feat(settings): add force_required_tool_choice to LlmSettings

feat(inputs): implement logic for required tool choice based on model

test(inputs): add tests for force_required_tool_choice behavior

test(runner): update tests to include force_required_tool_choice in settings

tests/test_config_loader.py

@@ -26,6 +26,7 @@ _LLM_ENV_KEYS = [
     "LITELLM_BASE_URL",
     "OLLAMA_API_BASE",
     "STRIX_REASONING_EFFORT",
+    "STRIX_FORCE_REQUIRED_TOOL_CHOICE",
     "LLM_TIMEOUT",
     "PERPLEXITY_API_KEY",
     # RuntimeSettings

tests/test_inputs.py

@@ -7,7 +7,7 @@ from typing import Any
 
 import pytest
 
-from strix.core.inputs import build_root_task, child_initial_input
+from strix.core.inputs import build_root_task, child_initial_input, make_model_settings
 
 
 def _child_kwargs(parent_history: list[Any]) -> dict[str, Any]:
@@ -112,3 +112,26 @@ def test_build_root_task_diff_scope() -> None:
     assert "Scope Constraints:" in task
     assert "3 changed file(s)" in task
     assert "2 deleted file(s)" in task
+
+
+@pytest.mark.parametrize("model_name", ["openai/o3", "gpt-4o"])
+def test_make_model_settings_forces_required_tool_choice_for_openai_models(
+    model_name: str,
+) -> None:
+    settings = make_model_settings(
+        "none",
+        model_name=model_name,
+        force_required_tool_choice=True,
+    )
+
+    assert settings.tool_choice == "required"
+
+
+def test_make_model_settings_skips_required_tool_choice_for_non_openai_models() -> None:
+    settings = make_model_settings(
+        "none",
+        model_name="anthropic/claude-3-7-sonnet-latest",
+        force_required_tool_choice=True,
+    )
+
+    assert settings.tool_choice is None

tests/test_runner_rate_limit.py

@@ -33,7 +33,11 @@ async def test_persistent_rate_limit_stops_gracefully(
     monkeypatch.setattr(runner, "set_scan_id", lambda _scan_id: None)
 
     settings = types.SimpleNamespace(
-        llm=types.SimpleNamespace(model="openai/gpt-4o", reasoning_effort="high")
+        llm=types.SimpleNamespace(
+            model="openai/gpt-4o",
+            reasoning_effort="high",
+            force_required_tool_choice=False,
+        )
     )
     monkeypatch.setattr(runner, "load_settings", lambda: settings)
     monkeypatch.setattr(runner, "configure_sdk_model_defaults", lambda _settings: None)