domain-cli_skill

Overview

This skill provides practical guidelines and patterns for building robust Rust CLI tools. It captures domain constraints (user communication, config precedence, exit codes, interrupt handling) and maps them to concrete crates and code patterns for argument parsing, config layering, progress display, and terminal UI. Use it to design predictable, scriptable, and user-friendly command-line applications.

How this skill works

The skill inspects common CLI domain rules and translates them into design constraints and Rust implementations. It recommends crates (clap, figment/config, indicatif, dialoguer, ratatui, crossterm) and patterns (derive-based args structs, subcommands, layered config, RAII progress bars). It also enumerates common mistakes and the fixes to enforce correct stdout/stderr usage, exit codes, and config precedence.

When to use it

• Building a new Rust command-line tool or utility
• Designing argument parsing and subcommands with type safety
• Implementing layered configuration (CLI > env > file > defaults)
• Adding progress indicators, prompts, or TUI components
• Ensuring correct exit codes and scriptable output

Best practices

• Send data to stdout and errors to stderr (println! vs eprintln!)
• Enforce config precedence: CLI args > environment vars > config file > defaults
• Use #[derive(Parser)] and #[derive(Subcommand)] from clap for type-driven args
• Return Result from main or call std::process::exit with non-zero codes on error
• Use RAII-style progress bars (indicatif) for long operations and signal handling for interrupts

Example use cases

• A scaffolding tool with Init and Run subcommands parsed via clap derives
• A background worker that reads config from file, environment, and CLI with clear precedence
• An installer that shows progress bars and interactive prompts (indicatif + dialoguer)
• A TUI-based admin tool using ratatui + crossterm with proper terminal cleanup
• A CLI intended for automation where stdout is machine-readable and stderr contains human messages