+type CheckTaskStatusInputT = z.infer<typeof CheckTaskStatusInput>;
+
+export const checkTaskStatusTool: ToolDef<CheckTaskStatusInputT> = {
+  name: 'check_task_status',
+  description: 'Check the status and output of a subtask by ID. Returns state, output_summary, and timing.',
+  inputSchema: CheckTaskStatusInput,
+  jsonSchema: {
+    type: 'function',
+    function: {
+      name: 'check_task_status',
+      description: 'Check the status and output of a subtask by ID.',
+      parameters: {
+        type: 'object',
+        properties: {
+          task_id: { type: 'string', description: 'ID of the task to check' },
+        },
+        required: ['task_id'],
+      },
+    },
+  },
+
+  async execute(input: CheckTaskStatusInputT, _projectRoot: string, context: ToolContext): Promise<unknown> {
+    const { sql } = context;
+
+    const [task] = await sql<{ id: string; state: string; output_summary: string | null; started_at: string | null; ended_at: string | null }[]>`
+      SELECT id, state, output_summary, started_at, ended_at
+      FROM tasks
+      WHERE id = ${input.task_id}
+    `;
+
+    if (!task) {
+      return { error: `Task ${input.task_id} not found` };
+    }
+
+    return {
+      id: task.id,
+      state: task.state,
+      output_summary: task.output_summary,
+      started_at: task.started_at,
+      ended_at: task.ended_at,
+    };
+  },
+};
--- a/apps/coder/src/services/tools/create_file.ts
+++ b/apps/coder/src/services/tools/create_file.ts
@@ -0,0 +1,51 @@
+import { z } from 'zod';
+import type { ToolDef, ToolContext } from './types.js';
+import { queueCreate } from '../pending_changes.js';
+
+const CreateFileInput = z.object({
+  file_path: z.string().min(1),
+  content: z.string(),
+});
+type CreateFileInputT = z.infer<typeof CreateFileInput>;
+
+export const createFileTool: ToolDef<CreateFileInputT> = {
+  name: 'create_file',
+  description:
+    'Queue creation of a new file with the given content. ' +
+    'The change is staged in pending_changes and must be applied explicitly.',
+  inputSchema: CreateFileInput,
+  jsonSchema: {
+    type: 'function',
+    function: {
+      name: 'create_file',
+      description:
+        'Queue creation of a new file with the given content. ' +
+        'The change is staged in pending_changes and must be applied explicitly.',
+      parameters: {
+        type: 'object',
+        properties: {
+          file_path: { type: 'string', description: 'Path for the new file (relative to project root or absolute)' },
+          content: { type: 'string', description: 'Full content of the file to create' },
+        },
+        required: ['file_path', 'content'],
+      },
+    },
+  },
+  async execute(input: CreateFileInputT, projectRoot: string, context: ToolContext): Promise<unknown> {
+    const change = await queueCreate(
+      context.sql,
+      context.sessionId,
+      context.taskId,
+      input.file_path,
+      input.content,
+      projectRoot,
+    );
+    return {
+      status: 'queued',
+      change_id: change.id,
+      file_path: change.file_path,
+      operation: 'create',
+      message: `File creation queued: ${change.file_path}. Use apply_pending to write changes to disk.`,
+    };
+  },
+};
--- a/apps/coder/src/services/tools/delete_file.ts
+++ b/apps/coder/src/services/tools/delete_file.ts
@@ -0,0 +1,48 @@
+import { z } from 'zod';
+import type { ToolDef, ToolContext } from './types.js';
+import { queueDelete } from '../pending_changes.js';
+
+const DeleteFileInput = z.object({
+  file_path: z.string().min(1),
+});
+type DeleteFileInputT = z.infer<typeof DeleteFileInput>;
+
+export const deleteFileTool: ToolDef<DeleteFileInputT> = {
+  name: 'delete_file',
+  description:
+    'Queue deletion of a file. ' +
+    'The change is staged in pending_changes and must be applied explicitly.',
+  inputSchema: DeleteFileInput,
+  jsonSchema: {
+    type: 'function',
+    function: {
+      name: 'delete_file',
+      description:
+        'Queue deletion of a file. ' +
+        'The change is staged in pending_changes and must be applied explicitly.',
+      parameters: {
+        type: 'object',
+        properties: {
+          file_path: { type: 'string', description: 'Path to the file to delete (relative to project root or absolute)' },
+        },
+        required: ['file_path'],
+      },
+    },
+  },
+  async execute(input: DeleteFileInputT, projectRoot: string, context: ToolContext): Promise<unknown> {
+    const change = await queueDelete(
+      context.sql,
+      context.sessionId,
+      context.taskId,
+      input.file_path,
+      projectRoot,
+    );
+    return {
+      status: 'queued',
+      change_id: change.id,
+      file_path: change.file_path,
+      operation: 'delete',
+      message: `File deletion queued: ${change.file_path}. Use apply_pending to write changes to disk.`,
+    };
+  },
+};
--- a/apps/coder/src/services/tools/edit_file.ts
+++ b/apps/coder/src/services/tools/edit_file.ts
@@ -0,0 +1,54 @@
+import { z } from 'zod';
+import type { ToolDef, ToolContext } from './types.js';
+import { queueEdit } from '../pending_changes.js';
+
+const EditFileInput = z.object({
+  file_path: z.string().min(1),
+  old_string: z.string().min(1),
+  new_string: z.string(),
+});
+type EditFileInputT = z.infer<typeof EditFileInput>;
+
+export const editFileTool: ToolDef<EditFileInputT> = {
+  name: 'edit_file',
+  description:
+    'Queue an edit to a file. The edit replaces old_string with new_string. ' +
+    'The change is staged in pending_changes and must be applied explicitly.',
+  inputSchema: EditFileInput,
+  jsonSchema: {
+    type: 'function',
+    function: {
+      name: 'edit_file',
+      description:
+        'Queue an edit to a file. The edit replaces old_string with new_string. ' +
+        'The change is staged in pending_changes and must be applied explicitly.',
+      parameters: {
+        type: 'object',
+        properties: {
+          file_path: { type: 'string', description: 'Path to the file to edit (relative to project root or absolute)' },
+          old_string: { type: 'string', description: 'The exact string to find and replace (must appear in the file)' },
+          new_string: { type: 'string', description: 'The replacement string' },
+        },
+        required: ['file_path', 'old_string', 'new_string'],
+      },
+    },
+  },
+  async execute(input: EditFileInputT, projectRoot: string, context: ToolContext): Promise<unknown> {
+    const change = await queueEdit(
+      context.sql,
+      context.sessionId,
+      context.taskId,
+      input.file_path,
+      input.old_string,
+      input.new_string,
+      projectRoot,
+    );
+    return {
+      status: 'queued',
+      change_id: change.id,
+      file_path: change.file_path,
+      operation: 'edit',
+      message: `Edit queued for ${change.file_path}. Use apply_pending to write changes to disk.`,
+    };
+  },
+};
--- a/apps/coder/src/services/tools/index.ts
+++ b/apps/coder/src/services/tools/index.ts
@@ -0,0 +1,34 @@
+import type { ToolDef } from './types.js';
+import { editFileTool } from './edit_file.js';
+import { createFileTool } from './create_file.js';
+import { deleteFileTool } from './delete_file.js';
+import { applyPendingTool } from './apply_pending.js';
+import { rewindTool } from './rewind.js';
+import { newTaskTool } from './new_task.js';
+import { listTasksTool } from './list_tasks.js';
+import { checkTaskStatusTool } from './check_task_status.js';
+
+export type { ToolDef, ToolContext, ToolJsonSchema } from './types.js';
+
+// All BooCoder write tools. The inference loop (Phase 2B) will combine these
+// with BooChat's read-only tools to form the full tool set available to agents.
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export const WRITE_TOOLS: readonly ToolDef<any>[] = [
+  applyPendingTool,
+  createFileTool,
+  deleteFileTool,
+  editFileTool,
+  rewindTool,
+  // Boomerang subtask tools — orchestrator agents call these to spawn/monitor child tasks.
+  // An "Orchestrator" agent profile would whitelist [new_task, list_tasks, check_task_status].
+  newTaskTool,
+  listTasksTool,
+  checkTaskStatusTool,
+];
+
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export const WRITE_TOOLS_BY_NAME: ReadonlyMap<string, ToolDef<any>> = new Map(
+  WRITE_TOOLS.map((t) => [t.name, t]),
+);
+
+export { editFileTool, createFileTool, deleteFileTool, applyPendingTool, rewindTool, newTaskTool, listTasksTool, checkTaskStatusTool };
--- a/apps/coder/src/services/tools/inference_context.ts
+++ b/apps/coder/src/services/tools/inference_context.ts
@@ -0,0 +1,36 @@
+import type { Sql } from '../../db.js';
+
+/**
+ * Module-level inference context for write tools.
+ *
+ * Set via `setInferenceContext()` before each inference run starts.
+ * Write tools read it via `getInferenceContext()` during execute.
+ * Same pattern as BooChat's `loadConfig()` singleton — tools need
+ * ambient state that can't be threaded through the tool-phase execute
+ * signature (which is `execute(input, projectRoot, extraRoots?)`).
+ */
+
+export interface InferenceContext {
+  sql: Sql;
+  sessionId: string;
+  taskId: string | null;
+}
+
+let current: InferenceContext | null = null;
+
+export function setInferenceContext(ctx: InferenceContext): void {
+  current = ctx;
+}
+
+export function clearInferenceContext(): void {
+  current = null;
+}
+
+export function getInferenceContext(): InferenceContext {
+  if (!current) {
+    throw new Error(
+      'Write tool called outside inference context — setInferenceContext() was not called before this run',
+    );
+  }
+  return current;
+}
--- a/apps/coder/src/services/tools/list_tasks.ts
+++ b/apps/coder/src/services/tools/list_tasks.ts
@@ -0,0 +1,56 @@
+import { z } from 'zod';
+import type { ToolDef, ToolContext } from './types.js';
+import { getInferenceContext } from './inference_context.js';
+
+const ListTasksInput = z.object({
+  parent_task_id: z.string().uuid().optional().describe('Filter by parent task ID. Omit to list children of current task.'),
+});
+
+type ListTasksInputT = z.infer<typeof ListTasksInput>;
+
+export const listTasksTool: ToolDef<ListTasksInputT> = {
+  name: 'list_tasks',
+  description: 'List child tasks of the current task (or a specified parent). Returns id, state, input preview, and output_summary.',
+  inputSchema: ListTasksInput,
+  jsonSchema: {
+    type: 'function',
+    function: {
+      name: 'list_tasks',
+      description: 'List child tasks of the current task (or a specified parent).',
+      parameters: {
+        type: 'object',
+        properties: {
+          parent_task_id: { type: 'string', description: 'Filter by parent task ID. Omit to list children of current task.' },
+        },
+        required: [],
+      },
+    },
+  },
+
+  async execute(input: ListTasksInputT, _projectRoot: string, context: ToolContext): Promise<unknown> {
+    const { sql } = context;
+    const ctx = getInferenceContext();
+    const parentId = input.parent_task_id ?? ctx.taskId;
+
+    if (!parentId) {
+      return { tasks: [], note: 'No parent task context — not running inside a task.' };
+    }
+
+    const rows = await sql<{ id: string; state: string; input: string; output_summary: string | null }[]>`
+      SELECT id, state, input, output_summary
+      FROM tasks
+      WHERE parent_task_id = ${parentId}
+      ORDER BY created_at DESC
+      LIMIT 50
+    `;
+
+    return {
+      tasks: rows.map((r) => ({
+        id: r.id,
+        state: r.state,
+        input_preview: r.input.slice(0, 100),
+        output_summary: r.output_summary,
+      })),
+    };
+  },
+};
--- a/apps/coder/src/services/tools/new_task.ts
+++ b/apps/coder/src/services/tools/new_task.ts
@@ -0,0 +1,65 @@
+import { z } from 'zod';
+import type { ToolDef, ToolContext } from './types.js';
+import { getInferenceContext } from './inference_context.js';
+
+const NewTaskInput = z.object({
+  input: z.string().min(1).describe('Task description for the child subtask'),
+  agent: z.string().optional().describe('Optional: dispatch to a specific agent'),
+  model: z.string().optional().describe('Optional: model override for the subtask'),
+});
+
+type NewTaskInputT = z.infer<typeof NewTaskInput>;
+
+export const newTaskTool: ToolDef<NewTaskInputT> = {
+  name: 'new_task',
+  description:
+    'Spawn a subtask that runs in isolation. The subtask gets its own session and ' +
+    'worktree. Use check_task_status to monitor progress. Only the output_summary is ' +
+    'accessible to the parent — full isolation (Boomerang pattern).',
+  inputSchema: NewTaskInput,
+  jsonSchema: {
+    type: 'function',
+    function: {
+      name: 'new_task',
+      description:
+        'Spawn a subtask that runs in isolation. The subtask gets its own session and ' +
+        'worktree. Use check_task_status to monitor progress.',
+      parameters: {
+        type: 'object',
+        properties: {
+          input: { type: 'string', description: 'Task description for the child subtask' },
+          agent: { type: 'string', description: 'Optional: dispatch to a specific agent' },
+          model: { type: 'string', description: 'Optional: model override for the subtask' },
+        },
+        required: ['input'],
+      },
+    },
+  },
+
+  async execute(input: NewTaskInputT, _projectRoot: string, context: ToolContext): Promise<unknown> {
+    const { sql } = context;
+    // Get the current task's project_id from the inference context
+    const ctx = getInferenceContext();
+    const currentTaskId = ctx.taskId;
+
+    // Look up the project_id from the current session
+    const [session] = await sql<{ project_id: string }[]>`
+      SELECT project_id FROM sessions WHERE id = ${ctx.sessionId}
+    `;
+    if (!session) {
+      return { error: 'Cannot determine project_id from current session' };
+    }
+
+    const [task] = await sql<{ id: string; state: string }[]>`
+      INSERT INTO tasks (project_id, parent_task_id, input, agent, model)
+      VALUES (${session.project_id}, ${currentTaskId}, ${input.input}, ${input.agent ?? null}, ${input.model ?? null})
+      RETURNING id, state
+    `;
+
+    return {
+      message: `Subtask created (id: ${task!.id}). It will run in isolation. Use check_task_status to monitor.`,
+      task_id: task!.id,
+      state: task!.state,
+    };
+  },
+};
--- a/apps/coder/src/services/tools/rewind.ts
+++ b/apps/coder/src/services/tools/rewind.ts
@@ -0,0 +1,71 @@
+import { z } from 'zod';
+import type { ToolDef, ToolContext } from './types.js';
+import { rewindOne } from '../pending_changes.js';
+
+const RewindInput = z.object({
+  change_id: z.string().uuid().optional(),
+  all: z.boolean().optional(),
+});
+type RewindInputT = z.infer<typeof RewindInput>;
+
+export const rewindTool: ToolDef<RewindInputT> = {
+  name: 'rewind',
+  description:
+    'Revert applied changes. Provide change_id to revert a specific change, ' +
+    'or set all=true to revert all applied changes for the session (in reverse order).',
+  inputSchema: RewindInput,
+  jsonSchema: {
+    type: 'function',
+    function: {
+      name: 'rewind',
+      description:
+        'Revert applied changes. Provide change_id to revert a specific change, ' +
+        'or set all=true to revert all applied changes for the session (in reverse order).',
+      parameters: {
+        type: 'object',
+        properties: {
+          change_id: { type: 'string', format: 'uuid', description: 'ID of a specific change to revert' },
+          all: { type: 'boolean', description: 'If true, revert all applied changes for this session' },
+        },
+        required: [],
+      },
+    },
+  },
+  async execute(input: RewindInputT, projectRoot: string, context: ToolContext): Promise<unknown> {
+    if (input.change_id) {
+      const result = await rewindOne(context.sql, input.change_id, projectRoot);
+      return {
+        results: [result],
+        message: result.success
+          ? `Reverted change ${input.change_id} (${result.operation} on ${result.file_path}).`
+          : `Failed to revert: ${result.error}`,
+      };
+    }
+
+    if (input.all) {
+      // Rewind all applied changes for this session in reverse order
+      const applied = await context.sql<{ id: string }[]>`
+        SELECT id FROM pending_changes
+        WHERE session_id = ${context.sessionId} AND status = 'applied'
+        ORDER BY created_at DESC
+      `;
+      const results = [];
+      for (const row of applied) {
+        results.push(await rewindOne(context.sql, row.id, projectRoot));
+      }
+      const succeeded = results.filter((r) => r.success).length;
+      return {
+        total: results.length,
+        succeeded,
+        failed: results.length - succeeded,
+        results,
+        message:
+          results.length === 0
+            ? 'No applied changes to revert.'
+            : `Reverted ${succeeded}/${results.length} changes.`,
+      };
+    }
+
+    return { error: 'Provide either change_id or all=true.' };
+  },
+};
--- a/apps/coder/src/services/tools/types.ts
+++ b/apps/coder/src/services/tools/types.ts
@@ -0,0 +1,32 @@
+import type { z } from 'zod';
+import type { Sql } from '../../db.js';
+
+export interface ToolJsonSchema {
+  type: 'function';
+  function: {
+    name: string;
+    description: string;
+    parameters: Record<string, unknown>;
+  };
+}
+
+/**
+ * Context passed to BooCoder tool execute functions.
+ *
+ * Unlike BooChat's tools (which only need projectRoot), BooCoder's write tools
+ * interact with the database (pending_changes table) and need session/task
+ * context for proper attribution.
+ */
+export interface ToolContext {
+  sql: Sql;
+  sessionId: string;
+  taskId: string | null;
+}
+
+export interface ToolDef<TInput> {
+  name: string;
+  description: string;
+  inputSchema: z.ZodType<TInput>;
+  jsonSchema: ToolJsonSchema;
+  execute(input: TInput, projectRoot: string, context: ToolContext): Promise<unknown>;
+}
--- a/apps/coder/src/services/worktrees.ts
+++ b/apps/coder/src/services/worktrees.ts
@@ -0,0 +1,118 @@
+/**
+ * Git worktree management for external agent dispatch.
+ *
+ * Each dispatched task gets its own git worktree so the external agent
+ * can modify files freely without touching the main working tree.
+ * After the agent completes, we diff the worktree against HEAD and
+ * queue the diff into pending_changes.
+ */
+import { hostExec } from './host-exec.js';
+
+const WORKTREE_BASE = '/tmp/booworktrees';
+
+/**
+ * Create a git worktree for a task on the host.
+ * Returns the absolute path to the worktree directory.
+ */
+export async function createWorktree(
+  projectPath: string,
+  taskId: string,
+  opts?: { signal?: AbortSignal },
+): Promise<string> {
+  const worktreePath = `${WORKTREE_BASE}/${taskId}`;
+  const branchName = `task-${taskId}`;
+
+  // Ensure the base directory exists
+  await hostExec(`mkdir -p ${WORKTREE_BASE}`, { signal: opts?.signal });
+
+  // Create the worktree with a new branch from HEAD
+  const result = await hostExec(
+    `git -C ${shellEscape(projectPath)} worktree add ${shellEscape(worktreePath)} -b ${shellEscape(branchName)} HEAD`,
+    { signal: opts?.signal, timeoutMs: 30_000 },
+  );
+
+  if (result.exitCode !== 0) {
+    throw new Error(`Failed to create worktree: ${result.stderr.trim() || result.stdout.trim()}`);
+  }
+
+  return worktreePath;
+}
+
+/**
+ * Get the unified diff of changes made in the worktree vs the parent branch (HEAD).
+ * Returns an empty string if there are no changes.
+ */
+export async function diffWorktree(
+  worktreePath: string,
+  projectPath: string,
+  opts?: { signal?: AbortSignal },
+): Promise<string> {
+  // First, commit any uncommitted changes in the worktree so we can diff branches
+  // Stage all changes
+  const addResult = await hostExec(
+    `cd ${shellEscape(worktreePath)} && git add -A`,
+    { signal: opts?.signal, timeoutMs: 30_000 },
+  );
+  if (addResult.exitCode !== 0) {
+    throw new Error(`Failed to stage worktree changes: ${addResult.stderr.trim()}`);
+  }
+
+  // Check if there are staged changes
+  const statusResult = await hostExec(
+    `cd ${shellEscape(worktreePath)} && git diff --cached --quiet`,
+    { signal: opts?.signal, timeoutMs: 10_000 },
+  );
+
+  if (statusResult.exitCode === 0) {
+    // No changes
+    return '';
+  }
+
+  // Commit staged changes (needed to produce a clean branch diff)
+  await hostExec(
+    `cd ${shellEscape(worktreePath)} && git -c user.email=boocoder@local -c user.name=BooCoder commit -m "task changes" --allow-empty`,
+    { signal: opts?.signal, timeoutMs: 15_000 },
+  );
+
+  // Diff the worktree branch against the parent commit (HEAD of main tree)
+  const diffResult = await hostExec(
+    `git -C ${shellEscape(projectPath)} diff HEAD...$(git -C ${shellEscape(worktreePath)} rev-parse HEAD)`,
+    { signal: opts?.signal, timeoutMs: 60_000 },
+  );
+
+  if (diffResult.exitCode !== 0) {
+    throw new Error(`Failed to diff worktree: ${diffResult.stderr.trim()}`);
+  }
+
+  return diffResult.stdout;
+}
+
+/**
+ * Remove a worktree and its associated branch.
+ * Best-effort — does not throw on failure (task may have already been cleaned up).
+ */
+export async function cleanupWorktree(
+  projectPath: string,
+  taskId: string,
+): Promise<void> {
+  const worktreePath = `${WORKTREE_BASE}/${taskId}`;
+  const branchName = `task-${taskId}`;
+
+  // Remove the worktree (--force handles dirty state)
+  await hostExec(
+    `git -C ${shellEscape(projectPath)} worktree remove ${shellEscape(worktreePath)} --force`,
+    { timeoutMs: 15_000 },
+  ).catch(() => {});
+
+  // Delete the task branch
+  await hostExec(
+    `git -C ${shellEscape(projectPath)} branch -D ${shellEscape(branchName)}`,
+    { timeoutMs: 10_000 },
+  ).catch(() => {});
+}
+
+/** Minimal shell escape for paths (single-quote wrapping). */
+function shellEscape(s: string): string {
+  // Replace single quotes with escaped version, wrap in single quotes
+  return "'" + s.replace(/'/g, "'\\''") + "'";
+}
--- a/apps/coder/src/services/write_guard.ts
+++ b/apps/coder/src/services/write_guard.ts
@@ -0,0 +1,77 @@
+import { resolve, sep } from 'node:path';
+
+export class WriteGuardError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = 'WriteGuardError';
+  }
+}
+
+// Deny list: files that should never be written regardless of path-guard.
+// Subset of BooChat's secret_guard.ts — covers the most dangerous patterns.
+// Full parity with BooChat's deny list is not needed for write-guard because
+// the write tools are intentional (model chose to create/edit); we block only
+// files that are unambiguously secrets.
+const SECRET_PATTERNS: readonly string[] = [
+  '.env',
+  '.env.local',
+  '.env.production',
+  '.env.development',
+  '.env.staging',
+  'id_rsa',
+  'id_dsa',
+  'id_ecdsa',
+  'id_ed25519',
+  '*.pem',
+  '*.key',
+  '*.p12',
+  '*.pfx',
+  '*.crt',
+  'credentials.json',
+  '*.kdbx',
+  '.netrc',
+];
+
+export function isSecretPath(filePath: string): boolean {
+  const normalized = filePath.replace(/\\/g, '/');
+  const segments = normalized.split('/').filter((s) => s.length > 0);
+  if (segments.length === 0) return false;
+  const basename = segments[segments.length - 1]!;
+
+  return SECRET_PATTERNS.some((pattern) => {
+    if (pattern.startsWith('*')) {
+      return basename.endsWith(pattern.slice(1));
+    }
+    return basename === pattern;
+  });
+}
+
+/**
+ * Resolve and validate a write target path.
+ *
+ * Key difference from BooChat's pathGuard: no realpath() — the file may not
+ * exist yet (creates). Uses resolve() to normalize ../ segments and then
+ * checks the result stays within projectRoot.
+ */
+export function resolveWritePath(projectRoot: string, filePath: string): string {
+  if (!filePath || filePath.trim().length === 0) {
+    throw new WriteGuardError('file path is required');
+  }
+
+  if (filePath.includes('\x00')) {
+    throw new WriteGuardError('file path contains null byte');
+  }
+
+  const candidate = filePath.startsWith('/') ? filePath : resolve(projectRoot, filePath);
+  const normalized = resolve(candidate); // normalizes ../ segments
+
+  if (!normalized.startsWith(projectRoot + sep) && normalized !== projectRoot) {
+    throw new WriteGuardError(`path escapes project root: ${filePath}`);
+  }
+
+  if (isSecretPath(normalized)) {
+    throw new WriteGuardError(`cannot write to secret file: ${filePath}`);
+  }
+
+  return normalized;
+}
--- a/apps/coder/tsconfig.json
+++ b/apps/coder/tsconfig.json
@@ -0,0 +1,15 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "outDir": "dist",
+    "rootDir": "src",
+    "lib": ["ES2022"],
+    "types": ["node"],
+    "declaration": false,
+    "sourceMap": true
+  },
+  "include": ["src/**/*"],
+  "exclude": ["src/**/__tests__/**", "**/*.test.ts"]
+}
--- a/apps/coder/vitest.config.ts
+++ b/apps/coder/vitest.config.ts
@@ -0,0 +1,9 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    environment: 'node',
+    globals: false,
+    include: ['src/**/__tests__/**/*.test.ts'],
+  },
+});
--- a/apps/coder/web/index.html
+++ b/apps/coder/web/index.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<html lang="en" class="dark">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>BooCoder</title>
+  </head>
+  <body class="bg-zinc-900 text-zinc-100">
+    <div id="root"></div>
+    <script type="module" src="/src/main.tsx"></script>
+  </body>
+</html>
--- a/apps/coder/web/package.json
+++ b/apps/coder/web/package.json
@@ -0,0 +1,29 @@
+{
+  "name": "@boocode/coder-web",
+  "version": "2.0.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "tsc -b && vite build",
+    "typecheck": "tsc -b --noEmit",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "lucide-react": "^1.16.0",
+    "react": "^18.3.1",
+    "react-dom": "^18.3.1",
+    "react-markdown": "^10.1.0",
+    "react-router-dom": "^6.26.0",
+    "remark-gfm": "^4.0.1"
+  },
+  "devDependencies": {
+    "@tailwindcss/postcss": "^4.3.0",
+    "@types/react": "^18.3.3",
+    "@types/react-dom": "^18.3.0",
+    "@vitejs/plugin-react": "^4.3.1",
+    "tailwindcss": "^4.3.0",
+    "typescript": "^5.5.0",
+    "vite": "^5.3.4"
+  }
+}
--- a/apps/coder/web/postcss.config.js
+++ b/apps/coder/web/postcss.config.js
@@ -0,0 +1,5 @@
+export default {
+  plugins: {
+    '@tailwindcss/postcss': {},
+  },
+};
--- a/apps/coder/web/src/App.tsx
+++ b/apps/coder/web/src/App.tsx
@@ -0,0 +1,13 @@
+import { Routes, Route, Navigate } from 'react-router-dom';
+import { Home } from './pages/Home';
+import { Session } from './pages/Session';
+
+export function App() {
+  return (
+    <Routes>
+      <Route path="/" element={<Home />} />
+      <Route path="/sessions/:sessionId" element={<Session />} />
+      <Route path="*" element={<Navigate to="/" replace />} />
+    </Routes>
+  );
+}
--- a/apps/coder/web/src/api/client.ts
+++ b/apps/coder/web/src/api/client.ts
@@ -0,0 +1,101 @@
+import type { Project, Session, Chat, Message, PendingChange, AskUserAnswer } from './types';
+
+export class ApiError extends Error {
+  constructor(
+    public status: number,
+    public body: unknown,
+  ) {
+    super(
+      typeof body === 'object' && body && 'error' in body
+        ? String((body as { error: unknown }).error)
+        : `HTTP ${status}`,
+    );
+  }
+}
+
+async function request<T>(path: string, init: RequestInit = {}): Promise<T> {
+  const res = await fetch(path, {
+    ...init,
+    headers: {
+      'Content-Type': 'application/json',
+      ...(init.headers ?? {}),
+    },
+  });
+  if (res.status === 204) return undefined as T;
+  const text = await res.text();
+  const data = text ? JSON.parse(text) : undefined;
+  if (!res.ok) throw new ApiError(res.status, data);
+  return data as T;
+}
+
+export const api = {
+  health: () => request<{ ok: boolean; db: boolean; tools: number }>('/api/health'),
+
+  projects: {
+    list: (params?: { status?: 'open' | 'archived' }) =>
+      request<Project[]>(`/api/projects${params?.status ? `?status=${params.status}` : ''}`),
+  },
+
+  sessions: {
+    listForProject: (projectId: string, status?: 'open' | 'archived') =>
+      request<Session[]>(
+        `/api/projects/${projectId}/sessions${status ? `?status=${status}` : ''}`,
+      ),
+    get: (id: string) => request<Session>(`/api/sessions/${id}`),
+  },
+
+  chats: {
+    listForSession: (sessionId: string) =>
+      request<Chat[]>(`/api/sessions/${sessionId}/chats`),
+    create: (sessionId: string, body?: { name?: string }) =>
+      request<Chat>(`/api/sessions/${sessionId}/chats`, {
+        method: 'POST',
+        body: JSON.stringify(body ?? {}),
+      }),
+    answerUserInput: (chatId: string, toolCallId: string, answers: AskUserAnswer[]) =>
+      request<{ tool_message_id: string; assistant_message_id: string }>(
+        `/api/chats/${chatId}/answer_user_input`,
+        {
+          method: 'POST',
+          body: JSON.stringify({ tool_call_id: toolCallId, answers }),
+        },
+      ),
+  },
+
+  messages: {
+    send: (sessionId: string, chatId: string, content: string) =>
+      request<{ user_message_id: string; assistant_message_id: string }>(
+        `/api/sessions/${sessionId}/messages`,
+        {
+          method: 'POST',
+          body: JSON.stringify({ content, chat_id: chatId }),
+        },
+      ),
+    stop: (sessionId: string) =>
+      request<{ cancelled: boolean }>(`/api/sessions/${sessionId}/stop`, {
+        method: 'POST',
+      }),
+  },
+
+  pending: {
+    list: (sessionId: string) =>
+      request<PendingChange[]>(`/api/sessions/${sessionId}/pending`),
+    applyAll: (sessionId: string) =>
+      request<{ results: Array<{ id: string; success: boolean; error?: string }> }>(
+        `/api/sessions/${sessionId}/pending/apply`,
+        { method: 'POST' },
+      ),
+    applyOne: (changeId: string) =>
+      request<{ success: boolean; error?: string }>(`/api/pending/${changeId}/apply`, {
+        method: 'POST',
+      }),
+    rejectOne: (changeId: string) =>
+      request<{ ok: boolean }>(`/api/pending/${changeId}/reject`, {
+        method: 'POST',
+      }),
+    rewindOne: (changeId: string) =>
+      request<{ success: boolean; error?: string }>(`/api/pending/${changeId}/rewind`, {
+        method: 'POST',
+      }),
+  },
+};
--- a/apps/coder/web/src/api/types.ts
+++ b/apps/coder/web/src/api/types.ts
@@ -0,0 +1,110 @@
+// Minimal types for the BooCoder frontend.
+// Shared DB entities (same schema as BooChat).
+
+export interface Project {
+  id: string;
+  name: string;
+  path: string;
+  status: 'open' | 'archived';
+  created_at: string;
+  updated_at: string;
+}
+
+export interface Session {
+  id: string;
+  project_id: string;
+  name: string | null;
+  model: string | null;
+  status: 'open' | 'archived';
+  created_at: string;
+  updated_at: string;
+}
+
+export interface Chat {
+  id: string;
+  session_id: string;
+  name: string | null;
+  status: 'open' | 'archived';
+  created_at: string;
+  updated_at: string;
+}
+
+export interface ToolCall {
+  id: string;
+  name: string;
+  args: unknown;
+}
+
+export interface ToolResult {
+  tool_call_id: string;
+  output: unknown;
+  truncated?: boolean;
+  error?: boolean;
+}
+
+// Batch 9.7: ask_user_input shapes. The tool_call.args is { questions: AskUserQuestion[] }
+// (1-3 entries); the eventual tool_result.output is { answers: AskUserAnswer[] } in the
+// same order. AskUserInputCard renders questions and POSTs answers.
+export type AskUserQuestionType = 'single_select' | 'multi_select';
+
+export interface AskUserQuestion {
+  question: string;
+  type: AskUserQuestionType;
+  options: string[];
+}
+
+export interface AskUserAnswer {
+  question: string;
+  selected_options: string[];
+  free_text: string | null;
+}
+
+export interface AskUserAnswerSet {
+  answers: AskUserAnswer[];
+}
+
+export interface Message {
+  id: string;
+  session_id: string;
+  chat_id: string;
+  role: 'user' | 'assistant' | 'tool' | 'system';
+  content: string;
+  kind: string;
+  tool_calls: ToolCall[] | null;
+  tool_results: ToolResult | null;
+  status: 'streaming' | 'complete' | 'failed' | 'cancelled';
+  tokens_used: number | null;
+  ctx_used: number | null;
+  ctx_max: number | null;
+  started_at: string | null;
+  finished_at: string | null;
+  created_at: string;
+  metadata: unknown;
+}
+
+export interface PendingChange {
+  id: string;
+  session_id: string;
+  task_id: string | null;
+  file_path: string;
+  operation: 'create' | 'edit' | 'delete';
+  old_string: string | null;
+  new_string: string | null;
+  content: string | null;
+  diff: string | null;
+  status: 'pending' | 'applied' | 'rejected' | 'reverted';
+  created_at: string;
+  applied_at: string | null;
+}
+
+// WebSocket frame types (subset of what the coder backend publishes)
+export type WsFrame =
+  | { type: 'snapshot'; messages: Message[] }
+  | { type: 'message_started'; message_id: string; chat_id: string; role: Message['role'] }
+  | { type: 'delta'; message_id: string; chat_id: string; content: string }
+  | { type: 'tool_call'; message_id: string; chat_id: string; tool_call: ToolCall }
+  | { type: 'tool_result'; tool_message_id: string; chat_id: string; tool_call_id: string; output: string; truncated?: boolean; error?: boolean }
+  | { type: 'message_complete'; message_id: string; chat_id: string; tokens_used?: number; ctx_used?: number; ctx_max?: number; started_at?: string; finished_at?: string; metadata?: unknown }
+  | { type: 'error'; message_id?: string; error: string; reason?: string }
+  | { type: 'pending_change_added'; change: PendingChange }
+  | { type: 'pending_change_updated'; change: PendingChange };
--- a/apps/coder/web/src/components/AskUserInputCard.tsx
+++ b/apps/coder/web/src/components/AskUserInputCard.tsx
@@ -0,0 +1,323 @@
+import { useMemo, useState } from 'react';
+import { Check } from 'lucide-react';
+import { api } from '@/api/client';
+import { RadioGroup, RadioGroupItem } from '@/components/ui/radio-group';
+import { Button } from '@/components/ui/button';
+import type {
+  AskUserAnswer,
+  AskUserAnswerSet,
+  AskUserQuestion,
+  ToolCall,
+  ToolResult,
+} from '@/api/types';
+
+// Batch 9.7: Inline interactive picker. Renders inside MessageList in place of
+// the standard ToolCallLine when the assistant emits an ask_user_input tool
+// call. While the tool result is null (server pre-stamps a sentinel with
+// output=null), shows the form; once the WS tool_result frame arrives with a
+// real AnswerSet, flips to read-only review mode.
+
+interface Props {
+  toolCall: ToolCall;
+  toolResult: ToolResult | null;
+  chatId: string;
+}
+
+function parseQuestions(raw: unknown): AskUserQuestion[] {
+  if (!raw || typeof raw !== 'object' || !('questions' in raw)) return [];
+  const arr = (raw as { questions: unknown }).questions;
+  if (!Array.isArray(arr)) return [];
+  const out: AskUserQuestion[] = [];
+  for (const item of arr) {
+    if (!item || typeof item !== 'object') continue;
+    const q = item as { question?: unknown; type?: unknown; options?: unknown };
+    if (typeof q.question !== 'string') continue;
+    if (q.type !== 'single_select' && q.type !== 'multi_select') continue;
+    if (!Array.isArray(q.options)) continue;
+    const opts = q.options.filter((o): o is string => typeof o === 'string');
+    if (opts.length < 2) continue;
+    out.push({ question: q.question, type: q.type, options: opts });
+  }
+  return out;
+}
+
+function parseAnswerSet(raw: unknown): AskUserAnswerSet | null {
+  if (!raw || typeof raw !== 'object' || !('answers' in raw)) return null;
+  const arr = (raw as { answers: unknown }).answers;
+  if (!Array.isArray(arr)) return null;
+  const answers: AskUserAnswer[] = [];
+  for (const item of arr) {
+    if (!item || typeof item !== 'object') continue;
+    const a = item as { question?: unknown; selected_options?: unknown; free_text?: unknown };
+    if (typeof a.question !== 'string') continue;
+    if (!Array.isArray(a.selected_options)) continue;
+    if (a.free_text !== null && typeof a.free_text !== 'string') continue;
+    const sel = a.selected_options.filter((s): s is string => typeof s === 'string');
+    answers.push({
+      question: a.question,
+      selected_options: sel,
+      free_text: (a.free_text as string | null) ?? null,
+    });
+  }
+  return { answers };
+}
+
+export function AskUserInputCard({ toolCall, toolResult, chatId }: Props) {
+  const questions = useMemo(() => parseQuestions(toolCall.args), [toolCall.args]);
+
+  if (questions.length === 0) {
+    return (
+      <div className="rounded border border-destructive/40 bg-destructive/10 text-xs px-3 py-2 text-destructive">
+        ask_user_input: malformed tool args
+      </div>
+    );
+  }
+
+  // Tool result with a non-null output means the answer is already submitted.
+  // The pending sentinel uses output=null, so this branch only triggers after
+  // the real WS tool_result frame lands.
+  const answered = toolResult && toolResult.output !== null;
+  if (answered) {
+    const answerSet = parseAnswerSet(toolResult!.output);
+    return <AnsweredView questions={questions} answers={answerSet} />;
+  }
+
+  return (
+    <PendingView questions={questions} toolCallId={toolCall.id} chatId={chatId} />
+  );
+}
+
+function PendingView({
+  questions,
+  toolCallId,
+  chatId,
+}: {
+  questions: AskUserQuestion[];
+  toolCallId: string;
+  chatId: string;
+}) {
+  // Per-question selections + free text. Selections are option arrays so the
+  // multi_select case is uniform; single_select just constrains to length 1.
+  const [selections, setSelections] = useState<string[][]>(() => questions.map(() => []));
+  const [freeTexts, setFreeTexts] = useState<string[]>(() => questions.map(() => ''));
+  const [submitting, setSubmitting] = useState(false);
+
+  const singleQuestion = questions.length === 1;
+  const anyFreeText = freeTexts.some((t) => t.trim().length > 0);
+
+  // Submit button shows when:
+  //   - more than one question (always batched), OR
+  //   - one question and the user has typed free text (committing it needs an
+  //     explicit Submit so an accidental Tab/click doesn't lose it).
+  // For one question with no free text, clicking an option submits inline.
+  const showSubmitButton = !singleQuestion || anyFreeText;
+
+  // Every question must have at least one of (option, free text).
+  const allComplete = questions.every((_, i) => {
+    return selections[i]!.length > 0 || freeTexts[i]!.trim().length > 0;
+  });
+
+  function buildAnswers(): AskUserAnswer[] {
+    return questions.map((q, i) => {
+      const freeText = freeTexts[i]!.trim();
+      return {
+        question: q.question,
+        selected_options: selections[i]!,
+        free_text: freeText.length > 0 ? freeText : null,
+      };
+    });
+  }
+
+  async function submit(answers: AskUserAnswer[]) {
+    if (submitting) return;
+    setSubmitting(true);
+    try {
+      await api.chats.answerUserInput(chatId, toolCallId, answers);
+      // Card stays mounted; the incoming WS tool_result frame will flip it
+      // into AnsweredView via the parent prop change.
+    } catch (err) {
+      console.error('ask_user_input submit failed:', err instanceof Error ? err.message : err);
+      setSubmitting(false);
+    }
+  }
+
+  function pickSingle(qIdx: number, option: string) {
+    setSelections((prev) => prev.map((arr, i) => (i === qIdx ? [option] : arr)));
+    // Immediate submit for the single-question single-select shortcut. Only
+    // fires when no free text exists anywhere — once the user typed, the
+    // Submit button takes over so the typed text isn't silently dropped.
+    if (singleQuestion && !anyFreeText) {
+      const answers: AskUserAnswer[] = [
+        {
+          question: questions[0]!.question,
+          selected_options: [option],
+          free_text: null,
+        },
+      ];
+      void submit(answers);
+    }
+  }
+
+  function toggleMulti(qIdx: number, option: string) {
+    setSelections((prev) =>
+      prev.map((arr, i) => {
+        if (i !== qIdx) return arr;
+        return arr.includes(option) ? arr.filter((o) => o !== option) : [...arr, option];
+      }),
+    );
+  }
+
+  function setFreeText(qIdx: number, value: string) {
+    setFreeTexts((prev) => prev.map((t, i) => (i === qIdx ? value : t)));
+  }
+
+  return (
+    <div className="rounded-lg border bg-muted/20 text-sm">
+      <div className="px-4 py-3 space-y-4">
+        {questions.map((q, i) => (
+          <div key={i} className="space-y-2">
+            {questions.length > 1 && (
+              <div className="text-[10px] uppercase tracking-wide text-muted-foreground/70">
+                Question {i + 1}
+              </div>
+            )}
+            <div className="font-medium leading-snug">{q.question}</div>
+            {q.type === 'single_select' ? (
+              <RadioGroup
+                value={selections[i]![0] ?? ''}
+                onValueChange={(v) => pickSingle(i, v)}
+                disabled={submitting}
+                className="gap-1.5"
+              >
+                {q.options.map((opt, j) => {
+                  const id = `q${i}-opt${j}`;
+                  return (
+                    <label
+                      key={j}
+                      htmlFor={id}
+                      className="flex items-start gap-2 text-sm leading-snug cursor-pointer rounded px-1 py-0.5 hover:bg-muted/40"
+                    >
+                      <RadioGroupItem id={id} value={opt} className="mt-0.5" />
+                      <span>{opt}</span>
+                    </label>
+                  );
+                })}
+              </RadioGroup>
+            ) : (
+              <div className="grid gap-1.5">
+                {q.options.map((opt, j) => {
+                  const id = `q${i}-opt${j}`;
+                  const checked = selections[i]!.includes(opt);
+                  return (
+                    <label
+                      key={j}
+                      htmlFor={id}
+                      className="flex items-start gap-2 text-sm leading-snug cursor-pointer rounded px-1 py-0.5 hover:bg-muted/40"
+                    >
+                      <input
+                        id={id}
+                        type="checkbox"
+                        checked={checked}
+                        disabled={submitting}
+                        onChange={() => toggleMulti(i, opt)}
+                        className="mt-1 size-3.5 rounded border-input accent-primary"
+                      />
+                      <span>{opt}</span>
+                    </label>
+                  );
+                })}
+              </div>
+            )}
+            <div className="pt-1 space-y-1">
+              <div className="text-[10px] uppercase tracking-wide text-muted-foreground/70">
+                Or type a custom answer
+              </div>
+              <input
+                type="text"
+                value={freeTexts[i]}
+                disabled={submitting}
+                placeholder="Free text…"
+                onChange={(e) => setFreeText(i, e.target.value)}
+                className="w-full rounded border border-input bg-background px-2 py-1 text-sm outline-none focus-visible:ring-2 focus-visible:ring-ring/40 disabled:opacity-60"
+              />
+            </div>
+          </div>
+        ))}
+      </div>
+      {showSubmitButton && (
+        <div className="flex justify-end gap-2 border-t px-4 py-2">
+          <Button
+            type="button"
+            size="sm"
+            disabled={!allComplete || submitting}
+            onClick={() => void submit(buildAnswers())}
+          >
+            {submitting ? 'Submitting…' : 'Submit'}
+          </Button>
+        </div>
+      )}
+    </div>
+  );
+}
+
+function AnsweredView({
+  questions,
+  answers,
+}: {
+  questions: AskUserQuestion[];
+  answers: AskUserAnswerSet | null;
+}) {
+  if (!answers) {
+    return (
+      <div className="rounded-lg border bg-muted/20 text-xs px-4 py-3 text-muted-foreground">
+        ask_user_input: answers unavailable
+      </div>
+    );
+  }
+
+  return (
+    <div className="rounded-lg border bg-muted/10 text-sm">
+      <div className="px-4 py-3 space-y-3">
+        {questions.map((q, i) => {
+          const a = answers.answers[i];
+          if (!a) return null;
+          return (
+            <div key={i} className="space-y-1.5">
+              {questions.length > 1 && (
+                <div className="text-[10px] uppercase tracking-wide text-muted-foreground/70">
+                  Question {i + 1}
+                </div>
+              )}
+              <div className="font-medium leading-snug">{q.question}</div>
+              <div className="space-y-0.5">
+                {q.options.map((opt, j) => {
+                  const selected = a.selected_options.includes(opt);
+                  return (
+                    <div
+                      key={j}
+                      className={
+                        selected
+                          ? 'flex items-start gap-2 text-sm leading-snug text-foreground'
+                          : 'flex items-start gap-2 text-sm leading-snug text-muted-foreground/60 line-through'
+                      }
+                    >
+                      <span className="mt-0.5 size-3.5 shrink-0 inline-flex items-center justify-center">
+                        {selected && <Check className="size-3 text-primary" />}
+                      </span>
+                      <span>{opt}</span>
+                    </div>
+                  );
+                })}
+              </div>
+              {a.free_text && (
+                <div className="rounded bg-background border px-2 py-1 text-xs font-mono whitespace-pre-wrap">
+                  {a.free_text}
+                </div>
+              )}
+            </div>
+          );
+        })}
+      </div>
+    </div>
+  );
+}
--- a/apps/coder/web/src/components/ChatPane.tsx
+++ b/apps/coder/web/src/components/ChatPane.tsx
@@ -0,0 +1,139 @@
+import { useState, useRef, useEffect } from 'react';
+import { Send, Square } from 'lucide-react';
+import type { Message, ToolResult } from '@/api/types';
+import { api } from '@/api/client';
+import { MessageBubble } from './MessageBubble';
+
+interface Props {
+  sessionId: string;
+  chatId: string;
+  messages: Message[];
+  isStreaming: boolean;
+  connected: boolean;
+}
+
+export function ChatPane({ sessionId, chatId, messages, isStreaming, connected }: Props) {
+  const [input, setInput] = useState('');
+  const [sending, setSending] = useState(false);
+  const messagesEndRef = useRef<HTMLDivElement>(null);
+  const textareaRef = useRef<HTMLTextAreaElement>(null);
+
+  // Auto-scroll to bottom when messages change
+  useEffect(() => {
+    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' });
+  }, [messages]);
+
+  // Auto-resize textarea
+  useEffect(() => {
+    const el = textareaRef.current;
+    if (!el) return;
+    el.style.height = 'auto';
+    el.style.height = Math.min(el.scrollHeight, 200) + 'px';
+  }, [input]);
+
+  const handleSend = async () => {
+    const content = input.trim();
+    if (!content || sending || isStreaming) return;
+
+    setInput('');
+    setSending(true);
+    try {
+      await api.messages.send(sessionId, chatId, content);
+    } catch (err) {
+      console.error('send failed:', err);
+      // Restore input on failure
+      setInput(content);
+    } finally {
+      setSending(false);
+    }
+  };
+
+  const handleStop = async () => {
+    try {
+      await api.messages.stop(sessionId);
+    } catch (err) {
+      console.error('stop failed:', err);
+    }
+  };
+
+  const handleKeyDown = (e: React.KeyboardEvent) => {
+    if (e.key === 'Enter' && !e.shiftKey) {
+      e.preventDefault();
+      handleSend();
+    }
+  };
+
+  // Filter out system messages for display (sentinels)
+  const visibleMessages = messages.filter((m) => m.role !== 'system');
+
+  // Build a lookup map from tool_call_id -> ToolResult for all messages
+  const toolResultsMap: Record<string, ToolResult> = {};
+  for (const msg of messages) {
+    if (msg.tool_results) {
+      toolResultsMap[msg.tool_results.tool_call_id] = msg.tool_results;
+    }
+  }
+
+  return (
+    <div className="flex flex-col h-full">
+      {/* Connection indicator */}
+      <div className="flex items-center gap-2 px-4 py-2 border-b border-zinc-800 text-xs text-zinc-500">
+        <div
+          className={`w-1.5 h-1.5 rounded-full ${connected ? 'bg-green-500' : 'bg-red-500'}`}
+        />
+        <span>{connected ? 'Connected' : 'Disconnected'}</span>
+        {isStreaming && (
+          <span className="text-blue-400 ml-auto">Generating...</span>
+        )}
+      </div>
+
+      {/* Messages list */}
+      <div className="flex-1 overflow-y-auto px-4 py-4">
+        {visibleMessages.length === 0 && (
+          <div className="text-center text-zinc-500 mt-8">
+            <p className="text-lg font-medium">BooCoder</p>
+            <p className="text-sm mt-1">Send a message to start coding.</p>
+          </div>
+        )}
+        {visibleMessages.map((msg) => (
+          <MessageBubble key={msg.id} message={msg} chatId={msg.chat_id} toolResultsMap={toolResultsMap} />
+        ))}
+        <div ref={messagesEndRef} />
+      </div>
+
+      {/* Input area */}
+      <div className="border-t border-zinc-800 px-4 py-3">
+        <div className="flex items-end gap-2">
+          <textarea
+            ref={textareaRef}
+            value={input}
+            onChange={(e) => setInput(e.target.value)}
+            onKeyDown={handleKeyDown}
+            placeholder="Message BooCoder..."
+            rows={1}
+            className="flex-1 bg-zinc-800 border border-zinc-700 rounded-lg px-3 py-2 text-sm text-zinc-100 placeholder-zinc-500 resize-none focus:outline-none focus:ring-1 focus:ring-blue-500 focus:border-blue-500"
+            disabled={sending}
+          />
+          {isStreaming ? (
+            <button
+              onClick={handleStop}
+              className="p-2 rounded-lg bg-red-600 hover:bg-red-500 text-white transition-colors"
+              title="Stop generation"
+            >
+              <Square size={18} />
+            </button>
+          ) : (
+            <button
+              onClick={handleSend}
+              disabled={!input.trim() || sending}
+              className="p-2 rounded-lg bg-blue-600 hover:bg-blue-500 disabled:opacity-40 disabled:cursor-not-allowed text-white transition-colors"
+              title="Send message"
+            >
+              <Send size={18} />
+            </button>
+          )}
+        </div>
+      </div>
+    </div>
+  );
+}
--- a/apps/coder/web/src/components/DiffPane.tsx
+++ b/apps/coder/web/src/components/DiffPane.tsx
@@ -0,0 +1,352 @@
+import { useState, useEffect, useCallback } from 'react';
+import { Check, X, RotateCcw, FileText, FilePlus, Trash2, RefreshCw } from 'lucide-react';
+import type { PendingChange } from '@/api/types';
+import { api } from '@/api/client';
+
+interface Props {
+  sessionId: string;
+  onPendingChange: (cb: (change: PendingChange) => void) => () => void;
+}
+
+export function DiffPane({ sessionId, onPendingChange }: Props) {
+  const [changes, setChanges] = useState<PendingChange[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [expandedId, setExpandedId] = useState<string | null>(null);
+
+  const fetchPending = useCallback(async () => {
+    try {
+      const result = await api.pending.list(sessionId);
+      setChanges(result);
+    } catch (err) {
+      console.error('fetch pending failed:', err);
+    } finally {
+      setLoading(false);
+    }
+  }, [sessionId]);
+
+  // Initial load
+  useEffect(() => {
+    fetchPending();
+  }, [fetchPending]);
+
+  // Listen for WS pending change events
+  useEffect(() => {
+    const unsub = onPendingChange((change) => {
+      setChanges((prev) => {
+        const idx = prev.findIndex((c) => c.id === change.id);
+        if (idx >= 0) {
+          const next = [...prev];
+          next[idx] = change;
+          return next;
+        }
+        return [...prev, change];
+      });
+    });
+    return unsub;
+  }, [onPendingChange]);
+
+  const pendingChanges = changes.filter((c) => c.status === 'pending');
+  const resolvedChanges = changes.filter((c) => c.status !== 'pending');
+
+  const handleApplyOne = async (id: string) => {
+    try {
+      await api.pending.applyOne(id);
+      setChanges((prev) =>
+        prev.map((c) => (c.id === id ? { ...c, status: 'applied' as const } : c)),
+      );
+    } catch (err) {
+      console.error('apply failed:', err);
+    }
+  };
+
+  const handleRejectOne = async (id: string) => {
+    try {
+      await api.pending.rejectOne(id);
+      setChanges((prev) =>
+        prev.map((c) => (c.id === id ? { ...c, status: 'rejected' as const } : c)),
+      );
+    } catch (err) {
+      console.error('reject failed:', err);
+    }
+  };
+
+  const handleRewindOne = async (id: string) => {
+    try {
+      await api.pending.rewindOne(id);
+      setChanges((prev) =>
+        prev.map((c) => (c.id === id ? { ...c, status: 'reverted' as const } : c)),
+      );
+    } catch (err) {
+      console.error('rewind failed:', err);
+    }
+  };
+
+  const handleApplyAll = async () => {
+    try {
+      const result = await api.pending.applyAll(sessionId);
+      const appliedIds = new Set(
+        result.results.filter((r) => r.success).map((r) => r.id),
+      );
+      setChanges((prev) =>
+        prev.map((c) =>
+          appliedIds.has(c.id) ? { ...c, status: 'applied' as const } : c,
+        ),
+      );
+    } catch (err) {
+      console.error('apply all failed:', err);
+    }
+  };
+
+  const handleRejectAll = async () => {
+    // Reject each pending change individually (no batch reject endpoint)
+    for (const c of pendingChanges) {
+      await handleRejectOne(c.id);
+    }
+  };
+
+  const OpIcon = ({ op }: { op: PendingChange['operation'] }) => {
+    switch (op) {
+      case 'create':
+        return <FilePlus size={14} className="text-green-400" />;
+      case 'edit':
+        return <FileText size={14} className="text-blue-400" />;
+      case 'delete':
+        return <Trash2 size={14} className="text-red-400" />;
+    }
+  };
+
+  const StatusBadge = ({ status }: { status: PendingChange['status'] }) => {
+    const colors: Record<PendingChange['status'], string> = {
+      pending: 'bg-yellow-500/20 text-yellow-400',
+      applied: 'bg-green-500/20 text-green-400',
+      rejected: 'bg-zinc-500/20 text-zinc-400',
+      reverted: 'bg-orange-500/20 text-orange-400',
+    };
+    return (
+      <span className={`text-[10px] px-1.5 py-0.5 rounded ${colors[status]}`}>
+        {status}
+      </span>
+    );
+  };
+
+  return (
+    <div className="flex flex-col h-full">
+      {/* Header */}
+      <div className="flex items-center justify-between px-4 py-2 border-b border-zinc-800">
+        <h2 className="text-sm font-medium text-zinc-300">
+          Pending Changes
+          {pendingChanges.length > 0 && (
+            <span className="ml-1.5 text-xs text-zinc-500">
+              ({pendingChanges.length})
+            </span>
+          )}
+        </h2>
+        <div className="flex items-center gap-1">
+          <button
+            onClick={fetchPending}
+            className="p-1 rounded hover:bg-zinc-800 text-zinc-400 hover:text-zinc-200"
+            title="Refresh"
+          >
+            <RefreshCw size={14} />
+          </button>
+          {pendingChanges.length > 0 && (
+            <>
+              <button
+                onClick={handleApplyAll}
+                className="text-xs px-2 py-1 rounded bg-green-600/80 hover:bg-green-600 text-white"
+              >
+                Apply All
+              </button>
+              <button
+                onClick={handleRejectAll}
+                className="text-xs px-2 py-1 rounded bg-zinc-700 hover:bg-zinc-600 text-zinc-300"
+              >
+                Reject All
+              </button>
+            </>
+          )}
+        </div>
+      </div>
+
+      {/* Changes list */}
+      <div className="flex-1 overflow-y-auto">
+        {loading && (
+          <div className="text-center text-zinc-500 text-sm py-8">Loading...</div>
+        )}
+
+        {!loading && changes.length === 0 && (
+          <div className="text-center text-zinc-500 text-sm py-8">
+            No pending changes yet.
+          </div>
+        )}
+
+        {/* Pending changes first */}
+        {pendingChanges.map((change) => (
+          <ChangeItem
+            key={change.id}
+            change={change}
+            expanded={expandedId === change.id}
+            onToggle={() =>
+              setExpandedId((prev) => (prev === change.id ? null : change.id))
+            }
+            onApply={() => handleApplyOne(change.id)}
+            onReject={() => handleRejectOne(change.id)}
+            OpIcon={OpIcon}
+            StatusBadge={StatusBadge}
+          />
+        ))}
+
+        {/* Resolved changes */}
+        {resolvedChanges.length > 0 && pendingChanges.length > 0 && (
+          <div className="border-t border-zinc-800 my-1" />
+        )}
+        {resolvedChanges.map((change) => (
+          <ChangeItem
+            key={change.id}
+            change={change}
+            expanded={expandedId === change.id}
+            onToggle={() =>
+              setExpandedId((prev) => (prev === change.id ? null : change.id))
+            }
+            onRewind={
+              change.status === 'applied'
+                ? () => handleRewindOne(change.id)
+                : undefined
+            }
+            OpIcon={OpIcon}
+            StatusBadge={StatusBadge}
+          />
+        ))}
+      </div>
+    </div>
+  );
+}
+
+interface ChangeItemProps {
+  change: PendingChange;
+  expanded: boolean;
+  onToggle: () => void;
+  onApply?: () => void;
+  onReject?: () => void;
+  onRewind?: () => void;
+  OpIcon: React.ComponentType<{ op: PendingChange['operation'] }>;
+  StatusBadge: React.ComponentType<{ status: PendingChange['status'] }>;
+}
+
+function ChangeItem({
+  change,
+  expanded,
+  onToggle,
+  onApply,
+  onReject,
+  onRewind,
+  OpIcon,
+  StatusBadge,
+}: ChangeItemProps) {
+  const fileName = change.file_path.split('/').pop() || change.file_path;
+  const dirPath = change.file_path.split('/').slice(0, -1).join('/');
+
+  return (
+    <div className="border-b border-zinc-800/50">
+      <div
+        className="flex items-center gap-2 px-4 py-2 hover:bg-zinc-800/50 cursor-pointer"
+        onClick={onToggle}
+      >
+        <OpIcon op={change.operation} />
+        <div className="flex-1 min-w-0">
+          <span className="text-sm font-mono text-zinc-200 truncate block">
+            {fileName}
+          </span>
+          {dirPath && (
+            <span className="text-[11px] text-zinc-500 truncate block">
+              {dirPath}
+            </span>
+          )}
+        </div>
+        <StatusBadge status={change.status} />
+        {change.status === 'pending' && (
+          <div className="flex items-center gap-1 ml-1">
+            <button
+              onClick={(e) => {
+                e.stopPropagation();
+                onApply?.();
+              }}
+              className="p-1 rounded hover:bg-green-600/30 text-green-400"
+              title="Apply"
+            >
+              <Check size={14} />
+            </button>
+            <button
+              onClick={(e) => {
+                e.stopPropagation();
+                onReject?.();
+              }}
+              className="p-1 rounded hover:bg-red-600/30 text-red-400"
+              title="Reject"
+            >
+              <X size={14} />
+            </button>
+          </div>
+        )}
+        {change.status === 'applied' && onRewind && (
+          <button
+            onClick={(e) => {
+              e.stopPropagation();
+              onRewind();
+            }}
+            className="p-1 rounded hover:bg-orange-600/30 text-orange-400"
+            title="Rewind"
+          >
+            <RotateCcw size={14} />
+          </button>
+        )}
+      </div>
+
+      {expanded && (
+        <div className="px-4 pb-3">
+          {change.operation === 'edit' && (
+            <div className="space-y-2">
+              {change.old_string && (
+                <div className="rounded bg-red-950/30 border border-red-900/30 p-2">
+                  <div className="text-[10px] text-red-400 mb-1 font-medium">
+                    Remove
+                  </div>
+                  <pre className="text-xs text-red-200 whitespace-pre-wrap break-all font-mono">
+                    {change.old_string}
+                  </pre>
+                </div>
+              )}
+              {change.new_string && (
+                <div className="rounded bg-green-950/30 border border-green-900/30 p-2">
+                  <div className="text-[10px] text-green-400 mb-1 font-medium">
+                    Add
+                  </div>
+                  <pre className="text-xs text-green-200 whitespace-pre-wrap break-all font-mono">
+                    {change.new_string}
+                  </pre>
+                </div>
+              )}
+            </div>
+          )}
+          {change.operation === 'create' && change.content && (
+            <div className="rounded bg-green-950/30 border border-green-900/30 p-2">
+              <div className="text-[10px] text-green-400 mb-1 font-medium">
+                New file
+              </div>
+              <pre className="text-xs text-green-200 whitespace-pre-wrap break-all font-mono max-h-60 overflow-y-auto">
+                {change.content.length > 2000
+                  ? change.content.slice(0, 2000) + '\n... (truncated)'
+                  : change.content}
+              </pre>
+            </div>
+          )}
+          {change.operation === 'delete' && (
+            <div className="rounded bg-red-950/30 border border-red-900/30 p-2 text-xs text-red-300">
+              This file will be deleted.
+            </div>
+          )}
+        </div>
+      )}
+    </div>
+  );
+}
--- a/apps/coder/web/src/components/Layout.tsx
+++ b/apps/coder/web/src/components/Layout.tsx
@@ -0,0 +1,62 @@
+import { useState } from 'react';
+import { Code2, MessageSquare, GitPullRequest } from 'lucide-react';
+
+interface Props {
+  chatPane: React.ReactNode;
+  diffPane: React.ReactNode;
+}
+
+export function Layout({ chatPane, diffPane }: Props) {
+  const [activeTab, setActiveTab] = useState<'chat' | 'diff'>('chat');
+
+  return (
+    <div className="flex flex-col h-screen bg-zinc-900">
+      {/* Top bar */}
+      <header className="flex items-center gap-3 px-4 py-2 border-b border-zinc-800 bg-zinc-900/95">
+        <Code2 size={20} className="text-blue-400" />
+        <h1 className="text-sm font-semibold text-zinc-200">BooCoder</h1>
+      </header>
+
+      {/* Mobile tab bar (visible below lg breakpoint) */}
+      <div className="lg:hidden flex border-b border-zinc-800">
+        <button
+          onClick={() => setActiveTab('chat')}
+          className={`flex-1 flex items-center justify-center gap-1.5 py-2 text-sm ${
+            activeTab === 'chat'
+              ? 'text-blue-400 border-b-2 border-blue-400'
+              : 'text-zinc-500'
+          }`}
+        >
+          <MessageSquare size={14} />
+          Chat
+        </button>
+        <button
+          onClick={() => setActiveTab('diff')}
+          className={`flex-1 flex items-center justify-center gap-1.5 py-2 text-sm ${
+            activeTab === 'diff'
+              ? 'text-blue-400 border-b-2 border-blue-400'
+              : 'text-zinc-500'
+          }`}
+        >
+          <GitPullRequest size={14} />
+          Changes
+        </button>
+      </div>
+
+      {/* Desktop split layout */}
+      <div className="flex-1 hidden lg:flex overflow-hidden">
+        <div className="w-[60%] border-r border-zinc-800 overflow-hidden">
+          {chatPane}
+        </div>
+        <div className="w-[40%] overflow-hidden">
+          {diffPane}
+        </div>
+      </div>
+
+      {/* Mobile: show only the active tab */}
+      <div className="flex-1 lg:hidden overflow-hidden">
+        {activeTab === 'chat' ? chatPane : diffPane}
+      </div>
+    </div>
+  );
+}
--- a/apps/coder/web/src/components/MessageBubble.tsx
+++ b/apps/coder/web/src/components/MessageBubble.tsx
@@ -0,0 +1,135 @@
+import Markdown from 'react-markdown';
+import remarkGfm from 'remark-gfm';
+import type { Message, ToolResult } from '@/api/types';
+import { Wrench, AlertCircle, Loader2 } from 'lucide-react';
+import { AskUserInputCard } from './AskUserInputCard';
+
+interface Props {
+  message: Message;
+  chatId: string;
+  toolResultsMap: Record<string, ToolResult>;
+}
+
+export function MessageBubble({ message, chatId }: Props) {
+  if (message.role === 'tool') {
+    return <ToolResultBubble message={message} />;
+  }
+
+  const isUser = message.role === 'user';
+  const isStreaming = message.status === 'streaming';
+  const isFailed = message.status === 'failed';
+
+  return (
+    <div className={`flex ${isUser ? 'justify-end' : 'justify-start'} mb-3`}>
+      <div
+        className={`max-w-[85%] rounded-lg px-4 py-2.5 ${
+          isUser
+            ? 'bg-blue-600 text-white'
+            : 'bg-zinc-800 text-zinc-100 border border-zinc-700'
+        }`}
+      >
+        {isFailed && (
+          <div className="flex items-center gap-1.5 text-red-400 text-xs mb-1">
+            <AlertCircle size={12} />
+            <span>Failed</span>
+          </div>
+        )}
+
+        {message.tool_calls && message.tool_calls.length > 0 && (
+          <div className="mb-2 space-y-1">
+            {message.tool_calls.map((tc) => {
+              if (tc.name === 'ask_user_input') {
+                const result = message.tool_results ?? null;
+                return (
+                  <AskUserInputCard
+                    key={tc.id}
+                    toolCall={tc}
+                    toolResult={result}
+                    chatId={chatId}
+                  />
+                );
+              }
+              return (
+                <div
+                  key={tc.id}
+                  className="flex items-center gap-1.5 text-xs text-zinc-400 bg-zinc-900/50 rounded px-2 py-1"
+                >
+                  <Wrench size={11} />
+                  <span className="font-mono">{tc.name}</span>
+                  <span className="text-zinc-500 truncate max-w-[200px]">
+                    {truncateArgs(tc.args)}
+                  </span>
+                </div>
+              );
+            })}
+          </div>
+        )}
+
+        {message.content.trim() && (
+          <div className="prose prose-invert prose-sm max-w-none [&_pre]:bg-zinc-900 [&_pre]:p-3 [&_pre]:rounded [&_pre]:overflow-x-auto [&_code]:text-zinc-300 [&_p]:my-1.5">
+            <Markdown remarkPlugins={[remarkGfm]}>{message.content}</Markdown>
+          </div>
+        )}
+
+        {isStreaming && !message.content.trim() && (
+          <div className="flex items-center gap-1.5 text-zinc-400">
+            <Loader2 size={14} className="animate-spin" />
+            <span className="text-xs">Thinking...</span>
+          </div>
+        )}
+
+        {isStreaming && message.content.trim() && (
+          <span className="inline-block w-1.5 h-4 bg-zinc-400 animate-pulse ml-0.5 align-middle" />
+        )}
+      </div>
+    </div>
+  );
+}
+
+function ToolResultBubble({ message }: { message: Message }) {
+  const result = message.tool_results;
+  if (!result) return null;
+
+  const isError = result.error;
+  const output = result.output != null ? String(result.output) : '';
+  const displayOutput =
+    output.length > 300 ? output.slice(0, 300) + '...' : output;
+
+  return (
+    <div className="flex justify-start mb-2 ml-6">
+      <div
+        className={`max-w-[80%] rounded px-3 py-2 text-xs font-mono border ${
+          isError
+            ? 'bg-red-950/30 border-red-800/50 text-red-300'
+            : 'bg-zinc-800/50 border-zinc-700/50 text-zinc-400'
+        }`}
+      >
+        {result.truncated && (
+          <span className="text-yellow-500 text-[10px] block mb-1">
+            [truncated]
+          </span>
+        )}
+        <pre className="whitespace-pre-wrap break-all">{displayOutput}</pre>
+      </div>
+    </div>
+  );
+}
+
+function truncateArgs(args: unknown): string {
+  if (!args) return '';
+  try {
+    if (typeof args === 'object' && args !== null) {
+      const obj = args as Record<string, unknown>;
+      const keys = Object.keys(obj);
+      if (keys.length === 0) return '';
+      const first = keys[0]!;
+      const val = String(obj[first] ?? '');
+      const display = val.length > 40 ? val.slice(0, 40) + '...' : val;
+      return `${first}: ${display}`;
+    }
+    const str = String(args);
+    return str.length > 50 ? str.slice(0, 50) + '...' : str;
+  } catch {
+    return String(args).length > 50 ? String(args).slice(0, 50) + '...' : String(args);
+  }
+}
--- a/apps/coder/web/src/components/ui/button.tsx
+++ b/apps/coder/web/src/components/ui/button.tsx
@@ -0,0 +1,35 @@
+import * as React from 'react';
+
+export interface ButtonProps
+  extends React.ButtonHTMLAttributes<HTMLButtonElement> {
+  variant?: 'default' | 'destructive' | 'outline' | 'secondary' | 'ghost' | 'link';
+  size?: 'default' | 'sm' | 'lg' | 'icon';
+}
+
+const variantClasses: Record<string, string> = {
+  default: 'bg-primary text-primary-foreground hover:bg-primary/90',
+  destructive: 'bg-destructive text-destructive-foreground hover:bg-destructive/90',
+  outline: 'border border-input bg-background hover:bg-accent hover:text-accent-foreground',
+  secondary: 'bg-secondary text-secondary-foreground hover:bg-secondary/80',
+  ghost: 'hover:bg-accent hover:text-accent-foreground',
+  link: 'text-primary underline-offset-4 hover:underline',
+};
+
+const sizeClasses: Record<string, string> = {
+  default: 'h-9 px-4 py-2',
+  sm: 'h-8 rounded-md px-3 text-xs',
+  lg: 'h-10 rounded-md px-8',
+  icon: 'h-9 w-9',
+};
+
+const Button = React.forwardRef<HTMLButtonElement, ButtonProps>(
+  ({ className, variant = 'default', size = 'default', ...props }, ref) => {
+    const base =
+      'inline-flex items-center justify-center whitespace-nowrap rounded-md text-sm font-medium transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring/40 disabled:pointer-events-none disabled:opacity-60';
+    const cls = [base, variantClasses[variant] ?? '', sizeClasses[size] ?? '', className ?? ''].join(' ');
+    return <button className={cls} ref={ref} {...props} />;
+  },
+);
+Button.displayName = 'Button';
+
+export { Button };
--- a/Show More
+++ b/Show More