conditionalPlayback
Interaction-level field. This is authorable. Do not confuse it with
trigger-level conditionalLogic, which is gated off entirely — see
gated-capabilities.md.
Shape
An array of rule objects, not a keyed object:
conditionalPlayback: [
{type: 'prefers-reduced-motion', behavior: 'dont-animate'},
];Two forms:
{type: 'prefers-reduced-motion', behavior: 'dont-animate' | 'skip-to-end'}
{type: 'breakpoint', breakpoints: ['main' | 'medium' | 'small' | 'tiny'], behavior}A shape like {reducedMotion: 'skip'} is not the wire format and has never been.
On update, null clears the field; omitting it leaves the stored value alone.
Rejected
[REJECTED] Duplicate condition type values in the list.
Guard: findConditionalPlaybackError
[REJECTED] behavior: 'skip-to-end' while a continuous trigger
(wf:mouse-move) is present. Use dont-animate instead.
[LEGACY-OK-ON-UPDATE] The duplicate-type check is skipped on the update path
when the field is not being replaced, so stored data with duplicates is not forced
through a migration.
A deliberate carve-out
Scroll scrub is not covered by the skip-to-end restriction. The panel's own
filter checks controlType === 'continuous' only, and still offers skip-to-end
on scroll. The guard matches that deliberately, so the API is not stricter than
the panel.
Read that as the guard stopping where the panel stops, not as an oversight. If a future change tightens it, this note becomes incomplete rather than wrong.