feat: add reconnection logic with exponential backoff to shard client

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);
+    });
+  });
 });