anvil_skill

Overview

This skill builds and polishes command‑line interfaces and terminal UIs with cross‑platform reliability and CI readiness. It produces dual output modes (human + --json), respects TTY semantics, and enforces exit codes and graceful shutdowns. Use it when you need production‑quality CLI/TUI behavior, toolchain integration, and developer ergonomics delivered consistently across Node.js, Python, Go, and Rust.

How this skill works

I design the CLI surface (commands, flags, help) and scaffold argument parsing across languages, then add TUI components like progress bars, tables, spinners, and interactive menus. I integrate linters, test runners, and build tools and generate shell completion scripts and XDG‑friendly config loading. I validate environment dependencies, add non‑TTY JSON output, implement signal handling (CTRL+C cleanup), and produce handoff artifacts for CI and documentation.

When to use it

• Creating a new CLI or converting a prototype into a production CLI/TUI
• Adding human+machine output (pretty and --json) for automation and CI
• Integrating linters/formatters, test runners, or build tools into a CLI project
• Ensuring cross‑platform behavior (Windows/macOS/Linux, shell detection)
• Preparing a CLI for CI: non‑TTY behavior, exit code contracts, and graceful shutdown

Best practices

• Design clear command signatures and progressive disclosure in help text
• Keep business logic separate from presentation for testability
• Support --no-color and --yes to bypass interactive prompts in CI
• Provide deterministic exit codes and machine‑readable JSON for automation
• Avoid hardcoded paths; follow XDG and platform conventions

Example use cases

• Scaffold a multi‑subcommand CLI with consistent --help/--version and shell completion scripts
• Add interactive TUI menus and progress indicators to a long‑running build tool
• Create a doctor/doctor command that verifies dependencies and prints JSON for CI gating
• Integrate biome/ruff/golangci‑lint/clippy and wire test runner invocation into CI‑friendly commands
• Convert a prototype script into a hardened CLI with signal handling and non‑TTY behavior