feat: add reconnection logic with exponential backoff to shard client

backend/utils/ecast-shard-client.js

@@ -1,5 +1,7 @@
 const WebSocket = require('ws');
 
+const { getRoomInfo } = require('./jackbox-api');
+
 class EcastShardClient {
   static parsePlayersFromHere(here) {
     if (here == null || typeof here !== 'object') {
@@ -85,6 +87,11 @@ class EcastShardClient {
     this.manuallyStopped = false;
     this.seq = 0;
     this.appTag = null;
+    this.reconnecting = false;
+  }
+
+  buildReconnectUrl() {
+    return `wss://${this.host}/api/v2/rooms/${this.roomCode}/play?role=shard&name=GamePicker&format=json&secret=${this.secret}&id=${this.shardId}`;
   }
 
   handleMessage(message) {
@@ -241,16 +248,27 @@ class EcastShardClient {
 
   handleError(result) {
     console.error(`[Shard Monitor] Ecast error ${result?.code}: ${result?.msg}`);
+    if (result?.code === 2027) {
+      this.gameFinished = true;
+      this.onEvent('game.ended', {
+        sessionId: this.sessionId,
+        gameId: this.gameId,
+        roomCode: this.roomCode,
+        playerCount: this.playerCount,
+        players: [...this.playerNames],
+      });
+      this.onEvent('room.disconnected', {
+        sessionId: this.sessionId,
+        gameId: this.gameId,
+        roomCode: this.roomCode,
+        reason: 'room_closed',
+        finalPlayerCount: this.playerCount,
+      });
+      this.disconnect();
+    }
   }
 
-  async connect(roomInfo) {
-    this.disconnect();
-    this.host = roomInfo.host;
-    this.maxPlayers = roomInfo.maxPlayers || this.maxPlayers;
-    this.appTag = roomInfo.appTag;
-
-    const url = `wss://${this.host}/api/v2/rooms/${this.roomCode}/play?role=shard&name=GamePicker&userId=gamepicker-${this.sessionId}&format=json`;
-
+  _openWebSocket(url) {
     return new Promise((resolve, reject) => {
       let welcomeTimeoutId = null;
 
@@ -291,6 +309,10 @@ class EcastShardClient {
 
       this.ws.on('close', (code, reason) => {
         console.log(`[Shard Monitor] Disconnected from room ${this.roomCode} (code: ${code})`);
+        this.ws = null;
+        if (!this.manuallyStopped && !this.gameFinished && this.secret != null && this.host != null) {
+          void this.reconnectWithBackoff();
+        }
       });
 
       welcomeTimeoutId = setTimeout(() => {
@@ -303,6 +325,82 @@ class EcastShardClient {
     });
   }
 
+  async connect(roomInfo, reconnectUrl) {
+    this.disconnect();
+    this.shardId = null;
+    this.secret = null;
+    this.host = roomInfo.host;
+    this.maxPlayers = roomInfo.maxPlayers || this.maxPlayers;
+    this.appTag = roomInfo.appTag;
+
+    const url =
+      reconnectUrl ||
+      `wss://${this.host}/api/v2/rooms/${this.roomCode}/play?role=shard&name=GamePicker&userId=gamepicker-${this.sessionId}&format=json`;
+
+    return this._openWebSocket(url);
+  }
+
+  async reconnect() {
+    const url = this.buildReconnectUrl();
+    this.disconnect();
+    this.shardId = null;
+    return this._openWebSocket(url);
+  }
+
+  async reconnectWithBackoff() {
+    if (this.reconnecting || this.manuallyStopped || this.gameFinished) {
+      return false;
+    }
+    this.reconnecting = true;
+    const delays = [2000, 4000, 8000];
+
+    try {
+      for (let i = 0; i < delays.length; i++) {
+        await new Promise((r) => setTimeout(r, delays[i]));
+
+        const roomInfo = await getRoomInfo(this.roomCode);
+
+        if (!roomInfo.exists) {
+          this.gameFinished = true;
+          this.onEvent('game.ended', {
+            sessionId: this.sessionId,
+            gameId: this.gameId,
+            roomCode: this.roomCode,
+            playerCount: this.playerCount,
+            players: [...this.playerNames],
+          });
+          this.onEvent('room.disconnected', {
+            sessionId: this.sessionId,
+            gameId: this.gameId,
+            roomCode: this.roomCode,
+            reason: 'room_closed',
+            finalPlayerCount: this.playerCount,
+          });
+          return false;
+        }
+
+        try {
+          await this.reconnect();
+          console.log(`[Shard Monitor] Reconnected to room ${this.roomCode} (attempt ${i + 1})`);
+          return true;
+        } catch (e) {
+          console.error(`[Shard Monitor] Reconnect attempt ${i + 1} failed:`, e.message);
+        }
+      }
+
+      this.onEvent('room.disconnected', {
+        sessionId: this.sessionId,
+        gameId: this.gameId,
+        roomCode: this.roomCode,
+        reason: 'connection_failed',
+        finalPlayerCount: this.playerCount,
+      });
+      return false;
+    } finally {
+      this.reconnecting = false;
+    }
+  }
+
   disconnect() {
     if (this.ws) {
       try {

tests/api/ecast-shard-client.test.js

@@ -354,4 +354,46 @@ describe('EcastShardClient', () => {
       });
     });
   });
+
+  describe('buildReconnectUrl', () => {
+    test('uses stored secret and id', () => {
+      const client = new EcastShardClient({
+        sessionId: 1,
+        gameId: 1,
+        roomCode: 'TEST',
+        maxPlayers: 8,
+        onEvent: () => {},
+      });
+      client.secret = 'abc-123';
+      client.shardId = 5;
+      client.host = 'ecast-prod-use2.jackboxgames.com';
+
+      const url = client.buildReconnectUrl();
+      expect(url).toContain('secret=abc-123');
+      expect(url).toContain('id=5');
+      expect(url).toContain('role=shard');
+      expect(url).toContain('ecast-prod-use2.jackboxgames.com');
+    });
+  });
+
+  describe('handleError with code 2027', () => {
+    test('marks game as finished and emits events on room-closed error', () => {
+      const events = [];
+      const client = new EcastShardClient({
+        sessionId: 1,
+        gameId: 5,
+        roomCode: 'TEST',
+        maxPlayers: 8,
+        onEvent: (type, data) => events.push({ type, data }),
+      });
+      client.playerCount = 4;
+      client.playerNames = ['A', 'B', 'C', 'D'];
+
+      client.handleError({ code: 2027, msg: 'the room has already been closed' });
+
+      expect(client.gameFinished).toBe(true);
+      expect(events.some(e => e.type === 'game.ended')).toBe(true);
+      expect(events.some(e => e.type === 'room.disconnected' && e.data.reason === 'room_closed')).toBe(true);
+    });
+  });
 });