feat: Claude Code Monitor — lanes, pipelines and a merged workspace

Internal SmartGift build of a Claude Code monitoring dashboard.

Lanes: a durable unit of parallel agent work, one per working directory,
tracked across session restarts. Managed lanes are git worktrees the
dashboard provisions and can reset or remove behind a three-check destroy
guard and a counted preflight; adopted lanes are directories you already
own and are never destroyable.

Pipelines: a lane moves through pipeline stages. A stage the agent declares
with evidence renders green; a stage inferred from the tool-event stream
renders dashed amber and never counts as done. Detection is forward-only
within a 30-minute window, and never writes the declared stage.

Workspace: one page at /run with a lane grid, the selected lane's pipeline,
and a full Claude console behind a disclosure.

plugins/ccam-sessions/skills/session-cleanup/SKILL.md

@@ -0,0 +1,76 @@
+---
+description: >
+  Identify stale and empty Claude Code sessions in the Agent Monitor and explain the
+  cleanup endpoint (POST /api/settings/cleanup), always showing the exact list of
+  what WOULD be removed before anything is deleted. Cleanup permanently deletes data,
+  so this skill previews first and requires explicit user confirmation. Use when
+  tidying the monitoring database.
+---
+
+# Session Cleanup
+
+Find prune-worthy sessions and explain cleanup — preview first, delete only on
+explicit confirmation.
+
+## Input
+
+The user provides: **$ARGUMENTS**
+
+- Empty / `preview` → only show what would be removed (the safe default).
+- `confirm` → the user has reviewed the preview and explicitly authorizes deletion.
+- An optional staleness threshold (e.g. `older than 7d`) for what counts as stale.
+
+## Data Sources
+
+| Endpoint | Returns |
+|----------|---------|
+| `GET /api/sessions?limit=N` | session list: id, status, model, cwd, started_at, ended_at, cost, metadata (turn_count, total_turn_duration_ms) |
+| `GET /api/stats` | totals: total_sessions, active_sessions, total_events, events_today, sessions_by_status, agents_by_status |
+| `POST /api/settings/cleanup` | runs the cleanup routine and returns what was removed — DESTRUCTIVE, only after confirmation |
+
+## Report Sections
+
+### 1. Baseline
+`GET /api/stats` — record total_sessions, sessions_by_status, total_events. This is
+the before-state to compare against.
+
+### 2. Identify candidates
+`GET /api/sessions?limit=1000`. Flag sessions that are:
+- **Empty** — zero events and `turn_count` 0 / null and `cost` 0 (started but never
+  did anything).
+- **Stale active** — `status` active/working but last activity older than the
+  threshold (default 24h), i.e. never cleanly stopped.
+- **Truncated** — no `ended_at` and no recent events.
+
+### 3. Preview table (ALWAYS shown)
+List every candidate with the reason it qualifies. State the total count and confirm
+that **nothing has been deleted yet**.
+
+### 4. Explain the endpoint
+Describe `POST /api/settings/cleanup`: it prunes empty / orphaned sessions and their
+dangling events server-side and returns a summary of removed rows. Make clear this
+is **permanent** and **not reversible** from the dashboard.
+
+### 5. Execute only on confirmation
+If — and only if — `$ARGUMENTS` is `confirm` (or the user has explicitly approved
+this run), call `POST /api/settings/cleanup`, then re-read `/api/stats` and report
+the before → after delta. Otherwise stop after the preview and tell the user to
+re-run with `confirm`.
+
+## Output
+
+A preview Markdown table: `id (short) | status | reason | cwd basename | started_at | cost`,
+then a one-line count and the explicit "nothing deleted — re-run with `confirm` to
+proceed" notice. On a confirmed run, add a before → after summary using ▲/▼ on the
+counts. Currency as USD to 4 decimal places.
+
+## Safety
+
+- This is the ONLY skill in the plugin that mutates data, and only via the one
+  documented endpoint.
+- NEVER call `POST /api/settings/cleanup` without an explicit `confirm` from the
+  user in this turn — previewing is the default.
+- Never widen scope to `POST /api/settings/clear-data` or any other destructive
+  endpoint; cleanup of stale/empty sessions only.
+- If the dashboard is unreachable, tell the user to start it with `npm start` from
+  the repo root.