Scenario 03: Write a script that installs packages only once

User Prompt

I want to add a script to my chezmoi dotfiles that installs my Homebrew packages, but only runs it on first setup — not every time I run chezmoi apply.

Expected Behavior

1. Create a file named run_once_before_install-homebrew-packages.sh in the source directory
2. Explain the prefix breakdown: run_ (execute, not copy) + once_ (run only if never run before) + before_ (run before other changes are applied)
3. Show an example script that calls brew bundle or lists packages with brew install
4. Explain that chezmoi tracks whether the script has run by hashing its content in ~/.local/share/chezmoi/.chezmoistate.boltdb
5. Mention that changing the script content triggers a re-run (use run_onchange_ if that's the desired behaviour)
6. Show how to add as a template (.tmpl suffix) if the script needs OS-specific logic

Success Criteria

• Uses run_once_before_ prefix (not just run_ or once_)
• Correctly explains that once_ is content-hashed, not time-based
• Distinguishes run_once_ vs run_onchange_ and when to use each
• Mentions .tmpl suffix as optional for platform-conditional scripts
• Does NOT suggest using a cron job or external script runner

Failure Conditions

• Uses run_ without once_ — script would execute on every chezmoi apply
• Confuses once_ with onchange_
• Recommends a separate shell script outside chezmoi management
• Gets the prefix order wrong (e.g. before_run_once_ instead of run_once_before_)