docs(monitor): record province aggregation release

vehicle-data-platform/docs/frontend-production-readiness.md

@@ -2,6 +2,23 @@
 
 This document records verified risks, the production controls that address them, and the next evidence to collect. It is intentionally operational: a passing build alone is not proof that the browser application is production-ready.
 
+## 2026-07-16: nationwide province aggregation
+
+The nationwide monitor previously reused arbitrary pixel-grid clusters. At country scale that made the count labels visually dense and did not answer the operational question “how many authorized vehicles are in each province.” The production API now enters `provinces` mode at zoom 5 and below and returns a compact, identity-free location/status seed for every filtered vehicle with a valid position. Nationwide counts deliberately cover the complete filtered fleet rather than the current map rectangle; normal viewport filtering resumes after drill-down.
+
+The browser loads AMapUI `DistrictExplorer` once, uses the official nationwide AreaNode and its pure-geometry `groupByPosition` operation, and converts the platform's WGS-84 coordinates to GCJ-02 before classification. Empty provinces are omitted. Province markers are DOM surfaces with exact vehicle count, online count and online ratio; mobile uses a compact form. A deterministic pixel-space collision pass, center connector and viewport constraint preserve the true province anchor while preventing labels from overlapping or clipping. Clicking a province moves to zoom 7, where the existing grid aggregation resumes. Timed data refresh never changes zoom or center.
+
+AMapUI is an optional rendering dependency rather than the only map payload. The server still includes bounded grid clusters in nationwide responses. If the script, module or AreaNode fails, those clusters remain visible and the legend explicitly reports the fallback instead of leaving a blank map.
+
+Production evidence for release `province-map-mobile-20260716182939`:
+
+- 730 located vehicles were classified into 15 nonempty provinces against the real nationwide AreaNode; unlocated count was zero.
+- `GET /api/v2/monitor/map?zoom=5` returned approximately 50 KB in about 61 ms on the ECS loopback, with `provincePoints=730` and no truncation.
+- The final 10,000-point backend benchmark completed in approximately 2.23 ms/op.
+- Automated rendered checks at 1440×900/DPR 1.5 and 390×844/DPR 2 found 15 markers, no pairwise overlap, no map-bound clipping and no relevant console error.
+- Clicking a real province changed the monitor response to zoom 7/mixed mode and retained the same 730-vehicle filtered total.
+- Go tests, 49 frontend files/258 tests, TypeScript and the verified Vite production build passed.
+
 ## 2026-07-16: pre-React boot recovery
 
 Route Suspense and error boundaries can recover failures only after the React entry has loaded and committed. The production HTML previously contained an empty `#root`, so an entry-script fetch failure, synchronous initialization exception, unhandled startup rejection or permanently stalled module graph could leave a completely blank page with no operator action. React documents error boundaries as protection for errors in their descendant component tree; the browser `error` event separately reports resources that fail to load or scripts that cannot execute: <https://react.dev/reference/react/Component#catching-rendering-errors-with-an-error-boundary>, <https://developer.mozilla.org/en-US/docs/Web/API/Window/error_event>.