fxcss compare

fxcss compare --base shots/before --head shots/after --out diff/

Diffs two sets and writes one stacked before / after / changed-pixels image per view that differs. Views that render identically are reported rather than pictured, so you only look at what actually changed.

--out therefore holds comparison images for changed views only, plus a summary.json and a full/ directory carrying a normalised copy of every head capture, changed or not. So <out>/full/ is what a preview comment shows when nothing differs — and shot's own --out (flat, no full/) is what to read when you just want the screenshots.

Explore the verified before/after comparison.

This is what makes it useful in CI: render your theme at the base commit and at a pull request, and the diff shows a reviewer exactly what the change does. See Using it in CI.

A successful comparison reports differences; changed pixels alone do not make compare fail. Review the images to decide whether a change is intended. If your project needs a pass/fail threshold, use fxcss check or a custom check using summary.json. Added and missing views are reported as changes. Missing, empty or unreadable screenshot inputs return an error. Reusing an output directory clears the previous report's generated images so stale comparisons do not survive into a new result.