Rust CLI Tooling AI Skill Guide (Claude)

Overview & Engine Architecture

Rust CLIs are Cargo binary crates (often workspace members) that parse argv with clap, report failures with anyhow at the binary edge and structured thiserror in libraries when callers must match variants, and exit with meaningful codes. Agents keep I/O fallible, avoid unwrap/expect on user-facing paths, put data on stdout / diagnostics on stderr, and prove behavior with assert_cmd integration tests.