fix(gemini): bridge reasoning_config into thinking_config for chat-completions routes

tests/agent/transports/test_chat_completions.py

@@ -4,7 +4,7 @@ import pytest
 from types import SimpleNamespace
 
 from agent.transports import get_transport
-from agent.transports.types import NormalizedResponse, ToolCall
+from agent.transports.types import NormalizedResponse
 
 
 @pytest.fixture
@@ -122,6 +122,75 @@ class TestChatCompletionsBuildKwargs:
         )
         assert kw["extra_body"]["think"] is False
 
+    def test_gemini_without_explicit_reasoning_config_keeps_existing_behavior(self, transport):
+        msgs = [{"role": "user", "content": "Hi"}]
+        kw = transport.build_kwargs(
+            model="gemini-3-flash-preview",
+            messages=msgs,
+            provider_name="gemini",
+        )
+        assert "thinking_config" not in kw.get("extra_body", {})
+
+    def test_gemini_flash_reasoning_maps_to_thinking_config(self, transport):
+        msgs = [{"role": "user", "content": "Hi"}]
+        kw = transport.build_kwargs(
+            model="gemini-3-flash-preview",
+            messages=msgs,
+            provider_name="gemini",
+            reasoning_config={"enabled": True, "effort": "high"},
+        )
+        assert kw["extra_body"]["thinking_config"] == {
+            "includeThoughts": True,
+            "thinkingLevel": "high",
+        }
+
+    def test_gemini_25_reasoning_only_enables_visible_thoughts(self, transport):
+        msgs = [{"role": "user", "content": "Hi"}]
+        kw = transport.build_kwargs(
+            model="gemini-2.5-flash",
+            messages=msgs,
+            provider_name="gemini",
+            reasoning_config={"enabled": True, "effort": "high"},
+        )
+        assert kw["extra_body"]["thinking_config"] == {
+            "includeThoughts": True,
+        }
+
+    def test_gemini_pro_reasoning_clamps_to_supported_levels(self, transport):
+        msgs = [{"role": "user", "content": "Hi"}]
+        kw = transport.build_kwargs(
+            model="google/gemini-3.1-pro-preview",
+            messages=msgs,
+            provider_name="gemini",
+            reasoning_config={"enabled": True, "effort": "medium"},
+        )
+        assert kw["extra_body"]["thinking_config"] == {
+            "includeThoughts": True,
+            "thinkingLevel": "low",
+        }
+
+    def test_gemini_disabled_reasoning_hides_thoughts(self, transport):
+        msgs = [{"role": "user", "content": "Hi"}]
+        kw = transport.build_kwargs(
+            model="gemini-3-flash-preview",
+            messages=msgs,
+            provider_name="gemini",
+            reasoning_config={"enabled": False},
+        )
+        assert kw["extra_body"]["thinking_config"] == {
+            "includeThoughts": False,
+        }
+
+    def test_gemini_xhigh_clamps_to_high(self, transport):
+        msgs = [{"role": "user", "content": "Hi"}]
+        kw = transport.build_kwargs(
+            model="gemini-3-flash-preview",
+            messages=msgs,
+            provider_name="gemini",
+            reasoning_config={"enabled": True, "effort": "xhigh"},
+        )
+        assert kw["extra_body"]["thinking_config"]["thinkingLevel"] == "high"
+
     def test_max_tokens_with_fn(self, transport):
         msgs = [{"role": "user", "content": "Hi"}]
         kw = transport.build_kwargs(