update.sh

#!/usr/bin/env bash
# update.sh [--with-skills] — fast-forward the ONE shared engine install (#54, PRD #52). The engine
# lives at $HARNESS_HOME/engine (resolved here via ENGINE_DIR, set by bin/harness from the realpath
# of the entrypoint). One ff-pull updates every project at once — no per-project re-pull, no skew.
#   --with-skills  also refresh the superpowers/ralph-loop plugins + matt-pocock skills (host-level).
# Touches NO project .harness/: config + state live in the project, separate from the engine. Runs
# `git pull --ff-only` ONLY — no destructive git op that could discard untracked/ignored files.
set -uo pipefail
ENGINE_DIR="${ENGINE_DIR:-$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)}"
WITH_SKILLS=0; [[ "${1:-}" == "--with-skills" ]] && WITH_SKILLS=1

# fast-forward ONLY. No destructive git operations.
if ! git -C "$ENGINE_DIR" pull --ff-only; then
  echo "ERROR: 'git pull --ff-only' failed in $ENGINE_DIR (diverged or local engine edits)." >&2
  echo "       Resolve there manually; no project state is touched." >&2
  exit 1
fi
echo "  engine updated at $ENGINE_DIR — every project picks it up immediately."

# optional host-level plugin/skill refresh (reuse install.sh's ensure_skills + the /harness skill
# deploy). The engine was just ff-pulled, so redeploy its /harness skills to user scope from THIS
# engine — otherwise an engine update leaves stale ~/.claude/skills copies behind.
if (( WITH_SKILLS )); then
  HARNESS_INSTALL_NOMAIN=1 source "$ENGINE_DIR/install.sh"
  ensure_skills
  HARNESS_SKILL_SRC="${HARNESS_SKILL_SRC:-$ENGINE_DIR/skill}" install_harness_skills
fi

# if a pool is running (in this project's state dir), new engine logic only applies after a relaunch.
run_dir="${STATE_DIR:-$ENGINE_DIR}/run"
if compgen -G "$run_dir/worker-*.pid" >/dev/null 2>&1; then
  for pf in "$run_dir"/worker-*.pid; do
    kill -0 "$(cat "$pf" 2>/dev/null)" 2>/dev/null && {
      echo "NOTE: a worker pool is running. Live workers keep the OLD engine logic until relaunched."
      echo "      To apply this update safely: harness pause  →  let sessions drain  →  harness stop  →  harness start --recover"
      break
    }
  done
fi
echo "Update complete."