feat(dash): slot indicator dot states + warming pulse

[thinmintdev]

Investigation summary

/api/slots on hal0 LXC exposes state + metadata.updated_at (last state-change wall clock) but no last_used_at (last-serve wall clock). SlotManager already maintains _last_used: dict[str, float] in memory, bumped on every dispatched request via the serving() async context manager (manager.py:1421/1440/1443) — wired through Dispatcher.forward → _forward_with_serving for every slot-routed call. So the "recently live within 1h" signal already exists server-side; it just isn't surfaced. Minimum diff: thread _last_used.get(slot_name) onto the Slot snapshot returned from SlotManager.status(), surface it on as_dict(), and consume it in the frontend. No persistence — on hal0-api restart the field resets to null, which the dashboard treats as "stale" (yellow). That matches operator intuition: we don't actually know if the slot was hit during downtime.

State → dot.cls mapping

Slot state	Last-used age	Dot class	Color	Behaviour
ready	within 1h	recent	green (--ok)	static
ready	>1h or null	stale	yellow (--warn)	static
idle	—	stale	yellow (--warn)	static
warming / starting / pulling / unloading	—	warming	amber (--warn)	pulsing (1.2s ease-in-out)
serving	—	serving	cyan (--accent)	pulsing (pre-existing)
error	—	error	red (--err)	static
offline / unknown	—	offline	grey (--fg-4)	static

The 1h threshold lives as a single named const (RECENTLY_LIVE_MS = 60 * 60 * 1000) in slots.jsx. The mapping itself is the single function slotIndicator(slot), exported on window for unit testing.

Backend changes

• src/hal0/slots/manager.py: Slot.__init__ + Slot.as_dict() gain last_used_at: float | None. SlotManager.status() populates it from self._last_used.get(slot_name).

That's it. No new endpoint, no schema migration, no new bump-site (the existing serving() context already covers every dispatched request). _last_used is process-local; hal0-api restart resets to null and the UI degrades to yellow, which is honest.

Known limitation observed live (NOT a regression — this PR's scope is the indicator, not the bump path): on a hal0 install with no upstreams.toml configured, chat completions fall through to lemonade_proxy._proxy (api/routes/v1.py:241), which bypasses SlotManager.serving() and therefore doesn't bump last_used_at. On a normal install with primary registered as a slot upstream, the dispatcher's _forward_with_serving path bumps as expected. A follow-up could add the bump to the proxy fallback; flagged in the PR conversation for triage rather than expanded here.

Frontend changes

• ui/src/dash/slots.jsx: new slotIndicator(slot, now?) helper returning {cls, label, tooltip}. New IndicatorDot component. RECENTLY_LIVE_MS const. Replaces the two <span className={"dot " + state}/> sites in SlotCard + SlotListRow. All three exposed on window for tests.
• ui/src/dashboard.css: adds .dot.recent, .dot.stale, .dot.warming, .dot.offline. Reuses existing palette + pulse keyframe (now 0.4 ↔ 1.0 opacity as the brief suggested, was 0.35).
• ui/src/api/hooks/useSlots.ts: Slot interface gains last_used_at?: number | null so TS keeps its grip.

chrome.jsx (PR #306's territory) is not touched — its dots are lemond-status / coresident / follow-tail indicators, not per-slot state dots.

Tests

• tests/slots/test_manager.py: new test_status_surfaces_last_used_at asserts Slot.last_used_at round-trips through status() + as_dict(), both before and after a bump_last_used() call. All 117 existing slot tests still pass.
• ui/tests/e2e/specs/slot-indicator.spec.ts: 10 new Playwright cases pinning every cell of the mapping table — including the ≤1h is still recent / 1h + 1s is stale boundary cases and the null last_used_at "no requests since hal0-api started" tooltip.
• ui/tests/e2e/specs/slot-indicator-live-screenshot.spec.ts: opt-in capture against the LXC, gated by HAL0_LIVE_LXC=1 (skipped in CI, useful for follow-up visual reviews).

Full local suite: 444 pytest tests pass, 44 Playwright tests pass (9 environmentally skipped).

Live verification on hal0 LXC (10.0.1.142)

After clean rebuild (cd /opt/hal0/ui && rm -rf dist node_modules/.vite && npm run build && systemctl restart hal0-api):

#	Scenario	Verified?	Observation
1	/api/slots exposes last_used_at	✅	curl /api/slots returns "last_used_at": null for all 5 slots after restart
2	Ready slots with null last_used_at render yellow (stale)	✅	Captured screenshot: all 5 cards show --warn dot
3	Bump last_used_at → primary turns green (recent)	⚠️ simulated	Unit test proves the mapping; on this LXC the chat path falls through lemonade_proxy (no upstreams registered) and bypasses serving(). Documented as known limitation; not introduced by this PR.
4	Forced stale (last_used_at > 1h ago) → yellow	✅ implicit	The current LXC state IS this scenario (null reads as stale via the same code branch)
5	Restart → warming class (amber pulsing)	✅	POST /api/slots/primary/restart → screenshot captures primary's starting chip with amber dot, plus 4 other slots simultaneously in offline grey during the lemond cascade
6	Error state → red	⏭️ unit test only	Not safe to force on the shared LXC; Playwright case error → error (red), tooltip surfaces metadata.message covers it
7	Offline slot → grey	✅	Multiple slots showed .dot.offline grey during scenario 5's restart cascade

Commands used:

# Verify field exposure
ssh hal0 'curl -s http://127.0.0.1:8080/api/slots' | python3 -m json.tool | head

# Capture restart-cascade screenshot
ssh hal0 'curl -s -X POST http://127.0.0.1:8080/api/slots/primary/restart -d "{}" -H "content-type: application/json" >/dev/null &' &
sleep 0.4
HAL0_LIVE_LXC=1 npx playwright test slot-indicator-live-screenshot --grep @live-lxc

Files touched

M  src/hal0/slots/manager.py              (+13 -1 — Slot.last_used_at + status() wiring)
M  tests/slots/test_manager.py            (+28 — test_status_surfaces_last_used_at)
M  ui/src/api/hooks/useSlots.ts           (+8 — Slot.last_used_at typing)
M  ui/src/dash/slots.jsx                  (+121 — slotIndicator + IndicatorDot + 2 callsites)
M  ui/src/dashboard.css                   (+11 -2 — 4 new dot classes + tweaked pulse opacity)
A  ui/tests/e2e/specs/slot-indicator.spec.ts                (118 lines — 10 mapping cases)
A  ui/tests/e2e/specs/slot-indicator-live-screenshot.spec.ts (29 lines — opt-in capture)

Owned-by-sibling-PR files NOT touched: chrome.jsx (#306), dashboard.jsx (#308/#309), chat.jsx (#309), main.tsx (#309), idle.py (#307), models.jsx/settings.jsx, dispatcher/router.py.

Out of scope

• Animating colour transitions between states (warming pulse is the only animation)
• Per-slot health detail panel
• "Within 1h" history graph
• Tunable threshold (1h hard-coded; separate PR if needed)
• Bumping last_used_at from the lemonade proxy fallback path (separate PR — see the limitation note above)

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