The Bad News Every developer dreads the moment: the framework you built your application on is being discontinued. That's exactly what happened to us when Vaadin announced the deprecation of Hilla. Our system is a business application providing the following features: User registration and authentication Product search and browsing Online payment processing Multi-device support (web browsers and staffed/unstaffed business terminals) The tech stack: Spring Boot 3.x on the backend, a Lit + TypeScript SPA on the frontend. Around 20 views, 30 components, and 20 dialogs — a modest but non-trivial codebase with real-world requirements like authentication, payments, and multi-device support. What Hilla Gave Us For those unfamiliar, Hilla was Vaadin's full-stack framework that bridged Spring Boot backends with Lit-based frontends. It provided: Hilla Endpoints — Type-safe RPC from TypeScript to Java. Annotate a Java method with @Endpoint , and a TypeScript client stub is generated automatically.…