GSAP Next.js

mount → initial state → intro → settled → outro → end state → unmount

Mount and unmount belong to React; animation owns the five phases between them. With cacheComponents, treat route hide as unmount and re-show as mount on preserved DOM.

Keep the requested look and existing project conventions. Add GSAP/plugins only as needed; do not replace the chosen animation library unless asked.

This skill decides when motion runs. For what moves, and for a feel such as premium or playful, also load the animaxxing skill when it is installed: its recipes and its guide to finding the vibe plug into this lifecycle.

Start with the project

Read repository instructions, existing animation, layouts, navigation, CSS, accessibility conventions, and checks. Then:

1. Confirm the App Router. If the project uses the Pages Router, use version-matched Pages Router guidance instead of this skill.
2. Read the installed Next.js version. Prefer its bundled docs in node_modules/next/dist/docs/ over memory. Version gates: onNavigate and useLinkStatus (15.3), <ViewTransition> and transitionTypes (16.2), <Activity> route preservation when cacheComponents is enabled (16.0, opt-in).
3. Check the Next config for cacheComponents. It changes how long routes live.

Choose the engine

Use React <ViewTransition> for shared-element morphs, page crossfades, and Suspense swaps when supported by the installed Next.js version. Use GSAP for live-DOM outros that gate navigation, interruptible sequences, split text, or scroll-linked motion. One engine per element; see combining engines.

Read only what you need

• Invisible entrances, failed initialization, indexing, and first-load performance: Initialization and recovery, plus the framework integration.
• Loading/auth flashes and shifting async sections: Data readiness, plus React data integration.
• Page intros and outros, transition-aware links, back and forward, focus, route swaps: App Router navigation.
• The five phases, GSAP setup, React lifecycle, show and hide, layout stability, scroll, text, plugins: Lifecycle implementation.
• Lenis, ScrollSmoother, or eased page scrolling across routes: Smooth scrolling, plus the App Router integration.
• Curtains, first-visit preloaders, and shared-element morphs: Transition archetypes, plus where they live in the App Router.
• Touch, viewport changes, and device budgets: Devices and input.
• Tauri, Electron, or Wails desktop shells: Desktop webviews.
• Before calling work done: Verification.

Install the official GSAP skills alongside this repository. Load gsap-core for API details and gsap-react for component setup only as needed.

Rules

• Preserve invisible intros on successful setup; recover the current incoming owner on failure. Follow the initialization contract before adding hiding rules.
• GSAP runs only on the client. Scope selectors. Clean up every tween, trigger, split, and listener.
• Reserve final geometry with normal CSS and a stable wrapper; overlap outgoing/incoming content without doubling layout space.
• Reveal each owner when its structural data is ready; unresolved auth or queries must not masquerade as guest or empty content.
• Mount, then set initial values, then paint. Successful initialization never flashes settled content before the intro.
• Clear temporary styles at settled. Use will-change only while animating; this overrides gsap-performance's static hint.
• Use capability queries for device tiers. Touch states release; controls work without hover.
• Keep outgoing pages and components mounted and visible through outro and end state. Unmount, or let the router hide, only after the end callback.
• Under cacheComponents, a page lifecycle runs again on re-show against DOM that already holds settled values. Never assume a fresh node.
• Back and forward never run an outro. Give them an intro-only path.
• Keep native link behavior, focus, scroll, and no-JavaScript readability.
• Reduced motion reaches the same settled state and still fires every completion callback.
• Define interruption and rapid-click behavior; completion must release navigation waits exactly once.
• Verify in a real browser when practical. Use a production build for route, config, dependency, or release changes.