diff --git a/src/bub/core/model_runner.py b/src/bub/core/model_runner.py
index cb2dc832..381aff4a 100644
--- a/src/bub/core/model_runner.py
+++ b/src/bub/core/model_runner.py
@@ -166,7 +166,8 @@ async def _chat(self, prompt: str) -> _ChatResult:
         try:
             async with asyncio.timeout(self._model_timeout_seconds):
                 provider, _, _ = self._model.partition(":")
-                if provider.casefold() == "vertexai":
+                provider = provider.casefold()
+                if provider == "vertexai":
                     output = await self._tape.tape.run_tools_async(
                         prompt=prompt,
                         system_prompt=system_prompt,
@@ -174,7 +175,7 @@ async def _chat(self, prompt: str) -> _ChatResult:
                         tools=self._tools,
                         http_options={"headers": self.DEFAULT_HEADERS},
                     )
-                else:
+                elif provider == "openrouter":
                     output = await self._tape.tape.run_tools_async(
                         prompt=prompt,
                         system_prompt=system_prompt,
@@ -182,6 +183,13 @@ async def _chat(self, prompt: str) -> _ChatResult:
                         tools=self._tools,
                         extra_headers=self.DEFAULT_HEADERS,
                     )
+                else:
+                    output = await self._tape.tape.run_tools_async(
+                        prompt=prompt,
+                        system_prompt=system_prompt,
+                        max_tokens=self._max_tokens,
+                        tools=self._tools,
+                    )
                 return _ChatResult.from_tool_auto(output)
         except TimeoutError:
             return _ChatResult(
diff --git a/tests/test_model_runner.py b/tests/test_model_runner.py
index 4a9ed0a4..ef611dfe 100644
--- a/tests/test_model_runner.py
+++ b/tests/test_model_runner.py
@@ -432,7 +432,30 @@ async def test_model_runner_maps_headers_for_vertexai() -> None:
 
 
 @pytest.mark.asyncio
-async def test_model_runner_uses_extra_headers_for_unknown_provider() -> None:
+async def test_model_runner_does_not_send_headers_for_gemini() -> None:
+    tape = FakeTapeService(FakeTapeImpl(outputs=[ToolAutoResult.text_result("assistant-only")]))
+    runner = ModelRunner(
+        tape=tape,  # type: ignore[arg-type]
+        router=SingleStepRouter(),  # type: ignore[arg-type]
+        tool_view=FakeToolView(),  # type: ignore[arg-type]
+        tools=[],
+        list_skills=lambda: [],
+        model="gemini:test",
+        max_steps=1,
+        max_tokens=512,
+        model_timeout_seconds=90,
+        base_system_prompt="base",
+        get_workspace_system_prompt=lambda: "",
+    )
+
+    await runner.run("hi")
+    kwargs = tape.tape.call_kwargs[0]
+    assert "extra_headers" not in kwargs
+    assert "http_options" not in kwargs
+
+
+@pytest.mark.asyncio
+async def test_model_runner_does_not_send_headers_for_unknown_provider() -> None:
     tape = FakeTapeService(FakeTapeImpl(outputs=[ToolAutoResult.text_result("assistant-only")]))
     runner = ModelRunner(
         tape=tape,  # type: ignore[arg-type]
@@ -450,5 +473,5 @@ async def test_model_runner_uses_extra_headers_for_unknown_provider() -> None:
 
     await runner.run("hi")
     kwargs = tape.tape.call_kwargs[0]
-    assert kwargs.get("extra_headers") == ModelRunner.DEFAULT_HEADERS
+    assert "extra_headers" not in kwargs
     assert "http_options" not in kwargs