fix(chess): prevent duplicate players and fix move detection

- Prevent same player from joining as both white and black
- Add validation to reject duplicate players in RoomManager
- Fix spectator status not resetting when joining as player
- Use ref to track latest chess state in ChessBoard for accurate move validation

api/src/games/RoomManager.ts

@@ -46,7 +46,8 @@ export class RoomManager {
 
         const plugin = gameRegistry.get(room.gameSlug)!;
         if (room.players.length >= plugin.maxPlayers && role !== "admin") return { ok: false, error: "Room is full" };
-        if (room.players.includes(playerId) && role !== "admin") return { ok: true, started: room.status === "playing" };
+        if (room.players.includes(playerId) && role !== "admin") return { ok: true, started: room.status === "waiting" };
+        if (room.players.includes(playerId) && role === "admin") return { ok: false, error: "Already a player in this game" };
 
         if (!room.players.includes(playerId) || role === "admin") {
             room.players.push(playerId);

panel/src/games/chess/ChessBoard.tsx

@@ -17,6 +17,12 @@ export function ChessBoard({ state, myPlayerId, isSpectator, onAction, players }
     const [promotionTo, setPromotionTo] = useState<string | null>(null);
     const containerRef = useRef<HTMLDivElement>(null);
     const [boardWidth, setBoardWidth] = useState(400);
+    
+    // Track latest state in ref to avoid stale closures
+    const chessRef = useRef(chess);
+    useEffect(() => {
+        chessRef.current = chess;
+    }, [chess]);
 
     // Responsive board sizing
     useEffect(() => {
@@ -56,7 +62,7 @@ export function ChessBoard({ state, myPlayerId, isSpectator, onAction, players }
     function onDrop(sourceSquare: string, targetSquare: string): boolean {
         if (isSpectator || !isMyTurn) return false;
 
-        const testGame = new Chess(chess.fen);
+        const testGame = new Chess(chessRef.current.fen);
 
         // Check if this is a promotion move
         const piece = testGame.get(sourceSquare as any);

panel/src/lib/useGameRoom.ts

@@ -56,13 +56,16 @@ export function useGameRoom(roomId: string, userId: string, role?: string) {
                             return {
                                 ...prev,
                                 spectators: [...prev.spectators.filter(s => s.discordId !== msg.player.discordId), msg.player],
-                                isSpectator: isMe ? true : prev.isSpectator,
+                                isSpectator: isMe || prev.isSpectator,
                                 roomStatus: prev.roomStatus === "connecting" ? "waiting" : prev.roomStatus,
                             };
                         }
+                        
+                        const isMe = msg.player.discordId === userId;
                         return {
                             ...prev,
                             players: [...prev.players.filter(p => p.discordId !== msg.player.discordId), msg.player],
+                            isSpectator: isMe ? false : prev.isSpectator,
                             roomStatus: prev.roomStatus === "connecting" ? "waiting" : prev.roomStatus,
                         };
                     });

shared/games/chess/plugin.ts

@@ -23,9 +23,14 @@ export const chessPlugin: GamePlugin<ChessState, ChessAction> = {
 
     createInitialState(players: string[]): ChessState {
         const game = new Chess();
+        
+        if (players[0] === players[1]) {
+            throw new Error("Cannot create chess game with same player for both sides");
+        }
+        
         return {
             fen: game.fen(),
-            players: { white: players[0], black: players[1] },
+            players: { white: players[0]!, black: players[1]! },
             moveHistory: [],
             status: "playing",
             winner: null,