import argh

@argh.arg("paths", nargs="*", default=["x", "z"])
def fun(paths:list[str]):
    print(paths)

if __name__ == "__main__":
    argh.dispatch_command(fun)

> ./app.py
["x", "z"]    # as expected - the value of 'default'

> ./app.py a b  
[["a"], ["b"]]   # Bug? I would expect ["a", "b"]

parser = argparse.ArgumentParser()
parser.add_argument("paths", nargs="*", default=["x", "y"])
print(parser.parse_args([]))
print(parser.parse_args(["a", "b"]))
> Namespace(paths=['x', 'y'])
> Namespace(paths=['a', 'b'])

@argh.arg("paths", nargs="*")
def with_argh(paths:list[str]):
    print(paths)
>  ./app.py a b  
["a", "b"]

Using latest 0.30.4