feat(core): track animation settle with data-transitioning lifecycle

[sampotts]

Summary

• Adds a transitioning flag to createTransition that stays true until open/close animations settle, and exposes it as data-transitioning through popover/menu/tooltip/alert-dialog cores.
• Restores popover close-animation coordination (setElement, deferred reopen during ending) on top of the transition API changes.
• Adds generic data-transitioning:overflow-hidden skin hooks for popups and menus (submenu-view selectors remain in the viewport/settings stack).

Transitioning vs status

createTransition state has both status (idle | starting | ending) and a separate transitioning boolean. They are not folded into one field because they answer different questions:

Field	Question it answers	Drives
status	Which CSS style-hook phase are we in?	data-starting-style, data-ending-style
transitioning	Is motion still in progress (Web Animations / CSS settle)?	data-transitioning

On open, status becomes idle after a double-RAF so the browser can paint the “from” state and drop data-starting-style before the enter animation runs—but the popup may still be animating. transitioning stays true until getAnimations({ subtree: true }) settles. That gap (status: idle, transitioning: true) is intentional: style hooks and layout/interaction guards need different lifetimes.

On close, both overlap more (status: ending, transitioning: true), but status still tracks the ending-style hook while transitioning covers the full settle window—including descendant animations and CSS transition fallbacks.

Consumers use data-transitioning for concerns that should span the whole animation (overflow clipping, deferring trigger re-open until close finishes) without overloading status or keeping data-starting-style / data-ending-style active longer than the CSS hooks require.

Stack position

feat/captions-menu → feat/menu-popup-group (#1577) → this PR → feat/menu-viewport (#1579) → …

Test plan

• pnpm build:packages && pnpm typecheck
• pnpm -F @videojs/core test src/dom/ui/tests/transition.test.ts src/dom/ui/popover
• Manual: open/close a captions menu and confirm data-transitioning is present during the animation window

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Note

Medium Risk
Touches core open/close transition plumbing and popover interaction timing (click/blur/outside-dismiss), which can regress UI dismissal/animation behavior across platforms; changes are well-covered by updated and expanded tests.

Overview
Adds a first-class transitioning lifecycle for UI transitions. TransitionState now includes transitioning, getTransitionFlags/getTransitionStyleAttrs expose it as data-transitioning, and core UI states (PopoverCore, MenuCore, TooltipCore, AlertDialogCore, input indicators) propagate the flag.

Updates DOM transition + popover behavior to respect animation settling. createTransition now tracks a registered element via setElement, waits for getAnimations({ subtree: true }) (plus optional CSS-transition fallback), and keeps transitioning true until settle; createDismissLayer.open() can receive an element. createPopover is adjusted to pass the popup element into open, defer re-open clicks during ending until close completes, and harden blur/outside-dismiss edge cases (incl. group peer-trigger checks).

Skins/presets adopt the new attribute hook. Default/minimal CSS and Tailwind utilities add data-transitioning:overflow-hidden, and React/HTML presets stop composing popup.popover into menu content classes in favor of the menu root styling shell.

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Project	Deployment	Actions	Updated (UTC)
v10-sandbox	Ready	Preview, Comment	May 21, 2026 6:06am

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