Cli Developer

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

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Audit 0.4.1 · source sha b8ffc4391b71 · 31 Oct 2026Report an issue or request a re-scan

• PublisherJeffallan GitHub userOwner of the repository this skill is read from
• Source folderJeffallan/claude-skills/skills/cli-developerThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdictb8ffc4391b71A new audit runs when the source changes
• Repository statusNot archivedPushed today
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Use when building CLI tools, implementing argument parsing, or adding interactive prompts. Invoke for parsing flags and subcommands, displaying progress bars and spinners, generating bash/zsh/fish completion scripts,…

---
name: cli-developer
description: Use when building CLI tools, implementing argument parsing, or adding interactive prompts. Invoke for parsing flags and subcommands, displaying progress bars and spinners, generating bash/zsh/fish completion scripts, CLI design, shell completions, and cross-platform terminal applications using commander, click, typer, or cobra.
license: MIT
metadata:
  author: https://github.com/Jeffallan
  company: https://synergetic.solutions
  version: "1.1.0"
  domain: devops
  triggers: CLI, command-line, terminal app, argument parsing, shell completion, interactive prompt, progress bar, commander, click, typer, cobra
  role: specialist
  scope: implementation
  output-format: code
  related-skills: devops-engineer
---

# CLI Developer

## Core Workflow

1. **Analyze UX** — Identify user workflows, command hierarchy, common tasks. Validate by listing all commands and their expected `--help` output before writing code.
2. **Design commands** — Plan subcommands, flags, arguments, configuration. Confirm flag naming is consistent and no existing signatures are broken.
3. **Implement** — Build with the appropriate CLI framework for the language (see Reference Guide below). After wiring up commands, run `<cli> --help` to verify help text renders correctly and `<cli> --version` to confirm version output.
4. **Polish** — Add completions, help text, error messages, progress indicators. Verify TTY detection for color output and graceful SIGINT handling.
5. **Test** — Run cross-platform smoke tests; benchmark startup time (target: <50ms).

## Reference Guide

Load detailed guidance based on context:

| Topic | Reference | Load When |
|-------|-----------|-----------|
| Design Patterns | `references/design-patterns.md` | Subcommands, flags, config, architecture |
| Node.js CLIs | `references/node-cli.md` | commander, yargs, inquirer, chalk |
| Python CLIs | `references/python-cli.md` | click, typer, argparse, rich |
| Go CLIs | `references/go-cli.md` | cobra, viper, bubbletea |
| UX Patterns | `references/ux-patterns.md` | Progress bars, colors, help text |

## Quick-Start Example

### Node.js (commander)

```js
#!/usr/bin/env node
// npm install commander
const { program } = require('commander');

program
  .name('mytool')
  .description('Example CLI')
  .version('1.0.0');

program
  .command('greet <name>')
  .description('Greet a user')
  .option('-l, --loud', 'uppercase the greeting')
  .action((name, opts) => {
    const msg = `Hello, ${name}!`;
    console.log(opts.loud ? msg.toUpperCase() : msg);
  });

program.parse();
```

For Python (click/typer) and Go (cobra) quick-start examples, see `references/python-cli.md` and `references/go-cli.md`.

## Constraints

### MUST DO
- Keep startup time under 50ms
- Provide clear, actionable error messages
- Support `--help` and `--version` flags
- Use consistent flag naming conventions
- Handle SIGINT (Ctrl+C) gracefully
- Validate user input early
- Support both interactive and non-interactive modes
- Test on Windows, macOS, and Linux

### MUST NOT DO

- **Block on synchronous I/O unnecessarily** — use async reads or stream processing instead.
- **Print to stdout when output will be piped** — write logs/diagnostics to stderr.
- **Use colors when output is not a TTY** — detect before applying color:
  ```js
  // Node.js
  const useColor = process.stdout.isTTY;
  ```
  ```python
  # Python
  import sys
  use_color = sys.stdout.isatty()
  ```
  ```go
  // Go
  import "golang.org/x/term"
  useColor := term.IsTerminal(int(os.Stdout.Fd()))
  ```
- **Break existing command signatures** — treat flag/subcommand renames as breaking changes.
- **Require interactive input in CI/CD environments** — always provide non-interactive fallbacks via flags or env vars.
- **Hardcode paths or platform-specific logic** — use `os.homedir()` / `os.UserHomeDir()` / `Path.home()` instead.
- **Ship without shell completions** — all three frameworks above have built-in completion generation.

## Output Templates

When implementing CLI features, provide:
1. Command structure (main entry point, subcommands)
2. Configuration handling (files, env vars, flags)
3. Core implementation with error handling
4. Shell completion scripts if applicable
5. Brief explanation of UX decisions

## Knowledge Reference

CLI frameworks (commander, yargs, oclif, click, typer, argparse, cobra, viper), terminal UI (chalk, inquirer, rich, bubbletea), testing (snapshot testing, E2E), distribution (npm, pip, homebrew, releases), performance optimization

Maintained by [@jeffallan](https://github.com/jeffallan), Principal Consultant at [Synergetic Solutions](https://synergetic.solutions)

[Documentation](https://jeffallan.github.io/claude-skills/skills/devops/cli-developer/)

Excerpt, first 4,765 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

1. 2026-10-31
   ✓SAFE B 89 / 100

   first audit · source b8ffc4391b71

Questions about Cli Developer

• github.com/Jeffallan/claude-skills/tree/main/skills/cli-develope — the audited source at commit b8ffc4391b71 and every finding aboveObserved · 31 Oct 2026

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