phase: 02_overview_fleet_and_alerts

**Phase 02 final verification pass — all three tasks already complete; verified criteria, fixed 3 defects found live.**

- Verified: `/` = exactly 2 `<section>`s (Warnings & errors + Fleet), alerts render from `/api/summary` verdicts with each alert's own `href`; `/system`, `/llm`, `/ups` unchanged (charts + data live).
- Fixed (`src/dashboards/alerts.py`): a dead source's message printed the name twice — `gateway: UpstreamError: gateway: http://…`; the poller's `UpstreamError:` wrapper is now stripped (other exception names kept). Tests: 2 new in `tests/test_alerts.py`.
- Fixed (`src/dashboards/api.py`): `/api/summary` dropped a configured host/engine that had never answered post-start, so the fleet said `2/2 hosts` while a third was down. Stub rows (`unreachable: true`, all `n/a`) now match `/api/*/snapshot`; `hosts_total=3 / hosts_live=2`. Test: `test_a_host_that_has_never_answered_is_still_a_row_in_the_fleet`.
- Fixed (`web/static/page-index.js`): fleet row of a non-answering host is now dimmed with the shared `.stale` class (invariant 4 on `/`). Test: `test_overview_dims_the_fleet_row_of_a_host_that_stopped_answering`.
- `bash .agents/validate.sh` exit 0: `uv run pytest --cov --cov-fail-under=94` → **439 passed, 6 skipped, 96.82%** (`alerts.py` 100%, `api.py` 100%); `ruff check src tests agent` clean; `pyright` 0 errors; `node --check web/static` clean; hygiene clean; `uv pip list --outdated` empty; `uv run pytest -m live --live` → **6 passed**.
- Live proof (tunnel kill, then restored — all 6 sources `ok` again): killing the gateway forward produced exactly **one** alert, `fail gateway /system … unreachable (ConnectError)`; screenshots `data/logs/phase02-final-{alert,system,llm,ups,recovered}.png`.
- Completion criteria: two panels ✅ · `[]` when healthy ✅ (hermetic `healthy_client` + a live gateway-only instance returned `[]`; the real fleet can never be `[]` — its UPSes permanently warn on battery age/self-test) · one alert per dead host with `/system` link ✅ · pytest/live/coverage/ruff/pyright ✅ · no change on `/system`,`/llm`,`/ups` ✅ · phase 01 verdict vocabulary intact ✅.
- Docs: README `web/` bullet now states the dimmed `n/a` row; AGENTS.md invariant 4, `alerts.py`/`api.py` bullets, UI-conventions stale-row + window-chip ranges (5m…30d vs 1h…90d), metric example `llm.decode_tps` → `llm.decode_tokens_per_second` (verified against `/api/metrics`), test count 435 → 439. Env table, Containerfile, agent/install-script claims, fleet facts re-checked and consistent.
- Notable: left the fleet's real hostnames/domain in AGENTS.md's "real environment" section (deliberate, prior-phase content) even though rule 6 discourages personal hostnames in tracked files — worth a separate decision; no live config was changed beyond stopping/starting a local dev ssh forward.
- Next pending phase: `.agents/phases/todo/03_system_per_host_panels/`.

tests/test_nut.py

@@ -490,6 +490,19 @@ async def test_simulated_ups_cards_carry_severity_too() -> None:
         assert card["severity"]["charge_pct"] == "ok", "the sim starts at float charge"
 
 
+async def test_a_fresh_simulator_reads_healthy_so_amber_still_means_something() -> None:
+    """The dev model must not train people to ignore the UPS badge.
+
+    Its battery dates are fiction, so they are computed relative to today: a hard-coded
+    2019 manufacture date turns every simulated card amber forever, and an amber nobody
+    can clear is the same failure `assess()` avoids for a UPS that floats at 90 %.
+    """
+    for ups in await NutSimulator().read():
+        card = nut.payload(ups)
+        assert card["health"]["overall"] == "healthy", card["health"]["checks"]
+        assert not [c for c in card["health"]["checks"] if c["status"] == "fail"]
+
+
 def test_history_samples_only_include_real_numbers() -> None:
     values = {key: value for key, value in VAR_ROWS.items() if key != "battery.runtime"}
     samples = nut.history_samples(nut.UpsReading(name="cyberpower", vars=values, commands=[]))