Auditing Expo Exact's Runtime Boundaries on Web, macOS, iPhone, and Linux
A secondary report says Expo released a runtime called Exact that builds one TypeScript app for web, macOS, iPhone and Linux. That report is a headline: no SDK version, no module list, no packaging story. So this post doesn't review an architecture it can't see. What it does instead is give you an audit plan you can run against any candidate runtime: - Four boundaries worth testing separately: the render surface, the native API surface, the lifecycle and process model, and the build artifact graph. - A capability matrix with the four targets as columns and nine capability classes as rows, so disagreement between platforms shows up as a cell rather than a surprise in production. - A probe harness that records six statuses per cell, and catches the worst one: a native call that resolves to undefined and looks like a bug in your app instead of a gap in the runtime. - The cheapest signal of all, the web target. If you can select text and find it in the page, you're on the DOM and accessibility comes mostly free. If you can't, you're on canvas and you budget for remediation. Also covered: AppKit versus UIKit assumptions such as menu bars, window lifecycle, hover states and safe-area insets, plus the Linux questions about Wayland, X11 and distribution format that set your support burden. The point is not to score the release. It's to replace a platform count with a matrix you can fill in on a real build. Full write-up: https://hackyjs.com/posts/auditing-expo-exacts-runtime-boundaries-on-web-macos-iphone-and-linux