docs(lanes): document proof gallery (C)

ARCHITECTURE.md

@@ -387,6 +387,7 @@ graph TD
 | `lib/lane-env.js`         | (A2) `seedEnv` copies a repo's real `.env` into a lane on first boot (or `--force`) and rewrites the declared `ENV_REWRITE` keys (`DATABASE_URL`/`REDIS_URL`/`UPLOAD_DIR`) in place, byte-identical otherwise. A `--force` refresh preserves `ENV_PRESERVE` keys (e.g. `JWT_SECRET`) from the lane's own existing file — swapping in the source's secret would 401 a running lane until reboot. Falls back to `.env.example` with a warning when the source is missing. Refuses on an adopted lane: that file is the user's real config |
 | `lib/lane-services.js`    | (A2) `ensureDatabase`/`dropDatabase` call the profile's `db-create`/`db-drop` hooks — CCAM stays stack-agnostic on purpose. A state-dir marker file tracks whether a slot's database was already created, since a plain `createdb` can't be re-run safely and CCAM can't assume the hook is idempotent; this is also how `upLane` knows to seed only a freshly-created database. `dropDatabase` asserts the lane is `managed` and that the name being dropped is one this lane's own slot actually derives (itself or its `_test` sibling) before spawning anything |
 | `lib/lane-features.js`    | (B) Per-feature state and archive. `activateFeature` archives the lane's current active feature (if different) and restores the target's saved stage onto the live `lanes` row — the row stays the one live view every other reader already uses. `canonicalizeSlug` is a DELIBERATELY separate rule from `worktree.js:slugify` (drops a leading `feat/`, keeps `[A-Za-z0-9._-]`, does not lowercase) — the two must never be conflated. `clearLane` (`lib/lanes.js`) archives the active feature (if any) before resetting; a lane that never activated one is unaffected |
+| `lib/proof.js`            | (C) Proof gallery: lists/serves/deletes QC screenshots grouped by feature slug (Task B's `lane_features`) and phase, under `<lane.cwd>/.playwright-mcp/proof/<slug>/<group>/`. Every path is resolved, realpath'd, and containment-checked before touching `fs` — the entire security surface. `ensureProofLink` ports Shipyard's `ensure_proof_link` (converge a stray clone-root `proof/` onto the canonical dir); never auto-invoked, exposed only as `ccam lanes proof-link` |
 | `lib/named-lock.js`       | (D) Cross-lane named locks — the OTHER axis from `lib/lane-lock.js`'s per-lane, in-process serialization, deliberately a separate module. `mkdir` is the atomicity primitive (EEXIST decides "already held" in one syscall, never check-then-create). `LOCK_MAX_HOLD` (default 2700s) breaks a stale holder on the next acquire, floored at 300s so the floor — not the configurable default — is the actual safety property: nothing can force-break a live holder by setting the env var low. Single-shot only; the CLI's `ccam lock acquire` owns the polling loop, keeping the server side non-orchestrating like every other lane primitive |
 
 ### API Documentation