git-sync.sh

#!/bin/bash
# scripts/git-sync.sh
#
# One-command sync: bring local `main` back in line with `origin/main`,
# then delete any local feature branches whose PRs have already been
# merged on GitHub. Run this anytime — it's idempotent.
#
# Why this exists: the repo uses squash-merge PRs, which give merged
# commits a brand-new SHA on `main`. After a merge, local `main` and
# the local feature branch are both "diverged" from origin even though
# the work has shipped. This script cleans that up in one step.
#
# Usage:
#   ./scripts/git-sync.sh
#
# Requires: gh CLI authenticated against the same GitHub account that
# owns the repo (gh auth status to verify).

set -euo pipefail

REPO_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
cd "$REPO_ROOT"

# --- preflight ------------------------------------------------------------

if ! command -v gh >/dev/null 2>&1; then
  echo "❌ gh CLI not found. Install with: brew install gh"
  exit 1
fi

if ! gh auth status >/dev/null 2>&1; then
  echo "❌ gh CLI not authenticated. Run: gh auth login"
  exit 1
fi

# Stash uncommitted changes so the checkout/reset can't lose work.
# We pop the stash at the end if it was created.
STASH_CREATED=0
if [ -n "$(git status --porcelain)" ]; then
  echo "→ Stashing uncommitted changes (will pop at the end)"
  git stash push -u -m "git-sync.sh auto-stash $(date -u +%FT%TZ)" >/dev/null
  STASH_CREATED=1
fi

CURRENT_BRANCH="$(git branch --show-current)"

# --- sync main ------------------------------------------------------------

echo "→ Fetching origin + pruning stale remote refs"
git fetch origin --prune --quiet

echo "→ Resetting local main to origin/main"
git checkout main --quiet 2>/dev/null || git checkout -B main origin/main --quiet
git reset --hard origin/main --quiet
MAIN_SHA="$(git rev-parse --short HEAD)"
echo "  main is at $MAIN_SHA"

# --- prune merged feature branches ---------------------------------------

echo "→ Scanning local branches for ones whose PR has merged"

# Get every local branch except main into a tempfile, then iterate.
# Why a tempfile: bash 3.2 (still the macOS default) has no `mapfile`,
# and piping into `while read` puts the loop body in a subshell so
# array assignments to DELETED/KEPT wouldn't persist.
BRANCHES_TMP="$(mktemp)"
trap 'rm -f "$BRANCHES_TMP"' EXIT
git for-each-ref --format='%(refname:short)' refs/heads | grep -v '^main$' > "$BRANCHES_TMP" || true

DELETED=()
KEPT=()
while IFS= read -r br; do
  [ -z "$br" ] && continue
  # Squash-merged PRs don't show as "merged" in git's view (different SHAs),
  # so ask GitHub directly: is there a closed/merged PR whose head is this branch?
  STATE="$(gh pr list --state all --head "$br" --json state --jq '.[0].state' 2>/dev/null || true)"
  if [ "$STATE" = "MERGED" ]; then
    git branch -D "$br" --quiet
    DELETED+=("$br")
  else
    KEPT+=("$br${STATE:+ (PR: $STATE)}")
  fi
done < "$BRANCHES_TMP"

if [ ${#DELETED[@]} -gt 0 ]; then
  echo "  Deleted (PRs merged):"
  printf '    - %s\n' "${DELETED[@]}"
fi
if [ ${#KEPT[@]} -gt 0 ]; then
  echo "  Kept:"
  printf '    - %s\n' "${KEPT[@]}"
fi

# --- restore prior context ------------------------------------------------

# If the user was on a branch that's still around, switch back to it.
if [ "$CURRENT_BRANCH" != "main" ] && git show-ref --verify --quiet "refs/heads/$CURRENT_BRANCH"; then
  git checkout "$CURRENT_BRANCH" --quiet
  echo "→ Returned to branch: $CURRENT_BRANCH"
fi

if [ "$STASH_CREATED" -eq 1 ]; then
  echo "→ Popping stashed changes"
  git stash pop --quiet
fi

echo "✓ Sync complete."