fix(assets): fail safe to 503 when DB unavailable; keep --enable-assets as no-op

Address automated review feedback on the always-on assets change:
- setup_database(): on DB init failure or missing dependencies, call
  disable_assets_routes() + asset_seeder.disable() so /api/assets/* returns a
  clean 503 instead of 500s against an uninitialized DB (restores the fail-safe
  the removed else-branch used to provide).
- feature_flags: derive the advertised 'assets' capability from live backend
  availability instead of hardcoding True, so clients degrade gracefully.
- cli_args: re-add --enable-assets as a hidden deprecated no-op so existing
  launchers still passing the flag don't abort argparse.
- routes: add assets_enabled() accessor for the feature-flag derivation.

app/assets/api/routes.py

@@ -102,6 +102,15 @@ def disable_assets_routes() -> None:
     _ASSETS_ENABLED = False
 
 
+def assets_enabled() -> bool:
+    """Return whether the asset routes are currently serving requests.
+
+    Reflects live backend availability: False once disable_assets_routes() has
+    been called (e.g. after a database init failure or missing dependencies).
+    """
+    return _ASSETS_ENABLED
+
+
 def _build_error_response(
     status: int, code: str, message: str, details: dict | None = None
 ) -> web.Response:

comfy/cli_args.py

@@ -239,6 +239,9 @@ database_default_path = os.path.abspath(
     os.path.join(os.path.dirname(__file__), "..", "user", "comfyui.db")
 )
 parser.add_argument("--database-url", type=str, default=f"sqlite:///{database_default_path}", help="Specify the database URL, e.g. for an in-memory database you can use 'sqlite:///:memory:'.")
+# Deprecated no-op: the asset system is now always enabled. Kept (hidden) so that
+# existing launchers/containers still passing --enable-assets don't fail argparse.
+parser.add_argument("--enable-assets", action="store_true", help=argparse.SUPPRESS)
 parser.add_argument("--enable-asset-hashing", action="store_true", help="Compute blake3 content hashes when scanning assets. Hashing enables future asset-portability features (deduplication, cross-machine model resolution) but adds startup cost and per-output cost on large models directories. Off by default; enable to opt in.")
 parser.add_argument("--feature-flag", type=str, action='append', default=[], metavar="KEY[=VALUE]", help="Set a server feature flag. Use KEY=VALUE to set an explicit value, or bare KEY to set it to true. Can be specified multiple times. Boolean values (true/false) and numbers are auto-converted. Examples: --feature-flag show_signin_button=true  or  --feature-flag show_signin_button")
 parser.add_argument("--list-feature-flags", action="store_true", help="Print the registry of known CLI-settable feature flags as JSON and exit.")

comfy_api/feature_flags.py

@@ -162,4 +162,13 @@ def get_server_features() -> dict[str, Any]:
     Returns:
         Dictionary of server feature flags
     """
-    return SERVER_FEATURE_FLAGS.copy()
+    features = SERVER_FEATURE_FLAGS.copy()
+    # Advertise the assets capability based on live backend availability rather
+    # than a static default, so clients degrade gracefully when the database
+    # failed to initialize or its dependencies are missing.
+    try:
+        from app.assets.api.routes import assets_enabled
+        features["assets"] = assets_enabled()
+    except Exception:
+        features["assets"] = False
+    return features

main.py

@@ -20,6 +20,7 @@ from app.logger import setup_logger
 setup_logger(log_level=args.verbose, use_stdout=args.log_stdout)
 
 from app.assets.seeder import asset_seeder
+from app.assets.api.routes import disable_assets_routes
 from app.assets.services import register_output_files
 import itertools
 import utils.extra_config
@@ -459,6 +460,12 @@ def setup_database():
             init_db()
             if asset_seeder.start(roots=("models", "input", "output"), prune_first=True, compute_hashes=args.enable_asset_hashing):
                 logging.info("Background asset scan initiated for models, input, output")
+        else:
+            # Optional DB dependencies are missing, so init_db() is skipped and the
+            # asset backend has no database. Disable assets so /api/assets/* returns
+            # a clean 503 instead of 500s against an uninitialized DB.
+            disable_assets_routes()
+            asset_seeder.disable()
     except Exception as e:
         if "database is locked" in str(e):
             logging.error(
@@ -467,6 +474,10 @@ def setup_database():
                 "  --database-url sqlite:///path/to/another.db"
             )
             sys.exit(1)
+        # The database is unusable. Fail safe by disabling assets so endpoints
+        # return 503 (service unavailable) rather than 500s on every request.
+        disable_assets_routes()
+        asset_seeder.disable()
         logging.error(f"Failed to initialize database. Please ensure you have installed the latest requirements. If the error persists, please report this as in future the database will be required: {e}")