fix: clear pendingWrites on RelayClient destroy

Teardown resets the ephemeral write queue so stale events are not flushed
after re-init on the same instance.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: tyiuhc

packages/experiment-tag/src/behavioral-targeting/relay-client.ts

@@ -255,6 +255,7 @@ export class RelayClient {
     this.iframeWindow = null;
     this.available = false;
     this.ready = false;
+    this.pendingWrites = [];
     this.initPromise = null;
   }
 }

packages/experiment-tag/test/behavioral-targeting/relay-client.test.ts

@@ -192,6 +192,32 @@ describe('RelayClient', () => {
     expect(document.querySelectorAll('iframe')).toHaveLength(1);
   });
 
+  test('queued writes before destroy are cleared on teardown', async () => {
+    const { client, iframeWindow, postMessage } = setupClient();
+    client.writeEvent({
+      id: 42,
+      event_type: 'page_view',
+      timestamp: 100,
+      session_id: 's1',
+      properties: {},
+    });
+
+    const initPromise = client.init();
+    client.destroy();
+    await initPromise;
+
+    const reinitPromise = client.init();
+    signalRelayReady(iframeWindow);
+    await reinitPromise;
+
+    expect(postMessage).not.toHaveBeenCalledWith(
+      expect.objectContaining({
+        type: 'WRITE_EVENT',
+        payload: { event: expect.objectContaining({ id: 42 }) },
+      }),
+    );
+  });
+
   test('writeEvent after destroy is dropped', async () => {
     const { client, iframeWindow, postMessage } = setupClient();
     const initPromise = client.init();