Stabilize AMSC chart detail overlays

frontend/components/dashboard/scan-terminal/__tests__/refreshCadencePolicy.test.ts

@@ -253,6 +253,13 @@ export async function runTests() {
       chartLogicSource.includes("primeCityDetailCache"),
     "visible terminal chart detail fetches should be coalesced into one batch request and prime the shared chart cache",
   );
+  assert(
+    chartLogicSource.includes('from "@/lib/backend-api"') &&
+      chartLogicSource.includes("buildBrowserBackendHeaders") &&
+      chartLogicSource.includes('await buildBrowserBackendHeaders({ Accept: "application/json" })') &&
+      chartLogicSource.includes("headers,"),
+    "terminal chart detail batch fetches must attach the browser Supabase bearer so users without Supabase cookies do not get backend 401 and empty charts",
+  );
   assert(
     chartLogicSource.includes('scope: "chart"') &&
       chartLogicSource.includes("params.toString()"),
@@ -267,7 +274,7 @@ export async function runTests() {
       chartLogicSource.includes("missing?: string[]"),
     "frontend city detail batch payload should understand partial responses and missing city markers",
   );
-  const flushCityDetailBatchBlock = chartLogicSource.match(/async function flushCityDetailBatch[\s\S]*?\r?\n}\r?\n\r?\nfunction fetchCityDetailBatchWithTimeout/)?.[0] || "";
+  const flushCityDetailBatchBlock = chartLogicSource.match(/async function flushCityDetailBatch[\s\S]*?\r?\n}\r?\n\r?\n(?:async\s+)?function fetchCityDetailBatchWithTimeout/)?.[0] || "";
   assert(
     flushCityDetailBatchBlock.includes("partialMissingCities") &&
       flushCityDetailBatchBlock.includes("resolveBatchWaiters(waiters, null)") &&

frontend/components/dashboard/scan-terminal/temperature-chart-logic.ts

@@ -12,6 +12,7 @@ import type {
 } from "@/lib/dashboard-types";
 import { buildDebBaselinePath } from "@/lib/temperature-chart-paths";
 import { DASHBOARD_REFRESH_POLICY_MS } from "@/lib/refresh-policy";
+import { buildBrowserBackendHeaders } from "@/lib/backend-api";
 import type { CityPatch } from "@/hooks/use-sse-patches";
 const ROLLING_WINDOW_BEFORE_MS = 12 * 60 * 60 * 1000;
 const ROLLING_WINDOW_AFTER_LIVE_MS = 2 * 60 * 60 * 1000;
@@ -1715,7 +1716,7 @@ function resolveAllBatchWaitersAsNull(
   });
 }
 
-function fetchCityDetailBatchWithTimeout(
+async function fetchCityDetailBatchWithTimeout(
   cities: string[],
   resolution: string,
   forceRefresh: boolean,
@@ -1730,8 +1731,9 @@ function fetchCityDetailBatchWithTimeout(
     resolution,
     scope: "chart",
   });
+  const headers = await buildBrowserBackendHeaders({ Accept: "application/json" });
   return fetch(`/api/cities/detail-batch?${params.toString()}`, {
-    headers: { Accept: "application/json" },
+    headers,
     signal: controller.signal,
   })
     .then(async (res) => {

tests/test_latest_observation_overlay.py

@@ -46,3 +46,55 @@ def test_overlay_replaces_amos_when_old_local_time_string_looks_later_than_new_u
     assert result["amos"]["observation_time"] == "2026-06-14T17:23:00+00:00"
     assert result["amos"]["observation_time_local"] == "2026-06-15 01:23:00"
     assert result["amos"]["runway_obs"]["point_temperatures"][0]["runway"] == "17L/35R"
+
+
+def test_overlay_uses_latest_success_when_newer_status_row_has_no_observation():
+    class FakeDB:
+        def get_latest_raw_observation(self, source, city):
+            assert (source, city) == ("amsc_awos", "chengdu")
+            return {
+                "status": "no_results",
+                "observed_at": "",
+                "fetched_at": "2026-06-14T17:02:09+00:00",
+                "updated_at_ts": 1781456529.0,
+                "payload": {
+                    "source": "amsc_awos",
+                    "city": "chengdu",
+                    "status": "no_results",
+                    "error": "source returned no observation rows",
+                },
+            }
+
+        def list_latest_raw_observations_for_city(self, city, *, limit=100):
+            assert city == "chengdu"
+            return [
+                self.get_latest_raw_observation("amsc_awos", "chengdu"),
+                {
+                    "source": "amsc_awos",
+                    "city": "chengdu",
+                    "station_code": "ZUUU",
+                    "station_name": "Chengdu Shuangliu",
+                    "status": "ok",
+                    "observed_at": "2026-06-14T17:00:00+00:00",
+                    "fetched_at": "2026-06-14T17:00:30+00:00",
+                    "updated_at_ts": 1781456430.0,
+                    "payload": {
+                        "source": "amsc_awos",
+                        "source_label": "AMSC AWOS Chengdu Shuangliu (ZUUU)",
+                        "icao": "ZUUU",
+                        "temp_c": 25.8,
+                        "observation_time": "2026-06-14T17:00:00+00:00",
+                        "observation_time_local": "2026-06-15 01:00:00",
+                    },
+                },
+            ]
+
+    result = overlay_latest_amsc_observation(
+        FakeDB(),
+        "chengdu",
+        {"name": "chengdu", "temp_symbol": "°C", "amos": {}},
+    )
+
+    assert result["amos"]["temp_c"] == 25.8
+    assert result["current"]["temp"] == 25.8
+    assert result["airport_current"]["source_code"] == "amsc_awos"

tests/test_web_observability.py

@@ -1199,6 +1199,62 @@ def test_chart_data_cache_hit_starts_full_stale_refresh(monkeypatch):
     assert refresh_calls == ["paris"]
 
 
+def test_chart_data_cache_hit_overlays_latest_amsc_raw(monkeypatch):
+    import asyncio
+
+    class FakeCache:
+        def get_city_cache(self, kind, city):
+            assert kind == "full"
+            return {
+                "payload": {
+                    "name": city,
+                    "display_name": city.title(),
+                    "temp_symbol": "°C",
+                    "risk": {"icao": "ZUUU"},
+                    "current": {},
+                    "airport_current": {},
+                    "amos": {},
+                    "hourly": {"times": ["13:00"], "temps": [25.0]},
+                },
+            }
+
+        def get_runway_obs_recent(self, icao, minutes=60):
+            return []
+
+        def get_latest_raw_observation(self, source, city):
+            assert (source, city) == ("amsc_awos", "chengdu")
+            return {
+                "source": "amsc_awos",
+                "city": "chengdu",
+                "station_code": "ZUUU",
+                "station_name": "Chengdu Shuangliu",
+                "status": "ok",
+                "observed_at": "2026-06-14T17:00:00+00:00",
+                "fetched_at": "2026-06-14T17:00:30+00:00",
+                "payload": {
+                    "source": "amsc_awos",
+                    "source_label": "AMSC AWOS Chengdu Shuangliu (ZUUU)",
+                    "icao": "ZUUU",
+                    "temp_c": 25.8,
+                    "observation_time": "2026-06-14T17:00:00+00:00",
+                    "observation_time_local": "2026-06-15 01:00:00",
+                },
+            }
+
+    monkeypatch.setattr(city_api.legacy_routes, "_CACHE_DB", FakeCache())
+    monkeypatch.setattr(
+        city_api.legacy_routes,
+        "_overlay_latest_wunderground_current",
+        lambda city, payload: payload,
+    )
+
+    payload = asyncio.run(city_api._get_city_chart_data("chengdu", force_refresh=False))
+
+    assert payload["amos"]["temp_c"] == 25.8
+    assert payload["current"]["temp"] == 25.8
+    assert payload["airport_current"]["source_code"] == "amsc_awos"
+
+
 def test_chart_data_returns_cached_payload_when_optional_overlay_times_out(monkeypatch):
     import asyncio
 

web/services/city_api.py

@@ -419,6 +419,13 @@ async def _get_city_chart_data(city: str, *, force_refresh: bool) -> Dict[str, A
                 fn=_overlay_cached_runway_history_from_db,
                 args=(city, payload),
             )
+            payload = await _run_optional_city_chart_overlay(
+                city=city,
+                overlay_name="amsc_latest_raw",
+                payload=payload,
+                fn=overlay_latest_amsc_observation,
+                args=(legacy_routes._CACHE_DB, city, payload),
+            )
             return await _run_optional_city_chart_overlay(
                 city=city,
                 overlay_name="wunderground_current",

web/services/latest_observation_overlay.py

@@ -88,6 +88,11 @@ def _to_float(value: Any) -> Optional[float]:
         return None
 
 
+def _amsc_payload_has_observation(raw_payload: dict[str, Any]) -> bool:
+    temp = raw_payload.get("temp_c") if raw_payload.get("temp_c") is not None else raw_payload.get("temp")
+    return _to_float(temp) is not None
+
+
 def _latest_amsc_row(db: Any, city: str) -> tuple[Optional[dict[str, Any]], Optional[dict[str, Any]]]:
     getter = getattr(db, "get_latest_raw_observation", None)
     if not callable(getter):
@@ -100,9 +105,26 @@ def _latest_amsc_row(db: Any, city: str) -> tuple[Optional[dict[str, Any]], Opti
     if not isinstance(row, dict):
         return None, None
     raw_payload = row.get("payload")
-    if not isinstance(raw_payload, dict) or not raw_payload:
+    if isinstance(raw_payload, dict) and raw_payload and _amsc_payload_has_observation(raw_payload):
-        return row, None
+        return row, raw_payload
-    return row, raw_payload
+
+    lister = getattr(db, "list_latest_raw_observations_for_city", None)
+    if callable(lister):
+        try:
+            candidates = lister(city, limit=20)
+        except Exception as exc:
+            logger.debug("latest AMSC raw fallback list failed city={}: {}", city, exc)
+            candidates = []
+        for candidate in candidates if isinstance(candidates, list) else []:
+            if not isinstance(candidate, dict):
+                continue
+            if str(candidate.get("source") or "").strip().lower() != "amsc_awos":
+                continue
+            candidate_payload = candidate.get("payload")
+            if isinstance(candidate_payload, dict) and _amsc_payload_has_observation(candidate_payload):
+                return candidate, candidate_payload
+
+    return row, None
 
 
 def _raw_observation_update(