Read .worktreeinclude at the repo root (gitignore syntax) and copy matching
gitignored paths from the primary checkout into each newly created local
worktree, so .env and other local config carry over with zero per-user setup.
- Literal patterns resolve by direct stat; globs match against
ls-files --others --ignored --exclude-standard --directory (collapsed
dirs keep huge repos fast); every candidate is re-verified with
check-ignore so tracked or unignored files are never copied.
- Copy semantics, never symlink: APFS clone-copy on macOS, real copy
elsewhere, so each worktree owns its files (unlike repo.symlinkPaths,
which it merges with rather than replaces).
- Failures never block worktree creation.
- Remote (SSH) creation skips it, same as symlinkPaths.
- Split APFS clone helpers into worktree-apfs-clone.ts (max-lines).
Closes#7549