A high-personality cycling calculator, re-platformed with its business logic locked in tests
AlpeDuZwift was a single-page WordPress site — one interactive cycling-climb time calculator with a strong self-deprecating British comedic personality, and nothing else — hosted on Cloudways. We rebuilt it from scratch on Astro with React islands as a pnpm-workspaces monorepo deploying to Vercel, retiring the WordPress hosting. The calculator IP was extracted into a standalone, framework-agnostic engine package holding the formulas, the conversational-flow reducer, validation and the verbatim easter-egg copy — locked by a fidelity test suite so the UI can never drift from the original maths or jokes. Every number and message on the site routes through that one engine. The homepage is a "Neon Summit" retro-arcade / CRT redesign from a Claude design handoff, with twin pointer-drag sliders, a live readout, the full two-stage easter-egg chain and a draggable gradient profile — shipped as separate hand-tuned desktop and native-mobile builds behind a responsive island split so only the matching one hydrates. Architectural guardrails are enforced in code: ad markup is structurally barred from the calculator and homepage routes via a build-time tripwire. Built and live on a Vercel preview; the production DNS cutover is deliberately held until parity is signed off, with WordPress kept live until then.
The brief
A much-loved one-page WordPress calculator needed to come off Cloudways onto a fast, cheap-to-run static stack — without losing a single number or any of its verbatim British-comedy easter eggs.
What we did
A from-scratch Astro + Vercel rebuild that extracts the calculator into a tested, framework-agnostic engine package so behaviour is provably identical, with separate hand-tuned desktop and mobile arcade experiences and ad-placement guardrails enforced at build time.