git hook to auto clean up merged local branches

githooks-post-checkout

# 1. Create ~/.githooks
# -----------------------------------------------

mkdir -p ~/.githooks
git config --global core.hooksPath ~/.githooks

# -----------------------------------------------

# 2. Create ~/.githooks/post-checkout:
# -----------------------------------------------

cat > ~/.githooks/post-checkout <<'EOF'
#!/usr/bin/env bash

# post-checkout <old-ref> <new-ref> <flag>
# flag=1 for branch checkout, 0 for file checkout

flag="$3"
[ "$flag" = "1" ] || exit 0

branch="$(git symbolic-ref --quiet --short HEAD 2>/dev/null || true)"
case "$branch" in
  main|master) ;;
  *) exit 0 ;;
esac

# Only run if gh is available and authenticated
command -v gh >/dev/null 2>&1 || exit 0
gh auth status >/dev/null 2>&1 || exit 0

# Ensure we prune remote-tracking refs too
git fetch --prune >/dev/null 2>&1 || true

# Protect common long-lived branches
PROTECTED='^(main|master|develop|dev|staging|release|hotfix)$'

# Delete local branches whose PRs are merged on GitHub
# Notes:
# - headRefName is just the branch name; this assumes your PR head branches are on origin.
# - Limit can be increased; keep modest to avoid slowness.
gh pr list --state merged --limit 100 --json headRefName --jq '.[].headRefName' 2>/dev/null \
| while read -r br; do
    [ -z "$br" ] && continue
    echo "$br" | grep -Eq "$PROTECTED" && continue
    # Only delete if it exists locally and is not current branch
    [ "$br" = "$branch" ] && continue
    git show-ref --verify --quiet "refs/heads/$br" || continue
    git branch -D "$br" >/dev/null 2>&1 || true
  done

exit 0
EOF

# ---------------------------------------------------

# 3. Make ~/.githooks/post-checkout executable
# ---------------------------------------------------

chmod +x ~/.githooks/post-checkout

# ---------------------------------------------------