The Claude writer's containment was lexical only: a symlink at
~/.claude/<type>/<name>, or at any ancestor of it, is a string inside the
root while the write lands wherever it points. The backup destination had
the same exposure, and delete copies through the link before unlinking it.
PUT/DELETE /file also honoured ?cwd=, so a project-scope write could be
aimed at any directory on disk. PATCH /settings already refused that, with
the reasoning in a comment; the two other write routes never adopted it.
The guard moves into config-write.js so both writers run one copy.
nntrivi2001