Reduce terminal chart update timeouts

frontend/app/api/cities/detail-batch/route.ts

@@ -8,7 +8,7 @@ import {
 
 const API_BASE = process.env.POLYWEATHER_API_BASE_URL;
 const DETAIL_BATCH_PROXY_TIMEOUT_MS = Number(
-  process.env.POLYWEATHER_CITY_DETAIL_BATCH_PROXY_TIMEOUT_MS || "12000",
+  process.env.POLYWEATHER_CITY_DETAIL_BATCH_PROXY_TIMEOUT_MS || "15000",
 );
 
 export async function GET(req: NextRequest) {

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

@@ -258,7 +258,7 @@ export function runTests() {
     "single-runway charts must not show the runway-detail toggle because aggregate and individual views are visually redundant",
   );
   assert(
-    chartLogic.includes("HOURLY_DETAIL_REQUEST_TIMEOUT_MS = 12_000") &&
+    chartLogic.includes("HOURLY_DETAIL_REQUEST_TIMEOUT_MS = 16_000") &&
       chartLogic.includes("fetchCityDetailBatchWithTimeout") &&
       chartLogic.includes("signal: controller.signal") &&
       chartLogic.includes("controller.abort()"),

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

@@ -357,7 +357,7 @@ const HOURLY_FORCE_REFRESH_DEDUP_MS = 60_000;
 const _hourlyCache = new Map<string, { ts: number; data: HourlyForecast }>();
 const _hourlyRequestCache = new Map<string, Promise<HourlyForecast>>();
 const MAX_HOURLY_DETAIL_CONCURRENT_REQUESTS = 3;
-const HOURLY_DETAIL_REQUEST_TIMEOUT_MS = 12_000;
+const HOURLY_DETAIL_REQUEST_TIMEOUT_MS = 16_000;
 let _hourlyActiveDetailRequests = 0;
 const _hourlyDetailRequestQueue: Array<() => void> = [];
 const RUNWAY_LINE_COLORS = ["#00897b", "#d97706", "#7c3aed", "#0891b2", "#ea580c", "#64748b"];

frontend/components/ops/__tests__/apiPerformanceTiming.test.ts

@@ -41,6 +41,11 @@ export function runTests() {
   const detailBatchProxy = readFrontend("app", "api", "cities", "detail-batch", "route.ts");
   assert.match(detailBatchProxy, /createProxyTimer\(req,\s*"city_detail_batch"\)/);
   assert.match(detailBatchProxy, /timing:\s*timer/);
+  assert.match(
+    detailBatchProxy,
+    /POLYWEATHER_CITY_DETAIL_BATCH_PROXY_TIMEOUT_MS\s*\|\|\s*"15000"/,
+    "city detail batch proxy should leave room for backend partial responses instead of aborting at the chart fetch deadline",
+  );
   assert.match(
     detailBatchProxy,
     /fetchCache:\s*"no-store"/,

tests/test_web_observability.py

@@ -853,13 +853,17 @@ def test_city_detail_batch_chart_scope_returns_only_chart_fields(monkeypatch):
     assert "ai_analysis" not in detail
 
 
-def test_chart_detail_payload_avoids_threadpool_queue_and_reuses_short_cache(monkeypatch):
+def test_chart_detail_payload_uses_threadpool_and_reuses_short_cache(monkeypatch):
     import asyncio
 
     build_calls = 0
+    threadpool_calls = 0
 
-    async def fail_threadpool(*_args, **_kwargs):
-        raise AssertionError("chart payload should not wait behind the shared threadpool")
+    async def fake_run_in_threadpool(fn, *args, **kwargs):
+        nonlocal threadpool_calls
+        threadpool_calls += 1
+        await asyncio.sleep(0)
+        return fn(*args, **kwargs)
 
     def build_chart_detail(data, resolution):
         nonlocal build_calls
@@ -873,7 +877,7 @@ def test_chart_detail_payload_avoids_threadpool_queue_and_reuses_short_cache(mon
     city_api._CITY_CHART_DETAIL_PAYLOAD_CACHE.clear()
     city_api._CITY_CHART_DETAIL_PAYLOAD_CACHE_TS.clear()
     monkeypatch.setenv("POLYWEATHER_CITY_DETAIL_PAYLOAD_CACHE_TTL_SEC", "20")
-    monkeypatch.setattr(city_api, "run_in_threadpool", fail_threadpool)
+    monkeypatch.setattr(city_api, "run_in_threadpool", fake_run_in_threadpool)
     monkeypatch.setattr(city_api.legacy_routes, "_build_city_chart_detail_payload", build_chart_detail)
 
     data = {
@@ -888,6 +892,12 @@ def test_chart_detail_payload_avoids_threadpool_queue_and_reuses_short_cache(mon
     assert first == second
     assert first["resolution"] == "10m"
     assert build_calls == 1
+    assert threadpool_calls == 1
+
+
+def test_city_detail_batch_partial_timeout_default_stays_below_proxy_budget(monkeypatch):
+    monkeypatch.delenv("POLYWEATHER_CITY_DETAIL_BATCH_PARTIAL_TIMEOUT_MS", raising=False)
+    assert city_api._city_detail_batch_partial_timeout_seconds() == 6.0
 
 
 def test_city_detail_batch_endpoint_limits_backend_concurrency(monkeypatch):

web/services/city_api.py

@@ -282,7 +282,11 @@ async def _build_city_chart_detail_payload(
 ) -> Dict[str, Any]:
     ttl = _city_detail_payload_cache_ttl()
     if ttl <= 0:
-        return legacy_routes._build_city_chart_detail_payload(data, resolution)
+        return await run_in_threadpool(
+            legacy_routes._build_city_chart_detail_payload,
+            data,
+            resolution,
+        )
 
     key = _city_chart_detail_payload_cache_key(data, resolution)
     now_ts = time.time()
@@ -292,7 +296,11 @@ async def _build_city_chart_detail_payload(
         if cached is not None and now_ts - cached_ts < ttl:
             return cached
 
-    payload = legacy_routes._build_city_chart_detail_payload(data, resolution)
+    payload = await run_in_threadpool(
+        legacy_routes._build_city_chart_detail_payload,
+        data,
+        resolution,
+    )
 
     async with _CITY_CHART_DETAIL_PAYLOAD_LOCK:
         _CITY_CHART_DETAIL_PAYLOAD_CACHE[key] = payload
@@ -709,11 +717,11 @@ def _city_detail_batch_concurrency() -> int:
 def _city_detail_batch_partial_timeout_seconds() -> Optional[float]:
     try:
         timeout_ms = int(
-            os.getenv("POLYWEATHER_CITY_DETAIL_BATCH_PARTIAL_TIMEOUT_MS", "8500")
-            or "8500"
+            os.getenv("POLYWEATHER_CITY_DETAIL_BATCH_PARTIAL_TIMEOUT_MS", "6000")
+            or "6000"
         )
     except ValueError:
-        timeout_ms = 8500
+        timeout_ms = 6000
     if timeout_ms <= 0:
         return None
     return max(0.001, min(60.0, timeout_ms / 1000.0))