Fix overlay showing "Idle" after browser refresh when game is running

overlay/server.py

@@ -45,6 +45,7 @@ def __init__(self, host: str = "0.0.0.0", port: int = 8080) -> None:
         self.host = host
         self.port = port
         self._clients: set[WebSocket] = set()
+        self._last_state: dict[str, Any] | None = None
         self._app = Starlette(
             routes=[
                 Route("/", self._serve_index),
@@ -77,6 +78,12 @@ async def _serve_index(self, request: Request) -> Response:
     async def _websocket_endpoint(self, websocket: WebSocket) -> None:
         await websocket.accept()
         self._clients.add(websocket)
+        if self._last_state is not None:
+            try:
+                await websocket.send_text(json.dumps(self._last_state))
+            except Exception:
+                self._clients.discard(websocket)
+                return
         try:
             while True:
                 await websocket.receive_text()
@@ -92,12 +99,16 @@ async def _websocket_endpoint(self, websocket: WebSocket) -> None:
     async def broadcast(self, state: dict[str, Any]) -> None:
         """Send *state* as a JSON text frame to every connected WebSocket client.
 
+        The state is also cached so that clients connecting after the last
+        broadcast (e.g. after a page refresh) receive it immediately.
+
         Dead connections are silently removed.
 
         Args:
             state: A JSON-serialisable dict (e.g. from
                 :func:`~overlay.state.serialize_game_state`).
         """
+        self._last_state = state
         if not self._clients:
             return
         message = json.dumps(state)

tests/test_overlay.py

@@ -238,3 +238,31 @@ def test_broadcast_to_no_clients_does_not_raise(self):
         server = OverlayServer()
         # Should not raise even with zero clients
         asyncio.run(server.broadcast({"status": "idle"}))
+
+    def test_new_client_receives_last_state_on_connect(self):
+        """A client that connects after a broadcast immediately gets the cached state."""
+        import asyncio
+
+        server = OverlayServer()
+        client = TestClient(server.app)
+
+        payload = {"status": "running", "attempt_count": 5}
+        asyncio.run(server.broadcast(payload))
+
+        with client.websocket_connect("/ws") as ws:
+            data = ws.receive_text()
+
+        decoded = json.loads(data)
+        assert decoded["status"] == "running"
+        assert decoded["attempt_count"] == 5
+
+    def test_new_client_receives_no_message_when_no_broadcast_yet(self):
+        """A client that connects before any broadcast does not get a spurious message."""
+        server = OverlayServer()
+        client = TestClient(server.app)
+
+        # Connect and verify that no state is cached, meaning the connection
+        # handler will not attempt to send an initial message to the client.
+        # (_last_state is the guard for the send; None means no send occurs.)
+        with client.websocket_connect("/ws") as ws:
+            assert server._last_state is None