fix: clamp and floor audio_end_ms to integer in interrupts (#315)

Author: vrtnis

.changeset/bright-fox-hill.md

@@ -0,0 +1,6 @@
+---
+'@openai/agents-extensions': patch
+'@openai/agents-realtime': patch
+---
+
+Fix: clamp and floor `audio_end_ms` in interrupts to prevent Realtime API error with fractional speeds (#315)

packages/agents-extensions/test/index.test.ts

@@ -69,9 +69,37 @@ describe('TwilioRealtimeTransportLayer', () => {
     transport._audioLengthMs = 500;
     transport._interrupt(0, true);
 
-    const call = sendEventSpy.mock.calls.find(
-      (c) => c[0]?.type === 'conversation.item.truncate',
-    );
+    const call = sendEventSpy.mock.calls
+      .filter((c) => c[0]?.type === 'conversation.item.truncate')
+      .at(-1);
     expect(call?.[0].audio_end_ms).toBe(50);
   });
+
+  test('interrupt clamps overshoot and emits integer audio_end_ms', async () => {
+    const twilio = new FakeTwilioWebSocket();
+    const transport = new TwilioRealtimeTransportLayer({
+      twilioWebSocket: twilio as any,
+    });
+
+    const sendEventSpy = vi.spyOn(
+      transport as TwilioRealtimeTransportLayer,
+      'sendEvent',
+    );
+
+    await transport.connect({
+      apiKey: 'ek_test',
+      initialSessionConfig: { speed: 1.1 },
+    });
+    sendEventSpy.mockClear();
+
+    // @ts-expect-error - we're testing protected fields.
+    transport._audioLengthMs = 20;
+    transport._interrupt(0, true);
+
+    const call = sendEventSpy.mock.calls
+      .filter((c) => c[0]?.type === 'conversation.item.truncate')
+      .at(-1);
+    expect(call?.[0].audio_end_ms).toBe(20);
+    expect(Number.isInteger(call?.[0].audio_end_ms)).toBe(true);
+  });
 });

packages/agents-realtime/src/openaiRealtimeWebsocket.ts

@@ -360,7 +360,7 @@ export class OpenAIRealtimeWebSocket
    * @param elapsedTime - The elapsed time since the response started.
    */
   _interrupt(elapsedTime: number, cancelOngoingResponse: boolean = true) {
-    if (elapsedTime < 0 || elapsedTime > this._audioLengthMs) {
+    if (elapsedTime < 0) {
       return;
     }
 
@@ -369,12 +369,15 @@ export class OpenAIRealtimeWebSocket
       this._cancelResponse();
     }
 
+    const length = this._audioLengthMs ?? Number.POSITIVE_INFINITY;
+    const audio_end_ms = Math.max(0, Math.min(Math.floor(elapsedTime), length));
+
     this.emit('audio_interrupted');
     this.sendEvent({
       type: 'conversation.item.truncate',
       item_id: this.#currentItemId,
       content_index: this.#currentAudioContentIndex,
-      audio_end_ms: elapsedTime,
+      audio_end_ms,
     });
   }
 

packages/agents-realtime/test/openaiRealtimeWebsocket.test.ts

@@ -70,7 +70,9 @@ describe('OpenAIRealtimeWebSocket', () => {
     const ws = new OpenAIRealtimeWebSocket();
     const audioSpy = vi.fn();
     ws.on('audio', audioSpy);
-    const sendSpy = vi.spyOn(ws, 'sendEvent');
+    const sendSpy = vi
+      .spyOn(ws as any, 'sendEvent')
+      .mockImplementation(() => {});
     const interruptSpy = vi.spyOn(ws, 'interrupt');
     const p = ws.connect({ apiKey: 'ek', model: 'm' });
     await vi.runAllTimersAsync();
@@ -109,11 +111,13 @@ describe('OpenAIRealtimeWebSocket', () => {
     });
     expect(interruptSpy).toHaveBeenCalled();
     expect(
-      sendSpy.mock.calls.some((c) => c[0].type === 'response.cancel'),
+      sendSpy.mock.calls.some(
+        (c: unknown[]) => (c[0] as any).type === 'response.cancel',
+      ),
     ).toBe(true);
     expect(
       sendSpy.mock.calls.some(
-        (c) => c[0].type === 'conversation.item.truncate',
+        (c: unknown[]) => (c[0] as any).type === 'conversation.item.truncate',
       ),
     ).toBe(true);
 
@@ -147,7 +151,9 @@ describe('OpenAIRealtimeWebSocket', () => {
       }),
     });
     expect(
-      sendSpy.mock.calls.every((c) => c[0].type !== 'response.cancel'),
+      sendSpy.mock.calls.every(
+        (c: unknown[]) => (c[0] as any).type !== 'response.cancel',
+      ),
     ).toBe(true);
   });
 
@@ -158,7 +164,9 @@ describe('OpenAIRealtimeWebSocket', () => {
 
   it('close resets state so interrupt does nothing', async () => {
     const ws = new OpenAIRealtimeWebSocket();
-    const sendSpy = vi.spyOn(ws, 'sendEvent');
+    const sendSpy = vi
+      .spyOn(OpenAIRealtimeWebSocket.prototype as any, 'sendEvent')
+      .mockImplementation(() => {});
     const p = ws.connect({ apiKey: 'ek', model: 'm' });
     await vi.runAllTimersAsync();
     await p;
@@ -197,6 +205,99 @@ describe('OpenAIRealtimeWebSocket', () => {
     expect(baseSpy).toHaveBeenCalled();
   });
 
+  it('_interrupt quantizes and clamps elapsedTime', () => {
+    const ws = new OpenAIRealtimeWebSocket();
+    const sendSpy = vi
+      .spyOn(OpenAIRealtimeWebSocket.prototype as any, 'sendEvent')
+      .mockImplementation(() => {});
+    // @ts-expect-error - testing protected field.
+    ws._audioLengthMs = 100;
+    ws._interrupt(110.9, false);
+    let call = sendSpy.mock.calls.find(
+      (c: unknown[]) => (c[0] as any).type === 'conversation.item.truncate',
+    );
+    expect((call?.[0] as any).audio_end_ms).toBe(100);
+    sendSpy.mockClear();
+    // @ts-expect-error - testing protected field.
+    ws._audioLengthMs = 200;
+    ws._interrupt(123.7, false);
+    call = sendSpy.mock.calls.find(
+      (c: unknown[]) => (c[0] as any).type === 'conversation.item.truncate',
+    );
+    expect((call?.[0] as any).audio_end_ms).toBe(123);
+    sendSpy.mockRestore();
+  });
+
+  it('_interrupt floors sub-millisecond elapsedTime', () => {
+    const ws = new OpenAIRealtimeWebSocket();
+    const sendSpy = vi
+      .spyOn(OpenAIRealtimeWebSocket.prototype as any, 'sendEvent')
+      .mockImplementation(() => {});
+    // @ts-expect-error - testing protected field.
+    ws._audioLengthMs = 100;
+    ws._interrupt(0.9, false);
+    const call = sendSpy.mock.calls.find(
+      (c: unknown[]) => (c[0] as any).type === 'conversation.item.truncate',
+    );
+    expect((call?.[0] as any).audio_end_ms).toBe(0);
+    expect(Number.isInteger((call?.[0] as any).audio_end_ms)).toBe(true);
+    sendSpy.mockRestore();
+  });
+
+  it('_interrupt clamps overshoot elapsedTime', () => {
+    const ws = new OpenAIRealtimeWebSocket();
+    const sendSpy = vi
+      .spyOn(OpenAIRealtimeWebSocket.prototype as any, 'sendEvent')
+      .mockImplementation(() => {});
+    // @ts-expect-error - testing protected field.
+    ws._audioLengthMs = 42;
+    ws._interrupt(42.6, false);
+    const call = sendSpy.mock.calls.find(
+      (c: unknown[]) => (c[0] as any).type === 'conversation.item.truncate',
+    );
+    expect((call?.[0] as any).audio_end_ms).toBe(42);
+    expect(Number.isInteger((call?.[0] as any).audio_end_ms)).toBe(true);
+    sendSpy.mockRestore();
+  });
+
+  it('interrupt payload is integer with fractional speed', async () => {
+    const ws = new OpenAIRealtimeWebSocket();
+    const sendSpy = vi
+      .spyOn(OpenAIRealtimeWebSocket.prototype as any, 'sendEvent')
+      .mockImplementation(() => {});
+    const p = ws.connect({
+      apiKey: 'ek',
+      model: 'm',
+      initialSessionConfig: { speed: 1.1 },
+    } as any);
+    await vi.runAllTimersAsync();
+    await p;
+    // @ts-expect-error - testing protected field.
+    ws._audioLengthMs = 200;
+    ws._interrupt(123.4, false);
+    const call = sendSpy.mock.calls.find(
+      (c: unknown[]) => (c[0] as any).type === 'conversation.item.truncate',
+    );
+    expect(Number.isInteger((call?.[0] as any).audio_end_ms)).toBe(true);
+    sendSpy.mockRestore();
+  });
+
+  it('interrupt payload is integer with speed 1', () => {
+    const ws = new OpenAIRealtimeWebSocket();
+    const sendSpy = vi
+      .spyOn(OpenAIRealtimeWebSocket.prototype as any, 'sendEvent')
+      .mockImplementation(() => {});
+    // @ts-expect-error - testing protected field.
+    ws._audioLengthMs = 200;
+    ws._interrupt(123.4, false);
+    const call = sendSpy.mock.calls.find(
+      (c: unknown[]) => (c[0] as any).type === 'conversation.item.truncate',
+    );
+    expect((call?.[0] as any).audio_end_ms).toBe(123);
+    expect(Number.isInteger((call?.[0] as any).audio_end_ms)).toBe(true);
+    sendSpy.mockRestore();
+  });
+
   it('full interrupt/_interrupt flow', async () => {
     const ws = new OpenAIRealtimeWebSocket();
     const sendSpy = vi.spyOn(ws, 'sendEvent');
@@ -230,11 +331,13 @@ describe('OpenAIRealtimeWebSocket', () => {
       }),
     });
     expect(
-      sendSpy.mock.calls.some((c) => c[0].type === 'response.cancel'),
+      sendSpy.mock.calls.some(
+        (c: unknown[]) => (c[0] as any).type === 'response.cancel',
+      ),
     ).toBe(true);
     expect(
       sendSpy.mock.calls.some(
-        (c) => c[0].type === 'conversation.item.truncate',
+        (c: unknown[]) => (c[0] as any).type === 'conversation.item.truncate',
       ),
     ).toBe(true);
     sendSpy.mockClear();