feat: task 2.9 connection status + per-device staleness fade — Phase 2 done

- src/live/last-seen.ts: formatLastSeen(ts, now) — "now" / "Ns ago" /
  "Nm ago" / "HH:MM".
- src/live/use-staleness.ts: useStalenessTick(intervalMs=1000) hook
  re-renders subscribers every interval with the current epoch ms.
- src/ui/components/connection-chip.tsx: <ConnectionChip /> bottom-left,
  three states (connected / connecting+reconnecting / disconnected),
  aria-live polite + role status.
- src/map/layers/map-positions.tsx: every FeatureProps now carries
  staleSec; both symbol layers interpolate icon-opacity (and text-opacity
  on the non-selected layer) on staleSec — 0-60s full opacity,
  5min faded, 30min very faded. Update effect rebuilds features at the
  staleness tick rate (1Hz).
- src/routes/_authed/monitor.tsx: renders <ConnectionChip />.
- src/live/index.ts: re-exports formatLastSeen + useStalenessTick.

Strategy A (faded marker via interpolation) chosen over Strategy B
(separate warning-badge layer) per the task's open-question
resolution; simpler and easier to extend later.

Deviations:
1. stalenessTick is its own hook in src/live/use-staleness.ts rather
   than a property on the position store — keeps the store clean of
   UI-driven re-render concerns; the hook is reusable.
2. <DeviceLastSeen deviceId> standalone component skipped — the SPA
   doesn't have a sidebar yet (Phase 3.4); the per-marker fade IS the
   indicator for v1.

Bundle: main 396KB / 121KB gz — small bump from 2.8.

🎉 Phase 2 — Live monitoring map — complete. All 9 tasks shipped.
End-to-end: login -> /monitor -> event auto-selects -> snapshot
positions render -> live updates flow via WS through the rAF
coalescer -> staleness fades stale markers -> connection chip
surfaces WS state. Dogfood-blocking work for Rally Albania 2026 done.

.planning/phase-2-live-map/09-connection-status.md

@@ -147,4 +147,29 @@ useEffect(() => {
 
 ## Done
 
-(Filled in when the task lands.)
+- **`src/live/last-seen.ts`** — `formatLastSeen(ts, now)` returns `"now"` / `"Ns ago"` / `"Nm ago"` / wall-clock `"HH:MM"` based on age. Used by both the connection chip and Phase 3.4's per-device detail panel.
+- **`src/live/use-staleness.ts`** — `useStalenessTick(intervalMs = 1000)` hook. Re-renders subscribers every `intervalMs` with the current epoch ms. The position store doesn't change on its own once positions stop arriving; this keeps `staleSec` fresh on every `<MapPositions>` feature so the icon-opacity fade reflects "device went silent" without waiting for a new position.
+- **`src/ui/components/connection-chip.tsx`** — `<ConnectionChip />` floating bottom-left. Three states: `connected` (green dot + "Live"), `connecting`/`reconnecting` (amber pulsing dot + status word), `disconnected` (red dot + "Offline · last live HH:MM"). `aria-live="polite"` so screen readers announce transitions; `role="status"`.
+- **`src/map/layers/map-positions.tsx`** updated:
+  - Adds `staleSec` to every `FeatureProps`; computed as `Math.floor((now - position.ts) / 1000)`.
+  - Both non-selected and selected symbol layers gain `'icon-opacity'` interpolations on `staleSec` (0–60 s full opacity, 5 min faded, 30 min very faded). Non-selected layer also fades `text-opacity` so the device label ages along with the marker.
+  - Update effect now reads `useStalenessTick(1000)` and includes it in dependencies — feature collections rebuild every second so opacity stays fresh.
+- **`src/routes/_authed/monitor.tsx`** — renders `<ConnectionChip />` inside `<MapView>`.
+- **`src/live/index.ts`** — re-exports `formatLastSeen` and `useStalenessTick`.
+
+**Strategy A picked from the spec's open question**: faded marker via `icon-opacity` interpolation, no separate "warning" badge. Rationale per spec: simpler, fewer layers, cleaner visually. If it's not legible enough after dogfood feedback, layer B (a dedicated overlay sprite) is a single new symbol layer addition.
+
+**Deviations from spec:**
+
+1. Spec sketched a `stalenessTick` mutation inside the position store's actions. Pulled it out into a dedicated `useStalenessTick` hook in `src/live/use-staleness.ts` instead — keeps the position store free of UI-driven re-render concerns, and the hook is reusable in any component that needs an N-Hz tick (per-device detail panel in Phase 3.4 will).
+2. Spec referenced a per-device `<DeviceLastSeen deviceId>` component for use inside a sidebar / detail panel. Skipped — the SPA doesn't have a sidebar yet (Phase 3.4 territory), and the per-marker fade is the per-device indicator for v1. The `formatLastSeen` utility is exported and ready for that component when 3.4 lands.
+
+**Smoke check (`pnpm dev`):**
+- `/monitor` shows the connection chip bottom-left. While connecting the chip pulses amber. Once the WS opens, it flips to a green dot + "Live". Disconnect the network → flips to amber + "Reconnecting…". Stay disconnected past `STALE_CONNECTION_MS` (60 s) → red dot + "Offline · last live …".
+- Push a synthetic position via the console, wait > 60 s without further updates → marker visibly fades. Wait > 5 min → fades further. Each tier matches the interpolation breakpoints.
+- The visible fade is also gradual *within* each tier because the interpolation is `linear`.
+- Hard refresh while disconnected: chip starts as "Connecting…" (no `lastConnectedAt` yet), then either flips to "Live" or "Reconnecting…" based on whether the WS opens.
+
+**Bundle:** main 396KB / 121KB gz — small bump from 2.8.
+
+Landed in `PENDING_SHA`.