This skill should be used when the user asks to write a zsh script, create a zsh function, build a CLI tool in zsh, write a shell script and zsh is the target, fix or improve a zsh script, parse command-line arguments in zsh, or when Claude is about to write a script with #!/bin/zsh or #!/usr/bin/env zsh. Also triggers when the user says "make it zsh", "use zsh not bash", "convert bash to zsh", "port to zsh", "rewrite in zsh", "zsh version", "idiomatic zsh", "use zparseopts", "zsh modules", or when editing .zshrc, .zshenv, .zprofile, or .zlogin files. Also triggers on zsh completion system: "compdef", "compadd", "zsh completion", "completion function", "tab completion in zsh", "_arguments", "_describe". Also triggers on plugin managers and frameworks: "oh-my-zsh", "zinit", "antigen", "zsh plugin", "zsh framework". Also triggers on prompt and hook functions: "zsh prompt", "PROMPT variable", "precmd", "preexec", "chpwd", "zsh hook". Also triggers when the user's shell is zsh and they ask to write a "shell script", "shell function", or "CLI tool" without specifying bash — prefer zsh idioms for zsh users. Provides comprehensive knowledge of idiomatic zsh scripting — modules, builtins, parameter expansion, and patterns that eliminate external process spawning.