v2.1.0-provider-picker: BooCoder systemd migration + provider picker

- BooCoder moves from Docker to host systemd service (boocoder.service)
- Agent dispatch (ACP + PTY) switches from SSH to direct spawn/exec
- SSH helpers marked @deprecated (kept for one release cycle)
- Provider registry (5 providers: boocode, opencode, goose, claude, qwen)
- Agent probe with direct which/exec + model discovery (qwen settings, static claude models)
- GET /api/providers route with installed status, models, transport fallback
- ProviderPicker frontend component in CoderPane header
- External provider messages route through tasks row instead of inference enqueue
- Smart scroll: MessageList only auto-scrolls when near bottom (150px threshold)
- DB: available_agents gets models, label, transport columns
- Bug fix: loadContext SELECT includes allowed_read_paths
- Bug fix: cap hit sentinel inserted before buildMessagesPayload
- docker-compose.yml: boocoder service commented out, BOOCODER_URL env var added
- CLAUDE.md: updated docs for systemd, provider registry, JSONB gotcha, loadContext

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 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.
 
+## v2.1.0-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.
+
 ## v2.0.4-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).