What problem does it solve? Astro code written from memory is often a correct Astro 4 or 5 answer that fails at build time in Astro 7, and pages silently ship hundreds of kilobytes of unnecessary JavaScript through misused hydration directives. This Skill provides version-accurate guidance for Astro 7.3 covering islands, content collections, actions, middleware, and migrations, with explicit removed-API tables and audit workflows. ## Core Features & Use Cases - Island and hydration audits: Reviews client:* directives, island boundaries, prop serialisation, and server:defer usage to cut shipped JavaScript and fix broken cross-island state. - Content collections and routing: Defines loaders and Zod 4 schemas in src/content.config.ts, handles getStaticPaths constraints, output modes, adapters, and live collections. - Forms, actions, and middleware: Wires zero-JS form submissions through astro:actions with field-error rendering, authorization inside handlers, sessions, and typed astro:env configuration. - Use Case: A project upgraded to Astro 7 fails its build on legacy collections and a signup form whose action never runs; the Skill identifies output: 'hybrid' removal, the missing adapter, the missing accept: 'form', and produces corrected files. ## Quick Start Use the astro skill to review my Astro 7 product page and tell me which hydration directives to change and why the cart state never updates.