chore: hand adapt-time values to the adapter-node server as a module

.changeset/calm-adapters-handoff.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-node': patch
+---
+
+chore: hand adapt-time values to the server as a module instead of patching built chunks

documentation/docs/25-build-and-deploy/40-adapter-node.md

@@ -254,7 +254,7 @@ WantedBy=sockets.target
 
 ## Custom server
 
-The adapter creates two files in your build directory — `index.js` and `handler.js`. Running `index.js` — e.g. `node build`, if you use the default build directory — will start a server on the configured port.
+The build directory contains two entry points, `index.js` and `handler.js`. Running `index.js` — e.g. `node build`, if you use the default build directory — will start a server on the configured port.
 
 Alternatively, you can import the `handler.js` file, which exports a handler suitable for use with [Express](https://github.com/expressjs/express), [Connect](https://github.com/senchalabs/connect) or [Polka](https://github.com/lukeed/polka) (or even just the built-in [`http.createServer`](https://nodejs.org/dist/latest/docs/api/http.html#httpcreateserveroptions-requestlistener)) and set up your own server:
 

packages/adapter-node/index.d.ts

@@ -1,17 +1,6 @@
 import { Adapter } from '@sveltejs/kit';
 import './ambient.js';
 
-declare global {
-	const ENV_PREFIX: string;
-	const PRECOMPRESS: boolean;
-	const ORIGIN: string | undefined;
-	const UNCOMPRESSED_EXTENSIONS: Set<string>;
-	const BASE_PATH: string;
-	const APP_PATH: string;
-	const PRERENDERED: Set<string>;
-	const MIME_TYPES: Record<string, string>;
-}
-
 interface AdapterOptions {
 	/**
 	 * The directory to build the server to. It defaults to `build` — i.e.

packages/adapter-node/index.js

@@ -1,14 +1,10 @@
-/** @import { TopLevelFilterExpression } from '@rolldown/pluginutils' */
-import { existsSync, mkdirSync, readFileSync, renameSync, rmSync, writeFileSync } from 'node:fs';
-import { dirname, extname, relative } from 'node:path';
+import * as fs from 'node:fs';
+import { extname } from 'node:path';
 import { fileURLToPath } from 'node:url';
-import { and, id, importerId, include } from '@rolldown/pluginutils';
-import remapping from '@jridgewell/remapping';
-import MagicString from 'magic-string';
 
-const files = fileURLToPath(new URL('./files', import.meta.url).href);
-const posixified_files = posixify(files);
-const dir_id = posixify(`${files}/dir.js`);
+// posix so it matches the module ids Vite reports on every platform
+const files = fileURLToPath(new URL('./files', import.meta.url).href).replaceAll('\\', '/');
+const handoff = '#@sveltejs/adapter-node';
 
 /** @type {typeof import('./index.js').default} */
 export default function (opts = {}) {
@@ -17,11 +13,7 @@ export default function (opts = {}) {
 	return {
 		name: '@sveltejs/adapter-node',
 		async adapt(builder) {
-			const tmp = builder.getBuildDirectory('adapter-node');
-
-			rmSync(out, { force: true, recursive: true });
-			rmSync(tmp, { force: true, recursive: true });
-			mkdirSync(tmp, { recursive: true });
+			fs.rmSync(out, { force: true, recursive: true });
 
 			builder.log.minor('Copying assets');
 			const written = [
@@ -50,15 +42,12 @@ export default function (opts = {}) {
 			);
 
 			const server = builder.getServerDirectory();
-			const manifest = JSON.parse(readFileSync(`${server}/.vite/manifest.json`, 'utf8'));
-			const adapter_index = find_entry(manifest, 'adapter-index');
-			const handler = find_entry(manifest, 'handler');
 
 			builder.generateServerInstance(`${server}/server.js`);
 
 			if (builder.hasServerInstrumentationFile()) {
 				builder.instrument({
-					entrypoint: `${server}/${adapter_index.file}`,
+					entrypoint: `${server}/adapter-index.js`,
 					instrumentation: `${server}/instrumentation.server.js`,
 					initializer: builder.createInstrumentationInitializer({ outputDirectory: server }),
 					module: {
@@ -67,235 +56,80 @@ export default function (opts = {}) {
 				});
 			}
 
-			const output_server = `${out}/server`;
-			builder.copy(server, output_server);
-
-			// `dir.js` must evaluate at the output root because it anchors the asset directories
-			renameSync(`${output_server}/dir.js`, `${out}/dir.js`);
-			if (existsSync(`${output_server}/dir.js.map`)) {
-				renameSync(`${output_server}/dir.js.map`, `${out}/dir.js.map`);
-			}
-			writeFileSync(`${output_server}/dir.js`, `export * from '../dir.js';\n`);
-
-			// replace the stubs whose values are only known after the build
-			replace_stubs(output_server, handler.chunks, {
-				__SVELTEKIT_ADAPTER_NODE_UNCOMPRESSED_EXTENSIONS__: `new Set(${JSON.stringify([...uncompressed_extensions])})`,
-				__SVELTEKIT_ADAPTER_NODE_PRERENDERED__: `new Set(${JSON.stringify([...builder.prerendered.paths])})`,
-				__SVELTEKIT_ADAPTER_NODE_MIMETYPES__: JSON.stringify(builder.mimeTypes),
-				__SVELTEKIT_ADAPTER_NODE_SERVER__: (chunk) => {
-					const server = posixify(relative(dirname(chunk), 'server.js'));
-					return server.startsWith('.') ? server : `./${server}`;
-				}
-			});
+			builder.copy(server, `${out}/server`);
+
+			// values only known after the build. `dir` needs the output root
+			fs.writeFileSync(
+				`${out}/adapter-node.js`,
+				[
+					`import { dirname } from 'node:path';`,
+					`import { fileURLToPath } from 'node:url';`,
+					`export { server } from './server/server.js';`,
+					`export const dir = dirname(fileURLToPath(import.meta.url));`,
+					`export const base = ${JSON.stringify(builder.config.paths.base)};`,
+					`export const app_path = ${JSON.stringify(builder.getAppPath())};`,
+					`export const origin = ${JSON.stringify(builder.config.paths.origin)};`,
+					`export const env_prefix = ${JSON.stringify(envPrefix)};`,
+					`export const precompress = ${precompress};`,
+					`export const uncompressed_extensions = new Set(${JSON.stringify([...uncompressed_extensions])});`,
+					`export const prerendered = new Set(${JSON.stringify(builder.prerendered.paths)});`,
+					`export const mime_types = ${JSON.stringify(builder.mimeTypes)};`
+				].join('\n')
+			);
 
-			writeFileSync(`${out}/index.js`, `export * from './server/${adapter_index.file}';\n`);
-			writeFileSync(`${out}/handler.js`, `export * from './server/${handler.file}';\n`);
+			fs.writeFileSync(`${out}/index.js`, `export * from './server/adapter-index.js';\n`);
+			fs.writeFileSync(`${out}/handler.js`, `export * from './server/handler.js';\n`);
 		},
 
 		supports: {
 			read: () => true,
 			instrumentation: () => true
 		},
 
-		vite({ config }) {
-			/** @type {Record<string, string>} */
-			const defines = {
-				// these get replaced later in the adapt step
-				UNCOMPRESSED_EXTENSIONS: '__SVELTEKIT_ADAPTER_NODE_UNCOMPRESSED_EXTENSIONS__',
-				PRERENDERED: '__SVELTEKIT_ADAPTER_NODE_PRERENDERED__',
-				MIME_TYPES: '__SVELTEKIT_ADAPTER_NODE_MIMETYPES__',
-
-				BASE_PATH: JSON.stringify(config.paths.base),
-				APP_PATH: JSON.stringify(
-					`${config.paths.base.slice(1)}${config.paths.base ? '/' : ''}${config.appDir}`
-				),
-				ORIGIN: JSON.stringify(config.paths.origin) || 'undefined',
-				ENV_PREFIX: JSON.stringify(envPrefix),
-				PRECOMPRESS: JSON.stringify(precompress)
-			};
-
-			return {
-				plugins: {
-					post: [
-						{
-							name: 'vite-plugin-sveltekit-adapter-node',
-							apply: 'build',
-							config() {
-								const pkg = JSON.parse(readFileSync('package.json', 'utf8'));
-
-								return {
-									environments: {
-										ssr: {
-											build: {
-												rolldownOptions: {
-													// Copy the prebuilt entrypoints into the build directory so that the
-													// adapter's own bundled dependencies resolve correctly, then bundle them
-													// together with the app's server code. Bundling everything in a single
-													// pass means shared modules (e.g. `SvelteKitError` from `@sveltejs/kit`)
-													// aren't duplicated. See https://github.com/sveltejs/kit/issues/15755
-													input: {
-														'adapter-index': `${files}/index.js`,
-														'adapter-env': `${files}/adapter-env.js`,
-														handler: `${files}/handler.js`
-													},
-													output: {
-														chunkFileNames(chunk) {
-															if (chunk.name === 'dir') return '[name].js';
-															return 'chunks/[name].js';
-														},
-														codeSplitting: {
-															groups: [
-																{
-																	name: 'dir',
-																	test: dir_id
-																}
-															]
-														}
-													},
-													// deployments only need their production dependencies.
-													// Anything in devDependencies will get included in the
-													// bundled code
-													external: [
-														// dependencies could have deep exports, so we need a regex
-														...Object.keys(pkg.dependencies || {}).map(
-															(d) => new RegExp(`^${d}(\\/.*)?$`)
-														)
-													]
+		vite: {
+			plugins: {
+				post: [
+					{
+						name: 'vite-plugin-sveltekit-adapter-node',
+						apply: 'build',
+						config() {
+							const pkg = JSON.parse(fs.readFileSync('package.json', 'utf8'));
+
+							return {
+								environments: {
+									ssr: {
+										build: {
+											rolldownOptions: {
+												// bundled with the app's server code so shared modules aren't duplicated (#15755)
+												input: {
+													'adapter-index': `${files}/index.js`,
+													'adapter-env': `${files}/adapter-env.js`,
+													handler: `${files}/handler.js`
+												},
+												// only production dependencies (and their deep imports) stay external
+												external: [
+													handoff,
+													...Object.keys(pkg.dependencies || {}).map(
+														(d) => new RegExp(`^${d}(\\/.*)?$`)
+													)
+												],
+												output: {
+													paths: { [handoff]: '../adapter-node.js' },
+													// the hand-off path only holds at the output root, so adapter chunks may not nest
+													chunkFileNames: (chunk) =>
+														chunk.moduleIds.some((id) => id.startsWith(files))
+															? 'adapter-node-[name].js'
+															: 'chunks/[name].js'
 												}
 											}
 										}
 									}
-								};
-							},
-							applyToEnvironment(environment) {
-								return environment.name === 'ssr';
-							},
-							transform: {
-								filter: { id: new RegExp(`^${escape_regex(posixified_files)}/`) },
-								handler(code) {
-									const s = new MagicString(code);
-
-									for (const [from, to] of Object.entries(defines)) {
-										for (const match of code.matchAll(new RegExp(`\\b${from}\\b`, 'g'))) {
-											s.overwrite(match.index, match.index + from.length, to);
-										}
-									}
-
-									return {
-										code: s.toString(),
-										map: s.generateMap({ hires: 'boundary' })
-									};
-								}
-							},
-							resolveId: {
-								// composable filters are not accepted type-wise but still work during build
-								// see https://github.com/vitejs/rolldown-vite/issues/605
-								filter: /** @type {any} */ (
-									/** @satisfies {TopLevelFilterExpression[]} */ ([
-										include(
-											and(
-												importerId(new RegExp(`^${escape_regex(posixified_files)}/`)),
-												id(/^SERVER$/)
-											)
-										)
-									])
-								),
-								handler() {
-									return { external: true, id: '__SVELTEKIT_ADAPTER_NODE_SERVER__' };
 								}
-							}
+							};
 						}
-					]
-				}
-			};
+					}
+				]
+			}
 		}
 	};
 }
-
-/**
- * @typedef {{ file: string; imports?: string[]; isEntry?: boolean; name?: string }} ManifestEntry
- */
-
-/**
- * @param {Record<string, ManifestEntry>} manifest
- * @param {string} name
- */
-function find_entry(manifest, name) {
-	const match = Object.entries(manifest).find(([, entry]) => entry.isEntry && entry.name === name);
-	if (!match) throw new Error(`Could not find adapter-node entry ${name} in the Vite manifest`);
-
-	/** @type {string[]} */
-	const chunks = [];
-	const seen = new Set();
-
-	/** @param {string} key */
-	const visit = (key) => {
-		if (seen.has(key)) return;
-		seen.add(key);
-
-		const chunk = manifest[key];
-		if (!chunk) throw new Error(`Could not find ${key} in the Vite manifest`);
-
-		chunks.push(chunk.file);
-		for (const dependency of chunk.imports ?? []) visit(dependency);
-	};
-
-	visit(match[0]);
-	return { file: match[1].file, chunks };
-}
-
-/**
- * @param {string} dir
- * @param {string[]} chunks
- * @param {Record<string, string | ((chunk: string) => string)>} replacements
- */
-function replace_stubs(dir, chunks, replacements) {
-	const pattern = new RegExp(`\\b(${Object.keys(replacements).join('|')})\\b`, 'g');
-	const found = new Set();
-
-	for (const chunk of chunks) {
-		const file = `${dir}/${chunk}`;
-		const code = readFileSync(file, 'utf8');
-		const matches = [...code.matchAll(pattern)];
-		if (matches.length === 0) continue;
-
-		const s = new MagicString(code);
-
-		for (const match of matches) {
-			found.add(match[0]);
-			const replacement = replacements[match[0]];
-			const value = typeof replacement === 'function' ? replacement(chunk) : replacement;
-			s.overwrite(match.index, match.index + match[0].length, value);
-		}
-
-		writeFileSync(file, s.toString());
-
-		const map_file = `${file}.map`;
-		if (!existsSync(map_file)) continue;
-
-		const map = remapping(
-			[
-				JSON.parse(s.generateMap({ hires: 'boundary', source: chunk }).toString()),
-				JSON.parse(readFileSync(map_file, 'utf8'))
-			],
-			() => null
-		);
-		writeFileSync(map_file, map.toString());
-	}
-
-	const missing = Object.keys(replacements).filter((stub) => !found.has(stub));
-	if (missing.length > 0) {
-		throw new Error(`Could not find adapter-node stubs: ${missing.join(', ')}`);
-	}
-}
-
-/** @param {string} str */
-function escape_regex(str) {
-	// TODO replace with `RegExp.escape(str)` when we require Node >= 24
-	return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
-}
-
-/** @param {string} str */
-function posixify(str) {
-	return str.replace(/\\/g, '/');
-}

packages/adapter-node/internal.d.ts

@@ -1,3 +1,14 @@
-declare module 'SERVER' {
+// generated by `adapt` in the output directory
+declare module '#@sveltejs/adapter-node' {
 	export const server: import('@sveltejs/kit').Server;
+	/** the output directory */
+	export const dir: string;
+	export const base: string;
+	export const app_path: string;
+	export const origin: string | undefined;
+	export const env_prefix: string;
+	export const precompress: boolean;
+	export const uncompressed_extensions: Set<string>;
+	export const prerendered: Set<string>;
+	export const mime_types: Record<string, string>;
 }