/clean-bak-branches — Delete merged -bak backup branches

/prepare-merge saves the pre-squash history as <branch>-bak (-bak2, -bak-20260917, … on reruns) and pushes it. Nothing removes those refs after the PR merges, so they pile up. This skill removes the current user's ones.

Arguments

• none — every -bak branch of the current user whose source PR is merged.
• --dry-run — list what would be deleted and stop.
• <pattern> — only branches whose name contains it (e.g. an issue number).

Steps

1. Collect

git fetch --prune origin
me=$(git config user.email)
git for-each-ref --format='%(refname)|%(objectname:short)|%(authoremail)' \
    refs/heads refs/remotes/origin \
  | grep -E -- '-bak[0-9a-z-]*\|' | grep -F "<$me>"

Ownership is the author of the branch tip. The -bak refs of other people are theirs to delete — never touch them, even when asked for "all".

A branch checked out in a worktree (git worktree list) is skipped and reported.

2. Check that the backup is no longer needed

Strip the -bak… suffix to get the source branch, then:

gh pr list --head <source-branch> --state all --json number,state

Source PR	Action
MERGED	delete
OPEN, CLOSED unmerged, or no PR	keep, unless the user confirms via AskUserQuestion — the backup may be the only copy of the unsquashed history

3. Delete

Print the name sha list first: it is the only way back (git branch <name> <sha> works while the commits are still unreachable but not yet collected).

git branch -D <local names…>
git push origin --delete <remote names…>

One git push --delete for all remote names, not one per branch.

4. Report

Counts of local and remote refs deleted, what was kept and why, and a rerun of step 1 showing nothing of the user's is left.