prune stale git branches and worktrees

prune-stale-branches

#!/usr/bin/env bash
# Prune local branches whose PRs are merged (and optionally closed-unmerged).
# Also removes the matching worktree if one exists.
#
# Usage:
#   prune-stale-branches           # prompt per merged branch (default)
#   prune-stale-branches -f        # also include closed-unmerged PRs
#   prune-stale-branches --apply   # no prompts, delete all candidates
#   prune-stale-branches --dry-run # print only, no deletion

set -euo pipefail

APPLY=0
INCLUDE_CLOSED=0
PROMPT=1
DRY_RUN=0
for arg in "$@"; do
  case "$arg" in
    --apply|-y) APPLY=1; PROMPT=0 ;;
    -f|--force-closed) INCLUDE_CLOSED=1 ;;
    -p|--prompt) PROMPT=1; APPLY=0 ;;
    -n|--dry-run) DRY_RUN=1; PROMPT=0; APPLY=0 ;;
    -h|--help) sed -n '2,10p' "$0"; exit 0 ;;
    *) echo "unknown arg: $arg" >&2; exit 2 ;;
  esac
done

command -v gh >/dev/null || { echo "gh CLI required" >&2; exit 1; }
git rev-parse --git-dir >/dev/null || exit 1

PROTECTED_RE='^(main|master|HEAD)$'
CURRENT="$(git symbolic-ref --short -q HEAD || true)"

TMP="$(mktemp -d)"
trap 'rm -rf "$TMP"' EXIT

JQ_FILTER='.[] | select(.state=="MERGED"'
[[ $INCLUDE_CLOSED -eq 1 ]] && JQ_FILTER="$JQ_FILTER"' or .state=="CLOSED"'
JQ_FILTER="$JQ_FILTER"') | [.headRefName, .state] | @tsv'

gh pr list --state all --limit 500 --json headRefName,state --jq "$JQ_FILTER" \
  | sort -u > "$TMP/prs"

# worktree map via porcelain: emit "branch<TAB>path"
awk '
  /^worktree / { p=$2 }
  /^branch refs\/heads\// { sub("refs/heads/","",$2); print $2 "\t" p }
' <(git worktree list --porcelain) > "$TMP/wts"

lookup_state() { awk -F'\t' -v b="$1" '$1==b{print $2; exit}' "$TMP/prs"; }
lookup_wt()    { awk -F'\t' -v b="$1" '$1==b{print $2; exit}' "$TMP/wts"; }

act() {
  if [[ $DRY_RUN -eq 1 ]]; then echo "  DRY: $*"; else "$@"; fi
}

pruned=0
skipped=0
while read -r branch; do
  [[ -z "$branch" ]] && continue
  [[ "$branch" =~ $PROTECTED_RE ]] && continue
  if [[ "$branch" == "$CURRENT" ]]; then echo "skip $branch (current)"; continue; fi

  state="$(lookup_state "$branch")"
  if [[ -z "$state" ]]; then skipped=$((skipped+1)); continue; fi

  echo "prune $branch ($state)"
  wt="$(lookup_wt "$branch")"
  if [[ $PROMPT -eq 1 ]]; then
    [[ -n "$wt" ]] && echo "  worktree: $wt"
    printf "  delete? [y/N/q] "
    read -r ans </dev/tty
    case "$ans" in
      y|Y) ;;
      q|Q) echo "aborted."; break ;;
      *) echo "  skipped."; skipped=$((skipped+1)); continue ;;
    esac
  fi
  if [[ -n "$wt" ]]; then
    act git worktree remove "$wt"
  fi
  act git branch -D "$branch"
  pruned=$((pruned+1))
done < <(git for-each-ref --format='%(refname:short)' refs/heads/)

echo
echo "candidates: $pruned, unmatched local branches: $skipped"
[[ $DRY_RUN -eq 1 ]] && echo "(dry-run — rerun without --dry-run to delete)"