Comment by OJFord

It just creates the same symlink on any other checkout. (On Linux/macOS at least, Windows I believe requires local settings changes.)

Only sane (guaranteed portable) option is for it to be a relative symlink to another file within the same repo, of course. i.e. CLAUDE.md would be -> 'AGENTS.md', not '/home/simonw/projects/pelicans-on-bicycles/AGENTS.md' or whatever.