Articles

Articles for developers, by developers

Technical articles on React, React Native, and AI engineering. We share what we learn from building products, maintaining open source, and putting agents to work across software delivery.

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Virtual Reality
10/15/2026

Multi-Window React Native Apps With the Meta VR Layout SDK

Add a second Quest window to your existing React Native tree without creating another Android activity. Follow a Meta VR Layout SDK companion-panel demo covering setup, shared state, window positioning, fallbacks, and testing with Meta Spatial Simulator.

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Tomasz Włodarczyk

Software Engineer

@

Callstack

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Testing
10/13/2026

Agentic Mobile Testing With e2e and agent-device

TesterArmy's e2e uses agent-device to drive mobile tests on iOS and Android. This article walks through goal-based actions, deterministic checks, the mobile engine, and replay caching, then shows how to initialize a test setup. Cached agent.act steps skip model calls; agent.assert continues to evaluate the current screen.

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Michał Pierzchala

Principal Engineer

@

Callstack

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AI
10/9/2026

How to Maximize AI SDLC? Measure the Outer Business Loop, Not the Inner Developer Loop

Matt Hargett explains how to measure AI-assisted development through the Outer Business Loop, which follows a change from its initial hypothesis to its effect on users and the business. An online platform optimization anchors his systems thinking approach to checking feature exposure, investigating mixed results, and calculating the holistic end-to-end cost of a measurable improvement.

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Matt Hargett

Consulting Principal Engineer

@

Callstack

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AI
10/8/2026

Building Reliable AI Figma-to-Code Loops

AI-generated screens can match a Figma design while bypassing your component library. Vitaly Kuprin explains how his team built a workflow that guides agents toward existing components, blocks unsupported imports, and compares rendered screens with the design. He also shares the checks that caught misleading screenshot results and the limits of visual verification.

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Vitaly Kuprin

Software Engineer

@

Callstack

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AI
10/2/2026

Introducing Mobile Dev: full mobile dev tooling right in your Codex app

Mobile Dev brings live device previews, annotations, logs, and performance profiling into Codex. Explore the initial preview for iOS and Android development, with built-in agent-device support.

Laurids Kern

Laurids Kern

Software Engineer

@

Margelo

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AI
10/1/2026

Apex Is Now Generally Available: Agentic Coding Model for Mobile and Web, Specialized in React

Apex is now publicly available. Built by Callstack, it brings React Native expertise to feature development, code reviews, debugging, and testing, with strong performance on Next.js tasks too. See the benchmark results, compare API pricing, explore self-hosting options, and get started with Apex in your own project.

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Michał Pierzchala

Principal Engineer

@

Callstack

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AI
9/17/2026

Exploring Jev for AI-Driven QA with agent-device

Jev is a model from TypeSafe that chooses between predefined options instead of generating text. We paired it with agent-device to explore what that approach could mean for AI-driven QA: reading app state, selecting actions, and checking the result. We walk through our proof of concept, how the two tools work together, and a recorded run that took 14 seconds and cost $0.0023 in model inference.

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Mike Grabowski

CEO & Founder

@

Callstack

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Super Apps
8/31/2026

Working With the React Native Super App Showcase Repository

This article explains how the Super App Showcase structures a React Native super app around a Host Shell, federated mini apps, and a Shared SDK. It covers how Re.Pack and Module Federation load feature bundles at runtime while the host keeps native code and shared singletons consistent. The cold-start sequence shows how these parts work together, while the sections that follow cover module setup, shared state, real-time data, and UI performance. The final section focuses on production requirements for remote bundle discovery and version compatibility.

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Bartłomiej Krok

Software Engineer

@

Callstack

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Brownfield
8/27/2026

React Native in .NET MAUI: A Practical Brownfield Integration Guide

This article walks through how we embedded React Native inside a .NET MAUI application using a brownfield setup. It covers the packaging layer, lifecycle wiring on iOS and Android, navigation through MAUI Shell, and shared state between the MAUI and React Native runtimes.

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Juozas Petkelis

React Native Developer

@

Callstack

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CI/CD
8/21/2026

Automating React Native Evals With Airflow

React Native Evals tests coding models on real React Native tasks. This article follows one automated run from model selection through solving, judging, result tracking, and human review.

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Lech Kalinowski

Senior AI System Engineer

@

Callstack

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Testing
8/4/2026

Automating Mobile QA With Cloud Agents

Agent-written PRs raise the volume of plausible code changes, but mobile release confidence still depends on what happens at runtime. This article explains why code review and E2E suites leave a gap, how bounded mobile QA agents close it, and why cloud-connected device hosts matter when teams need reviewable evidence before merge.

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Michał Pierzchala

Principal Engineer

@

Callstack

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Explore articles, interviews, and demos on React, React Native, and AI engineering, with lessons from the people building the tools.

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Article
10/15/2026

Multi-Window React Native Apps With the Meta VR Layout SDK

Build multi-window React Native apps for Meta Quest with the Meta VR Layout SDK. Learn shared state, fallbacks, positioning, and simulator testing.
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Article
10/13/2026

Agentic Mobile Testing With e2e and agent-device

See how e2e uses agent-device for AI-driven iOS and Android tests, combines exact assertions with agent actions, and replays cached steps without model calls.
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Article
10/9/2026

How to Maximize AI SDLC? Measure the Outer Business Loop, Not the Inner Developer Loop

Connect AI-assisted development to measurable business outcomes. Matt Hargett shares a checklist for assessing user exposure, results, and delivery costs.
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Article
10/8/2026

Building Reliable AI Figma-to-Code Loops

Build an AI Figma-to-code workflow that uses your design system and checks its output. Learn how component mappings, import checks, and visual feedback work.
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Article
10/2/2026

Introducing Mobile Dev: full mobile dev tooling right in your Codex app

Build mobile apps in Codex with live iOS and Android previews, annotations, native and JavaScript logs, and performance profiling in one plugin.
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Article
10/1/2026

Apex Is Now Generally Available: Agentic Coding Model for Mobile and Web, Specialized in React

Apex is now publicly available. Explore Callstack’s coding model for React Native and Next.js, with API pricing, benchmarks, and self-hosting options.
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Live Stream
Live Stream
10/15/2026

Who Left the Agents Running? React Native Software Factories

Join Kewin Wereszczyński and Szymon Chmal to explore what can go wrong in a React Native software factory overnight and the controls that keep agents on track.
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Live Stream
Live Stream
10/1/2026

Can Jev Make AI Agent Decisions Faster?

Explore Jev with Kewin Wereszczyński and Szymon Chmal: how it works, its approach to faster agent decisions, and possible local alternatives.
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Live Stream
Live Stream
8/27/2026

Graph Agentic Coding Extends AI Workflows

How connected state, retrieval, memory, and verification carry coding agents across complex, multi-step workflows. Kewin Wereszczyński and Lech Kalinowski discuss the structures that let agents plan, retrieve context, use tools, and keep working across longer tasks.
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Podcast
10/14/2026

When Coding Gets Faster, What Breaks Next?

Matt Hargett explains how AI moves bottlenecks across testing, deployment, infrastructure, support, and the rest of software delivery.
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Podcast
10/13/2026

MCP and Supervisor Agents in eBay's Monitoring Workflow With Leonel Candido da Silva

Leonel Candido da Silva explains eBay's agentic monitoring workflow: specialized agents, MCP, PagerDuty reports, and plans to learn from past incidents.
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Podcast
10/12/2026

AI Agent Observability With Ivana Huckova and Sven Großmann

Grafana's Ivana Huckova and Sven Großmann discuss AI agent observability, coding-agent costs, PR analytics, secret redaction, and local guardrails.
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Tutorial
March 19, 2026

The Hard Way vs. The React Native AI SDK Way: Stop Writing Custom Modules for Every Model

Learn how React Native AI uses a unified provider model to switch between cloud and on-device LLMs without rewriting application logic, enabling reliable AI experiences online and offline.
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Tutorial
March 12, 2026

Build Smarter Apps: Tool Calling & AI Orchestration Explained

Learn how on-device models in React Native can call tools, interact with external APIs, and return structured outputs you can use directly in application logic.
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Tutorial
March 5, 2026

MLC LLM + React Native: On-Device AI Without the Pain

Learn how to run third-party on-device LLMs in React Native using MLC LLM. Choose your models, run them efficiently across platforms, and keep a unified JavaScript API with React Native AI.
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Tutorial
February 24, 2026

Intelligent Fallbacks with Apple Intelligence in React Native

Learn how to use Apple’s built-in Foundation Models in React Native apps, reduce memory usage, and enable fast, fully on-device AI with React Native AI Apple.
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Tutorial
February 10, 2026

What Is the React Native AI SDK? A Complete Intro & Quickstart

Learn why on-device AI matters for React Native apps, how local LLMs behave offline, and what problems React Native AI is designed to solve from day one.
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Tutorial
January 29, 2026

Implementing an Android TurboModule with Kotlin

Learn how to implement a React Native TurboModule on Android, from the TypeScript spec and Codegen to the Kotlin implementation and package registration.
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Tutorial
January 19, 2026

Working with Different Threads in Swift TurboModules

Learn how JavaScript, native module, background, and main threads interact in React Native TurboModules, and how to use GCD queues to run async work safely in Swift.
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Tutorial
January 9, 2026

How to Add Type-Safe Constants to Swift TurboModules

Learn how to expose typed, immutable constants from a Swift TurboModule using Codegen, and get full end-to-end type safety between native and JavaScript.
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Tutorial
December 30, 2025

Adding Event Emitters to Your TurboModule in Swift

Learn how to emit native events from a Swift TurboModule and subscribe to them in JavaScript, including proper memory management and Codegen integration.
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Tutorial
December 22, 2025

Writing Your First TurboModule in Swift

Learn how to build a fully working TurboModule in Swift, integrate it with Codegen, and bridge it through Objective‑C inside an Expo app.