Python: Fix response_format resolution in streaming finalizer

python/packages/core/agent_framework/_agents.py

@@ -935,6 +935,11 @@ def _propagate_conversation_id(update: AgentResponseUpdate) -> AgentResponseUpda
                 session.service_session_id = conv_id
             return update
 
+        def _finalizer(updates: Sequence[AgentResponseUpdate]) -> AgentResponse[Any]:
+            ctx = ctx_holder["ctx"]
+            rf = ctx.get("chat_options", {}).get("response_format") if ctx else (options.get("response_format") if options else None)
+            return self._finalize_response_updates(updates, response_format=rf)
+
         return (
             ResponseStream
             .from_awaitable(_get_stream())
@@ -943,9 +948,7 @@ def _propagate_conversation_id(update: AgentResponseUpdate) -> AgentResponseUpda
                     map_chat_to_agent_update,
                     agent_name=self.name,
                 ),
-                finalizer=partial(
-                    self._finalize_response_updates, response_format=options.get("response_format") if options else None
-                ),
+                finalizer=_finalizer,
             )
             .with_transform_hook(_propagate_conversation_id)
             .with_result_hook(_post_hook)

python/packages/core/tests/core/test_agents.py

@@ -97,6 +97,58 @@ async def test_chat_client_agent_run_streaming(client: SupportsChatGetResponse)
     assert result.text == "test streaming response another update"
 
 
+async def test_chat_client_agent_streaming_response_format_from_default_options(
+    client: SupportsChatGetResponse,
+) -> None:
+    """AgentResponse.value must be parsed when response_format is set in default_options and streaming."""
+    from pydantic import BaseModel
+
+    class Greeting(BaseModel):
+        greeting: str
+
+    json_text = '{"greeting": "Hello"}'
+    client.streaming_responses.append(  # type: ignore[attr-defined]
+        [ChatResponseUpdate(contents=[Content.from_text(json_text)], role="assistant", finish_reason="stop")]
+    )
+
+    agent = Agent(client=client, default_options={"response_format": Greeting})
+    stream = agent.run("Hello", stream=True)
+    async for _ in stream:
+        pass
+    result = await stream.get_final_response()
+
+    assert result.text == json_text
+    assert result.value is not None
+    assert isinstance(result.value, Greeting)
+    assert result.value.greeting == "Hello"
+
+
+async def test_chat_client_agent_streaming_response_format_from_run_options(
+    client: SupportsChatGetResponse,
+) -> None:
+    """AgentResponse.value must be parsed when response_format is passed via run() options kwarg."""
+    from pydantic import BaseModel
+
+    class Greeting(BaseModel):
+        greeting: str
+
+    json_text = '{"greeting": "Hi"}'
+    client.streaming_responses.append(  # type: ignore[attr-defined]
+        [ChatResponseUpdate(contents=[Content.from_text(json_text)], role="assistant", finish_reason="stop")]
+    )
+
+    agent = Agent(client=client)
+    stream = agent.run("Hello", stream=True, options={"response_format": Greeting})
+    async for _ in stream:
+        pass
+    result = await stream.get_final_response()
+
+    assert result.text == json_text
+    assert result.value is not None
+    assert isinstance(result.value, Greeting)
+    assert result.value.greeting == "Hi"
+
+
 async def test_chat_client_agent_create_session(client: SupportsChatGetResponse) -> None:
     agent = Agent(client=client)
     session = agent.create_session()