fix: #1907 guardrails w/ turn_detection.interrupt_response: true

src/agents/realtime/model_inputs.py

@@ -95,6 +95,9 @@ class RealtimeModelSendToolOutput:
 class RealtimeModelSendInterrupt:
     """Send an interrupt to the model."""
 
+    force_response_cancel: bool = False
+    """Force sending a response.cancel event even if automatic cancellation is enabled."""
+
 
 @dataclass
 class RealtimeModelSendSessionUpdate:

src/agents/realtime/openai_realtime.py

@@ -395,36 +395,36 @@ async def _send_interrupt(self, event: RealtimeModelSendInterrupt) -> None:
         current_item_id = playback_state.get("current_item_id")
         current_item_content_index = playback_state.get("current_item_content_index")
         elapsed_ms = playback_state.get("elapsed_ms")
+
         if current_item_id is None or elapsed_ms is None:
             logger.debug(
                 "Skipping interrupt. "
                 f"Item id: {current_item_id}, "
                 f"elapsed ms: {elapsed_ms}, "
                 f"content index: {current_item_content_index}"
             )
-            return
-
-        current_item_content_index = current_item_content_index or 0
-        if elapsed_ms > 0:
-            await self._emit_event(
-                RealtimeModelAudioInterruptedEvent(
-                    item_id=current_item_id,
-                    content_index=current_item_content_index,
-                )
-            )
-            converted = _ConversionHelper.convert_interrupt(
-                current_item_id,
-                current_item_content_index,
-                int(elapsed_ms),
-            )
-            await self._send_raw_message(converted)
         else:
-            logger.debug(
-                "Didn't interrupt bc elapsed ms is < 0. "
-                f"Item id: {current_item_id}, "
-                f"elapsed ms: {elapsed_ms}, "
-                f"content index: {current_item_content_index}"
-            )
+            current_item_content_index = current_item_content_index or 0
+            if elapsed_ms > 0:
+                await self._emit_event(
+                    RealtimeModelAudioInterruptedEvent(
+                        item_id=current_item_id,
+                        content_index=current_item_content_index,
+                    )
+                )
+                converted = _ConversionHelper.convert_interrupt(
+                    current_item_id,
+                    current_item_content_index,
+                    int(elapsed_ms),
+                )
+                await self._send_raw_message(converted)
+            else:
+                logger.debug(
+                    "Didn't interrupt bc elapsed ms is < 0. "
+                    f"Item id: {current_item_id}, "
+                    f"elapsed ms: {elapsed_ms}, "
+                    f"content index: {current_item_content_index}"
+                )
 
         session = self._created_session
         automatic_response_cancellation_enabled = (
@@ -434,12 +434,16 @@ async def _send_interrupt(self, event: RealtimeModelSendInterrupt) -> None:
             and session.audio.input.turn_detection is not None
             and session.audio.input.turn_detection.interrupt_response is True
         )
-        if not automatic_response_cancellation_enabled:
+        should_cancel_response = event.force_response_cancel or (
+            not automatic_response_cancellation_enabled
+        )
+        if should_cancel_response:
             await self._cancel_response()
 
-        self._audio_state_tracker.on_interrupted()
-        if self._playback_tracker:
-            self._playback_tracker.on_interrupted()
+        if current_item_id is not None and elapsed_ms is not None:
+            self._audio_state_tracker.on_interrupted()
+            if self._playback_tracker:
+                self._playback_tracker.on_interrupted()
 
     async def _send_session_update(self, event: RealtimeModelSendSessionUpdate) -> None:
         """Send a session update to the model."""

src/agents/realtime/session.py

@@ -704,7 +704,7 @@ async def _run_output_guardrails(self, text: str, response_id: str) -> bool:
             )
 
             # Interrupt the model
-            await self._model.send_event(RealtimeModelSendInterrupt())
+            await self._model.send_event(RealtimeModelSendInterrupt(force_response_cancel=True))
 
             # Send guardrail triggered message
             guardrail_names = [result.guardrail.get_name() for result in triggered_results]

tests/realtime/test_openai_realtime.py

@@ -1,4 +1,5 @@
 import json
+from types import SimpleNamespace
 from typing import Any, cast
 from unittest.mock import AsyncMock, Mock, patch
 
@@ -509,6 +510,59 @@ async def test_send_event_dispatch(self, model, monkeypatch):
         # session update -> 1
         assert send_raw.await_count == 8
 
+    @pytest.mark.asyncio
+    async def test_interrupt_force_cancel_overrides_auto_cancellation(self, model, monkeypatch):
+        """Interrupt should send response.cancel even when auto cancel is enabled."""
+        model._audio_state_tracker.set_audio_format("pcm16")
+        model._audio_state_tracker.on_audio_delta("item_1", 0, b"\x00" * 4800)
+        model._ongoing_response = True
+        model._created_session = SimpleNamespace(
+            audio=SimpleNamespace(
+                input=SimpleNamespace(
+                    turn_detection=SimpleNamespace(interrupt_response=True)
+                )
+            )
+        )
+
+        send_raw = AsyncMock()
+        emit_event = AsyncMock()
+        monkeypatch.setattr(model, "_send_raw_message", send_raw)
+        monkeypatch.setattr(model, "_emit_event", emit_event)
+
+        await model._send_interrupt(RealtimeModelSendInterrupt(force_response_cancel=True))
+
+        assert send_raw.await_count == 2
+        payload_types = {call.args[0].type for call in send_raw.call_args_list}
+        assert payload_types == {"conversation.item.truncate", "response.cancel"}
+        assert model._ongoing_response is False
+        assert model._audio_state_tracker.get_last_audio_item() is None
+
+    @pytest.mark.asyncio
+    async def test_interrupt_respects_auto_cancellation_when_not_forced(self, model, monkeypatch):
+        """Interrupt should avoid sending response.cancel when relying on automatic cancellation."""
+        model._audio_state_tracker.set_audio_format("pcm16")
+        model._audio_state_tracker.on_audio_delta("item_1", 0, b"\x00" * 4800)
+        model._ongoing_response = True
+        model._created_session = SimpleNamespace(
+            audio=SimpleNamespace(
+                input=SimpleNamespace(
+                    turn_detection=SimpleNamespace(interrupt_response=True)
+                )
+            )
+        )
+
+        send_raw = AsyncMock()
+        emit_event = AsyncMock()
+        monkeypatch.setattr(model, "_send_raw_message", send_raw)
+        monkeypatch.setattr(model, "_emit_event", emit_event)
+
+        await model._send_interrupt(RealtimeModelSendInterrupt())
+
+        assert send_raw.await_count == 1
+        assert send_raw.call_args_list[0].args[0].type == "conversation.item.truncate"
+        assert all(call.args[0].type != "response.cancel" for call in send_raw.call_args_list)
+        assert model._ongoing_response is True
+
     def test_add_remove_listener_and_tools_conversion(self, model):
         listener = AsyncMock()
         model.add_listener(listener)