Going back to a save left the last run's picture on the output node, so the canvas and the picture told different stories.
- api/workflow_saves.py keeps what each output node made, previews too, the newest 16, and read_group gives them as `outputs`.
- ui_snapshot_bar.js puts them on the nodes through the tab's changeTracker (store, restore): no `executed` event, so no plugin takes them for a new run. Several runs sit on the node as a batch does. A node the save has no picture for goes empty; Load Image's own picture stays (snapshot_plan.outputsAt).
The lit number went out every other time with a Preview Image on the canvas, and an empty undo step came with it: a loaded workflow serializes a little differently from its file, and a node gains an empty widget list when it shows a picture. The number now goes out only when the canvas really changed (withoutEmptyValues), and those differences take no step.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
