Hash seat tokens at rest (security review finding)

Raw seat tokens no longer touch disk or long-lived memory: rooms store
sha-256 hashes, joins compare timing-safely, sessions keep the raw
token they authenticated with only for minting transfer phrases, and
legacy plaintext room files still load (hashed on read). Verified:
rejoin and transfer both work, and the room file contains only
hostTokenHash — no raw token anywhere.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/server/src/index.ts

@@ -36,6 +36,8 @@ interface Session {
   socket: WebSocket;
   playerId: PlayerId | null;
   roomId: string | null;
+  /** The raw seat token this connection authenticated with (memory only). */
+  token: string | null;
   claimFails: number;
 }
 
@@ -71,7 +73,7 @@ function broadcastRoomState(room: Room): void {
 }
 
 wss.on("connection", (socket) => {
-  const session: Session = { socket, playerId: null, roomId: null, claimFails: 0 };
+  const session: Session = { socket, playerId: null, roomId: null, token: null, claimFails: 0 };
   sessions.add(session);
   send(socket, { type: "welcome", game: "wizwar" });
 
@@ -93,6 +95,7 @@ wss.on("connection", (socket) => {
           const { room, token } = createRoom(name);
           session.playerId = name;
           session.roomId = room.id;
+          session.token = token;
           send(socket, { type: "seat", playerId: name, token });
           broadcastRoomState(room);
           break;
@@ -107,6 +110,7 @@ wss.on("connection", (socket) => {
           if ("error" in result) return send(socket, { type: "error", message: result.error });
           session.playerId = name;
           session.roomId = room.id;
+          session.token = result.token;
           send(socket, { type: "seat", playerId: name, token: result.token });
           // Rejoining a running game: replay the chronicle so far.
           if (room.state) {
@@ -137,7 +141,7 @@ wss.on("connection", (socket) => {
         case "makeTransfer": {
           const room = session.roomId ? getRoom(session.roomId) : undefined;
           if (!room || !session.playerId) return send(socket, { type: "error", message: "not in a room" });
-          const result = makeTransferCode(room, session.playerId);
+          const result = makeTransferCode(room, session.playerId, session.token);
           if ("error" in result) return send(socket, { type: "error", message: result.error });
           send(socket, { type: "transferCode", code: result.code, expiresAt: result.expiresAt });
           break;