docs: archive shipped openspec batches; add feature/plan/research notes

Move 13 shipped openspec change docs under openspec/changes/archived/.
Add docs/features/git-diff-panel, docs/plans/post-review-backlog, and
docs/research/cross-app-contract-ssot.md (the research behind the
@boocode/contracts SSOT work). Update BOOCHAT.md, BOOCODER.md, and
boocode_roadmap.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

openspec/changes/archived/v2-3-provider-lifecycle/proposal.md

@@ -0,0 +1,63 @@
+# v2.3 Provider lifecycle (Paseo-style registry)
+
+**Status:** ✅ **Shipped** across `v2.5.4`–`v2.5.13` (2026-05-29; reconciled 2026-05-31) — all 6 phases live; only the 3 optional Tier-2 items deferred  
+**Depends on:** v2.2 Paseo providers (snapshot, modes, commands, ACP dispatch)  
+**Reference fork:** `/opt/forks/paseo`  
+**Related deferred work:** [`docs/DEFERRED-WORK.md`](../../../docs/DEFERRED-WORK.md) §2 (cold-probe skip)
+
+> **Shipped mapping (reconciled 2026-05-31):** Phase 1 → `v2.5.4`, Phase 2 → `v2.5.5`, Phase 3 → `v2.5.6`, Phase 4 → `v2.5.12`, Phase 5 → `v2.5.13`, Phase 6 docs → `v2.5.13`/`v2.5.14`. **Deferred (tasks O.1–O.3):** WS `provider_snapshot_updated` frame, `available_agents.enabled` column, diagnostic row-click modal — tracked in `docs/DEFERRED-WORK.md`. (Cursor was retired in `v2.5.3`, so the success-criterion mention below is historical.)
+
+## Why
+
+BooCode v2.2 copied Paseo’s **snapshot wire shape** (modes, thinking, commands) but not Paseo’s **provider lifecycle**:
+
+- Providers are hardcoded in `provider-registry.ts`; adding one requires a code change and redeploy.
+- Uninstalled agents **disappear** from the picker instead of showing “not installed.”
+- There is no **enable/disable** toggle — every probed binary appears.
+- Every snapshot cache miss runs a **full cold ACP probe** for all installed agents (5–30s).
+
+Paseo’s model (see `/opt/forks/paseo/public-docs/providers.md`) treats providers as **registered entries** in a config-backed registry, then probes the machine for readiness, then lets the user toggle visibility. That fits a one-person homelab: edit JSON, refresh, flip a switch — no TypeScript deploy for each new ACP CLI.
+
+## Scope
+
+### In scope
+
+1. **Config file** `/data/coder-providers.json` — add/disable/custom ACP providers without code changes
+2. **Merged registry** — built-ins + config overrides at runtime
+3. **Snapshot lifecycle** — `loading` | `ready` | `unavailable` | `error`; always list registered providers; `enabled` flag
+4. **Two-tier probe** — fast binary check vs slow ACP session (DB `last_probed_at` gate)
+5. **Generic ACP dispatch** — config entries spawn via `{ command, env }` without new `acp-spawn` cases
+6. **HTTP API** — read/patch config, per-provider refresh, optional diagnostic
+7. **Web UI** — settings drawer: provider list, enable toggle, refresh, add-from-catalog (curated ~5–10 entries)
+8. **Tests + docs** — snapshot unit tests, `BOOCODER.md` refresh contract
+
+### Out of scope (this batch)
+
+- Full Paseo ACP catalog (30+ agents) — curate a small local catalog only
+- React Native settings app port
+- Replacing `acp-dispatch.ts` with Paseo’s `ACPAgentClient` hierarchy
+- Voice provider stack
+- MCP `list_providers` / `inspect_provider` tools (Tier 2 follow-up)
+- WS push of snapshot updates (Tier 2 follow-up)
+
+## Non-goals
+
+- Multi-user provider prefs (single-user homelab)
+- Installing CLIs from the UI (link to install instructions only, like Paseo)
+- Removing `available_agents` table — keep it as probe cache, extend with `enabled` or mirror config
+
+## Success criteria
+
+- ✅ Add `amp-acp` via catalog → appears in picker after refresh without coder redeploy *(catalog smoke-test entry; per `boocode_code_review_v2.md` §5m, Amp itself is paid-cloud, not a usable local provider)*
+- ✅ Disable goose in settings → gone from picker, still visible as “Disabled” in settings
+- ✅ opencode not on PATH → shows “Not installed” in settings, hidden from picker
+- ✅ Second snapshot open within warm window completes in <500ms (no ACP spawns)
+- ✅ `POST /api/providers/refresh` still runs full cold probe
+- ✅ Existing v2.2 dispatch unchanged for built-ins *(opencode, claude, qwen, goose — cursor + copilot retired `v2.5.3`)*
+
+## Deliverables
+
+| Doc | Purpose |
+|-----|---------|
+| [`design.md`](./design.md) | Full architecture, schemas, file map, Tier 3 reference |
+| [`tasks.md`](./tasks.md) | Numbered implementation checklist |