ComfyUI takes undo steps on mouse-up and key-up; a drag-and-drop ends in
neither, and writes made in click handlers or after a fetch landed in no
step, so Ctrl+Z could undo the step before instead. canvas_history.js asks
for a step after each write (applied values, drops, created or inserted
nodes, recipes, prompt notes).
A drop's receipt also pops up at the top right with Undo (shared with the
receipt's own button); prompt nodes made by a drop on empty canvas can be
undone there. canvas_undo.js keeps what each canvas activity entry did, in
full, while the page is open; the log offers Undo while nothing changed it
since. Entries that removed nodes or rewired existing ones, seeds, and
choices this computer no longer has are never offered.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
