astro-developer/repository-context/packages/astro/src/core/README.md

core/

Code that executes directly on Node (not processed by vite). Contains the main Astro logic for the build, dev, preview, and sync commands, and also manages the lifecycle of the Vite server.

The core/index.ts module exports the CLI commands as functions and is the main entrypoint of the astro package.

import { dev, build, preview, sync } from 'astro';

See CONTRIBUTING.md for a code overview.

Request handling: the functional core

Server-side request handling is a purely functional core keyed off the SSRManifest — the one allowed ambient source of truth, exposed to bundled code as the virtual:astro:manifest virtual module. There are no stateful app/pipeline god objects: behavior lives in plain functions that read static data from the manifest plus per-request state.

• Owning modules hold per-manifest derived/mutable state in WeakMaps and expose accessors: routing/route-table.ts (getRouteTable, matchRoute, updateRouteTable), middleware/load.ts, ../actions/load.ts, session/driver.ts, cache/provider.ts, render/route-cache.ts, routing/default.ts, logger/manifest-logger.ts, fetch/features.ts, manifest/ambient.ts.
• environment/ expresses what genuinely varies between rendering environments (production SSR, the two dev paths, build/prerender, the container) as a stateless RenderEnvironment record registered per manifest via setEnvironment; production is the unregistered default.
• fetch/ owns the per-request FetchState (constructible from a bare Request, resolving the ambient manifest) and the handler functions (handleRequest and the middleware/pages/error stages) that drive a request through the chain.
• Facades: App (core/app/) and NodeApp (core/app/node.ts) survive as thin public compatibility shells — every method delegates to the functional core.