Live Dev Session: <Activity>, Expo SDK 54, Router v6, Lynx 3.4, TanStack Start

This week’s livestream was packed with fresh releases, new components, and framework updates across the React ecosystem. From React’s new <Activity> component to Expo Router v6 and beyond, there’s a lot for devs to dig into.

Here’s what we covered, why it matters, and where to try it yourself.

React’s new <Activity> component

React is experimenting with a brand new <Activity> component. It’s something between conditional rendering and display: none:

• Hides parts of the tree without unmounting them
• Preserves state & DOM
• Keeps effects alive
• Deprioritizes rendering to improve app performance

Try it in the playground.

Why it matters: <Activity> is a big step toward giving devs more fine-grained control over rendering without losing app state or introducing unnecessary unmounts. Expect to see more around this as React 19+ continues to roll out.

Expo SDK 54

Expo 54 is out, and it’s one of the biggest releases of the year. Some highlights:

• Targets Android 16 (API 36) with edge-to-edge layouts always on
• Precompiled React Native binaries → dramatically faster iOS builds
• Transitive autolinking → cleaner native module setup
• Stable object-based file system API → better performance & New Architecture support

Here’s the full changelog.

Why it matters: SDK 54 puts developer experience first: faster iOS builds and fewer native headaches mean smoother iteration, especially on larger apps.

Expo Router v6

Expo Router v6 brings navigation a step closer to a truly native experience. What’s new:

• Link previews (<Link.Preview>) → iOS-style peek & pop
• Context menus → richer interactions out of the box
• Server middleware → hybrid SSR/web support
• Liquid glass tab transitions + improved modals

Why it matters: Router v6 pushes Expo closer to parity with native navigation, while also bridging into web + SSR territory. It’s becoming more than just a router — it’s a core app architecture piece.

Lynx 3.4

The Lynx team shipped a big release with platform support, core elements, and new dev tools. Highlights:

• HarmonyOS support + full Windows dev environment
• Long-awaited <input> and <textarea> support
• New Trace (rendering pipeline visualizer) & Recorder (session replay debugger) tools
• Optimized list recycling & improved animations

Why it matters: Lynx continues to expand as a cross-platform UI runtime. With proper input support and powerful dev tools, it’s becoming a serious contender for complex apps.

TanStack Start RC

TanStack Start, the full-stack React framework from the TanStack team, is now in Release Candidate.

Features include:

• Built on TanStack Router
• SSR and streaming baked in
• First-class server functions
• Data caching + full-stack integration

Why it matters: TanStack has consistently raised the bar for React tooling. Start positions itself as a modern, production-ready full-stack framework with smart defaults and strong performance.

React Router: RSC Framework Mode preview

React Router is previewing a new Framework Mode that leans into React Server Components.

Why it matters: Framework Mode represents a shift; React Router isn’t just a client router anymore, it’s moving into the RSC-native era with server-first patterns.

Final thoughts

This was a dense couple of weeks for React devs. <Activity> could change how we handle rendering state, Expo 54 and Router v6 are pushing the ecosystem forward, Lynx is becoming more capable, and TanStack + React Router are shaping the next wave of full-stack React.

Catch the livestream replay for demos, examples, and live takes. And as always, huge thanks to the This Week in React crew (@sebastienlorber, @tboba_, and @piaskowyk) for sharing insights and context.

‍