Review an edit
Call capturePreview before applying a change when you need a stable comparison. After the operation completes, render the selected frame or comparison and check the revision, changed pixels, frame IDs, layer IDs, crop, and contact-sheet layout returned by the preview helper. A preview is evidence for review; it does not save the document.
Verify generated files
An export response means that file generation finished; it does not prove that a browser download completed. In the browser, fetch the page-local URL before the next export or editor unmount and verify the reported byte count. In desktop MCP, list artifacts, read at most 1 MiB at a time, verify the SHA-256 metadata, and save through the approved export folder.
Artifact records are temporary local handoff data. They expire after 24 hours and are bounded to 64 files, 128 MiB total, and 64 MiB per file.