fix(lanes): keep stage detection honest across rollbacks and feature switches

Three defects let a lane's pipeline map claim progress that was not this
pass's work, all of them on the "going back" path a new request takes:

- `setStage` cleared the detection columns on a real transition but never
  pruned the `stages` records AHEAD of the new stage. A lane that ran through
  `done` and was then declared back at `plan` rendered `plan` as `current`
  while `tests`/`review`/`done` still read `done`, carrying the previous
  pass's evidence, and contradicting `progress` (computed from the declared
  index alone). A backwards declaration now drops every record it can prove
  is ahead; a key matching no node is unplaceable and left alone.
- `activateFeature` rewrote the live lane row for the incoming feature but
  carried the outgoing one's `detected_*` across. A never-seen slug starts at
  `stage='idle'`/`stages={}`, exactly the shape `inferredDisplayStage` renders
  from detection, so the new feature opened painted with the old one's
  progress — and forward-only rejected every real detection for it until the
  carried-over one aged past DETECTION_TTL_MS. Now cleared, like every other
  real transition; deliberately not archived, since detection is live-only.
- `codex-ingest` classified a rollout journal by raw `now - mtime`, which goes
  negative for a future mtime (clock stepped back, NTP correction, a restore
  that preserved timestamps) and read as "written milliseconds ago". A
  finished thread's journal could replay as live work; a file claiming to be
  from the future is now idle.

Also fixes `check-headers.sh`, which audited via `find` and so reported local
gitignored runtime state (a lane's own `.ccam/profile/hooks/*.sh`) that is not
this repo's source and can never be made compliant here. It now lists files
through git (tracked + untracked-but-not-ignored), so a file an agent just
wrote is still caught before it is staged while ignored state is not.

Tests: 1359 pass (4 new). Header audit exits 0.

CLAUDE.md

@@ -1,6 +1,6 @@
 # Claude Code Working Guide
 
-_Last synced: b1734a4 (2026-08-27)._ A change that makes any statement in this file, `AGENTS.md`, or a README wrong — a moved path, a new or changed extension point, a retired rule — updates that file in the same change-set and bumps this marker.
+_Last synced: 13b2bc4 (2026-09-03)._ A change that makes any statement in this file, `AGENTS.md`, or a README wrong — a moved path, a new or changed extension point, a retired rule — updates that file in the same change-set and bumps this marker.
 
 ## Project mission
 - Maintain a reliable local-first dashboard for Claude Code session monitoring.
@@ -24,6 +24,7 @@ A **lane** is a durable unit of parallel agent work — one working directory, m
 - A lane's stage is **declared** by the driving Claude session (via `ccam stage <stage> [--evidence "..."]`), not inferred by the dashboard.
 - **A CLI command resolves its lane by (cwd, tool), never cwd alone.** `resolveLaneArg` (`bin/ccam.js`) answers in order: `--lane`/leading id → `CCAM_LANE_ID` (every tmux pane the dashboard starts carries it, via `tmux new-session -e`) → `--tool`, else the harness marker (`CLAUDECODE` ⇒ claude; Codex has NO reliable env marker, so it passes `--tool codex`) → the owning lane. Two candidates at one directory and no signal is an ERROR that names both, never a pick — writing a codex session's stage onto the claude lane's card is a lie about which agent did the work.
 - **The console never writes a lane's stage.** Declared stages come from `ccam stage` (a skill calling the CLI command), and inferred stages come from tool-event detection only. The UI's run console and the Workspace page never call `POST /api/lanes/:id/stage` — that boundary exists because the console observes tool calls but cannot see their outcomes. A lane's stage is the session's truth about progress; the console's observation of tool execution would not be proof of completion.
+- **Going back is a declaration, and it takes the nodes ahead with it.** A declaration landing on a node BEFORE the lane's current one (a fix-loop re-entry, or a new request on a lane that already reached `done`) clears the detection columns like every real transition AND drops the `stages` records of every node ahead of it — those belong to the previous pass, and left in place they render `done` with the old work's evidence beside a `current` ring further back, contradicting `progress` (computed from the declared index alone). Records under a key matching no node are left alone: unplaceable, so unprovably ahead. `ccam feature activate <slug>` is the other half of this — a feature switch archives the outgoing pipeline and clears detection too, because a detection belongs to the feature that produced it.
 - **A detection expires, an evidence rule does not.** `recordDetection` skips its forward-only comparison once `detected_at` is older than `DETECTION_TTL_MS` (default 5 min), so a lane can move backwards between work sessions. That window changes only WHICH detection is current — it never relaxes declared-wins (an agent's own claim has no expiry) and never lets an inferred node render `done`. Declared-wins has exactly ONE exception: a declaration on the pipeline's LAST node (`done`) stops vetoing, because the pipeline is over there and a later detection is new work — without it a lane left at `done` rejects every detection for the rest of its life.
 - **Working-copy facts live at `GET /api/lanes/:id/git`, never inside `GET /api/lanes`.** That endpoint shells out to git three times; the lane list is polled and re-broadcast on every hook. A cwd that is not a readable repo returns `{available:false}` with HTTP 200 — a normal state, not a fault. Cards fetch it themselves every 30s and fail silently.
 - **The Workspace console collapses with CSS, never by unmounting.** Unmounting `RunConsole` disposes the run subscription and drops a live run's rendered history.