Method guarded

src/workflow/runtime.py:238–245

(index: int, item)

        base = current_branch().path + (current_branch().next_slot(),)

        async def guarded(index: int, item):
            token = use_branch(base + (index,))
            try:
                return await await_item(item)
            except Exception:
                return None  # the barrier never rejects
            finally:
                reset_branch(token)

        return list(await asyncio.gather(*(guarded(i, it) for i, it in enumerate(items))))