fix: align tests with model validation and API error reporting

decnet/web/router/fleet/api_mutate_interval.py

@@ -6,19 +6,27 @@ from decnet.web.db.models import MutateIntervalRequest
 
 router = APIRouter()
 
+_UNIT_TO_MINUTES = {"m": 1, "d": 1440, "M": 43200, "y": 525600, "Y": 525600}
+
+
+def _parse_duration(s: str) -> int:
+    """Convert a duration string (e.g. '5d') to minutes."""
+    value, unit = int(s[:-1]), s[-1]
+    return value * _UNIT_TO_MINUTES[unit]
+
 
 @router.put("/deckies/{decky_name}/mutate-interval", tags=["Fleet Management"],
     responses={
-        400: {"description": "No active deployment found"},
+        400: {"description": "Bad Request (e.g. malformed JSON)"},
         401: {"description": "Could not validate credentials"},
-        404: {"description": "Decky not found"},
+        404: {"description": "No active deployment or decky not found"},
         422: {"description": "Validation error"}
     },
 )
 async def api_update_mutate_interval(decky_name: str, req: MutateIntervalRequest, current_user: str = Depends(get_current_user)) -> dict[str, str]:
     state_dict = await repo.get_state("deployment")
     if not state_dict:
-        raise HTTPException(status_code=400, detail="No active deployment")
+        raise HTTPException(status_code=404, detail="No active deployment")
 
     config = DecnetConfig(**state_dict["config"])
     compose_path = state_dict["compose_path"]
@@ -27,7 +35,7 @@ async def api_update_mutate_interval(decky_name: str, req: MutateIntervalRequest
     if not decky:
         raise HTTPException(status_code=404, detail="Decky not found")
 
-    decky.mutate_interval = req.mutate_interval
+    decky.mutate_interval = _parse_duration(req.mutate_interval) if req.mutate_interval else None
 
     await repo.set_state("deployment", {"config": config.model_dump(), "compose_path": compose_path})
     return {"message": "Mutation interval updated"}