Support raw CoT reasoning from LM Studio and other OpenAI Responses-compatible APIs

docs/thinking.md

@@ -34,6 +34,9 @@ agent = Agent(model, model_settings=settings)
 ...
 ```
 
+!!! note "Raw reasoning without summaries"
+    Some OpenAI-compatible APIs (such as LM Studio, vLLM, or OpenRouter with gpt-oss models) may return raw reasoning content without reasoning summaries. In this case, [`ThinkingPart.content`][pydantic_ai.messages.ThinkingPart.content] will be empty, but the raw reasoning is available in `provider_details['raw_content']`. Following [OpenAI's guidance](https://cookbook.openai.com/examples/responses_api/reasoning_items) that raw reasoning should not be shown directly to users, we store it in `provider_details` rather than in the main `content` field.
+
 ## Anthropic
 
 To enable thinking, use the [`AnthropicModelSettings.anthropic_thinking`][pydantic_ai.models.anthropic.AnthropicModelSettings.anthropic_thinking] [model setting](agents.md#model-run-settings).

pydantic_ai_slim/pydantic_ai/models/anthropic.py

@@ -1106,25 +1106,26 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
             elif isinstance(event, BetaRawContentBlockStartEvent):
                 current_block = event.content_block
                 if isinstance(current_block, BetaTextBlock) and current_block.text:
-                    maybe_event = self._parts_manager.handle_text_delta(
+                    for event_ in self._parts_manager.handle_text_delta(
                         vendor_part_id=event.index, content=current_block.text
-                    )
-                    if maybe_event is not None:  # pragma: no branch
-                        yield maybe_event
+                    ):
+                        yield event_
                 elif isinstance(current_block, BetaThinkingBlock):
-                    yield self._parts_manager.handle_thinking_delta(
+                    for event_ in self._parts_manager.handle_thinking_delta(
                         vendor_part_id=event.index,
                         content=current_block.thinking,
                         signature=current_block.signature,
                         provider_name=self.provider_name,
-                    )
+                    ):
+                        yield event_
                 elif isinstance(current_block, BetaRedactedThinkingBlock):
-                    yield self._parts_manager.handle_thinking_delta(
+                    for event_ in self._parts_manager.handle_thinking_delta(
                         vendor_part_id=event.index,
                         id='redacted_thinking',
                         signature=current_block.data,
                         provider_name=self.provider_name,
-                    )
+                    ):
+                        yield event_
                 elif isinstance(current_block, BetaToolUseBlock):
                     maybe_event = self._parts_manager.handle_tool_call_delta(
                         vendor_part_id=event.index,
@@ -1185,23 +1186,24 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
 
             elif isinstance(event, BetaRawContentBlockDeltaEvent):
                 if isinstance(event.delta, BetaTextDelta):
-                    maybe_event = self._parts_manager.handle_text_delta(
+                    for event_ in self._parts_manager.handle_text_delta(
                         vendor_part_id=event.index, content=event.delta.text
-                    )
-                    if maybe_event is not None:  # pragma: no branch
-                        yield maybe_event
+                    ):
+                        yield event_
                 elif isinstance(event.delta, BetaThinkingDelta):
-                    yield self._parts_manager.handle_thinking_delta(
+                    for event_ in self._parts_manager.handle_thinking_delta(
                         vendor_part_id=event.index,
                         content=event.delta.thinking,
                         provider_name=self.provider_name,
-                    )
+                    ):
+                        yield event_
                 elif isinstance(event.delta, BetaSignatureDelta):
-                    yield self._parts_manager.handle_thinking_delta(
+                    for event_ in self._parts_manager.handle_thinking_delta(
                         vendor_part_id=event.index,
                         signature=event.delta.signature,
                         provider_name=self.provider_name,
-                    )
+                    ):
+                        yield event_
                 elif isinstance(event.delta, BetaInputJSONDelta):
                     maybe_event = self._parts_manager.handle_tool_call_delta(
                         vendor_part_id=event.index,

pydantic_ai_slim/pydantic_ai/models/bedrock.py

@@ -751,24 +751,25 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
                     delta = content_block_delta['delta']
                     if 'reasoningContent' in delta:
                         if redacted_content := delta['reasoningContent'].get('redactedContent'):
-                            yield self._parts_manager.handle_thinking_delta(
+                            for event in self._parts_manager.handle_thinking_delta(
                                 vendor_part_id=index,
                                 id='redacted_content',
                                 signature=redacted_content.decode('utf-8'),
                                 provider_name=self.provider_name,
-                            )
+                            ):
+                                yield event
                         else:
                             signature = delta['reasoningContent'].get('signature')
-                            yield self._parts_manager.handle_thinking_delta(
+                            for event in self._parts_manager.handle_thinking_delta(
                                 vendor_part_id=index,
                                 content=delta['reasoningContent'].get('text'),
                                 signature=signature,
                                 provider_name=self.provider_name if signature else None,
-                            )
+                            ):
+                                yield event
                     if text := delta.get('text'):
-                        maybe_event = self._parts_manager.handle_text_delta(vendor_part_id=index, content=text)
-                        if maybe_event is not None:  # pragma: no branch
-                            yield maybe_event
+                        for event in self._parts_manager.handle_text_delta(vendor_part_id=index, content=text):
+                            yield event
                     if 'toolUse' in delta:
                         tool_use = delta['toolUse']
                         maybe_event = self._parts_manager.handle_tool_call_delta(

pydantic_ai_slim/pydantic_ai/models/function.py

@@ -292,26 +292,26 @@ class FunctionStreamedResponse(StreamedResponse):
     def __post_init__(self):
         self._usage += _estimate_usage([])
 
-    async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
+    async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:  # noqa: C901
         async for item in self._iter:
             if isinstance(item, str):
                 response_tokens = _estimate_string_tokens(item)
                 self._usage += usage.RequestUsage(output_tokens=response_tokens)
-                maybe_event = self._parts_manager.handle_text_delta(vendor_part_id='content', content=item)
-                if maybe_event is not None:  # pragma: no branch
-                    yield maybe_event
+                for event in self._parts_manager.handle_text_delta(vendor_part_id='content', content=item):
+                    yield event
             elif isinstance(item, dict) and item:
                 for dtc_index, delta in item.items():
                     if isinstance(delta, DeltaThinkingPart):
                         if delta.content:  # pragma: no branch
                             response_tokens = _estimate_string_tokens(delta.content)
                             self._usage += usage.RequestUsage(output_tokens=response_tokens)
-                        yield self._parts_manager.handle_thinking_delta(
+                        for event in self._parts_manager.handle_thinking_delta(
                             vendor_part_id=dtc_index,
                             content=delta.content,
                             signature=delta.signature,
                             provider_name='function' if delta.signature else None,
-                        )
+                        ):
+                            yield event
                     elif isinstance(delta, DeltaToolCall):
                         if delta.json_args:
                             response_tokens = _estimate_string_tokens(delta.json_args)

pydantic_ai_slim/pydantic_ai/models/gemini.py

@@ -465,11 +465,10 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
                 if 'text' in gemini_part:
                     # Using vendor_part_id=None means we can produce multiple text parts if their deltas are sprinkled
                     # amongst the tool call deltas
-                    maybe_event = self._parts_manager.handle_text_delta(
+                    for event in self._parts_manager.handle_text_delta(
                         vendor_part_id=None, content=gemini_part['text']
-                    )
-                    if maybe_event is not None:  # pragma: no branch
-                        yield maybe_event
+                    ):
+                        yield event
 
                 elif 'function_call' in gemini_part:
                     # Here, we assume all function_call parts are complete and don't have deltas.

pydantic_ai_slim/pydantic_ai/models/google.py

@@ -722,15 +722,15 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
                     if len(part.text) == 0 and not provider_details:
                         continue
                     if part.thought:
-                        yield self._parts_manager.handle_thinking_delta(
+                        for event in self._parts_manager.handle_thinking_delta(
                             vendor_part_id=None, content=part.text, provider_details=provider_details
-                        )
+                        ):
+                            yield event
                     else:
-                        maybe_event = self._parts_manager.handle_text_delta(
+                        for event in self._parts_manager.handle_text_delta(
                             vendor_part_id=None, content=part.text, provider_details=provider_details
-                        )
-                        if maybe_event is not None:  # pragma: no branch
-                            yield maybe_event
+                        ):
+                            yield event
                 elif part.function_call:
                     maybe_event = self._parts_manager.handle_tool_call_delta(
                         vendor_part_id=uuid4(),

pydantic_ai_slim/pydantic_ai/models/groq.py

@@ -551,9 +551,10 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
                         reasoning = True
 
                     # NOTE: The `reasoning` field is only present if `groq_reasoning_format` is set to `parsed`.
-                    yield self._parts_manager.handle_thinking_delta(
+                    for event in self._parts_manager.handle_thinking_delta(
                         vendor_part_id=f'reasoning-{reasoning_index}', content=choice.delta.reasoning
-                    )
+                    ):
+                        yield event
                 else:
                     reasoning = False
 
@@ -576,14 +577,13 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
                 # Handle the text part of the response
                 content = choice.delta.content
                 if content:
-                    maybe_event = self._parts_manager.handle_text_delta(
+                    for event in self._parts_manager.handle_text_delta(
                         vendor_part_id='content',
                         content=content,
                         thinking_tags=self._model_profile.thinking_tags,
                         ignore_leading_whitespace=self._model_profile.ignore_streamed_leading_whitespace,
-                    )
-                    if maybe_event is not None:  # pragma: no branch
-                        yield maybe_event
+                    ):
+                        yield event
 
                 # Handle the tool calls
                 for dtc in choice.delta.tool_calls or []:

pydantic_ai_slim/pydantic_ai/models/huggingface.py

@@ -487,14 +487,13 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
             # Handle the text part of the response
             content = choice.delta.content
             if content:
-                maybe_event = self._parts_manager.handle_text_delta(
+                for event in self._parts_manager.handle_text_delta(
                     vendor_part_id='content',
                     content=content,
                     thinking_tags=self._model_profile.thinking_tags,
                     ignore_leading_whitespace=self._model_profile.ignore_streamed_leading_whitespace,
-                )
-                if maybe_event is not None:  # pragma: no branch
-                    yield maybe_event
+                ):
+                    yield event
 
             for dtc in choice.delta.tool_calls or []:
                 maybe_event = self._parts_manager.handle_tool_call_delta(

pydantic_ai_slim/pydantic_ai/models/mistral.py

@@ -639,7 +639,8 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
             content = choice.delta.content
             text, thinking = _map_content(content)
             for thought in thinking:
-                self._parts_manager.handle_thinking_delta(vendor_part_id='thinking', content=thought)
+                for event in self._parts_manager.handle_thinking_delta(vendor_part_id='thinking', content=thought):
+                    yield event
             if text:
                 # Attempt to produce an output tool call from the received text
                 output_tools = {c.name: c for c in self.model_request_parameters.output_tools}
@@ -655,9 +656,8 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
                             tool_call_id=maybe_tool_call_part.tool_call_id,
                         )
                 else:
-                    maybe_event = self._parts_manager.handle_text_delta(vendor_part_id='content', content=text)
-                    if maybe_event is not None:  # pragma: no branch
-                        yield maybe_event
+                    for event in self._parts_manager.handle_text_delta(vendor_part_id='content', content=text):
+                        yield event
 
             # Handle the explicit tool calls
             for index, dtc in enumerate(choice.delta.tool_calls or []):