React 19 is now stable and shipping quietly into production apps. No flashy APIs, no hype-driven features — just a series of deep fixes that materially change how React behaves at scale. This is what actually changed, why it matters, and what senior frontend engineers should (and should not) refactor.

SPAs dominated frontend for a decade. SSR, streaming, and island architectures are now reshaping performance, DX, and scalability. This guide breaks down where each model wins—and where it fails.

Browser‑resident AI agents like Claude-in-Chrome and emerging AI browsers are no longer demos. They change how we think about DOM access, automation, testing, and frontend architecture. Here’s what senior engineers should realistically prepare for.

Generative UI systems can now design, generate, and operate entire frontends from prompts. This isn’t a demo trend—it’s an architectural shift every frontend engineer should understand.

TypeScript 7 drops its JavaScript heritage and moves to a native toolchain. Build times shrink, configs simplify, and strictness tightens. Here’s how this shift impacts real-world frontend systems.

CSS Subgrid is finally supported across all major browsers, unlocking layout capabilities we’ve been hacking around for years. Here’s a deep, practical breakdown for senior frontend engineers.