[rich-iannone]

This PR makes the shell that runs a script's steps start with a clean environment: it passes through only a few variables, such as PATH, HOME and LANG, so editor and CI settings like VS Code's PYTHONSTARTUP or NO_COLOR no longer leak into recordings. This changes behaviour for existing scripts, and the new record.inherit_env: true setting restores it.

great-docs termshow check --json prints the results as one JSON object, with a summary and each script's status, diffs and errors, and keeps the same exit status. The user guide gains a "Keeping demos up to date in CI" section with a GitHub Actions workflow that checks demos on pull requests and opens a pull request with re-recorded demos on a schedule.

[github-actions]

📚 Preview this PR's docs locally

Fetch the just-built site and open it in your browser:

# this exact build
great-docs preview --run 40619421683

# or always the latest build for this PR
great-docs preview --pr 459

Auth & tips

• Requires great-docs: pip install great-docs (or run via pipx/uvx).
• Auth: run gh auth login then add --use-gh, or set GITHUB_TOKEN (needs Actions: read).
• Jump to a page: add --path reference/index.html.
• Latest vs exact: --pr <n> grabs the newest build; --run <id> pins this one.
• Re-download: --refresh ignores the local cache.