fix radar web

orangepi-server/visualizer.py

@@ -83,6 +83,7 @@ class RadarState:
 
     def to_json(self) -> dict:
         """Serialize to something the browser can render."""
+        now = time.time()
         return {
             "node_id": self.node_id,
             "sequence": self.sequence,
@@ -97,7 +98,12 @@ class RadarState:
                     "speed_cm_s": t.speed_cm_s,
                     "distance_mm": round(t.distance_mm, 1),
                     "angle_deg": round(t.angle_deg, 2),
-                    "last_seen": round(time.time() - t.last_seen, 2) if t.last_seen else None,
+                    # seconds since this target was last valid; None if never seen
+                    "last_seen": (
+                        round(now - t.last_seen, 2)
+                        if t.valid or (t.last_seen and t.last_seen > 0)
+                        else None
+                    ),
                 }
                 for t in self.targets
             ],
@@ -113,8 +119,13 @@ class RadarState:
                 for z in self.zones
             ],
             "frames_received": self.frames_received,
-            "last_update": round(time.time() - self.last_update, 2) if self.last_update else None,
+            "last_update": (
+                round(now - self.last_update, 2)
+                if self.last_update and self.last_update > 0
+                else None
+            ),
             "esp32_connected": self.esp32_connected,
+            "server_time": round(now, 2),
         }
 
     def update_from_frame(self, frame: dict):
@@ -187,6 +198,19 @@ def _update_zone_occupancy_from_targets(state: RadarState):
                 break
 
 
+# ============================================================
+# Heartbeat: broadcast last known state to browsers every 1s
+# even if ESP32 hasn't sent a new frame yet (parser stub scenario).
+# ============================================================
+async def heartbeat_broadcast():
+    while True:
+        try:
+            await broadcast_to_browsers()
+        except Exception:
+            pass
+        await asyncio.sleep(1.0)
+
+
 # ============================================================
 # ESP32 WebSocket client — runs as a background task
 # ============================================================
@@ -199,14 +223,20 @@ async def esp32_ws_forever(esp32_host: str):
         try:
             STATE.esp32_connected = False
             log.info(f"Đang kết nối ESP32 tại {uri} ...")
+            # Push initial "not connected" state to any browser that joined early
+            await broadcast_to_browsers()
+
             async with websockets.connect(
-                uri, ping_interval=30, ping_timeout=10, close_timeout=5
+                uri, ping_interval=30, ping_timeout=10, close_timeout=5,
+                open_timeout=8, max_size=1_000_000,
             ) as ws:
                 STATE.esp32_connected = True
                 log.info(f"Đã kết nối WebSocket tới ESP32 ({esp32_host})")
 
                 # Fetch zones from ESP32 after successful connect
                 await fetch_zones_from_esp32(esp32_host)
+                # Broadcast immediately so browsers see zones right after connect
+                await broadcast_to_browsers()
 
                 async for message in ws:
                     try:
@@ -217,9 +247,12 @@ async def esp32_ws_forever(esp32_host: str):
 
                     STATE.update_from_frame(frame)
                     _update_zone_occupancy_from_targets(STATE)
+                    # Always push the latest state
                     await broadcast_to_browsers()
 
             log.info("ESP32 WebSocket đóng, đang kết nối lại...")
+            STATE.esp32_connected = False
+            await broadcast_to_browsers()
 
         except websockets.exceptions.ConnectionClosed as e:
             STATE.esp32_connected = False
@@ -325,14 +358,15 @@ TEMPLATES_DIR.mkdir(exist_ok=True)
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):
-    """Start ESP32 client task when app starts, cancel it on shutdown."""
-    task = asyncio.create_task(esp32_ws_forever(ESP32_HOST))
+    """Start background tasks when app starts, cancel them on shutdown."""
+    tasks = [
+        asyncio.create_task(esp32_ws_forever(ESP32_HOST)),
+        asyncio.create_task(heartbeat_broadcast()),
+    ]
     yield
-    task.cancel()
-    try:
-        await task
-    except asyncio.CancelledError:
-        pass
+    for t in tasks:
+        t.cancel()
+    await asyncio.gather(*tasks, return_exceptions=True)
 
 
 app = FastAPI(