AI-assisted build · offline-first PWA

RainCheck

A tiny, framework-free weather app that tells you whether it is raining and when that may change — built with Codex, TypeScript, SCSS and Vite.

Open RainCheck View the source

No frameworkvanilla TypeScript + SCSS

50.3 KBJavaScript + CSS · 15.4 KB gzip

PWA · SPAoffline shell · hash routes

Built with AI, grounded in a real app

RainCheck was developed with Codex as an AI-assisted engineering project. The app itself has no UI framework or runtime AI dependency: Vite builds a small vanilla TypeScript and SCSS frontend. The production JavaScript and compiled CSS total 50.3 KB uncompressed (15.4 KB gzip); install icons are separate assets fetched when the browser needs them.

Offline-ready PWA: the service worker caches the app shell, while weather snapshots saved in the browser remain available offline and are clearly historical.
Single-page app: lightweight hash routing switches between the weather screen and concise About, Terms and Cookies pages without discarding the current screen.
Small by design: strict TypeScript, modular SCSS and Vite — with no frontend framework in the delivered app.

Documentation, written backwards

We built the working application first. Then we distilled the decisions and lessons from that implementation into a reusable, AI-oriented PWA Generation Playbook, with a reference architecture, a domain specification and a UX/icon system. The general guide grew from a real product and its trade-offs rather than leading to a hypothetical rebuild.

Explore the code and playbook on GitHub