dep-typer

name	dep-typer
description	Use when writing or editing a Typer CLI in this repo — declaring commands, arguments vs options, the 0/1/2/3 exit-code contract via typer.Exit, no_args_is_help, and testing with CliRunner. Curated for typer 0.12.
auto_trigger	{"keywords":["typer","typer.Option","typer.Argument","typer.Exit","CliRunner","add a CLI command","exit code contract","no_args_is_help"]}

typer — building a CLI the *man-family way

A curated, usage-gated skill: it is installed into a repo only when that repo actually depends on typer. Written against typer 0.12.

Command surface

Declare one typer.Typer app; each subcommand is a @app.command() function. Make a bare invocation print help instead of erroring:

app = typer.Typer(help="...", no_args_is_help=True)

@app.command()
def sync() -> None: ...

Arguments vs. options

Declared as parameter defaults, never decorators:

• positional → lib: str = typer.Argument(...)
• flag → force: bool = typer.Option(False, "--force") (a bool yields --force/--no-force)

Exit codes are the contract

Raise typer.Exit(code=...) — 0 ok · 1 domain decision/finding · 2 infra/config · 3 invalid usage. Don't collapse everything to 0/1; the exit code is the CLI's API.

raise typer.Exit(code=self_check_exit(checks))

Output

Use typer.echo, not print. Render structured results through Pydantic models at the edge so output stays normalized across the family.

Testing

from typer.testing import CliRunner
runner = CliRunner()
result = runner.invoke(app, ["sync", "--vendor-root", str(p)])
assert result.exit_code == 0

Deeper gotchas live in this entry's notes.md (curation source, not installed).