A node's "Mark this state" keeps the serialized canvas as a mark in a bar
under it. A mark's number goes back to that state, each has its runs, and
seeds are Random or Locked (one per round, shared by the marks; a fixed
seed alone would come from ComfyUI's cache). Run checks every mark with
validate_prompt first, then compiles detached copies with their seeds
written, so the canvas and its seeds stay as they are.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
