principle-test-behavior-not-implementation

Build an animation from scratch, making the decisions in the order that determines whether it feels right — should it animate at all, what purpose, which…

Build animations in React Native and Expo, making the decisions in the order that determines whether they feel right — should it animate, which thread it runs…

Apple's approach to interface design and fluid, physical motion, translated for the web.

Guide to Sonner, the React toast library — install and wire up the Toaster, pick the right toast() call, promise and loading toasts, updating, dismissing and…

Search a codebase or UI for places that don't animate but should, and reject everything that shouldn't.

Survey a codebase's animation and motion code as a senior motion advisor, then produce a prioritized audit and self-contained implementation plans for other…

Make a web app feel native on a phone — the small CSS and meta-tag fixes that separate "a website in a browser" from something that feels installed.

Pick the right library for a given frontend task from a curated, opinionated list — numbers, OTP inputs, charts, command menus, virtualization, drag and drop…

Build multiple genuinely different versions of a UI piece you describe, rendered behind a visual picker so you can flip through them live and promote the one…

How to write modern Swift well — modeling with value types, Swift 6 data-race safety and approachable concurrency (@concurrent, main-actor-by-default, actors…

Reviews animation and motion code against a high craft bar derived from Emil Kowalski's design engineering philosophy.

Sketch types, signatures, and module structure before code, then stay in the loop while implementation fills in.