fix(realtime): terminate web worker on disconnect to prevent memory leak

Web Workers were created in _startWorkerHeartbeat() but never terminated
in _teardownConnection(), causing memory accumulation with each
disconnect/reconnect cycle.

This fix adds a _terminateWorker() private method that properly terminates
the Web Worker and clears the reference, then calls it during connection
teardown.

Fixes #1902

Author: tanmaysharma2001

packages/core/realtime-js/src/RealtimeClient.ts

@@ -645,6 +645,7 @@ export default class RealtimeClient {
       this.conn = null
     }
     this._clearAllTimers()
+    this._terminateWorker()
     this.channels.forEach((channel) => channel.teardown())
   }
 
@@ -710,6 +711,18 @@ export default class RealtimeClient {
       interval: this.heartbeatIntervalMs,
     })
   }
+
+  /**
+   * Terminate the Web Worker and clear the reference
+   * @internal
+   */
+  private _terminateWorker(): void {
+    if (this.workerRef) {
+      this.log('worker', 'terminating worker')
+      this.workerRef.terminate()
+      this.workerRef = undefined
+    }
+  }
   /** @internal */
   private _onConnClose(event: any) {
     this._setConnectionState('disconnected')

packages/core/realtime-js/test/RealtimeClient.worker.test.ts

@@ -98,3 +98,27 @@ test('creates worker with blob URL when no workerUrl provided', () => {
     global.URL.createObjectURL = originalCreateObjectURL
   }
 })
+
+test('terminates worker on disconnect', () => {
+  // Establish connection first
+  client.connect()
+
+  // Trigger worker creation
+  client._onConnOpen()
+
+  // Verify worker was created
+  assert.ok(client.workerRef)
+  const worker = client.workerRef
+
+  // Spy on worker terminate method
+  const terminateSpy = vi.spyOn(worker, 'terminate')
+
+  // Disconnect the client
+  client.disconnect()
+
+  // Verify worker was terminated
+  expect(terminateSpy).toHaveBeenCalled()
+
+  // Verify workerRef was cleared
+  assert.equal(client.workerRef, undefined)
+})