ENG-815 - Three collateral smells from PR #82's blind startswith-sweep

backend/druks/harnesses/registry.py

@@ -1,5 +1,3 @@
-from druks.user_settings.models import HarnessSettings
-
 from .base import Harness
 from .exceptions import HarnessError
 
@@ -24,6 +22,8 @@ def get_harness_for_model(model: str) -> type[Harness]:
     A miss raises loudly; namespace-shaped models do not route until a fetch
     stores them on the harness settings row.
     """
+    from druks.user_settings.models import HarnessSettings
+
     for row in HarnessSettings.all():
         if model == row.name or any(m["id"] == model for m in row.allowed_models):
             return row.harness

backend/druks/harnesses/subprocess.py

@@ -16,9 +16,9 @@ def read_result_json(output_path: Path, *, name: str) -> dict[str, Any]:
     except FileNotFoundError as error:
         raise HarnessInvalidOutputError(f"{name} did not write result JSON.") from error
 
-    if text[:3] == "```":
+    if text.startswith("```"):
         lines = text.splitlines()
-        if lines and lines[0][:3] == "```":
+        if lines and lines[0].startswith("```"):
             lines = lines[1:]
         if lines and lines[-1].strip() == "```":
             lines = lines[:-1]

backend/druks/user_settings/routes.py

@@ -71,16 +71,13 @@ async def update_harness_settings(
     if "model" in updates:
         try:
             resolved = get_harness_for_model(updates["model"])
+            if resolved.name != harness.name:
+                raise HarnessError
         except HarnessError as exc:
             raise HTTPException(
                 status_code=422,
                 detail=f"{updates['model']!r} is not a {harness.name} model.",
             ) from exc
-        if resolved.name != harness.name:
-            raise HTTPException(
-                status_code=422,
-                detail=f"{updates['model']!r} is not a {harness.name} model.",
-            )
     _validate_effort(updates.get("effort"))
     _validate_timeout(updates.get("timeout"))
     if updates:

backend/tests/test_harness_model_routing.py

@@ -44,15 +44,25 @@ def test_settings_reject_model_missing_from_lists_returns_422(druks_db):
     assert error.value.detail == "No installed harness runs model 'llama-3-70b'."
 
 
-async def test_settings_reject_model_from_another_harness_returns_422(druks_db):
+@pytest.mark.parametrize(
+    ("model", "detail"),
+    [
+        ("gpt-5.5", "'gpt-5.5' is not a claude model."),
+        ("llama-3-70b", "'llama-3-70b' is not a claude model."),
+    ],
+)
+async def test_settings_reject_invalid_model_returns_422(druks_db, model, detail):
     account = Account.get_or_create("op@example.com")
+    settings = HarnessSettings.require("claude")
+    original_model = settings.model
 
     with pytest.raises(HTTPException) as error:
         await update_harness_settings(
             name="claude",
-            body=HarnessUpdate(model="gpt-5.5"),
+            body=HarnessUpdate(model=model),
             account=account,
         )
 
     assert error.value.status_code == 422
-    assert "is not a claude model" in error.value.detail
+    assert error.value.detail == detail
+    assert settings.model == original_model