[Eapp1e]

What

typer.core._get_default_string is a copy of Click's default-string formatting with the parts Click special-cases for Typer. The empty string case is missing, so an option whose default is deliberately "" prints no default at all:

@app.command()
def main(name: str = typer.Option("", help="Name to greet", show_default=True)) -> None:
    ...

Click 8 renders Name to greet [default: ""], Typer renders Name to greet. An empty default is indistinguishable from "this option has no default to show", which is exactly the case a help string usually needs to spell out — the reader cannot tell whether --name will be empty or absent.

How

Add the branch Click has, before the None check:

    elif default_value == "":
        default_string = '""'
    elif default_value is None:
        default_string = ""

Both the Rich help formatter (rich_utils._get_parameter_help) and the plain Click one read this helper, so the two stay consistent.

Tests

tests/test_rich_utils.py::test_rich_utils_show_default_empty_string renders the command above and asserts [default: ""] appears in the help output. It fails on the current implementation and passes with the change; the rest of the file still passes (13 passed).

Prepared with the help of an AI assistant.

[Eapp1e]

Closing this to avoid leaving a stale pull request open. The change itself is small and the branch stays in my fork, so it can be revived if maintainers want it later.