fix(mm): yaml migration fixup

- If the metadata yaml has an invalid version, exist the app. If we don't, the app will crawl the models dir and add models to the db without having first parsed `models.yaml`. This should not happen often, as the vast majority of users are on v3.0.0 models.yaml files.
- Fix off-by-one error with models count (need to pop the `__metadata__` stanza
- After a successful migration, rename `models.yaml` to `models.yaml.bak` to prevent the migration logic from re-running on subsequent app startups.

invokeai/app/services/model_install/model_install_default.py

@@ -1,7 +1,6 @@
 """Model installation class."""
 
 import os
-import pathlib
 import re
 import threading
 import time
@@ -297,38 +296,40 @@ class ModelInstallService(ModelInstallServiceBase):
         except OSError:
             return
 
-        if len(db_models) == 0 and len(yaml.items()) != 0:
+        yaml_metadata = yaml.pop("__metadata__")
+        yaml_version = yaml_metadata.get("version")
+
+        if yaml_version != "3.0.0":
+            raise ValueError(
+                f"Attempted migration of unsupported `models.yaml` v{yaml_version}. Only v3.0.0 is supported. Exiting."
+            )
+
         self._logger.info(
-                f"Starting one-time migration of {len(yaml.items())} models in yaml file to DB. This may take a few minutes."
+            f"Starting one-time migration of {len(yaml.items())} models from `models.yaml` to database. This may take a few minutes."
         )
 
+        if len(db_models) == 0 and len(yaml.items()) != 0:
             for model_key, stanza in yaml.items():
-                if model_key == "__metadata__":
-                    try:
-                        assert (
-                            stanza["version"] == "3.0.0"
-                        ), f"This script works on version 3.0.0 yaml files, but your configuration points to a {stanza['version']} version"
-                    except AssertionError:
-                        self._logger.warn(
-                            f"Skipping entry with path {stanza.get('path', '')} with outdated metadata version"
-                        )
-                        continue
-                    continue
-
                 _, _, model_name = str(model_key).split("/")
-                model_path = pathlib.Path(stanza["path"])
+                model_path = Path(stanza["path"])
                 if not model_path.is_absolute():
                     model_path = self._app_config.models_path / model_path
                 model_path = model_path.resolve()
-                description = stanza.get("description", "")
+
-                config_path = stanza.get("config", "")
+                config: dict[str, Any] = {}
-                model_info = {"name": model_name, "description": description, "config_path": config_path}
+                config["name"] = model_name
+                config["description"] = stanza.get("description")
+                config["config_path"] = stanza.get("config")
 
                 try:
-                    id = self.register_path(model_path=model_path, config=model_info)
+                    id = self.register_path(model_path=model_path, config=config)
-                    self._logger.info(f"Registered {model_name} with id {id}")
+                    self._logger.info(f"Migrated {model_name} with id {id}")
                 except Exception as e:
-                    self._logger.warning(f"Model at {model_path} could not be loaded into database: {e}")
+                    self._logger.warning(f"Model at {model_path} could not be migrated: {e}")
+
+        # Rename `models.yaml` to `models.yaml.bak` to prevent re-migration
+        yaml_path = self._app_config.model_conf_path
+        yaml_path.rename(yaml_path.with_suffix(".bak"))
 
     def scan_directory(self, scan_dir: Path, install: bool = False) -> List[str]:  # noqa D102
         self._cached_model_paths = {Path(x.path).absolute() for x in self.record_store.all_models()}