Development record

`17-guard.md:765` says the delete entries only warn, and refuse in a repository. Outside any repository `git branch -D x` also blocks as `git-delete-unproven`, exit 1, with the reason `the directory the command runs in is not a git checkout abcd can read` (`internal/core/sweep/deleteproof.go:159`); `git worktree remove x` and `git push origin --delete x` do the same.