Gate Reasoning(effort=...) on registry support (#528)

OpenAI's Responses API rejects reasoning.effort on non-reasoning
models like gpt-4o with `unsupported_parameter`, so any scan with
the default STRIX_REASONING_EFFORT=high against gpt-4o crashed at
the first model call. drop_params=True absorbs the rejected param
on LiteLLM-routed models but the SDK's native OpenAI path has no
equivalent.

Lift model_supports_reasoning to a public helper that strips
litellm/, any-llm/, openai/ prefixes and falls back to last-segment
lookup so prefixed forms like anthropic/claude-opus-4-7 resolve
through the bare model_cost entry. make_model_settings regains
model_name and skips Reasoning() when the registry doesn't confirm
support. uses_chat_completions_tool_schema reuses the same helper
(was duplicating the lookup under a misleading name).

strix/config/models.py

@@ -119,15 +119,21 @@ def uses_chat_completions_tool_schema(model_name: str, settings: Settings) -> bo
         return True
     if settings.llm.api_base:
         return True
-    return not _supports_responses_custom_tools(model_name)
+    return not model_supports_reasoning(model_name)
 
 
-def _supports_responses_custom_tools(model_name: str) -> bool:
+def model_supports_reasoning(model_name: str) -> bool:
     import litellm
 
-    name = model_name.strip().lower().removeprefix("openai/")
+    name = model_name.strip().lower()
-    entry = litellm.model_cost.get(name) or {}
+    for prefix in ("litellm/", "any-llm/", "openai/"):
-    return bool(entry.get("supports_reasoning"))
+        if name.startswith(prefix):
+            name = name[len(prefix) :]
+            break
+    entry = litellm.model_cost.get(name)
+    if entry is None and "/" in name:
+        entry = litellm.model_cost.get(name.rsplit("/", 1)[1])
+    return bool(entry and entry.get("supports_reasoning"))
 
 
 def is_known_openai_bare_model(model_name: str) -> bool:

strix/core/inputs.py

@@ -8,7 +8,7 @@ from typing import TYPE_CHECKING, Any
 from agents.model_settings import ModelSettings
 from openai.types.shared import Reasoning
 
-from strix.config.models import DEFAULT_MODEL_RETRY
+from strix.config.models import DEFAULT_MODEL_RETRY, model_supports_reasoning
 
 
 if TYPE_CHECKING:
@@ -106,13 +106,21 @@ def build_scope_context(scan_config: dict[str, Any]) -> dict[str, Any]:
     }
 
 
-def make_model_settings(reasoning_effort: ReasoningEffort | None) -> ModelSettings:
+def make_model_settings(
+    reasoning_effort: ReasoningEffort | None,
+    *,
+    model_name: str,
+) -> ModelSettings:
     model_settings = ModelSettings(
         parallel_tool_calls=False,
         retry=DEFAULT_MODEL_RETRY,
         include_usage=True,
     )
-    if reasoning_effort is not None and reasoning_effort != "none":
+    if (
+        reasoning_effort is not None
+        and reasoning_effort != "none"
+        and model_supports_reasoning(model_name)
+    ):
         model_settings = model_settings.resolve(
             ModelSettings(reasoning=Reasoning(effort=reasoning_effort)),
         )

strix/core/runner.py

@@ -153,7 +153,10 @@ async def run_strix_scan(
         is_whitebox = any(t.get("type") == "local_code" for t in targets)
         skills = list(scan_config.get("skills") or [])
         root_task = build_root_task(scan_config)
-        model_settings = make_model_settings(settings.llm.reasoning_effort)
+        model_settings = make_model_settings(
+            settings.llm.reasoning_effort,
+            model_name=resolved_model,
+        )
         run_config = RunConfig(
             model=resolved_model,
             model_provider=StrixProvider(),