Git Checkpoint

git_checkpoint.sh

#!/usr/bin/env bash
set -euo pipefail

# install-git-checkpoint.sh
#
# Installs a global Git alias:
#
#   git checkpoint "message"
#   git checkpoint list
#   git checkpoint apply
#   git checkpoint apply 2
#   git checkpoint pop
#   git checkpoint pop 2
#
# What it does:
#
#   git checkpoint "add matrix code"
#
# Creates a named stash:
#
#   checkpoint: add matrix code
#
# Then immediately reapplies it, so your working tree stays dirty and you can
# keep working. This gives you a lightweight checkpoint without making a commit.
#
# Notes:
#
# - Uses git stash push -u, so untracked files are included.
# - apply restores a checkpoint but keeps it in the stash list.
# - pop restores a checkpoint and removes it if it applies cleanly.
# - apply/pop with no number defaults to stash@{0}.
# - apply/pop with a number maps to stash@{N}.
#
# Remove the alias later with:
#
#   git config --global --unset alias.checkpoint
#
# Check the installed alias with:
#
#   git config --global --get alias.checkpoint

git config --global alias.checkpoint '!f() {
  ref() {
    case "$1" in
      stash@\{*\}) printf "%s\n" "$1" ;;
      "") printf "%s\n" "stash@{0}" ;;
      *) printf "%s\n" "stash@{$1}" ;;
    esac
  }

  case "$1" in
    list)
      git stash list | grep "checkpoint:" || true
      ;;

    apply)
      shift
      git stash apply --index "$(ref "$1")"
      ;;

    pop)
      shift
      git stash pop --index "$(ref "$1")"
      ;;

    help|--help|-h)
      echo "Usage:"
      echo "  git checkpoint \"message\""
      echo "  git checkpoint list"
      echo "  git checkpoint apply [N|stash@{N}]"
      echo "  git checkpoint pop [N|stash@{N}]"
      ;;

    *)
      if [ -z "$(git status --porcelain)" ]; then
        echo "No changes to checkpoint."
        exit 0
      fi

      msg="${*:-manual checkpoint}"
      git stash push -u -m "checkpoint: $msg" &&
      git stash apply --index stash@{0}
      ;;
  esac
}; f'

echo "Installed git checkpoint alias."
echo
echo "Try:"
echo "  git checkpoint \"add matrix code\""
echo "  git checkpoint list"