Stopping a generation is a normal thing to do -- a bad seed, a wrong prompt,
a rental minute -- so it is not an error path that can be left approximate.
A leak here is invisible: the run AFTER a cancel just behaves slightly wrong.
The sampler says a run was cancelled and re-raises. It is not ours to
absorb; ComfyUI ends the queue item. But a run that simply stops with
nothing said is indistinguishable from one that broke.
Verified against the real engine: a 40-step generation interrupted mid-way
reports execution_interrupted, and the next one completes as run 2. Tests
cover what must be left behind, which is nothing -- no wrappers on the shared
model after five cancelled runs, the sharp anchor put back on a denoiser that
outlives the run, and no modifier marked as dropped, because a cancelled
modifier did not fail and disabling it next time would punish the user for
stopping.
Temp previews needed no change: core's PreviewImage already writes to the
temp directory under a unique prefix, so where the app SHOWS them is a UI
decision and is recorded as one rather than built here.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
