GSAP TanStack Router

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

Mount and unmount belong to React; animation owns the five phases between them. TanStack Router preserves shared layouts and can reuse routes on parameter changes; pending UI and loaders also affect when the new page appears.

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 @tanstack/react-router. Next.js belongs to gsap-nextjs, React Router to gsap-react-router, React without a router to gsap-react. Solid Router is out of scope.
2. Read the installed @tanstack/react-router version and, when present, @tanstack/react-start. Prefer their bundled types over memory: node_modules/@tanstack/router-core/dist/esm/router.d.ts for RouterOptions, RouterState, and RouterEvents, node_modules/@tanstack/react-router/dist/esm/useBlocker.d.ts for the blocker, node_modules/@tanstack/history/dist/esm/index.d.ts for history actions. The TanStack/router repository's docs/router/ and docs/start/ are the source of truth. The loading architecture changed during the 1.16x and 1.17x releases; RouterState.isTransitioning is gone from router-core 1.171.2x, and useBlocker is still marked experimental.
3. Tell file-based routes (createFileRoute, routeTree.gen.ts, __root.tsx) from code-based routes (createRoute, createRootRoute). The lifecycle is the same; only where route options live differs.
4. Tell TanStack Start (SSR, a root document shell with HeadContent and Scripts) from a client-only Vite app (RouterProvider rendered into a div). Client-only apps paint nothing before React, so they need no pre-paint rule. Check ssr per route, defaultSsr, spa.enabled, and prerendering.
5. Read the router options: defaultPreload, defaultPendingComponent, defaultPendingMs, defaultPendingMinMs, defaultViewTransition, scrollRestoration, defaultStaleTime, defaultRemountDeps. Each changes when pages mount and what the user sees while they load.

Choose the engine

Use defaultViewTransition or Link/navigate viewTransition for snapshot morphs or page crossfades. 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.
• Router APIs and the order of one navigation, outro before navigation with useBlocker or an intercepted Link, the lock, back and forward, pending UI, the swap gap, scroll, focus, View Transitions: TanStack navigation.
• Route reuse versus remountDeps, layouts and Outlet, the React lifecycle for GSAP, conditional content, TanStack Start SSR and hydration, deferred data: Route lifetime.
• The five phases, GSAP setup, show and hide, layout stability, scroll, text, plugins: Lifecycle implementation.
• Lenis, ScrollSmoother, or eased page scrolling across routes: Smooth scrolling, plus the TanStack integration.
• Curtains, first-visit preloaders, and shared-element morphs: Transition archetypes, plus where they live under TanStack 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. useGSAP never runs on the server; keep GSAP calls out of module scope in files Start renders on the server. 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.
• Mount, then set initial values, then paint. Successful initialization never flashes settled content before the intro. Under Start, server HTML paints before hydration, so hide intro targets only under a root attribute set by a ScriptOnce inline script, only during the initial phase, with a no-JavaScript path.
• 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 mounted and visible through outro and end state. The router swaps only after every blocker allows the navigation and the loaders finish; resolve the blocker from the end callback.
• No router event fires before the URL changes. onBeforeNavigate runs after the history commit; only a blocker runs before it.
• A navigation to the same route with new params reuses the component. Run the lifecycle again against DOM that already holds settled values, keyed on the params, or set remountDeps.
• Back and forward arrive with action BACK, FORWARD, or GO. Never run an outro for them; the URL has already moved when the blocker runs. Give them an intro-only path after scroll restoration.
• useLocation moves to the destination when loading starts, before the new page mounts. Do not key route content on it; key on the presented matches or on resolvedLocation.
• Keep native link behavior, preloading, activeProps, focus, scroll, and no-JavaScript readability.
• Reduced motion reaches the same settled state and still fires every completion callback, including the one that lets the blocked navigation proceed.
• 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.