feat(map): add cached public station navigation

vehicle-map/server.py

@@ -31,8 +31,8 @@ PORT = int(os.getenv("VEHICLE_MAP_PORT", "20800"))
 OPEN_PLATFORM_BASE_URL = os.getenv("OPEN_PLATFORM_BASE_URL", "https://open.d.lnoneos.com").rstrip("/")
 OPEN_PLATFORM_APP_KEY = os.getenv("OPEN_PLATFORM_APP_KEY", "").strip()
 UPSTREAM_TIMEOUT_SECONDS = float(os.getenv("UPSTREAM_TIMEOUT_SECONDS", "15"))
-DASHBOARD_CACHE_SECONDS = int(os.getenv("DASHBOARD_CACHE_SECONDS", "5"))
-STATION_CACHE_SECONDS = int(os.getenv("STATION_CACHE_SECONDS", "3600"))
+DASHBOARD_CACHE_SECONDS = int(os.getenv("DASHBOARD_CACHE_SECONDS", "120"))
+STATION_CACHE_SECONDS = int(os.getenv("STATION_CACHE_SECONDS", "120"))
 _cache_lock = threading.Lock()
 _cache = {}
 
@@ -149,6 +149,18 @@ def _load_dashboard():
     }
 
 
+def _prewarm_dashboard_cache():
+    """Warm the first dashboard snapshot after a process restart.
+
+    A warm snapshot lets the first visitor receive the cached response instead
+    of waiting for the three upstream requests to complete.
+    """
+    try:
+        _cached("dashboard", DASHBOARD_CACHE_SECONDS, _load_dashboard)
+    except Exception as exc:  # A later request can retry; startup must stay available.
+        print(f"vehicle map cache warmup deferred: {exc}")
+
+
 class VehicleMapHandler(SimpleHTTPRequestHandler):
     server_version = "LingniuVehicleMap/1.0"
 
@@ -215,6 +227,7 @@ class VehicleMapHandler(SimpleHTTPRequestHandler):
 
 if __name__ == "__main__":
     server = ThreadingHTTPServer((HOST, PORT), VehicleMapHandler)
+    threading.Thread(target=_prewarm_dashboard_cache, daemon=True).start()
     print(f"Lingniu Vehicle Map listening on http://{HOST}:{PORT}")
     try:
         server.serve_forever()