Retained files

When you switch chapters, source files in the learning folder are replaced by that chapter’s snapshot. The snapshot is copied in place, then paths that are not in the snapshot are deleted. The two chapters are not merged.

retain in course.jsonc lists .gitignore-style patterns. Matching uses the same rules as .gitignore, evaluated from the learning folder root:

• node_modules keeps every node_modules directory anywhere in the tree
• /node_modules keeps only the root node_modules
• node_modules/ matches directories only
• *.log matches that suffix in any directory
• !important.txt un-ignores a path (gitignore negation)

When retain is omitted, node_modules is kept. An explicit [] keeps no extra project paths.

The learning copy at .learn/course/course.jsonc also adds .git, .learn, .gitignore, and *.code-workspace. Do not add those yourself.

The workspace .gitignore still tells git what not to commit. It does not decide which files stay when you switch chapters — that is only retain.

Notes

• Files that are in the snapshot are still overwritten, even when a retain pattern matches them.
• A gitignored folder such as dist/ is deleted unless a retain pattern matches it.