Harden YOLO compatibility preflight

backend/app/services/yolo_preflight_service.py

@@ -17,6 +17,7 @@ class YoloPreflightService:
         tile_manifest_path: str | None = None,
         yolo_adapter_class: Type[YoloDetectionAdapter] = YoloDetectionAdapter,
         assume_dependencies: bool = False,
+        check_model_load: bool = False,
     ) -> dict[str, Any]:
         resolved_settings = settings or get_settings()
         result: dict[str, Any] = {
@@ -30,6 +31,8 @@ class YoloPreflightService:
                 "dependencies_available": None,
                 "model_path_set": None,
                 "model_file_exists": None,
+                "model_load_requested": check_model_load,
+                "model_load_ok": None,
                 "manifest_path_set": None,
                 "manifest_valid": None,
                 "tile_paths_exist": None,
@@ -64,6 +67,24 @@ class YoloPreflightService:
             result["message"] = "YOLO_MODEL_PATH does not point to an existing local model file."
             return result
 
+        if check_model_load:
+            try:
+                yolo_adapter_class(resolved_settings).load_model(model_path)
+            except AppError as exc:
+                result["status"] = "model_load_failed"
+                result["message"] = exc.message
+                result["error_code"] = exc.code
+                result["checks"]["model_load_ok"] = False
+                return result
+            except Exception as exc:
+                result["status"] = "model_load_failed"
+                result["message"] = "Configured YOLO model could not be loaded during compatibility smoke."
+                result["error_code"] = "DETECTION_MODEL_LOAD_FAILED"
+                result["details"] = {"error": str(exc)}
+                result["checks"]["model_load_ok"] = False
+                return result
+            result["checks"]["model_load_ok"] = True
+
         result["checks"]["manifest_path_set"] = bool(tile_manifest_path)
         if not tile_manifest_path:
             result["status"] = "manifest_unavailable"
@@ -89,5 +110,8 @@ class YoloPreflightService:
         result["checks"]["tile_limit_ok"] = len(tile_paths) <= resolved_settings.yolo_max_tiles
         result["tile_count"] = len(tile_paths)
         result["status"] = "ready"
-        result["message"] = "Configured YOLO preflight passed. No model was loaded and no inference was run."
+        if check_model_load:
+            result["message"] = "Configured YOLO preflight passed. Local model load smoke passed and no inference was run."
+        else:
+            result["message"] = "Configured YOLO preflight passed. No model was loaded and no inference was run."
         return result