📨 #301: TanStack Start, React Aria, Base UI, Satori, Next.js, Vitest RSC, MobX | RN Web, Tamagui, One, Skia, Observe, Screens, Hot Updater, Nano Icons | Deno, Bun, TS, JPEG XL, AsyncContext, Playwright, pnpm, Partytown

Hi everyone, Seb and Jan here 👋!

TanStack Start 1.0 is finally stable, a client-first alternative to server-first React frameworks.

On mobile, Expo will maintain React Native Web, under the React Foundation. Tamagui v3 and One v2 are out. React Native 0.88 is at RC5, so it should land very soon!

Deno is joining Cloudflare. JPEG XL lands in Chrome and Firefox. TypeScript is getting ported to Rust, twice.

Let's dive in!

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⚛️ React

TanStack Start 1.0

The full-stack framework is officially stable and production-ready, supporting both React and Solid. It has already been used on millions of apps during its beta/RC phase. As its 𝕏 launch video puts it: "Feels like building a SPA. With the whole server behind you".

• Client-first: SPA-style routing, state and caching, with server rendering, streaming and typed server functions.
• Type-safe end to end: route params, search params, loader data and server function inputs are all typed, keeping changes consistent for both humans and agents. Type checking speed has been thoroughly optimized.
• Agent-ready: packages ship TanStack Intent skills, so agents can learn Start's APIs and best practices.
• RSC is opt-in: supported, but the team removed it from tanstack.com because it made the codebase harder to reason about.
• Deploy anywhere with Vite and Nitro. Rsbuild is also supported.

• 💸 Lingui - React i18n macros now compile natively in Vite, 2.5x faster than SWC and nearly 30x faster than Babel
• 💬 React RFC - React work counters - Suggests improving the production observability of React by exposing metrics such as number of re-renders, setState calls or commits. I like the idea of giving metrics for agents to hill-climb and optimize against.
• 👀 MobX PR - MobX React plugin - An upcoming bundler plugin will help MobX and the React Compiler coexist. Wraps components in observer(), adds "use no memo" directives, turns async methods into MobX flows.
• 👀 Next.js PR - eslint-config-next supports ESLint 10 - eslint-plugin-react still doesn't support ESLint 10, so Next.js 16.5 canary patches it in place. Next.js users can finally upgrade.
• 🔐 Next.js - Upcoming security update - Planned for October 14: 2 critical and 1 high severity vulnerabilities in upstream dependencies.
• 📜 Can we Make React Faster using the React Compiler? - Explains what the compiler outputs, how it works, and then prototypes various optimizations: component inlining, Million.js-style blocks, Solid-like list selection, automatic context and Zustand selectors...
• 📜 className Considered Harmful - How design systems drift when components accept className, and how popular design systems restrict it. Why not a DANGEROUS_className prop 🤔.
• 📜 How we made a 9 MB WebAssembly module feel faster without removing a single byte - A chain of suspending components delayed the loading of a large WASM file. Preloading it made the first canvas render 15-19% faster.
• 📜 A visual notation for React's parent and owner trees - A diagram format for showing component structure, ownership, and context at a glance.
• 📜 Debugging Suspense with the React Suspense Panel - A practical tour of the new React DevTools 8.0 Suspense tab.
• 💸 Sentry - Stop scrubbing replays. Learn the sampling, filters, and React hooks that find the right session, live on Nov 5th. Save your spot
• 📦 React Aria 1.22 - New Sheet component, virtual-keyboard-aware overlays - The new swipeable Sheet component uses no JS touch handlers, only CSS scroll snapping and view timelines.
• 📦 Satori 0.36 → 0.55 - Converts JSX/HTML and CSS to SVG - Lots of releases this week, notably switching its layout engine from Yoga to Taffy, unlocking many new features like CSS grid and more.
• 📦 Vitest Plugin RSC 0.3 - Run Next.js App Router apps in Vitest Browser Mode - Lets you test the full RSC pipeline (server render, hydration, Server Actions) of a component or a whole route. Requires Next.js 16.4+.
• 📦 Base UI 1.9 - Filterable Menu, faster Select/Combobox/Menu, improved Drawer gestures
• 📦 Styled Components 6.6 - StyledComponent type for isolatedDeclarations, faster type-checking, RSC global styles fix
• 📦 React Hook Form 7.90 - Many bug fixes and perf improvements
• 📦 Astryx 0.7 - Easier form styling, better mobile and touch support, spacing in rem
• 📦 Vinext 1.1 - Next.js parity fixes, stale-while-revalidate for "use cache"
• 📦 Remocn Studio 1.0 - A macOS app where your coding agent makes Remotion videos
• 🎥 Ankita Kulkarni - Next.js 16.4 Is Built for Agents (Here's Why)
• 🎙️ This Month in React - September 2026 - React 19.3, a eulogy to software engineering?

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📱 React-Native

• 💸 PostHog - 10,000 PRs a month is easy: How devex is evolving at PostHog
• 👀 Expo to maintain React Native Web, moving to React Foundation
• 👀 RNTester moves to native UITabBarController for iPhone Duo support
• 📜 Your skills need an evaluation mechanism - Direct invocation doesn't prove discovery. Evals must test normal prompts and traces.
• 📜 Sharing a TypeScript Domain Layer Between Next.js and Expo - Share types, validation schemas and thin API client. Keep navigation, UI, storage and session handling app-local.
• 📜 You Don’t Need a Rewrite: Expo’s New Brownfield React Native Story - Brownfield has historically been hard, but things changed with Expo SDK 54. Covers myths vs. realities.
• 💸 Maestro MCP - Open-source MCP server for mobile UI testing with AI agents
• 📦 Skia 3.1 → 3.4 - New snapshot API, shared WebGPU instance via Dawn, tvOS and Mac Catalyst support
• 📦 RNTL 14.1 - fireEvent.layout, userEvent.pullToRefresh, userEvent.accessibilityAction, RN 0.88 support
• 📦 Tamagui 3 - New C++ native runtime, Rust compiler, Strict DOM, flat style props, Tailwind syntax
• 📦 One 2.0 - All-in-one RN framework, Bun for cross-platform, Rust bundler, SwiftUI and Compose generated
• 📦 Better PDF 1.0 - PDFKit and PdfRenderer, Native viewer on Nitro Views, no WebView or JS in scroll path - 91ms for 1,000 pages, 8x faster than react-native-pdf on large docs per author benchmark.
• 📦 Expo Native Variants - Generate Xcode schemes and Android flavors using an Expo config plugin in one prebuild
• 📦 WiFi Aware - Peer-to-peer discovery and high-bandwidth data over Wi-Fi Aware
• 📦 Hot Updater 1.0 - Shared release catalog, insights, remote config, plugins
• 📦 Sentry 8.30 - Cellular generation in connection type, Hermes Expo trace fixes
• 📦 Nano Icons 1.0 - Hot reload Metro plugin, native tab bar symbols, animatable size and color
• 📦 Screens 4.29 - iOS Tabs move to UITab API, search tab, sidebar placement, custom icons - Pairs well with Nano Icons.
• 📦 Argent 0.28 - iOS launch arguments, flows over a link, failed-step screenshots
• 📦 Expo Observe - Native crash reporting on Android and iOS, no setup, AI handoff
• 📦 Rozenite 2.5 - Lynx project detection, XHR-first network capture, Redux action filters, agent grammar v3
• 📦 Galeria 3.1 - Photo and video galleries on iOS, Android and web
• 🎥 Callstack - Ten Agents Waiting for Input: Tzvetan Mikov on AI Coding and Hermes
• 🎙️ RNR 375 - RNR Explains: EAS Update

🔀 Other

• 👀 HTML PR - AsyncContext integration - Still TC39 stage 2, this exciting feature is actively worked on, in particular its integration with web platform APIs.
• 📣 Deno is joining Cloudflare - The Deno team is joining to work on the Workers and toward making the Durable Objects programming model self-hostable. The Deno runtime and Deno Deploy will be sunset.
• 📜 The best way to use icons in Web UIs - Using icons as CSS design tokens, inserted and tweaked with pseudo-elements, masks, and style queries.
• 📜 Iframes that finally fit their content - Chrome 154 ships frame-sizing: content-height. Iframes can now adjust their size without the postMessage + ResizeObserver dance.
• 📜 JPEG XL finally lands in Chrome 155 and Firefox 158. Safari already has partial support.
• 📦 Bun 1.4.3 - bun check type checker, 67% lower idle CPU in servers, Bun.FetchSession, faster JSON.parse - Includes a port of typescript-go running 3-6x faster. No emit, no LSP. Coming next: 𝕏 bun lint with 1,000+ built-in rules and 𝕏 bun fmt, a 320x faster Prettier alternative.
• 📦 tsc-rs - Rust port of the TypeScript 7 compiler, type checker, and LSP - Theo’s agent-driven port of TS, with the Effect language service diagnostics built in.
• 📦 Playwright 1.64 - WebMCP testing APIs, better videos (custom fps, CSS-styled actions, VP9), --shuffle, locator.within()
• 📦 pnpm 12.11 → 12.13 - Agent skills linking, remote cache for task results and builds
• 📦 Partytown 1.0 - Run third-party scripts in a web worker, now stable
• 📦 Safari Technology Preview 254 - calc-size(), interpolate-size, CSS linked parameters, and more

🤭 Fun

See ya! 👋