fix: serialize OllamaChatGenerator think parameter (#3455)

Co-authored-by: ly-wang19 <ly-wang19@users.noreply.github.com>

Author: ly-wang19

integrations/ollama/src/haystack_integrations/components/generators/ollama/chat/chat_generator.py

@@ -341,6 +341,7 @@ def to_dict(self) -> dict[str, Any]:
             streaming_callback=callback_name,
             tools=serialize_tools_or_toolset(self.tools),
             response_format=self.response_format,
+            think=self.think,
         )
 
     @classmethod

integrations/ollama/tests/test_chat_generator.py

@@ -848,11 +848,24 @@ def test_to_dict(self):
                     "type": "object",
                     "properties": {"name": {"type": "string"}, "age": {"type": "number"}},
                 },
+                "think": False,
             },
         }
 
         assert data == expected_dict
 
+    def test_to_dict_and_from_dict_preserves_think(self):
+        """`think` enables a model's reasoning output and must survive a
+        to_dict/from_dict round-trip; otherwise a reloaded generator silently
+        falls back to think=False (reasoning disabled)."""
+        component = OllamaChatGenerator(model="gpt-oss", think="high")
+
+        data = component.to_dict()
+        assert data["init_parameters"]["think"] == "high"
+
+        restored = OllamaChatGenerator.from_dict(data)
+        assert restored.think == "high"
+
     def test_from_dict(self):
         tool = Tool(
             name="name",