For each animation it resolves the role, reads what the export recorded under reduced motion, and compares that record with the role's ceilings. A decorative animation that never stops has to stop; an animation carrying essential feedback has to leave something behind when it does.
This walkthrough uses the tool's public README and checked-in example files. Run the command from a repository checkout with Node.js 22+.
Run the checked-in example
# a clean run: the perpetual decorative animation stops, and the progress feedback survives
node bin/motion-reduction-auditor.mjs \
--capture examples/clean/capture.json \
--rules examples/clean/motion.rules.json \
--now 2026-09-18
# exit 0, status "pass"
# a failing run: an animation that keeps spinning, one with no declaration at all,
# and progress feedback that disappears
node bin/motion-reduction-auditor.mjs \
--capture examples/failing/capture.json \
--rules examples/failing/motion.rules.json \
--now 2026-09-18
# exit 1, status "fail"
# an undetermined run: an animation nobody inspected, a pause control nobody recorded,
# and a static alternative the rules do not recognise
node bin/motion-reduction-auditor.mjs \
--capture examples/undetermined/capture.json \
--rules examples/undetermined/motion.rules.json \
--now 2026-09-18
# exit 2, status "incomplete"Read the result
--now is optional and defaults to the system clock. Supply it to make a run that checks capture age reproducible; every example above is pinned to one instant for that reason.
Scope
These are behaviour, not caveats. Each one is enforced by a test.