refactor(backend): allow multi-client rooms and drop room-full

Anyone may join and watch/throw; game auto-starts on first connection.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/src/main.rs

@@ -50,7 +50,6 @@ impl AppState {
 #[derive(Deserialize)]
 struct RoomQuery {
     room: String,
-    team: Option<Team>,
 }
 
 #[derive(Serialize)]
@@ -95,74 +94,43 @@ async fn ws_handler(
     Query(query): Query<RoomQuery>,
     State(state): State<Arc<AppState>>,
 ) -> impl IntoResponse {
-    ws.on_upgrade(move |socket| handle_socket(socket, state, query.room, query.team))
+    ws.on_upgrade(move |socket| handle_socket(socket, state, query.room))
 }
 
 async fn handle_socket(
     socket: WebSocket,
     state: Arc<AppState>,
     room_id: String,
-    preferred_team: Option<Team>,
 ) {
     let room = state.get_or_create_room(&room_id).await;
     let (mut sender, receiver) = socket.split();
 
-    if try_join_room(&room).await.is_err() {
+    {
-        let err = serde_json::to_string(&ServerMessage::Error {
+        let mut room_guard = room.lock().await;
-            message: "Room is full".to_string(),
+        if matches!(room_guard.game.game_state_message(), ServerMessage::GameState { phase: Phase::Waiting, .. }) {
-        })
+            room_guard.game.start();
-        .unwrap();
+        }
-        let _ = sender.send(Message::Text(Utf8Bytes::from(err))).await;
-        return;
     }
-
-    let player_id = Uuid::new_v4().to_string();
-    let team = register_player(&room, &player_id, preferred_team).await;
 
     let joined = serde_json::to_string(&ServerMessage::Joined {
         room: room_id.clone(),
-        team,
     })
     .unwrap();
-    let _ = sender.send(Message::Text(Utf8Bytes::from(joined))).await;
+    if sender.send(Message::Text(Utf8Bytes::from(joined))).await.is_err() {
+        return;
+    }
 
     let tx = { room.lock().await.tx.clone() };
 
     let send_task = spawn_forwarder(sender, tx.subscribe());
     broadcast_room_state(&room, &tx).await;
 
-    let recv_task = spawn_message_handler(room.clone(), player_id.clone(), tx, receiver);
+    let recv_task = spawn_message_handler(room.clone(), tx, receiver);
 
     tokio::select! {
         _ = send_task => {}
         _ = recv_task => {}
     }
-
-    remove_player(&room, &player_id).await;
-}
-
-async fn try_join_room(room: &Arc<Mutex<Room>>) -> Result<(), ()> {
-    let room_guard = room.lock().await;
-    if room_guard.game.can_start() {
-        return Err(());
-    }
-    Ok(())
-}
-
-async fn register_player(
-    room: &Arc<Mutex<Room>>,
-    player_id: &str,
-    preferred_team: Option<Team>,
-) -> Team {
-    let mut room_guard = room.lock().await;
-    let team = room_guard
-        .game
-        .add_player(player_id.to_string(), preferred_team)
-        .unwrap_or(Team::Red);
-    if room_guard.game.can_start() {
-        room_guard.game.start();
-    }
-    team
 }
 
 fn spawn_forwarder(
@@ -192,33 +160,25 @@ async fn broadcast_room_state(
     tx: &tokio::sync::broadcast::Sender<ServerMessage>,
 ) {
     let room_guard = room.lock().await;
-    let msg = if room_guard.game.can_start() {
+    let _ = tx.send(room_guard.game.game_state_message());
-        room_guard.game.game_state_message()
-    } else {
-        ServerMessage::Waiting {
-            message: "Waiting for other player".to_string(),
-        }
-    };
-    let _ = tx.send(msg);
 }
 
 fn spawn_message_handler(
     room: Arc<Mutex<Room>>,
-    player_id: String,
     tx: tokio::sync::broadcast::Sender<ServerMessage>,
     mut receiver: WsReceiver,
 ) -> tokio::task::JoinHandle<()> {
     tokio::spawn(async move {
         while let Some(Ok(msg)) = receiver.next().await {
-            let Message::Text(text) = msg else { continue; };
+            let Message::Text(text) = msg else { continue };
             let text_ref = text.as_str();
             let parsed: Result<ClientMessage, _> = serde_json::from_str(text_ref);
             match parsed {
-                Ok(ClientMessage::Throw { broom_x, broom_y, weight, curl, friction }) => {
+                Ok(ClientMessage::Throw { team, broom_x, broom_y, weight, curl, friction }) => {
                     let mut room_guard = room.lock().await;
                     match room_guard
                         .game
-                        .process_throw(&player_id, broom_x, broom_y, weight, curl, friction)
+                        .process_throw(team, broom_x, broom_y, weight, curl, friction)
                     {
                         Ok(ThrowOutcome {
                             trajectory,
@@ -226,7 +186,7 @@ fn spawn_message_handler(
                             state_message,
                             game_over,
                         }) => {
-                            let _ = tx.send(ServerMessage::Trajectory { path: trajectory });
+                            let _ = tx.send(ServerMessage::Trajectory { paths: trajectory });
                             if let Some(scored) = end_scored {
                                 let _ = tx.send(scored);
                             }
@@ -247,8 +207,3 @@ fn spawn_message_handler(
         }
     })
 }
-
-async fn remove_player(room: &Arc<Mutex<Room>>, player_id: &str) {
-    let mut room_guard = room.lock().await;
-    room_guard.game.remove_player(player_id);
-}