Astro
Overview
Astro is an all-in-one web framework for building fast, content-focused websites. It uses an islands architecture that ships zero JavaScript by default, hydrating only interactive components on demand. Components from React, Svelte, Vue, Solid, and Preact can coexist in a single project.
When to use: Content-driven sites (blogs, docs, marketing), portfolios, e-commerce storefronts, any site where most pages are primarily static with isolated interactive regions.
When NOT to use: Highly interactive single-page applications (dashboards, real-time collaboration tools), apps requiring full client-side routing with shared global state across all components.
Quick Reference
| Pattern | API / Directive | Key Points |
|---|---|---|
| Content collection | defineCollection({loader, schema}) | Zod schemas, glob/file loaders, type-safe queries |
| Query collection | getCollection('blog') | Returns typed array, supports filter callback |
| Single entry | getEntry('blog', 'my-post') | Fetch by collection name and entry ID |
| Island (load) | <Component client:load /> | Hydrate immediately on page load |
| Island (idle) | <Component client:idle /> | Hydrate when browser is idle |
| Island (visible) | <Component client:visible /> | Hydrate when component enters viewport |
| Island (media) | <Component client:media="(max-width: 768px)" /> | Hydrate on media query match |
| Island (client-only) | <Component client:only="react" /> | Skip SSR, render only on client |
| View transitions | <ClientRouter /> | Add to <head>, enables SPA-like navigation |
| Persist state | transition:persist | Maintain island state across navigations |
| Programmatic navigate | navigate(href) | Client-side navigation from scripts |
| Static output | output: 'static' | Pre-render all pages at build time (default) |
| Server output | output: 'server' | Server-render all pages on demand |
| Hybrid (opt-in SSR) | output: 'static' + per-page prerender = false | Static by default, opt individual pages into SSR |
| Hybrid (opt-in static) | output: 'server' + per-page prerender = true | SSR by default, opt individual pages into static |
| Server islands | <Component server:defer /> | Defer server rendering for dynamic content in static |
| Middleware | onRequest(context, next) | Runs before every route, chain with sequence() |
| Astro DB table | defineTable({columns}) | Type-safe SQL with column definitions |
| Framework component | Import .jsx / .svelte / .vue | Auto-detected by file extension |
| Integration | astro add react | CLI to add framework adapters and tools |
| Render content | const {Content} = await entry.render() | Compile Markdown/MDX to component |
| Dynamic routes | getStaticPaths() + collection query | Generate pages from collection entries |
| API endpoint | export const GET: APIRoute | Server-rendered REST endpoints |
| Shared island state | nanostores | Reactive state across framework boundaries |
| Environment variables | import.meta.env.PUBLIC_* | PUBLIC_ prefix for client-accessible vars |
| Transition animation | transition:animate="slide" | initial, fade, slide, none |
| Prefetch links | data-astro-prefetch | hover, viewport, load, or false |
| Collection reference | reference('authors') | Type-safe cross-collection relations |
| Script re-execution | data-astro-rerun | Re-run <script> on every view transition navigation |
| Redirect | context.redirect(url, status) | Redirect from middleware or server pages |
Common Mistakes
| Mistake | Correct Pattern |
|---|---|
Adding client: directive to .astro components | Only UI framework components (React, Svelte, Vue) accept client: |
Using client:load everywhere | Default to client:idle or client:visible; use client:load sparingly |
Forgetting framework string with client:only | Must specify framework: client:only="react" |
| Mixing framework components in non-Astro files | Only .astro files can compose components from multiple frameworks |
Using output: 'server' for mostly static sites | Use output: 'static' with per-page prerender = false for hybrid |
Omitting <ClientRouter /> for view transitions | Must be in <head> of every page (use shared layout) |
Content config not at src/content.config.ts | File must be named content.config.ts in src/ root |
Not awaiting getCollection() calls | Always await collection queries in frontmatter |
Importing from astro:content in client scripts | Content APIs are server-only; pass data as props to client components |
Placing middleware outside src/middleware.ts | Middleware must be at src/middleware.ts or src/middleware/index.ts |
| Passing functions as props to islands | Only serializable data crosses the server/client boundary |
Using transition:persist without matching pages | Component must appear on both old and new page with same persist value |
| Missing adapter for server/hybrid mode | Install an adapter: npx astro add vercel (or node, netlify, etc.) |
Delegation
- Pattern discovery: Use
Exploreagent - Build configuration: Use
Taskagent - Code review: Delegate to
code-revieweragent
If thetailwindskill is available, delegate styling and Tailwind CSS configuration to it. If thevitestskill is available, delegate unit testing patterns to it. If theplaywrightskill is available, delegate end-to-end testing patterns to it. If theviteskill is available, delegate build configuration and Vite plugin setup to it. If thedrizzleskill is available, delegate advanced database query patterns to it. If thesentryskill is available, delegate error monitoring and observability setup to it. If thepino-loggingskill is available, delegate server-side logging configuration to it. If thetanstack-queryskill is available, delegate client-side data fetching and caching to it.
References
- Content collections, schemas, loaders, and querying
- Island architecture and hydration directives
- View transitions and client-side navigation
- Rendering modes: static, server, and hybrid
- Middleware patterns and request handling
- Framework component integration (React, Svelte, Vue)
- Astro DB schema, seeding, and queries