I've been working with Re.Pack lately and needed to explain how it works to my team. So I made this with Opus 5.5. Host, mini apps, and why a mini app can never ship native code, in under 4 minutes. #ReactNative #RePack @repack_rn @callstackio

Meet TraceSift ⚡️ An open-source tool that turns CPU and React profiles into actionable performance insights without flooding your agent’s context. Early benchmark (GPT-5.6 Terra): • Codex: 45K tokens • TraceSift: 1.6K tokens That’s ~28× fewer tokens 👀

I'm finalizing Android support react-native-arrangement-view 🤖 Docs will include comparisons between iOS and Android in all poses and orientations, which I think it's pretty nice Screenshots taken with @agent_device obviously

T-5

Meta just announced new ways to build for Meta VR devices, and React Native is part of that story. The new Meta VR Layout SDK brings spatial, multi-panel experiences to React Native, while the new Expo Launch integration makes the path from an Expo project to Meta's Release Channels and Store much simpler. We've been working with @Meta on React Native support for VR, and today we're updating our developer documentation alongside the announcements. More coming soon in our React Native reference app as we add examples for the new spatial APIs. Read more 👉 clstk.com/3VvaKMc

RN PlainText 0.9 is out ✨ Even faster rendering, even better compatibility, and the big one: a drop-in replacement for RN <Text>. Want to try it in your app? Just change one import and feel the perf difference!

Software development is moving from hand-written implementation toward systems where engineers direct agents, shape context, and judge the result. In the Agent Conf 2026 keynote, Mike Grabowski and Michał Pierzchała share how @callstackio is adapting to that shift. Follow @apex__ai and @agent_device for real-time updates.

I think @maker__mark has the best argument for why React Native is the most operationally efficient choice for building mobile apps. Over the air updates help @Chime maximize their internal dogfooding They have over 250 OTA channels 🤯

I became a T3 Code user recently - it’s great especially if you have many subs and many machines to manage. I recommend giving it a shot if you haven’t already 👏. I also like in-app simulator preview experience support powered by @expo device hub (for streaming) and @agent_device (for agentic control) 😎

One of my favorite contributions to Callstack was establishing the Open Source fund back in 2023. We hand-pick the key contributors in our community and just send them money. Since then we donated over $26,000. There are many ways to give back. Find your own or steal this.

Here’s are @satya164 @ThomasreTech @ChmalSzymon and Victor Henrion! Only amazing content 🤩

Grateful for @o_kwasniewski sending over 20 PRs to agent-device while testing their e2e package 🙌 tester.army/e2e

Open source has been part of our DNA since 2016. To give back to those who shared their RN experience for RN at Scale 2026, we donated $1.3K to hot-updater, lerna-lite, changesets, release-it, react-native-maps, and react-native-keychain. Thank you to everyone maintaining them 💜

It's a good app, using it daily

Nice to learn about Voltra (RN Live Activities & Widgets) under the hood. Tough constraints, super cool ⚡ @ChmalSzymon @ReactNativeConn

Your app knows when checkout is done. Now your agent does too. postEvent() in the app. waitForEvent() in the agent or test. 12 real runs: sleep(3000) failed 5 and wasted 11 s. Waiting for the event: 12 passes. github.com/callstackincubato…

Opus 5.5 is finally good at handling multiple PRs in a single long-running thread. Previously I needed Fable to do this kind of thing.

Are you in Paris and want to grab a coffee and talk about agents testing your work or Apex - our go-to model for React Native? Let me know! We can catch up tomorrow before I head back to Poland 👀

I want to bring C++ exceptions to Swift. My proposal is to add a new 𝚂𝚆𝙸𝙵𝚃_𝚃𝙷𝚁𝙾𝚆𝚂 annotation to C++ methods, which imports them as 𝚝𝚑𝚛𝚘𝚠𝚜 in Swift. The 𝚜𝚝𝚍::𝚎𝚡𝚌𝚎𝚙𝚝𝚒𝚘𝚗::𝚠𝚑𝚊𝚝() will be copied into Swift to represent a Swift 𝙴𝚛𝚛𝚘𝚛 - fully on-stack. With the newly proposed compiler option -𝚌𝚡𝚡-𝚎𝚡𝚌𝚎𝚙𝚝𝚒𝚘𝚗-𝚖𝚘𝚍𝚎=𝚜𝚝𝚛𝚒𝚌𝚝, every C++ method that is not marked 𝚗𝚘𝚎𝚡𝚌𝚎𝚙𝚝 will be imported as 𝚝𝚑𝚛𝚘𝚠𝚜 in Swift - no 𝚂𝚆𝙸𝙵𝚃_𝚃𝙷𝚁𝙾𝚆𝚂 needed. This highlights why Swift's explicit 𝚝𝚑𝚛𝚘𝚠𝚜 requirement is a better language design decision than C++'s implicit "everything can throw". It's interesting that C++ exceptions are zero overhead if they are not throwing, while Swift is - because it essentially wraps everything that can throw in a 𝚁𝚎𝚜𝚞𝚕𝚝<𝚃>. forums.swift.org/t/handling-…

And that engineer was Albert Einstein