git-bclean-empty

#!/usr/bin/env bash
# Delete local branches that are ancestors of the default branch, have no
# upstream, and are not checked out in any worktree. Safe for cleaning up
# stranded Conductor workspace branches (e.g., haacked/<city>) that never
# received commits or were never pushed.
# Usage: git bclean-empty [-n|--dry-run]

set -e

dry_run=0
case "${1:-}" in
    -n|--dry-run) dry_run=1 ;;
esac

default_branch=$(bash "$HOME/.dotfiles/bin/lib/git-default-branch.sh")

# Build set of branches checked out in any worktree
declare -A has_worktree
while IFS= read -r line; do
    if [[ "$line" == branch\ refs/heads/* ]]; then
        branch="${line#branch refs/heads/}"
        has_worktree["$branch"]=1
    fi
done < <(git worktree list --porcelain)

current_branch=$(git symbolic-ref --quiet --short HEAD 2>/dev/null || echo "")

deleted=0
refused=0

while IFS=$'\t' read -r refname upstream; do
    [[ "$refname" == "$current_branch" ]] && continue
    [[ "$refname" == "$default_branch" ]] && continue
    [[ -n "$upstream" ]] && continue
    [[ -n "${has_worktree[$refname]:-}" ]] && continue
    if ! git merge-base --is-ancestor "$refname" "$default_branch" 2>/dev/null; then
        continue
    fi

    if [ "$dry_run" -eq 1 ]; then
        echo "Would delete: $refname"
        deleted=$((deleted + 1))
        continue
    fi

    # Use -d (not -D) so git itself refuses anything it considers unmerged.
    if git branch -d "$refname" 2>/dev/null; then
        echo "Deleted: $refname"
        deleted=$((deleted + 1))
    else
        echo "Refused:  $refname (git considers it unmerged)"
        refused=$((refused + 1))
    fi
done < <(git for-each-ref --format='%(refname:short)%09%(upstream:short)' refs/heads/)

if [ "$dry_run" -eq 1 ]; then
    echo "Dry run: $deleted branch(es) would be deleted."
else
    echo "Deleted $deleted branch(es)."
    [ "$refused" -gt 0 ] && echo "Refused $refused branch(es)."
fi