React 19 Runtime Proof

Use this when React 19.2 primitives are proposed as part of a perf lane.

Activity

Use Activity for hidden/background UI panels, inspectors, preview panes, or likely-next views where hidden mode can unmount effects and defer updates.

Do not treat Activity hidden as a Slate hidden editable content primitive. It does not solve browser find, native selection, IME, copy/paste, screen-reader, or DOM point mapping.

Transitions And Deferred Work

Use transitions/deferred values for overlays, search results, sidebars, background summaries, and non-urgent projections.

Keep visible typing, DOM text sync, selection import/export, caret repair, and IME urgent.

Effect Events

Use useEffectEvent only for event-like callbacks fired from effects or external subscriptions. Do not use it to silence dependency warnings.

Performance Tracks

Capture React Performance Tracks when React work breadth is suspicious:

Scheduler priority
blocking vs transition work
component render/mount
effect cost
blocked/yielded work

React tracks prove React work breadth. They do not prove editor dirtiness, selection mapping, or native behavior correctness.

Server APIs

cacheSignal and partial pre-rendering are page-shell/server tools. They are usually irrelevant to the editor body hot path.