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

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]],