feat: add generic --feature-flag CLI arg and --list-feature-flags registry (#13685)

comfy/cli_args.py

@@ -238,6 +238,8 @@ database_default_path = os.path.abspath(
 )
 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:'.")
 parser.add_argument("--enable-assets", action="store_true", help="Enable the assets system (API routes, database synchronization, and background scanning).")
+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.")
 
 if comfy.options.args_parsing:
     args = parser.parse_args()

comfy_api/feature_flags.py

@@ -5,12 +5,95 @@ This module handles capability negotiation between frontend and backend,
 allowing graceful protocol evolution while maintaining backward compatibility.
 """
 
-from typing import Any
+import logging
+from typing import Any, TypedDict
 
 from comfy.cli_args import args
 
+
+class FeatureFlagInfo(TypedDict):
+    type: str
+    default: Any
+    description: str
+
+
+# Registry of known CLI-settable feature flags.
+# Launchers can query this via --list-feature-flags to discover valid flags.
+CLI_FEATURE_FLAG_REGISTRY: dict[str, FeatureFlagInfo] = {
+    "show_signin_button": {
+        "type": "bool",
+        "default": False,
+        "description": "Show the sign-in button in the frontend even when not signed in",
+    },
+}
+
+
+def _coerce_bool(v: str) -> bool:
+    """Strict bool coercion: only 'true'/'false' (case-insensitive).
+
+    Anything else raises ValueError so the caller can warn and drop the flag,
+    rather than silently treating typos like 'ture' or 'yes' as False.
+    """
+    lower = v.lower()
+    if lower == "true":
+        return True
+    if lower == "false":
+        return False
+    raise ValueError(f"expected 'true' or 'false', got {v!r}")
+
+
+_COERCE_FNS: dict[str, Any] = {
+    "bool": _coerce_bool,
+    "int": lambda v: int(v),
+    "float": lambda v: float(v),
+}
+
+
+def _coerce_flag_value(key: str, raw_value: str) -> Any:
+    """Coerce a raw string value using the registry type, or keep as string.
+
+    Returns the raw string if the key is unregistered or the type is unknown.
+    Raises ValueError/TypeError if the key is registered with a known type but
+    the value cannot be coerced; callers are expected to warn and drop the flag.
+    """
+    info = CLI_FEATURE_FLAG_REGISTRY.get(key)
+    if info is None:
+        return raw_value
+    coerce = _COERCE_FNS.get(info["type"])
+    if coerce is None:
+        return raw_value
+    return coerce(raw_value)
+
+
+def _parse_cli_feature_flags() -> dict[str, Any]:
+    """Parse --feature-flag key=value pairs from CLI args into a dict.
+
+    Items without '=' default to the value 'true' (bare flag form).
+    Flags whose value cannot be coerced to the registered type are dropped
+    with a warning, so a typo like '--feature-flag some_bool=ture' does not
+    silently take effect as the wrong value.
+    """
+    result: dict[str, Any] = {}
+    for item in getattr(args, "feature_flag", []):
+        key, sep, raw_value = item.partition("=")
+        key = key.strip()
+        if not key:
+            continue
+        if not sep:
+            raw_value = "true"
+        try:
+            result[key] = _coerce_flag_value(key, raw_value.strip())
+        except (ValueError, TypeError) as e:
+            info = CLI_FEATURE_FLAG_REGISTRY.get(key, {})
+            logging.warning(
+                "Could not coerce --feature-flag %s=%r to %s (%s); dropping flag.",
+                key, raw_value.strip(), info.get("type", "?"), e,
+            )
+    return result
+
+
 # Default server capabilities
-SERVER_FEATURE_FLAGS: dict[str, Any] = {
+_CORE_FEATURE_FLAGS: dict[str, Any] = {
     "supports_preview_metadata": True,
     "max_upload_size": args.max_upload_size * 1024 * 1024, # Convert MB to bytes
     "extension": {"manager": {"supports_v4": True}},
@@ -18,6 +101,11 @@ SERVER_FEATURE_FLAGS: dict[str, Any] = {
     "assets": args.enable_assets,
 }
 
+# CLI-provided flags cannot overwrite core flags
+_cli_flags = {k: v for k, v in _parse_cli_feature_flags().items() if k not in _CORE_FEATURE_FLAGS}
+
+SERVER_FEATURE_FLAGS: dict[str, Any] = {**_CORE_FEATURE_FLAGS, **_cli_flags}
+
 
 def get_connection_feature(
     sockets_metadata: dict[str, dict[str, Any]],

main.py

@@ -1,13 +1,21 @@
 import comfy.options
 comfy.options.enable_args_parsing()
 
+from comfy.cli_args import args
+
+if args.list_feature_flags:
+    import json
+    from comfy_api.feature_flags import CLI_FEATURE_FLAG_REGISTRY
+    print(json.dumps(CLI_FEATURE_FLAG_REGISTRY, indent=2))  # noqa: T201
+    raise SystemExit(0)
+
 import os
 import importlib.util
 import shutil
 import importlib.metadata
 import folder_paths
 import time
-from comfy.cli_args import args, enables_dynamic_vram
+from comfy.cli_args import enables_dynamic_vram
 from app.logger import setup_logger
 setup_logger(log_level=args.verbose, use_stdout=args.log_stdout)
 

tests-unit/feature_flags_test.py

@@ -1,10 +1,15 @@
 """Tests for feature flags functionality."""
 
+import pytest
+
 from comfy_api.feature_flags import (
     get_connection_feature,
     supports_feature,
     get_server_features,
+    CLI_FEATURE_FLAG_REGISTRY,
     SERVER_FEATURE_FLAGS,
+    _coerce_flag_value,
+    _parse_cli_feature_flags,
 )
 
 
@@ -96,3 +101,83 @@ class TestFeatureFlags:
         result = get_connection_feature(sockets_metadata, "sid1", "any_feature")
         assert result is False
         assert supports_feature(sockets_metadata, "sid1", "any_feature") is False
+
+
+class TestCoerceFlagValue:
+    """Test suite for _coerce_flag_value."""
+
+    def test_registered_bool_true(self):
+        assert _coerce_flag_value("show_signin_button", "true") is True
+        assert _coerce_flag_value("show_signin_button", "True") is True
+
+    def test_registered_bool_false(self):
+        assert _coerce_flag_value("show_signin_button", "false") is False
+        assert _coerce_flag_value("show_signin_button", "FALSE") is False
+
+    def test_unregistered_key_stays_string(self):
+        assert _coerce_flag_value("unknown_flag", "true") == "true"
+        assert _coerce_flag_value("unknown_flag", "42") == "42"
+
+    def test_bool_typo_raises(self):
+        """Strict bool: typos like 'ture' or 'yes' must raise so the flag can be dropped."""
+        with pytest.raises(ValueError):
+            _coerce_flag_value("show_signin_button", "ture")
+        with pytest.raises(ValueError):
+            _coerce_flag_value("show_signin_button", "yes")
+        with pytest.raises(ValueError):
+            _coerce_flag_value("show_signin_button", "1")
+        with pytest.raises(ValueError):
+            _coerce_flag_value("show_signin_button", "")
+
+    def test_failed_int_coercion_raises(self, monkeypatch):
+        """Malformed values for typed flags must raise; caller decides what to do."""
+        monkeypatch.setitem(
+            CLI_FEATURE_FLAG_REGISTRY,
+            "test_int_flag",
+            {"type": "int", "default": 0, "description": "test"},
+        )
+        with pytest.raises(ValueError):
+            _coerce_flag_value("test_int_flag", "not_a_number")
+
+
+class TestParseCliFeatureFlags:
+    """Test suite for _parse_cli_feature_flags."""
+
+    def test_single_flag(self, monkeypatch):
+        monkeypatch.setattr("comfy_api.feature_flags.args", type("Args", (), {"feature_flag": ["show_signin_button=true"]})())
+        result = _parse_cli_feature_flags()
+        assert result == {"show_signin_button": True}
+
+    def test_missing_equals_defaults_to_true(self, monkeypatch):
+        """Bare flag without '=' is treated as the string 'true' (and coerced if registered)."""
+        monkeypatch.setattr("comfy_api.feature_flags.args", type("Args", (), {"feature_flag": ["show_signin_button", "valid=1"]})())
+        result = _parse_cli_feature_flags()
+        assert result == {"show_signin_button": True, "valid": "1"}
+
+    def test_empty_key_skipped(self, monkeypatch):
+        monkeypatch.setattr("comfy_api.feature_flags.args", type("Args", (), {"feature_flag": ["=value", "valid=1"]})())
+        result = _parse_cli_feature_flags()
+        assert result == {"valid": "1"}
+
+    def test_invalid_bool_value_dropped(self, monkeypatch, caplog):
+        """A typo'd bool value must be dropped entirely, not silently set to False
+        and not stored as a raw string. A warning must be logged."""
+        monkeypatch.setattr(
+            "comfy_api.feature_flags.args",
+            type("Args", (), {"feature_flag": ["show_signin_button=ture", "valid=1"]})(),
+        )
+        with caplog.at_level("WARNING"):
+            result = _parse_cli_feature_flags()
+        assert result == {"valid": "1"}
+        assert "show_signin_button" not in result
+        assert any("show_signin_button" in r.message and "drop" in r.message.lower() for r in caplog.records)
+
+
+class TestCliFeatureFlagRegistry:
+    """Test suite for the CLI feature flag registry."""
+
+    def test_registry_entries_have_required_fields(self):
+        for key, info in CLI_FEATURE_FLAG_REGISTRY.items():
+            assert "type" in info, f"{key} missing 'type'"
+            assert "default" in info, f"{key} missing 'default'"
+            assert "description" in info, f"{key} missing 'description'"