Add Gemini 3 Pro support to OpenRouterModel (#3548)

Co-authored-by: zeyu <zeyu@ip-172-19-0-1.ap-southeast-1.compute.internal>
Co-authored-by: Douwe Maan <douwe@pydantic.dev>

Author: 3 people

pydantic_ai_slim/pydantic_ai/models/openrouter.py

@@ -244,7 +244,11 @@ class _BaseReasoningDetail(BaseModel, frozen=True):
     """Common fields shared across all reasoning detail types."""
 
     id: str | None = None
-    format: Literal['unknown', 'openai-responses-v1', 'anthropic-claude-v1', 'xai-responses-v1'] | None
+    format: (
+        Literal['unknown', 'openai-responses-v1', 'anthropic-claude-v1', 'xai-responses-v1', 'google-gemini-v1']
+        | str
+        | None
+    )
     index: int | None
     type: Literal['reasoning.text', 'reasoning.summary', 'reasoning.encrypted']
 
@@ -610,13 +614,21 @@ def _map_thinking_delta(self, choice: chat_completion_chunk.Choice) -> Iterable[
         assert isinstance(choice, _OpenRouterChunkChoice)
 
         if reasoning_details := choice.delta.reasoning_details:
-            for detail in reasoning_details:
+            for i, detail in enumerate(reasoning_details):
                 thinking_part = _from_reasoning_detail(detail)
+                # Use unique vendor_part_id for each reasoning detail type to prevent
+                # different detail types (e.g., reasoning.text, reasoning.encrypted)
+                # from being incorrectly merged into a single ThinkingPart.
+                # This is required for Gemini 3 Pro which returns multiple reasoning
+                # detail types that must be preserved separately for thought_signature handling.
+                vendor_id = f'reasoning_detail_{detail.type}_{i}'
                 yield self._parts_manager.handle_thinking_delta(
-                    vendor_part_id='reasoning_detail',
+                    vendor_part_id=vendor_id,
                     id=thinking_part.id,
                     content=thinking_part.content,
+                    signature=thinking_part.signature,
                     provider_name=self._provider_name,
+                    provider_details=thinking_part.provider_details,
                 )
         else:
             return super()._map_thinking_delta(choice)

tests/models/test_openrouter.py

@@ -112,23 +112,23 @@ async def test_openrouter_stream_with_reasoning(allow_model_requests: None, open
 
         thinking_event_start = chunks[0]
         assert isinstance(thinking_event_start, PartStartEvent)
-        assert thinking_event_start.part == snapshot(
-            ThinkingPart(
-                content='',
-                id='rs_0aa4f2c435e6d1dc0169082486816c8193a029b5fc4ef1764f',
-                provider_name='openrouter',
-            )
-        )
+        thinking_part = thinking_event_start.part
+        assert isinstance(thinking_part, ThinkingPart)
+        assert thinking_part.id == 'rs_0aa4f2c435e6d1dc0169082486816c8193a029b5fc4ef1764f'
+        assert thinking_part.content == ''
+        assert thinking_part.provider_name == 'openrouter'
+        # After fix: signature and provider_details are now properly preserved
+        assert thinking_part.signature is not None
+        assert thinking_part.provider_details is not None
+        assert thinking_part.provider_details['type'] == 'reasoning.encrypted'
+        assert thinking_part.provider_details['format'] == 'openai-responses-v1'
 
         thinking_event_end = chunks[1]
         assert isinstance(thinking_event_end, PartEndEvent)
-        assert thinking_event_end.part == snapshot(
-            ThinkingPart(
-                content='',
-                id='rs_0aa4f2c435e6d1dc0169082486816c8193a029b5fc4ef1764f',
-                provider_name='openrouter',
-            )
-        )
+        thinking_part_end = thinking_event_end.part
+        assert isinstance(thinking_part_end, ThinkingPart)
+        assert thinking_part_end.id == 'rs_0aa4f2c435e6d1dc0169082486816c8193a029b5fc4ef1764f'
+        assert thinking_part_end.signature is not None
 
 
 async def test_openrouter_stream_error(allow_model_requests: None, openrouter_api_key: str) -> None: