Environment API experiments

package.json

@@ -28,6 +28,11 @@
 		"playwright": "^1.44.1",
 		"typescript-eslint": "^8.0.0"
 	},
+	"pnpm": {
+		"overrides": {
+			"vite": "6.0.0-beta.1"
+		}
+	},
 	"packageManager": "[email protected]",
 	"engines": {
 		"pnpm": "^9.0.0"

packages/kit/src/exports/public.d.ts

@@ -48,6 +48,7 @@ export interface Adapter {
 	/**
 	 * Creates an `Emulator`, which allows the adapter to influence the environment
 	 * during dev, build and prerendering
+	 * @deprecated
 	 */
 	emulate?(): MaybePromise<Emulator>;
 }
@@ -268,6 +269,7 @@ export interface Cookies {
 
 /**
  * A collection of functions that influence the environment during dev, build and prerendering
+ * @deprecated
  */
 export interface Emulator {
 	/**

packages/kit/src/exports/vite/dev/cloudflare_entrypoint.js

@@ -0,0 +1,34 @@
+// This should be exported from @sveltejs/kit so that the path isn't relative
+import { Server } from '../../../runtime/server/index.js';
+
+export default {
+	/**
+	 * This fetch handler is the entrypoint for the environment.
+	 * @param {Request & { cf: any }} request
+	 * @param {any} env
+	 * @param {any} context
+	 */
+	fetch: async (request, env, context) => {
+		const environment_context = await import('__sveltekit/environment_context');
+		const server = new Server(environment_context.manifest);
+
+		await server.init({
+			env: environment_context.env
+		});
+
+		return server.respond(request, {
+			getClientAddress: () => {
+				if (environment_context.remote_address) return environment_context.remote_address;
+				throw new Error('Could not determine clientAddress');
+			},
+			// We can provide the platform properties directly as the code is executed in a workerd environment.
+			// TODO we should probably deprecate both `platform` and `emulate`
+			platform: {
+				env,
+				cf: request.cf,
+				context,
+				caches
+			}
+		});
+	}
+};

packages/kit/src/exports/vite/dev/default_environment.js

@@ -0,0 +1,69 @@
+import {
+	DevEnvironment,
+	BuildEnvironment,
+	createServerHotChannel,
+	createServerModuleRunner
+} from 'vite';
+
+export const AsyncFunction = /** @type {typeof Function} */ (async function () {}.constructor);
+
+export const asyncFunctionDeclarationPaddingLineCount = /** #__PURE__ */ (() => {
+	const body = '/*code*/';
+	const source = new AsyncFunction('a', 'b', body).toString();
+	return source.slice(0, source.indexOf(body)).split('\n').length - 1;
+})();
+
+class NodeDevEnvironment extends DevEnvironment {
+	/** @type {{ entrypoint: string }} */
+	#options;
+
+	/** @type {import('vite/module-runner').ModuleRunner} */
+	#runner;
+
+	/**
+	 * @param {string} name
+	 * @param {import('vite').ResolvedConfig} config
+	 * @param {{ entrypoint: string }} options
+	 */
+	constructor(name, config, options) {
+		super(name, config, {
+			hot: createServerHotChannel(),
+			runner: {
+				processSourceMap(map) {
+					// this assumes that "new AsyncFunction" is used to create the module
+					return Object.assign({}, map, {
+						mappings: ';'.repeat(asyncFunctionDeclarationPaddingLineCount) + map.mappings
+					});
+				}
+			}
+		});
+
+		this.#options = options;
+		this.#runner = createServerModuleRunner(this);
+	}
+
+	/** @param {Request} request */
+	async dispatchFetch(request) {
+		const entrypoint = await this.#runner.import(this.#options.entrypoint);
+		return entrypoint.default.fetch(request);
+	}
+}
+
+/**
+ * @param {{ entrypoint: string }} options
+ * @returns {import('vite').EnvironmentOptions}
+ */
+export function createNodeEnvironment(options) {
+	return {
+		dev: {
+			createEnvironment(name, config) {
+				return new NodeDevEnvironment(name, config, options);
+			}
+		},
+		build: {
+			createEnvironment(name, config) {
+				return new BuildEnvironment(name, config);
+			}
+		}
+	};
+}