astro

# Astro 6 — static-first sites, islands, content collections ## The prime directive **Ship zero client JavaScript by default. Hydrate the smallest possible surface, as late as you can get away with.** An `.astro` component renders to HTML at build time and ships *no* runtime; every island is a bundle the visitor downloads, parses, and executes. Content and marketing sites win on TTFB/LCP and Lighthouse, not on React-everywhere. If you find yourself adding `client:load` to make a page "work," stop — the page already works; you are adding interactivity, and interactivity is the expensive exception, not the default. ## First: detect the project version Astro 6.0 is stable ([released 2026-03-10](https://astro.build/blog/astro-6/)); the Astro 5 line is still production-ready. Do not mix advice across majors — read `package.json` → the `astro` version before advising. What v6 changes, per the [upgrade-to-v6 guide](https://docs.astro.build/en/guides/upgrade-to/v6/): - **Node `22.12.0` or higher is required** (18 and 20 are dropped) — check the actual runtime. - Content config lives at `src/content.config.ts`. The legacy `src/content/config.ts` path is **removed**, not merely discouraged, and the old auto-detection (`legacy.collections`) is gone. The `legacy.collectionsBackwardsCompat` escape hatch is a migration crutch, not a supported layout. - **Vite 7** and **Zod 4** for content schemas — `z` is imported from `astro/zod`, **not** `astro:content` (see Content collection...