help.tsx and help()

Override what --help prints, and show it yourself when the input cannot be acted on.

--help is generated from argv.tsx (and stdin.tsx). help.tsx lets a command, or a group, add to it or replace it. The generated text arrives as auto, so the common case is appending examples:

// app/count/help.tsx
import { Br, Line, Text, type HelpProps } from 'decopin-cli';

export default function Help({ auto, program, command }: HelpProps) {
  return (
    <>
      {auto}
      <Br />
      <Line>
        <Text bold>Examples:</Text>
      </Line>
      <Line>{`  cat file.txt | ${program} ${command}`}</Line>
      <Line>{`  git status --porcelain | ${program} ${command} -n`}</Line>
    </>
  );
}

help.tsx is per directory, not inherited. A group directory (one without cmd.tsx) can have one too, and it decorates the command listing.

Asking for --help explicitly prints to stdout and exits 0. Ending up without a command prints to stderr and exits 2.

help(): when the input cannot be acted on

help() shows this command's usage and stops. It builds the same thing --help does, including a help.tsx override, but since it was not asked for, it goes to stderr with exit 2, matching how the framework already treats misuse.

// app/deploy/cmd.tsx
import { help, Success, type CmdProps } from 'decopin-cli';

export default function Command({ args, options }: CmdProps<'deploy'>) {
  if (args.target === undefined && !options.all) {
    help({ message: 'give a target, or pass --all' });
  }
  return (
    <Success>deploying {options.all ? 'everything' : args.target}</Success>
  );
}

$ ./dist/index.js deploy          # exit 2, all of it on stderr
✖ give a target, or pass --all
Usage: decopin-cli deploy [target] [options]

Deploy a target, or everything with --all.
...