# apps/coder — BooCoder (deep reference)

> Per-app engineering notes for `apps/coder/src/`. BooCoder runs as a **systemd service on the host** (`boocoder.service`), NOT in Docker — Fastify at port 9502, postgres at `127.0.0.1:5500`. Cross-cutting commands, database, environment, workflow, and cross-app contracts live in the **root `CLAUDE.md`**. This file auto-loads when you read/edit files under `apps/coder/`.

## Probe & provider discovery

- **`services/provider-registry.ts`** — 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). `PROBED_AGENT_NAMES` derives from it — adding/removing providers means editing this file, not the frontend.
- **`services/agent-probe.ts`** — Startup probe via direct `exec()` (not SSH): discovers installed agents, versions, ACP support, models. Qwen models from `~/.qwen/settings.json`; Claude models static from the registry. Persisted to `available_agents`.
- **`routes/providers.ts`** — `GET /api/providers` returns installed providers with models. Transport reflects actual capability (checks `supports_acp` from DB, not just registry preference). The apps/server side is "Provider picker dispatch" (see `apps/server/CLAUDE.md`).
- **Provider snapshot lifecycle** (`services/`): `provider-config.ts` (Zod config, never-throws) → `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** (live runtime config — the coder reads AND writes it on UI toggles); tracked reference is `data/coder-providers.example.json`. The loader falls back to `{providers:{}}` (built-ins only) when absent, so a fresh checkout needs no copy.

## Build, deploy, dispatch

- **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 packages/contracts build && 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 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 shape). Restart, don't re-debug.
- `:9502/api/health` is down ~15–20s after a boocoder restart while the startup agent-probe scan runs — retry; an early connection-refused is not a failed deploy.
- Agent dispatch spawns binaries directly using `install_path` from `available_agents` — no `spawn('sh', ['-c', ...])` (fails under systemd). 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. 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 can't find `.d.ts` files and tsc fails "Cannot find module" here.
- Write tools (`edit_file`, `create_file`, `delete_file`, `apply_pending`, `rewind`) queue in `pending_changes`. Nothing hits disk until `apply_pending`. `write_guard.ts` validates paths (resolve + prefix-check, no realpath since files may not exist for creates).

## Backends

> Behavioral overview + flows + data model: see [/docs/coder-backends.md](/docs/coder-backends.md). The notes below are the deep per-fact reference.

- **opencode** runs as a warm HTTP server (`services/backends/opencode-server.ts` — `opencode serve` per BooCoder process, one opencode session per BooCode session, resumed via `agent_sessions`). goose/qwen/claude dispatch **one-shot** ACP/PTY with no ctx/token usage; only native `boocode` (llama-swap) tracks ctx.
- **opencode SSE** (`opencode-server.ts`): live streaming is `session.next.text.delta` / `.reasoning.delta` / `.tool.{called,success,failed}` — NOT `message.part.*` (terminal/post-hoc). `client.event.subscribe({ directory })` MUST pass the session's worktree dir; omit it and opencode scopes events to the server `process.cwd()` → zero session events (empty turns, 180s timeout). Each live session owns its own subscribe loop + AbortController (a `sessionID` demux guard drops cross-session events when two share a dir). Turn completes on `session.idle`; `promptAsync` is fire-and-forget (204).
- **opencode model strings** must be provider-prefixed (`llama-swap/<model>`) AND exist in `~/.config/opencode/opencode.json` `provider.llama-swap.models` — not merely loadable by llama-swap. `parseModel` infers `llama-swap/` for a bare id; the dispatcher coalesces empty→DEFAULT_MODEL then prefixes. `agent-probe` populates opencode's `available_agents.models` via `mergeLlamaSwap` (fetches `/v1/models`); empty model list → frontend sends `''` → no inference (empty turn).
- **agent_sessions resume**: `config_hash = sha256('opencode_server|<model>')` — must NOT include the server port (random per boot; breaks cross-restart resume). Keyed `(chat_id, agent)` — the tab/chat is the context unit (two opencode tabs = two contexts sharing one worktree). `chat_id` CASCADEs from `chats`; `session_id`/`worktree_id` are informational `SET NULL`. The `worktrees` table (one-per-session, survives session delete) supersedes the defanged `session_worktrees`. `tasks.chat_id` threads the tab id to the dispatcher; `runOpenCodeServerTask` resolves-or-creates a chat when null. The `@opencode-ai/sdk` v2 client takes flattened params (`{sessionID, directory, parts, model:{providerID,modelID}}`), `createOpencodeClient` from `@opencode-ai/sdk/v2/client`.
- **Claude SDK backend tool RESULTS arrive as `type:'user'` SDK messages** (tool_result content blocks): `mapSdkMessage` (`claude-sdk-map.ts`) MUST map the `user` case → a terminal `tool_update` (completed/failed + output), else the tool_call persists `status:'running'` and the UI spinner never stops. The dispatcher's `tool_update` path then publishes + persists it.
- **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) discover from disk via `claude-command-discovery.ts` (`~/.claude/commands` + `enabledPlugins`, 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.
- **A new per-message coder field silently drops unless you update every mapper**: the HTTP read SELECT + `mapCoderMessageRow` (`apps/coder/src/routes/messages.ts`), **the WS `snapshot` SELECT (`apps/coder/src/routes/ws.ts`)** — it has its OWN column list and the client's `snapshot` handler `setMessages`-overwrites the HTTP load, so a field present in the HTTP route but absent here shows live yet vanishes on refresh — `CoderPane.tsx` (`RawCoderMessage`/`CoderMessage`/`mapCoderTimelineRow` + the live `message_complete` WS reducer), `CoderMessageWire` (`CoderMessageList.tsx`), and `api/types.ts`. The client `mapCoderTimelineRow` whitelists fields — easiest to forget. This bit `model` twice: the client chain (`v2.7.9`) and then the WS snapshot SELECT (`v2.7.11`) — the chip showed live but vanished on coder refresh until both were fixed.
