Live apply now accepts only :5433/agent_system_dev plus a data/dev
host root, maps stored work dirs fail-closed, and reports unique
O_EXCL backups after a parent-directory fsync.
Co-authored-by: Cursor <cursoragent@cursor.com>
Apply now writes the destructive old head markdown beside the original
file, refuses to clobber existing backups, and fsyncs the parent
directory after the atomic persist.
Co-authored-by: Cursor <cursoragent@cursor.com>