pkgs/cli: Fix adding common flags for aliases

pkgs/clan-cli/clan_cli/__init__.py

@@ -55,6 +55,16 @@ def default_flake() -> FlakeId | None:
 
 
 def add_common_flags(parser: argparse.ArgumentParser) -> None:
+    def argument_exists(parser: argparse.ArgumentParser, arg: str) -> bool:
+        """
+        Check if an argparse argument already exists.
+        This is needed because the aliases subcommand doesn't *really*
+        create an alias - it duplicates the actual parser in the tree
+        making duplication inevitable while naively traversing.
+        """
+        return any(arg in action.option_strings for action in parser._actions)  # noqa: SLF001 -> private_member accessed
+
+    if not argument_exists(parser, "--debug"):
         parser.add_argument(
             "--debug",
             help="Enable debug logging",
@@ -62,6 +72,7 @@ def add_common_flags(parser: argparse.ArgumentParser) -> None:
             default=False,
         )
 
+    if not argument_exists(parser, "--option"):
         parser.add_argument(
             "--option",
             help="Nix option to set",
@@ -71,6 +82,7 @@ def add_common_flags(parser: argparse.ArgumentParser) -> None:
             default=[],
         )
 
+    if not argument_exists(parser, "--flake"):
         parser.add_argument(
             "--flake",
             help="path to the flake where the clan resides in, can be a remote flake or local, can be set through the [CLAN_DIR] environment variable",