run_cron_tool() {
  install_cron_direct() {
    local repo="${SKILLS_ZIG_REPO:-$HOME/workspace/tk/skills-zig}"
    if ! command -v zig >/dev/null 2>&1; then
      echo "zig not found. Install Zig from https://ziglang.org/download/ and retry." >&2
      return 1
    fi
    if [ ! -d "$repo" ]; then
      echo "skills-zig repo not found at $repo." >&2
      echo "clone it with: git clone https://github.com/tkersey/skills-zig \"$repo\"" >&2
      return 1
    fi
    if ! (cd "$repo" && zig build build-cron -Doptimize=ReleaseFast); then
      echo "direct Zig build failed in $repo." >&2
      return 1
    fi
    if [ ! -x "$repo/zig-out/bin/cron" ]; then
      echo "direct Zig build did not produce $repo/zig-out/bin/cron." >&2
      return 1
    fi
    mkdir -p "$HOME/.local/bin"
    install -m 0755 "$repo/zig-out/bin/cron" "$HOME/.local/bin/cron"
  }

  local os="$(uname -s)"
  if command -v cron >/dev/null 2>&1 && cron --help 2>&1 | grep -q "cron.zig"; then
    cron "$@"
    return
  fi

  if [ "$os" = "Darwin" ]; then
    if ! command -v brew >/dev/null 2>&1; then
      echo "homebrew is required on macOS: https://brew.sh/" >&2
      return 1
    fi
    if ! brew install tkersey/tap/cron; then
      echo "brew install tkersey/tap/cron failed." >&2
      return 1
    fi
  elif ! (command -v cron >/dev/null 2>&1 && cron --help 2>&1 | grep -q "cron.zig"); then
    if ! install_cron_direct; then
      return 1
    fi
  fi

  if command -v cron >/dev/null 2>&1 && cron --help 2>&1 | grep -q "cron.zig"; then
    cron "$@"
    return
  fi
  echo "cron binary missing or incompatible after install attempt." >&2
  if [ "$os" = "Darwin" ]; then
    echo "expected install path: brew install tkersey/tap/cron" >&2
  else
    echo "expected direct path: SKILLS_ZIG_REPO=<skills-zig-path> zig build build-cron -Doptimize=ReleaseFast" >&2
  fi
  return 1
}