feat(ai): enforce direct image edit contract

app/gui/workers.py

@@ -3261,24 +3261,41 @@ class CMHubSettingsWorker(BaseWorker):
         return _elapsed_ms(started)
 
 class AIModelTestWorker(BaseWorker):
-    """Test one AI model connection without blocking the GUI thread."""
+    """Test text models or validate image-model configuration off the GUI thread."""
 
-    def __init__(self, model_name, ai_models_path=None, db_path=None, diagnostic_log_dir=None):
+    def __init__(
+        self,
+        model_name,
+        ai_models_path=None,
+        db_path=None,
+        diagnostic_log_dir=None,
+        check_image_config=False,
+    ):
         super().__init__()
         self.model_name = model_name
         self.ai_models_path = ai_models_path or appconfig.AI_MODELS_PATH
         self.db_path = db_path
         self.diagnostic_log_dir = diagnostic_log_dir
+        self.check_image_config = bool(check_image_config)
         self._run_id = None
 
     def execute(self):
         self._run_id = self._create_run_log()
         started = time.monotonic()
         self._log_run_event(
-            f"step=test_connection result=start detail=AI模型 {self.model_name}"
+            "step={step} result=start detail=AI模型 {name}".format(
+                step="check_image_config" if self.check_image_config else "test_connection",
+                name=self.model_name,
+            )
         )
         try:
-            result = appconfig.test_ai_model(self.model_name, path=self.ai_models_path)
+            if self.check_image_config:
+                result = appconfig.check_image_model_config(
+                    self.model_name,
+                    path=self.ai_models_path,
+                )
+            else:
+                result = appconfig.test_ai_model(self.model_name, path=self.ai_models_path)
         except Exception as exc:
             error = diagnostics.redact_log_text(str(exc) or exc.__class__.__name__)
             elapsed_ms = self._elapsed_ms(started)