accounted/.agents/skills/vercel-react-view-transitions/SKILL.md

name, description, license, metadata

name	description	license	metadata
vercel-react-view-transitions	Guide for implementing smooth, native-feeling animations using React's View Transition API (`<ViewTransition>` component, `addTransitionType`, and CSS view transition pseudo-elements). Use this skill whenever the user wants to add page transitions, animate route changes, create shared element animations, animate enter/exit of components, animate list reorder, implement directional (forward/back) navigation animations, or integrate view transitions in Next.js. Also use when the user mentions view transitions, `startViewTransition`, `ViewTransition`, transition types, or asks about animating between UI states in React without third-party animation libraries.	MIT	author version vercel 1.0.0

React View Transitions

Animate between UI states using the browser's native document.startViewTransition. Declare what with <ViewTransition>, trigger when with startTransition / useDeferredValue / Suspense, control how with CSS classes. Unsupported browsers skip animations gracefully.

When to Animate

Every <ViewTransition> should communicate a spatial relationship or continuity. If you can't articulate what it communicates, don't add it.

Implement all applicable patterns from this list, in this order:

Priority	Pattern	What it communicates
1	Shared element (name)	"Same thing — going deeper"
2	Suspense reveal	"Data loaded"
3	List identity (per-item key)	"Same items, new arrangement"
4	State change (enter/exit)	"Something appeared/disappeared"
5	Route change (layout-level)	"Going to a new place"

This is an implementation order, not a "pick one" list. Implement every pattern that fits the app. Only skip a pattern if the app has no use case for it.

Choosing Animation Style

Context	Animation	Why
Hierarchical navigation (list → detail)	Type-keyed nav-forward / nav-back	Communicates spatial depth
Lateral navigation (tab-to-tab)	Bare <ViewTransition> (fade) or default="none"	No depth to communicate
Suspense reveal	enter/exit string props	Content arriving
Revalidation / background refresh	default="none"	Silent — no animation needed

Reserve directional slides for hierarchical navigation (list → detail) and ordered sequences (prev/next photo, carousel, paginated results). For ordered sequences, the direction communicates position: "next" slides from right, "previous" from left. Lateral/unordered navigation (tab-to-tab) should not use directional slides — it falsely implies spatial depth.

---

Availability

• Next.js: Do not install react@canary — the App Router already bundles React canary internally. ViewTransition works out of the box. npm ls react may show a stable-looking version; this is expected.
• Without Next.js: Install react@canary react-dom@canary (ViewTransition is not in stable React).
• Browser support: Chromium 111+, Firefox 144+, Safari 18.2+. Graceful degradation on unsupported browsers.

---

Implementation Workflow

When adding view transitions to an existing app, follow references/implementation.md step by step. Start with the audit — do not skip it. Copy the CSS recipes from references/css-recipes.md into the global stylesheet — do not write your own animation CSS.

---

Core Concepts

The <ViewTransition> Component

import { ViewTransition } from 'react';

<ViewTransition>
  <Component />
</ViewTransition>

React auto-assigns a unique view-transition-name and calls document.startViewTransition behind the scenes. Never call startViewTransition yourself.

Animation Triggers

Trigger	When it fires
enter	<ViewTransition> first inserted during a Transition
exit	<ViewTransition> first removed during a Transition
update	DOM mutations inside a <ViewTransition>. With nested VTs, mutation applies to the innermost one
share	Named VT unmounts and another with same name mounts in the same Transition

Only startTransition, useDeferredValue, or Suspense activate VTs. Regular setState does not animate.

Critical Placement Rule

<ViewTransition> only activates enter/exit if it appears before any DOM nodes:

// Works
<ViewTransition enter="auto" exit="auto">
  <div>Content</div>
</ViewTransition>

// Broken — div wraps the VT, suppressing enter/exit
<div>
  <ViewTransition enter="auto" exit="auto">
    <div>Content</div>
  </ViewTransition>
</div>

---

Styling with View Transition Classes

Props

Values: "auto" (browser cross-fade), "none" (disabled), "class-name" (custom CSS), or { [type]: value } for type-specific animations.

<ViewTransition default="none" enter="slide-in" exit="slide-out" share="morph" />

If default is "none", all triggers are off unless explicitly listed.

CSS Pseudo-Elements

• ::view-transition-old(.class) — outgoing snapshot
• ::view-transition-new(.class) — incoming snapshot
• ::view-transition-group(.class) — container
• ::view-transition-image-pair(.class) — old + new pair

See references/css-recipes.md for ready-to-use animation recipes.

---

Transition Types

Tag transitions with addTransitionType so VTs can pick different animations based on context. Call it multiple times to stack types — different VTs in the tree react to different types:

startTransition(() => {
  addTransitionType('nav-forward');
  addTransitionType('select-item');
  router.push('/detail/1');
});

Pass an object to map types to CSS classes. Works on enter, exit, and share:

<ViewTransition
  enter={{ 'nav-forward': 'slide-from-right', 'nav-back': 'slide-from-left', default: 'none' }}
  exit={{ 'nav-forward': 'slide-to-left', 'nav-back': 'slide-to-right', default: 'none' }}
  share={{ 'nav-forward': 'morph-forward', 'nav-back': 'morph-back', default: 'morph' }}
  default="none"
>
  <Page />
</ViewTransition>

enter and exit don't have to be symmetric. For example, fade in but slide out directionally:

<ViewTransition
  enter={{ 'nav-forward': 'fade-in', 'nav-back': 'fade-in', default: 'none' }}
  exit={{ 'nav-forward': 'nav-forward', 'nav-back': 'nav-back', default: 'none' }}
  default="none"
>

TypeScript: ViewTransitionClassPerType requires a default key in the object.

For apps with multiple pages, extract the type-keyed VT into a reusable wrapper:

export function DirectionalTransition({ children }: { children: React.ReactNode }) {
  return (
    <ViewTransition
      enter={{ 'nav-forward': 'nav-forward', 'nav-back': 'nav-back', default: 'none' }}
      exit={{ 'nav-forward': 'nav-forward', 'nav-back': 'nav-back', default: 'none' }}
      default="none"
    >
      {children}
    </ViewTransition>
  );
}

router.back() and Browser Back Button

router.back() and the browser's back/forward buttons do not trigger view transitions (popstate is synchronous, incompatible with startViewTransition). Use router.push() with an explicit URL instead.

Types and Suspense

Types are available during navigation but not during subsequent Suspense reveals (separate transitions, no type). Use type maps for page-level enter/exit; use simple string props for Suspense reveals.

---

Shared Element Transitions

Same name on two VTs — one unmounting, one mounting — creates a shared element morph:

<ViewTransition name="hero-image">
  <img src="/thumb.jpg" onClick={() => startTransition(() => onSelect())} />
</ViewTransition>

// On the other view — same name
<ViewTransition name="hero-image">
  <img src="/full.jpg" />
</ViewTransition>

• Only one VT with a given name can be mounted at a time — use unique names (photo-${id}). Watch for reusable components: if a component with a named VT is rendered in both a modal/popover and a page, both mount simultaneously and break the morph. Either make the name conditional (via a prop) or move the named VT out of the shared component into the specific consumer.
• share takes precedence over enter/exit. Think through each navigation path: when no matching pair forms (e.g., the target page doesn't have the same name), enter/exit fires instead. Consider whether the element needs a fallback animation for those paths.
• Never use a fade-out exit on pages with shared morphs — use a directional slide instead.

---

Common Patterns

Enter/Exit

{show && (
  <ViewTransition enter="fade-in" exit="fade-out"><Panel /></ViewTransition>
)}

List Reorder

{items.map(item => (
  <ViewTransition key={item.id}><ItemCard item={item} /></ViewTransition>
))}

Trigger inside startTransition. Avoid wrapper <div>s between list and VT.

Composing Shared Elements with List Identity

Shared elements and list identity are independent concerns — don't confuse one for the other. When a list item contains a shared element (e.g., an image that morphs into a detail view), use two nested <ViewTransition> boundaries:

{items.map(item => (
  <ViewTransition key={item.id}>                                      {/* list identity */}
    <Link href={`/items/${item.id}`}>
      <ViewTransition name={`item-image-${item.id}`} share="morph">   {/* shared element */}
        <Image src={item.image} />
      </ViewTransition>
      <p>{item.name}</p>
    </Link>
  </ViewTransition>
))}

The outer VT handles list reorder/enter animations. The inner VT handles the cross-route shared element morph. Missing either layer means that animation silently doesn't happen.

Force Re-Enter with key

<ViewTransition key={searchParams.toString()} enter="slide-up" default="none">
  <ResultsGrid />
</ViewTransition>

Caution: If wrapping <Suspense>, changing key remounts the boundary and refetches.

Suspense Fallback to Content

Simple cross-fade:

<ViewTransition>
  <Suspense fallback={<Skeleton />}><Content /></Suspense>
</ViewTransition>

Directional reveal:

<Suspense fallback={<ViewTransition exit="slide-down"><Skeleton /></ViewTransition>}>
  <ViewTransition enter="slide-up" default="none"><Content /></ViewTransition>
</Suspense>

For more patterns, see references/patterns.md.

---

How Multiple VTs Interact

Every VT matching the trigger fires simultaneously in a single document.startViewTransition. VTs in different transitions (navigation vs later Suspense resolve) don't compete.

Use default="none" Liberally

Without it, every VT fires the browser cross-fade on every transition — Suspense resolves, useDeferredValue updates, background revalidations. Always use default="none" and explicitly enable only desired triggers.

Two Patterns Coexist

Pattern A — Directional slides: Type-keyed VT on each page, fires during navigation. Pattern B — Suspense reveals: Simple string props, fires when data loads (no type).

They coexist because they fire at different moments. default="none" on both prevents cross-interference. Always pair enter with exit. Place directional VTs in page components, not layouts.

Nested VT Limitation

When a parent VT exits, nested VTs inside it do not fire their own enter/exit — only the outermost VT animates. Per-item staggered animations during page navigation are not possible today. See react#36135 for an experimental opt-in fix.

---

Next.js Integration

For Next.js setup (experimental.viewTransition flag, transitionTypes prop on next/link, App Router patterns, Server Components), see references/nextjs.md.

---

Accessibility

Always add the reduced motion CSS from references/css-recipes.md to your global stylesheet.

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Reference Files

• references/implementation.md — Step-by-step implementation workflow.
• references/patterns.md — Patterns, animation timing, events API, troubleshooting.
• references/css-recipes.md — Ready-to-use CSS animation recipes.
• references/nextjs.md — Next.js App Router patterns and Server Component details.

Full Compiled Document

For the complete guide with all reference files expanded: AGENTS.md