fix(cloudflare): Bind non-instrumented Queue methods to the underlying binding

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

Author: rytkhs

packages/cloudflare/src/instrumentations/worker/instrumentQueueProducer.ts

@@ -99,7 +99,9 @@ export function instrumentQueueProducer<T extends Queue>(queue: T, bindingName:
         };
       }
 
-      return Reflect.get(target, prop, receiver);
+      const value = Reflect.get(target, prop, receiver) as unknown;
+
+      return typeof value === 'function' ? value.bind(target) : value;
     },
   });
 }

packages/cloudflare/test/instrumentations/worker/instrumentQueueProducer.test.ts

@@ -1,4 +1,4 @@
-import type { Queue } from '@cloudflare/workers-types';
+import type { Queue, QueueMetrics } from '@cloudflare/workers-types';
 import * as SentryCore from '@sentry/core';
 import { beforeEach, describe, expect, test, vi } from 'vitest';
 import { instrumentQueueProducer } from '../../../src/instrumentations/worker/instrumentQueueProducer';
@@ -10,6 +10,15 @@ function createMockQueue(): Queue {
   } as unknown as Queue;
 }
 
+// `metrics()` reads a private field, so it throws when `this` is the Proxy, as workerd's native methods do.
+class BrandCheckedQueue {
+  readonly #metrics: QueueMetrics = { backlogCount: 3, backlogBytes: 2048 };
+
+  public metrics(): Promise<QueueMetrics> {
+    return Promise.resolve(this.#metrics);
+  }
+}
+
 describe('instrumentQueueProducer', () => {
   beforeEach(() => {
     vi.clearAllMocks();
@@ -178,4 +187,13 @@ describe('instrumentQueueProducer', () => {
     const wrapped = instrumentQueueProducer(queue, 'MY_QUEUE') as Queue & { customMethod: () => string };
     expect(wrapped.customMethod()).toBe('hi');
   });
+
+  test('calls non-instrumented methods on the underlying queue', async () => {
+    const queue = new BrandCheckedQueue() as unknown as Queue;
+    const wrapped = instrumentQueueProducer(queue, 'MY_QUEUE');
+
+    const metrics = await wrapped.metrics();
+
+    expect(metrics).toEqual({ backlogCount: 3, backlogBytes: 2048 });
+  });
 });