Use when building CLI tools. Keywords: CLI, command line, terminal, clap, structopt, argument parsing, subcommand, interactive, TUI, ratatui, crossterm, indicatif, progress bar, colored output, shell completion, config file, environment variable, 命令行, 终端应用, 参数解析

CLI Domain Layer 3: Domain Constraints Domain Constraints → Design Implications Domain Rule Design Constraint Rust Implication User ergonomics Clear help, errors clap derive macros Config precedence CLI env file Layered config loading Exit codes Non zero on error Proper Result handling Stdout/stderr Data vs errors eprintln! for errors Interruptible Handle Ctrl+C Signal handling Critical Constraints User Communication Configuration Priority Exit Codes Trace Down ↓ From constraints to design (Layer 2): Key Crates Purpose Crate Argument parsing clap Interactive prompts dialoguer Progress bars indicatif Colored output colored Terminal UI ratatui Terminal control crossterm Console utilities console Design Patterns Pattern Purpose Implementation Args struct Type safe args [derive(Parser)] Subcommands Command hierarchy [derive(Subcommand)] Config layers Override precedence CLI env file Progress User feedback ProgressBar::new(len) Code Pattern: CLI Structure Common Mistakes Mistake Domain Violation Fix Errors to stdout Breaks piping eprintln! No help text Poor UX [arg(help = "...")] Panic on error Bad exit code Result + proper handling No progress for long ops User uncertainty indicatif Trace to Layer 1 Constraint Layer 2 Pattern Layer 1 Implementation Type safe args Derive macros clap Parser Error handling Result propagation anyhow + exit codes User feedback Progress RAII indicatif ProgressBar Config precedence Builder pattern Layered sources Related Skills When See Error handling m06 error handling Type driven args m05 type driven Progress lifecycle m12 lifecycle Async CLI m07 concurrency

domain-cli