Remove support for simple objects in endpoints (#9181)

* Deprecate simple object from endpoints

* Update changeset

* Add missing Response return

Co-authored-by: Happydev <81974850+MoustaphaDev@users.noreply.github.com>

* Update .changeset/clever-beds-notice.md

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

---------

Co-authored-by: Happydev <81974850+MoustaphaDev@users.noreply.github.com>
Co-authored-by: Matthew Phillips <matthew@skypack.dev>
Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

56 files changed, 206 insertions, 529 deletions

diff --git a/.changeset/clever-beds-notice.md b/.changeset/clever-beds-notice.md
new file mode 100644
index 000000000..6be65bde1
--- /dev/null
+++ b/.changeset/clever-beds-notice.md
@@ -0,0 +1,9 @@
+---
+'astro': major
+---
+
+Removes support for returning simple objects from endpoints (deprecated since Astro 3.0). You should return a `Response` instead.
+
+`ResponseWithEncoding` is also removed. You can refactor the code to return a response with an array buffer instead, which is encoding agnostic.
+
+The types for middlewares have also been revised. To type a middleware function, you should now use `MiddlewareHandler` instead of `MiddlewareResponseHandler`. If you used `defineMiddleware()` to type the function, no changes are needed.
diff --git a/packages/astro/src/@types/astro.ts b/packages/astro/src/@types/astro.ts
index a769bcdf4..e77222c0c 100644
--- a/packages/astro/src/@types/astro.ts
+++ b/packages/astro/src/@types/astro.ts
@@ -19,7 +19,6 @@ import type { AstroConfigType } from '../core/config/index.js';
 import type { AstroTimer } from '../core/config/timer.js';
 import type { TSConfig } from '../core/config/tsconfig.js';
 import type { AstroCookies } from '../core/cookies/index.js';
-import type { ResponseWithEncoding } from '../core/endpoint/index.js';
 import type { AstroIntegrationLogger, Logger, LoggerLevel } from '../core/logger/core.js';
 import type { AstroDevOverlay, DevOverlayCanvas } from '../runtime/client/dev-overlay/overlay.js';
 import type { DevOverlayHighlight } from '../runtime/client/dev-overlay/ui-library/highlight.js';
@@ -2005,8 +2004,6 @@ export interface AstroAdapter {
 	supportedAstroFeatures: AstroFeatureMap;
 }
 
-type Body = string;
-
 export type ValidRedirectStatus = 300 | 301 | 302 | 303 | 304 | 307 | 308;
 
 // Shared types between `Astro` global and API context object
@@ -2163,7 +2160,6 @@ export interface APIContext<
 	 * ```
 	 */
 	locals: App.Locals;
-	ResponseWithEncoding: typeof ResponseWithEncoding;
 
 	/**
 	 * Available only when `experimental.i18n` enabled and in SSR.
@@ -2199,22 +2195,12 @@ export interface APIContext<
 	currentLocale: string | undefined;
 }
 
-export type EndpointOutput =
-	| {
-			body: Body;
-			encoding?: BufferEncoding;
-	  }
-	| {
-			body: Uint8Array;
-			encoding: 'binary';
-	  };
-
 export type APIRoute<Props extends Record<string, any> = Record<string, any>> = (
 	context: APIContext<Props>
-) => EndpointOutput | Response | Promise<EndpointOutput | Response>;
+) => Response | Promise<Response>;
 
 export interface EndpointHandler {
-	[method: string]: APIRoute | ((params: Params, request: Request) => EndpointOutput | Response);
+	[method: string]: APIRoute | ((params: Params, request: Request) => Response);
 }
 
 export type Props = Record<string, unknown>;
@@ -2319,20 +2305,16 @@ export interface AstroIntegration {
 	};
 }
 
-export type MiddlewareNext<R> = () => Promise<R>;
-export type MiddlewareHandler<R> = (
+export type MiddlewareNext = () => Promise<Response>;
+export type MiddlewareHandler = (
 	context: APIContext,
-	next: MiddlewareNext<R>
-) => Promise<R> | R | Promise<void> | void;
-
-export type MiddlewareResponseHandler = MiddlewareHandler<Response>;
-export type MiddlewareEndpointHandler = MiddlewareHandler<Response | EndpointOutput>;
-export type MiddlewareNextResponse = MiddlewareNext<Response>;
+	next: MiddlewareNext
+) => Promise<Response> | Response | Promise<void> | void;
 
 // NOTE: when updating this file with other functions,
 // remember to update `plugin-page.ts` too, to add that function as a no-op function.
-export type AstroMiddlewareInstance<R> = {
-	onRequest?: MiddlewareHandler<R>;
+export type AstroMiddlewareInstance = {
+	onRequest?: MiddlewareHandler;
 };
 
 export type AstroIntegrationMiddleware = {
diff --git a/packages/astro/src/core/app/index.ts b/packages/astro/src/core/app/index.ts
index 23ecba837..3e72c3810 100644
--- a/packages/astro/src/core/app/index.ts
+++ b/packages/astro/src/core/app/index.ts
@@ -1,7 +1,6 @@
 import type {
 	EndpointHandler,
 	ManifestData,
-	MiddlewareEndpointHandler,
 	RouteData,
 	SSRElement,
 	SSRManifest,
@@ -181,16 +180,14 @@ export class App {
 			);
 			if (i18nMiddleware) {
 				if (mod.onRequest) {
-					this.#pipeline.setMiddlewareFunction(
-						sequence(i18nMiddleware, mod.onRequest as MiddlewareEndpointHandler)
-					);
+					this.#pipeline.setMiddlewareFunction(sequence(i18nMiddleware, mod.onRequest));
 				} else {
 					this.#pipeline.setMiddlewareFunction(i18nMiddleware);
 				}
 				this.#pipeline.onBeforeRenderRoute(i18nPipelineHook);
 			} else {
 				if (mod.onRequest) {
-					this.#pipeline.setMiddlewareFunction(mod.onRequest as MiddlewareEndpointHandler);
+					this.#pipeline.setMiddlewareFunction(mod.onRequest);
 				}
 			}
 			response = await this.#pipeline.renderRoute(renderContext, pageModule);
@@ -322,7 +319,7 @@ export class App {
 				);
 				const page = (await mod.page()) as any;
 				if (skipMiddleware === false && mod.onRequest) {
-					this.#pipeline.setMiddlewareFunction(mod.onRequest as MiddlewareEndpointHandler);
+					this.#pipeline.setMiddlewareFunction(mod.onRequest);
 				}
 				if (skipMiddleware) {
 					// make sure middleware set by other requests is cleared out
@@ -367,8 +364,8 @@ export class App {
 		const status = override?.status
 			? override.status
 			: oldResponse.status === 200
-			? newResponse.status
-			: oldResponse.status;
+			  ? newResponse.status
+			  : oldResponse.status;
 
 		return new Response(newResponse.body, {
 			status,
diff --git a/packages/astro/src/core/build/generate.ts b/packages/astro/src/core/build/generate.ts
index 4750f2afc..a7d286b40 100644
--- a/packages/astro/src/core/build/generate.ts
+++ b/packages/astro/src/core/build/generate.ts
@@ -8,7 +8,6 @@ import type {
 	AstroSettings,
 	ComponentInstance,
 	GetStaticPathsItem,
-	MiddlewareEndpointHandler,
 	RouteData,
 	RouteType,
 	SSRError,
@@ -269,15 +268,13 @@ async function generatePage(
 	);
 	if (config.experimental.i18n && i18nMiddleware) {
 		if (onRequest) {
-			pipeline.setMiddlewareFunction(
-				sequence(i18nMiddleware, onRequest as MiddlewareEndpointHandler)
-			);
+			pipeline.setMiddlewareFunction(sequence(i18nMiddleware, onRequest));
 		} else {
 			pipeline.setMiddlewareFunction(i18nMiddleware);
 		}
 		pipeline.onBeforeRenderRoute(i18nPipelineHook);
 	} else if (onRequest) {
-		pipeline.setMiddlewareFunction(onRequest as MiddlewareEndpointHandler);
+		pipeline.setMiddlewareFunction(onRequest);
 	}
 	if (!pageModulePromise) {
 		throw new Error(
@@ -560,7 +557,6 @@ async function generatePath(pathname: string, gopts: GeneratePathOptions, pipeli
 		});
 
 		let body: string | Uint8Array;
-		let encoding: BufferEncoding | undefined;
 
 		let response: Response;
 		try {
@@ -603,7 +599,6 @@ async function generatePath(pathname: string, gopts: GeneratePathOptions, pipeli
 			// If there's no body, do nothing
 			if (!response.body) return;
 			body = Buffer.from(await response.arrayBuffer());
-			encoding = (response.headers.get('X-Astro-Encoding') as BufferEncoding | null) ?? 'utf-8';
 		}
 
 		const outFolder = getOutFolder(pipeline.getConfig(), pathname, route.type);
@@ -611,7 +606,7 @@ async function generatePath(pathname: string, gopts: GeneratePathOptions, pipeli
 		route.distURL = outFile;
 
 		await fs.promises.mkdir(outFolder, { recursive: true });
-		await fs.promises.writeFile(outFile, body, encoding);
+		await fs.promises.writeFile(outFile, body);
 	}
 }
 
diff --git a/packages/astro/src/core/build/types.ts b/packages/astro/src/core/build/types.ts
index 59fa06f6b..0722a293d 100644
--- a/packages/astro/src/core/build/types.ts
+++ b/packages/astro/src/core/build/types.ts
@@ -54,7 +54,7 @@ export interface SinglePageBuiltModule {
 	/**
 	 * The `onRequest` hook exported by the middleware
 	 */
-	onRequest?: MiddlewareHandler<unknown>;
+	onRequest?: MiddlewareHandler;
 	renderers: SSRLoadedRenderer[];
 }
 
diff --git a/packages/astro/src/core/endpoint/index.ts b/packages/astro/src/core/endpoint/index.ts
index f9c61d053..c0490a740 100644
--- a/packages/astro/src/core/endpoint/index.ts
+++ b/packages/astro/src/core/endpoint/index.ts
@@ -1,12 +1,4 @@
-import mime from 'mime';
-import type {
-	APIContext,
-	EndpointHandler,
-	EndpointOutput,
-	MiddlewareEndpointHandler,
-	MiddlewareHandler,
-	Params,
-} from '../../@types/astro.js';
+import type { APIContext, EndpointHandler, MiddlewareHandler, Params } from '../../@types/astro.js';
 import { renderEndpoint } from '../../runtime/server/index.js';
 import { ASTRO_VERSION } from '../constants.js';
 import { AstroCookies, attachCookiesToResponse } from '../cookies/index.js';
@@ -19,8 +11,6 @@ import {
 } from '../render/context.js';
 import { type Environment, type RenderContext } from '../render/index.js';
 
-const encoder = new TextEncoder();
-
 const clientAddressSymbol = Symbol.for('astro.clientAddress');
 const clientLocalsSymbol = Symbol.for('astro.locals');
 
@@ -69,7 +59,6 @@ export function createAPIContext({
 				},
 			});
 		},
-		ResponseWithEncoding,
 		get preferredLocale(): string | undefined {
 			if (preferredLocale) {
 				return preferredLocale;
@@ -143,36 +132,11 @@ export function createAPIContext({
 	return context;
 }
 
-type ResponseParameters = ConstructorParameters<typeof Response>;
-
-export class ResponseWithEncoding extends Response {
-	constructor(body: ResponseParameters[0], init: ResponseParameters[1], encoding?: BufferEncoding) {
-		// If a body string is given, try to encode it to preserve the behaviour as simple objects.
-		// We don't do the full handling as simple objects so users can control how headers are set instead.
-		if (typeof body === 'string') {
-			// In NodeJS, we can use Buffer.from which supports all BufferEncoding
-			if (typeof Buffer !== 'undefined' && Buffer.from) {
-				body = Buffer.from(body, encoding);
-			}
-			// In non-NodeJS, use the web-standard TextEncoder for utf-8 strings
-			else if (encoding == null || encoding === 'utf8' || encoding === 'utf-8') {
-				body = encoder.encode(body);
-			}
-		}
-
-		super(body, init);
-
-		if (encoding) {
-			this.headers.set('X-Astro-Encoding', encoding);
-		}
-	}
-}
-
-export async function callEndpoint<MiddlewareResult = Response | EndpointOutput>(
+export async function callEndpoint(
 	mod: EndpointHandler,
 	env: Environment,
 	ctx: RenderContext,
-	onRequest: MiddlewareHandler<MiddlewareResult> | undefined
+	onRequest: MiddlewareHandler | undefined
 ): Promise<Response> {
 	const context = createAPIContext({
 		request: ctx.request,
@@ -187,107 +151,13 @@ export async function callEndpoint<MiddlewareResult = Response | EndpointOutput>
 
 	let response;
 	if (onRequest) {
-		response = await callMiddleware<Response | EndpointOutput>(
-			env.logger,
-			onRequest as MiddlewareEndpointHandler,
-			context,
-			async () => {
-				return await renderEndpoint(mod, context, env.ssr, env.logger);
-			}
-		);
+		response = await callMiddleware(onRequest, context, async () => {
+			return await renderEndpoint(mod, context, env.ssr, env.logger);
+		});
 	} else {
 		response = await renderEndpoint(mod, context, env.ssr, env.logger);
 	}
 
-	const isEndpointSSR = env.ssr && !ctx.route?.prerender;
-
-	if (response instanceof Response) {
-		if (isEndpointSSR && response.headers.get('X-Astro-Encoding')) {
-			env.logger.warn(
-				null,
-				'`ResponseWithEncoding` is ignored in SSR. Please return an instance of Response. See https://docs.astro.build/en/core-concepts/endpoints/#server-endpoints-api-routes for more information.'
-			);
-		}
-		attachCookiesToResponse(response, context.cookies);
-		return response;
-	}
-
-	// The endpoint returned a simple object, convert it to a Response
-
-	// TODO: Remove in Astro 4.0
-	env.logger.warn(
-		null,
-		`${ctx.route.component} returns a simple object which is deprecated. Please return an instance of Response. See https://docs.astro.build/en/core-concepts/endpoints/#server-endpoints-api-routes for more information.`
-	);
-
-	if (isEndpointSSR) {
-		if (response.hasOwnProperty('headers')) {
-			env.logger.warn(
-				null,
-				'Setting headers is not supported when returning an object. Please return an instance of Response. See https://docs.astro.build/en/core-concepts/endpoints/#server-endpoints-api-routes for more information.'
-			);
-		}
-
-		if (response.encoding) {
-			env.logger.warn(
-				null,
-				'`encoding` is ignored in SSR. To return a charset other than UTF-8, please return an instance of Response. See https://docs.astro.build/en/core-concepts/endpoints/#server-endpoints-api-routes for more information.'
-			);
-		}
-	}
-
-	let body: BodyInit;
-	const headers = new Headers();
-
-	// Try to get the MIME type for this route
-	const pathname = ctx.route
-		? // Try the static route `pathname`
-		  ctx.route.pathname ??
-		  // Dynamic routes don't include `pathname`, so synthesize a path for these (e.g. 'src/pages/[slug].svg')
-		  ctx.route.segments.map((s) => s.map((p) => p.content).join('')).join('/')
-		: // Fallback to pathname of the request
-		  ctx.pathname;
-	const mimeType = mime.getType(pathname) || 'text/plain';
-	headers.set('Content-Type', `${mimeType};charset=utf-8`);
-
-	// Save encoding to X-Astro-Encoding to be used later during SSG with `fs.writeFile`.
-	// It won't work in SSR and is already warned above.
-	if (response.encoding) {
-		headers.set('X-Astro-Encoding', response.encoding);
-	}
-
-	// For Uint8Array (binary), it can passed to Response directly
-	if (response.body instanceof Uint8Array) {
-		body = response.body;
-		headers.set('Content-Length', body.byteLength.toString());
-	}
-	// In NodeJS, we can use Buffer.from which supports all BufferEncoding
-	else if (typeof Buffer !== 'undefined' && Buffer.from) {
-		body = Buffer.from(response.body, response.encoding);
-		headers.set('Content-Length', body.byteLength.toString());
-	}
-	// In non-NodeJS, use the web-standard TextEncoder for utf-8 strings only
-	// to calculate the content length
-	else if (
-		response.encoding == null ||
-		response.encoding === 'utf8' ||
-		response.encoding === 'utf-8'
-	) {
-		body = encoder.encode(response.body);
-		headers.set('Content-Length', body.byteLength.toString());
-	}
-	// Fallback pass it to Response directly. It will mainly rely on X-Astro-Encoding
-	// to be further processed in SSG.
-	else {
-		body = response.body;
-		// NOTE: Can't calculate the content length as we can't encode to figure out the real length.
-		// But also because we don't need the length for SSG as it's only being written to disk.
-	}
-
-	response = new Response(body, {
-		status: 200,
-		headers,
-	});
 	attachCookiesToResponse(response, context.cookies);
 	return response;
 }
diff --git a/packages/astro/src/core/middleware/callMiddleware.ts b/packages/astro/src/core/middleware/callMiddleware.ts
index d0a6ceca2..4d79cd566 100644
--- a/packages/astro/src/core/middleware/callMiddleware.ts
+++ b/packages/astro/src/core/middleware/callMiddleware.ts
@@ -1,13 +1,6 @@
-import { bold } from 'kleur/colors';
-import type {
-	APIContext,
-	EndpointOutput,
-	MiddlewareHandler,
-	MiddlewareNext,
-} from '../../@types/astro.js';
+import type { APIContext, MiddlewareHandler, MiddlewareNext } from '../../@types/astro.js';
 import { attachCookiesToResponse, responseHasCookies } from '../cookies/index.js';
 import { AstroError, AstroErrorData } from '../errors/index.js';
-import type { Environment } from '../render/index.js';
 
 /**
  * Utility function that is in charge of calling the middleware.
@@ -43,15 +36,14 @@ import type { Environment } from '../render/index.js';
  * @param apiContext The API context
  * @param responseFunction A callback function that should return a promise with the response
  */
-export async function callMiddleware<R>(
-	logger: Environment['logger'],
-	onRequest: MiddlewareHandler<R>,
+export async function callMiddleware(
+	onRequest: MiddlewareHandler,
 	apiContext: APIContext,
-	responseFunction: () => Promise<R>
-): Promise<Response | R> {
+	responseFunction: () => Promise<Response>
+): Promise<Response> {
 	let nextCalled = false;
-	let responseFunctionPromise: Promise<R> | undefined = undefined;
-	const next: MiddlewareNext<R> = async () => {
+	let responseFunctionPromise: Promise<Response> | undefined = undefined;
+	const next: MiddlewareNext = async () => {
 		nextCalled = true;
 		responseFunctionPromise = responseFunction();
 		return responseFunctionPromise;
@@ -60,15 +52,6 @@ export async function callMiddleware<R>(
 	let middlewarePromise = onRequest(apiContext, next);
 
 	return await Promise.resolve(middlewarePromise).then(async (value) => {
-		if (isEndpointOutput(value)) {
-			logger.warn(
-				null,
-				apiContext.url.pathname +
-					' Using simple endpoints can cause unexpected issues in the chain of middleware functions.' +
-					`\nIt's strongly suggested to use full ${bold('Response')} objects.`
-			);
-		}
-
 		// first we check if `next` was called
 		if (nextCalled) {
 			/**
@@ -84,7 +67,7 @@ export async function callMiddleware<R>(
 				if (value instanceof Response === false) {
 					throw new AstroError(AstroErrorData.MiddlewareNotAResponse);
 				}
-				return ensureCookiesAttached(apiContext, value as Response);
+				return ensureCookiesAttached(apiContext, value);
 			} else {
 				/**
 				 * Here we handle the case where `next` was called and returned nothing.
@@ -107,7 +90,7 @@ export async function callMiddleware<R>(
 			throw new AstroError(AstroErrorData.MiddlewareNotAResponse);
 		} else {
 			// Middleware did not call resolve and returned a value
-			return ensureCookiesAttached(apiContext, value as Response);
+			return ensureCookiesAttached(apiContext, value);
 		}
 	});
 }
@@ -118,11 +101,3 @@ function ensureCookiesAttached(apiContext: APIContext, response: Response): Resp
 	}
 	return response;
 }
-
-function isEndpointOutput(endpointResult: any): endpointResult is EndpointOutput {
-	return (
-		!(endpointResult instanceof Response) &&
-		typeof endpointResult === 'object' &&
-		typeof endpointResult.body === 'string'
-	);
-}
diff --git a/packages/astro/src/core/middleware/index.ts b/packages/astro/src/core/middleware/index.ts
index c02761351..ffaafb3e5 100644
--- a/packages/astro/src/core/middleware/index.ts
+++ b/packages/astro/src/core/middleware/index.ts
@@ -1,8 +1,8 @@
-import type { MiddlewareEndpointHandler, Params } from '../../@types/astro.js';
+import type { MiddlewareHandler, Params } from '../../@types/astro.js';
 import { createAPIContext } from '../endpoint/index.js';
 import { sequence } from './sequence.js';
 
-function defineMiddleware(fn: MiddlewareEndpointHandler) {
+function defineMiddleware(fn: MiddlewareHandler) {
 	return fn;
 }
 
diff --git a/packages/astro/src/core/middleware/sequence.ts b/packages/astro/src/core/middleware/sequence.ts
index d20641ee3..9a6896394 100644
--- a/packages/astro/src/core/middleware/sequence.ts
+++ b/packages/astro/src/core/middleware/sequence.ts
@@ -1,4 +1,4 @@
-import type { APIContext, MiddlewareEndpointHandler } from '../../@types/astro.js';
+import type { APIContext, MiddlewareHandler } from '../../@types/astro.js';
 import { defineMiddleware } from './index.js';
 
 // From SvelteKit: https://github.com/sveltejs/kit/blob/master/packages/kit/src/exports/hooks/sequence.js
@@ -6,11 +6,11 @@ import { defineMiddleware } from './index.js';
  *
  * It accepts one or more middleware handlers and makes sure that they are run in sequence.
  */
-export function sequence(...handlers: MiddlewareEndpointHandler[]): MiddlewareEndpointHandler {
+export function sequence(...handlers: MiddlewareHandler[]): MiddlewareHandler {
 	const filtered = handlers.filter((h) => !!h);
 	const length = filtered.length;
 	if (!length) {
-		const handler: MiddlewareEndpointHandler = defineMiddleware((context, next) => {
+		const handler: MiddlewareHandler = defineMiddleware((context, next) => {
 			return next();
 		});
 		return handler;
diff --git a/packages/astro/src/core/pipeline.ts b/packages/astro/src/core/pipeline.ts
index 87f833ee5..b3493b7c0 100644
--- a/packages/astro/src/core/pipeline.ts
+++ b/packages/astro/src/core/pipeline.ts
@@ -1,10 +1,4 @@
-import type {
-	ComponentInstance,
-	EndpointHandler,
-	MiddlewareEndpointHandler,
-	MiddlewareHandler,
-	MiddlewareResponseHandler,
-} from '../@types/astro.js';
+import type { ComponentInstance, EndpointHandler, MiddlewareHandler } from '../@types/astro.js';
 import { callEndpoint, createAPIContext } from './endpoint/index.js';
 import { callMiddleware } from './middleware/callMiddleware.js';
 import { renderPage } from './render/core.js';
@@ -28,7 +22,7 @@ export type PipelineHookFunction = (ctx: RenderContext, mod: ComponentInstance |
  */
 export class Pipeline {
 	env: Environment;
-	#onRequest?: MiddlewareEndpointHandler;
+	#onRequest?: MiddlewareHandler;
 	#hooks: PipelineHooks = {
 		before: [],
 	};
@@ -60,7 +54,7 @@ export class Pipeline {
 	/**
 	 * A middleware function that will be called before each request.
 	 */
-	setMiddlewareFunction(onRequest: MiddlewareEndpointHandler) {
+	setMiddlewareFunction(onRequest: MiddlewareHandler) {
 		this.#onRequest = onRequest;
 	}
 
@@ -115,11 +109,11 @@ export class Pipeline {
 	 *
 	 * It throws an error if the page can't be rendered.
 	 */
-	async #tryRenderRoute<MiddlewareReturnType = Response>(
+	async #tryRenderRoute(
 		renderContext: Readonly<RenderContext>,
 		env: Readonly<Environment>,
 		mod: Readonly<ComponentInstance> | undefined,
-		onRequest?: MiddlewareHandler<MiddlewareReturnType>
+		onRequest?: MiddlewareHandler
 	): Promise<Response> {
 		const apiContext = createAPIContext({
 			request: renderContext.request,
@@ -137,19 +131,14 @@ export class Pipeline {
 			case 'fallback':
 			case 'redirect': {
 				if (onRequest) {
-					return await callMiddleware<Response>(
-						env.logger,
-						onRequest as MiddlewareResponseHandler,
-						apiContext,
-						() => {
-							return renderPage({
-								mod,
-								renderContext,
-								env,
-								cookies: apiContext.cookies,
-							});
-						}
-					);
+					return await callMiddleware(onRequest, apiContext, () => {
+						return renderPage({
+							mod,
+							renderContext,
+							env,
+							cookies: apiContext.cookies,
+						});
+					});
 				} else {
 					return await renderPage({
 						mod,
diff --git a/packages/astro/src/core/render/index.ts b/packages/astro/src/core/render/index.ts
index 6d466c411..5f3a702a3 100644
--- a/packages/astro/src/core/render/index.ts
+++ b/packages/astro/src/core/render/index.ts
@@ -24,5 +24,5 @@ export interface SSROptions {
 	/**
 	 * Optional middlewares
 	 */
-	middleware?: AstroMiddlewareInstance<unknown>;
+	middleware?: AstroMiddlewareInstance;
 }
diff --git a/packages/astro/src/i18n/middleware.ts b/packages/astro/src/i18n/middleware.ts
index 854a39b77..79ac2c962 100644
--- a/packages/astro/src/i18n/middleware.ts
+++ b/packages/astro/src/i18n/middleware.ts
@@ -1,5 +1,5 @@
 import { appendForwardSlash, joinPaths } from '@astrojs/internal-helpers/path';
-import type { MiddlewareEndpointHandler, RouteData, SSRManifest } from '../@types/astro.js';
+import type { MiddlewareHandler, RouteData, SSRManifest } from '../@types/astro.js';
 import type { PipelineHookFunction } from '../core/pipeline.js';
 
 const routeDataSymbol = Symbol.for('astro.routeData');
@@ -19,7 +19,7 @@ export function createI18nMiddleware(
 	i18n: SSRManifest['i18n'],
 	base: SSRManifest['base'],
 	trailingSlash: SSRManifest['trailingSlash']
-): MiddlewareEndpointHandler | undefined {
+): MiddlewareHandler | undefined {
 	if (!i18n) {
 		return undefined;
 	}
diff --git a/packages/astro/src/vite-plugin-astro-server/route.ts b/packages/astro/src/vite-plugin-astro-server/route.ts
index f87c4e147..4c49525e7 100644
--- a/packages/astro/src/vite-plugin-astro-server/route.ts
+++ b/packages/astro/src/vite-plugin-astro-server/route.ts
@@ -3,7 +3,7 @@ import { fileURLToPath } from 'node:url';
 import type {
 	ComponentInstance,
 	ManifestData,
-	MiddlewareEndpointHandler,
+	MiddlewareHandler,
 	RouteData,
 	SSRElement,
 	SSRManifest,
@@ -288,7 +288,7 @@ export async function handleRoute({
 		});
 	}
 
-	const onRequest = middleware?.onRequest as MiddlewareEndpointHandler | undefined;
+	const onRequest = middleware?.onRequest as MiddlewareHandler | undefined;
 	if (config.experimental.i18n) {
 		const i18Middleware = createI18nMiddleware(
 			config.experimental.i18n,
diff --git a/packages/astro/test/fixtures/api-routes/src/pages/context/data/[param].json.js b/packages/astro/test/fixtures/api-routes/src/pages/context/data/[param].json.js
index d18eb086f..cb9308ba4 100644
--- a/packages/astro/test/fixtures/api-routes/src/pages/context/data/[param].json.js
+++ b/packages/astro/test/fixtures/api-routes/src/pages/context/data/[param].json.js
@@ -15,10 +15,10 @@ export function getStaticPaths() {
 }
 
 export function GET({ params, request }) {
-	return {
-		body: JSON.stringify({
+	return new Response(
+		JSON.stringify({
 			param: params.param,
 			pathname: new URL(request.url).pathname
 		})
-	};
+	);
 }
diff --git a/packages/astro/test/fixtures/astro-get-static-paths/src/pages/data/[slug].json.ts b/packages/astro/test/fixtures/astro-get-static-paths/src/pages/data/[slug].json.ts
index 32a0fd140..21df537cd 100644
--- a/packages/astro/test/fixtures/astro-get-static-paths/src/pages/data/[slug].json.ts
+++ b/packages/astro/test/fixtures/astro-get-static-paths/src/pages/data/[slug].json.ts
@@ -1,14 +1,12 @@
 export async function getStaticPaths() {
-    return [
+	return [
         { params: { slug: 'thing1' } },
         { params: { slug: 'thing2' } }
     ];
 }
 
 export async function GET() {
-    return {
-        body: JSON.stringify({
-            title: '[slug]'
-        }, null, 4)
-    };
+	return Response.json({
+		title: '[slug]',
+	});
 }
diff --git a/packages/astro/test/fixtures/astro-markdown-frontmatter-injection/src/pages/glob.json.js b/packages/astro/test/fixtures/astro-markdown-frontmatter-injection/src/pages/glob.json.js
index 3aae6d89a..1916378c9 100644
--- a/packages/astro/test/fixtures/astro-markdown-frontmatter-injection/src/pages/glob.json.js
+++ b/packages/astro/test/fixtures/astro-markdown-frontmatter-injection/src/pages/glob.json.js
@@ -1,6 +1,4 @@
 export async function GET() {
 	const docs = await import.meta.glob('./*.md', { eager: true });
-	return {
-		body: JSON.stringify(Object.values(docs).map(doc => doc.frontmatter)),
-	}
+	return Response.json(Object.values(docs).map((doc) => doc.frontmatter));
 }
diff --git a/packages/astro/test/fixtures/astro-markdown/src/pages/headings-glob.json.js b/packages/astro/test/fixtures/astro-markdown/src/pages/headings-glob.json.js
index b2c9ea6ea..3cc852c6f 100644
--- a/packages/astro/test/fixtures/astro-markdown/src/pages/headings-glob.json.js
+++ b/packages/astro/test/fixtures/astro-markdown/src/pages/headings-glob.json.js
@@ -1,9 +1,7 @@
 import { getHeadings } from './with-layout.md';
 
 export async function GET() {
-	return {
-		body: JSON.stringify({
-			headings: getHeadings(),
-		}),
-	}
+	return Response.json({
+		headings: getHeadings(),
+	});
 }
diff --git a/packages/astro/test/fixtures/astro-markdown/src/pages/raw-content.json.js b/packages/astro/test/fixtures/astro-markdown/src/pages/raw-content.json.js
index 82977443d..cf499bb39 100644
--- a/packages/astro/test/fixtures/astro-markdown/src/pages/raw-content.json.js
+++ b/packages/astro/test/fixtures/astro-markdown/src/pages/raw-content.json.js
@@ -1,10 +1,8 @@
 import { rawContent, compiledContent } from './basic.md';
 
 export async function GET() {
-	return {
-		body: JSON.stringify({
-			raw: rawContent(),
-			compiled: await compiledContent(),
-		}),
-	}
+	return Response.json({
+		raw: rawContent(),
+		compiled: await compiledContent(),
+	});
 }
diff --git a/packages/astro/test/fixtures/astro-markdown/src/pages/vite-env-vars-glob.json.js b/packages/astro/test/fixtures/astro-markdown/src/pages/vite-env-vars-glob.json.js
index 7a5d00f47..7dfe96294 100644
--- a/packages/astro/test/fixtures/astro-markdown/src/pages/vite-env-vars-glob.json.js
+++ b/packages/astro/test/fixtures/astro-markdown/src/pages/vite-env-vars-glob.json.js
@@ -1,7 +1,5 @@
 import { frontmatter } from './vite-env-vars.md';
 
 export async function GET() {
-	return {
-		body: JSON.stringify(frontmatter),
-	}
+	return Response.json(frontmatter);
 }
diff --git a/packages/astro/test/fixtures/content-collections/src/pages/collections.json.js b/packages/astro/test/fixtures/content-collections/src/pages/collections.json.js
index e335d2b05..b7b7d8472 100644
--- a/packages/astro/test/fixtures/content-collections/src/pages/collections.json.js
+++ b/packages/astro/test/fixtures/content-collections/src/pages/collections.json.js
@@ -8,7 +8,7 @@ export async function GET() {
 	const withSlugConfig = stripAllRenderFn(await getCollection('with-custom-slugs'));
 	const withUnionSchema = stripAllRenderFn(await getCollection('with-union-schema'));
 
-	return {
-		body: devalue.stringify({withoutConfig, withSchemaConfig, withSlugConfig, withUnionSchema}),
-	}
+	return new Response(
+		devalue.stringify({ withoutConfig, withSchemaConfig, withSlugConfig, withUnionSchema })
+	);
 }
diff --git a/packages/astro/test/fixtures/content-collections/src/pages/entries.json.js b/packages/astro/test/fixtures/content-collections/src/pages/entries.json.js
index 311b76cc8..a05a9138b 100644
--- a/packages/astro/test/fixtures/content-collections/src/pages/entries.json.js
+++ b/packages/astro/test/fixtures/content-collections/src/pages/entries.json.js
@@ -5,10 +5,17 @@ import { stripRenderFn } from '../utils.js';
 export async function GET() {
 	const columbiaWithoutConfig = stripRenderFn(await getEntryBySlug('without-config', 'columbia'));
 	const oneWithSchemaConfig = stripRenderFn(await getEntryBySlug('with-schema-config', 'one'));
-	const twoWithSlugConfig = stripRenderFn(await getEntryBySlug('with-custom-slugs', 'interesting-two'));
+	const twoWithSlugConfig = stripRenderFn(
+		await getEntryBySlug('with-custom-slugs', 'interesting-two')
+	);
 	const postWithUnionSchema = stripRenderFn(await getEntryBySlug('with-union-schema', 'post'));
 
-	return {
-		body: devalue.stringify({columbiaWithoutConfig, oneWithSchemaConfig, twoWithSlugConfig, postWithUnionSchema}),
-	}
+	return new Response(
+		devalue.stringify({
+			columbiaWithoutConfig,
+			oneWithSchemaConfig,
+			twoWithSlugConfig,
+			postWithUnionSchema,
+		})
+	);
 }
diff --git a/packages/astro/test/fixtures/core-image-ssr/src/pages/api.ts b/packages/astro/test/fixtures/core-image-ssr/src/pages/api.ts
index 7847baf62..261fb6bb7 100644
--- a/packages/astro/test/fixtures/core-image-ssr/src/pages/api.ts
+++ b/packages/astro/test/fixtures/core-image-ssr/src/pages/api.ts
@@ -3,8 +3,5 @@ import type { APIRoute } from "../../../../../src/@types/astro";
 export const GET = (async ({ params, request }) => {
 	const url = new URL(request.url);
   const src = url.searchParams.get("src");
-
-	return {
-		body: "An image: " + JSON.stringify(src),
-	};
+	return new Response("An image: " + JSON.stringify(src));
 }) satisfies APIRoute;
diff --git a/packages/astro/test/fixtures/data-collections/src/pages/authors/[id].json.js b/packages/astro/test/fixtures/data-collections/src/pages/authors/[id].json.js
index 76f4d5760..8d5365a2e 100644
--- a/packages/astro/test/fixtures/data-collections/src/pages/authors/[id].json.js
+++ b/packages/astro/test/fixtures/data-collections/src/pages/authors/[id].json.js
@@ -1,9 +1,9 @@
 import { getEntry } from 'astro:content';
 
-const ids = ['Ben Holmes', 'Fred K Schott', 'Nate Moore']
+const ids = ['Ben Holmes', 'Fred K Schott', 'Nate Moore'];
 
 export function getStaticPaths() {
-	return ids.map(id => ({ params: { id } }))
+	return ids.map((id) => ({ params: { id } }));
 }
 
 /** @param {import('astro').APIContext} params */
@@ -11,12 +11,8 @@ export async function GET({ params }) {
 	const { id } = params;
 	const author = await getEntry('authors-without-config', id);
 	if (!author) {
-		return {
-			body: JSON.stringify({ error: `Author ${id} Not found` }),
-		}
+		return Response.json({ error: `Author ${id} Not found` });
 	} else {
-		return {
-			body: JSON.stringify(author),
-		}
+		return Response.json(author);
 	}
 }
diff --git a/packages/astro/test/fixtures/data-collections/src/pages/authors/all.json.js b/packages/astro/test/fixtures/data-collections/src/pages/authors/all.json.js
index 5b5007fed..79dd8cd9d 100644
--- a/packages/astro/test/fixtures/data-collections/src/pages/authors/all.json.js
+++ b/packages/astro/test/fixtures/data-collections/src/pages/authors/all.json.js
@@ -2,8 +2,5 @@ import { getCollection } from 'astro:content';
 
 export async function GET() {
 	const authors = await getCollection('authors-without-config');
-
-	return {
-		body: JSON.stringify(authors),
-	}
+	return Response.json(authors);
 }
diff --git a/packages/astro/test/fixtures/data-collections/src/pages/translations/[lang].json.js b/packages/astro/test/fixtures/data-collections/src/pages/translations/[lang].json.js
index ab8cc764e..c6b0cfff6 100644
--- a/packages/astro/test/fixtures/data-collections/src/pages/translations/[lang].json.js
+++ b/packages/astro/test/fixtures/data-collections/src/pages/translations/[lang].json.js
@@ -1,9 +1,9 @@
 import { getEntry } from 'astro:content';
 
-const langs = ['en', 'es', 'fr']
+const langs = ['en', 'es', 'fr'];
 
 export function getStaticPaths() {
-	return langs.map(lang => ({ params: { lang } }))
+	return langs.map((lang) => ({ params: { lang } }));
 }
 
 /** @param {import('astro').APIContext} params */
@@ -11,12 +11,8 @@ export async function GET({ params }) {
 	const { lang } = params;
 	const translations = await getEntry('i18n', lang);
 	if (!translations) {
-		return {
-			body: JSON.stringify({ error: `Translation ${lang} Not found` }),
-		}
+		return Response.json({ error: `Translation ${lang} Not found` });
 	} else {
-		return {
-			body: JSON.stringify(translations),
-		}
+		return Response.json(translations);
 	}
 }
diff --git a/packages/astro/test/fixtures/data-collections/src/pages/translations/all.json.js b/packages/astro/test/fixtures/data-collections/src/pages/translations/all.json.js
index e8a1fee92..f1ebb15b7 100644
--- a/packages/astro/test/fixtures/data-collections/src/pages/translations/all.json.js
+++ b/packages/astro/test/fixtures/data-collections/src/pages/translations/all.json.js
@@ -2,8 +2,5 @@ import { getCollection } from 'astro:content';
 
 export async function GET() {
 	const translations = await getCollection('i18n');
-
-	return {
-		body: JSON.stringify(translations),
-	}
+	return Response.json(translations);
 }
diff --git a/packages/astro/test/fixtures/data-collections/src/pages/translations/by-id.json.js b/packages/astro/test/fixtures/data-collections/src/pages/translations/by-id.json.js
index f7b84752d..5f71c80e9 100644
--- a/packages/astro/test/fixtures/data-collections/src/pages/translations/by-id.json.js
+++ b/packages/astro/test/fixtures/data-collections/src/pages/translations/by-id.json.js
@@ -2,8 +2,5 @@ import { getDataEntryById } from 'astro:content';
 
 export async function GET() {
 	const item = await getDataEntryById('i18n', 'en');
-
-	return {
-		body: JSON.stringify(item),
-	}
+	return Response.json(item);
 }
diff --git a/packages/astro/test/fixtures/dynamic-endpoint-collision/src/pages/api/catch/[...slug].ts b/packages/astro/test/fixtures/dynamic-endpoint-collision/src/pages/api/catch/[...slug].ts
index 8fccd6695..96a9d56f6 100644
--- a/packages/astro/test/fixtures/dynamic-endpoint-collision/src/pages/api/catch/[...slug].ts
+++ b/packages/astro/test/fixtures/dynamic-endpoint-collision/src/pages/api/catch/[...slug].ts
@@ -1,15 +1,13 @@
-import type { APIRoute } from "astro";
+import type { APIRoute } from 'astro';
 
-const slugs = ["one", undefined];
+const slugs = ['one', undefined];
 
 export const GET: APIRoute = ({ params }) => {
-  return {
-    body: JSON.stringify({
-      slug: params.slug || "index",
-    }),
-  };
+	return Response.json({
+		slug: params.slug || 'index',
+	});
 };
 
 export function getStaticPaths() {
-  return slugs.map((u) => ({ params: { slug: u } }));
+	return slugs.map((u) => ({ params: { slug: u } }));
 }
diff --git a/packages/astro/test/fixtures/non-html-pages/src/pages/about-object.json.ts b/packages/astro/test/fixtures/non-html-pages/src/pages/about-object.json.ts
deleted file mode 100644
index 3936cbe85..000000000
--- a/packages/astro/test/fixtures/non-html-pages/src/pages/about-object.json.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-// NOTE: test deprecated object form
-// Returns the file body for this non-HTML file.
-// The content type is based off of the extension in the filename,
-// in this case: about.json.
-export async function GET() {
-	return {
-		body: JSON.stringify({
-			name: 'Astro',
-			url: 'https://astro.build/',
-		}),
-	};
-}
diff --git a/packages/astro/test/fixtures/non-html-pages/src/pages/placeholder-object.png.ts b/packages/astro/test/fixtures/non-html-pages/src/pages/placeholder-object.png.ts
deleted file mode 100644
index 114159004..000000000
--- a/packages/astro/test/fixtures/non-html-pages/src/pages/placeholder-object.png.ts
+++ /dev/null
@@ -1,18 +0,0 @@
-import { promises as fs } from 'node:fs';
-
-import type { APIRoute } from 'astro';
-
-// NOTE: test deprecated object form
-export const GET: APIRoute = async function get() {
-	try {
-		// Image is in the public domain. Sourced from
-		// https://en.wikipedia.org/wiki/File:Portrait_placeholder.png
-		const buffer = await fs.readFile('./test/fixtures/non-html-pages/src/images/placeholder.png');
-		return {
-			body: buffer.toString('binary'),
-			encoding: 'binary',
-		} as const;
-	} catch (error: unknown) {
-		throw new Error(`Something went wrong in placeholder.png route!: ${error as string}`);
-	}
-};
diff --git a/packages/astro/test/fixtures/non-html-pages/src/pages/placeholder.png.ts b/packages/astro/test/fixtures/non-html-pages/src/pages/placeholder.png.ts
index 50c6b877b..1ac93597e 100644
--- a/packages/astro/test/fixtures/non-html-pages/src/pages/placeholder.png.ts
+++ b/packages/astro/test/fixtures/non-html-pages/src/pages/placeholder.png.ts
@@ -2,12 +2,13 @@ import { promises as fs } from 'node:fs';
 
 import type { APIRoute } from 'astro';
 
-export const GET: APIRoute = async function get({ ResponseWithEncoding }) {
+export const GET: APIRoute = async function get() {
 	try {
 		// Image is in the public domain. Sourced from
 		// https://en.wikipedia.org/wiki/File:Portrait_placeholder.png
 		const buffer = await fs.readFile('./test/fixtures/non-html-pages/src/images/placeholder.png');
-		return new ResponseWithEncoding(buffer.toString('binary'), undefined, 'binary')
+		// NOTE: SSG only so not Content-Type needed
+		return new Response(buffer.buffer)
 	} catch (error: unknown) {
 		throw new Error(`Something went wrong in placeholder.png route!: ${error as string}`);
 	}
diff --git a/packages/astro/test/fixtures/routing-priority/src/pages/api/catch/[...slug].json.ts b/packages/astro/test/fixtures/routing-priority/src/pages/api/catch/[...slug].json.ts
index bc7e1b774..4b26f41e5 100644
--- a/packages/astro/test/fixtures/routing-priority/src/pages/api/catch/[...slug].json.ts
+++ b/packages/astro/test/fixtures/routing-priority/src/pages/api/catch/[...slug].json.ts
@@ -1,11 +1,11 @@
 import type { APIRoute } from 'astro';
 
 export const GET: APIRoute = async ({ params }) => {
-  return {
-    body: JSON.stringify({
+  return new Response(
+    JSON.stringify({
       path: params.slug,
-    }),
-  };
+    })
+  );
 };
 
 export function getStaticPaths() {
diff --git a/packages/astro/test/fixtures/routing-priority/src/pages/api/catch/[foo]-[bar].json.ts b/packages/astro/test/fixtures/routing-priority/src/pages/api/catch/[foo]-[bar].json.ts
index b06efff6f..b9d2f0cab 100644
--- a/packages/astro/test/fixtures/routing-priority/src/pages/api/catch/[foo]-[bar].json.ts
+++ b/packages/astro/test/fixtures/routing-priority/src/pages/api/catch/[foo]-[bar].json.ts
@@ -1,12 +1,12 @@
 import type { APIRoute } from 'astro';
 
 export const GET: APIRoute = async ({ params }) => {
-  return {
-    body: JSON.stringify({
+  return new Response(
+    JSON.stringify({
       foo: params.foo,
-			bar: params.bar,
-    }),
-  };
+      bar: params.bar,
+    })
+  );
 };
 
 export function getStaticPaths() {
diff --git a/packages/astro/test/fixtures/ssr-api-route/src/pages/context/[param].js b/packages/astro/test/fixtures/ssr-api-route/src/pages/context/[param].js
index ba110ee13..d5c9f4033 100644
--- a/packages/astro/test/fixtures/ssr-api-route/src/pages/context/[param].js
+++ b/packages/astro/test/fixtures/ssr-api-route/src/pages/context/[param].js
@@ -1,18 +1,16 @@
 /**
- * @param {import('astro').APIContext} api 
+ * @param {import('astro').APIContext} api
  */
 export function GET(ctx) {
-	return {
-		body: JSON.stringify({
-			cookiesExist: !!ctx.cookies,
-			requestExist: !!ctx.request,
-			redirectExist: !!ctx.redirect,
-			propsExist: !!ctx.props,
-			params: ctx.params,
-			site: ctx.site?.toString(),
-			generator: ctx.generator,
-			url: ctx.url.toString(),
-			clientAddress: ctx.clientAddress,
-		})
-	};
+	return Response.json({
+		cookiesExist: !!ctx.cookies,
+		requestExist: !!ctx.request,
+		redirectExist: !!ctx.redirect,
+		propsExist: !!ctx.props,
+		params: ctx.params,
+		site: ctx.site?.toString(),
+		generator: ctx.generator,
+		url: ctx.url.toString(),
+		clientAddress: ctx.clientAddress,
+	});
 }
diff --git a/packages/astro/test/fixtures/ssr-api-route/src/pages/food-object.json.js b/packages/astro/test/fixtures/ssr-api-route/src/pages/food-object.json.js
deleted file mode 100644
index 7992e697a..000000000
--- a/packages/astro/test/fixtures/ssr-api-route/src/pages/food-object.json.js
+++ /dev/null
@@ -1,10 +0,0 @@
-// NOTE: test deprecated object form
-export function GET() {
-	return {
-		body: JSON.stringify([
-			{ name: 'lettuce' },
-			{ name: 'broccoli' },
-			{ name: 'pizza' }
-		])
-	};
-}
diff --git a/packages/astro/test/fixtures/ssr-dynamic/src/pages/api/products/[id].js b/packages/astro/test/fixtures/ssr-dynamic/src/pages/api/products/[id].js
index 8c7c39302..8956f0d4c 100644
--- a/packages/astro/test/fixtures/ssr-dynamic/src/pages/api/products/[id].js
+++ b/packages/astro/test/fixtures/ssr-dynamic/src/pages/api/products/[id].js
@@ -1,6 +1,3 @@
-
 export function GET({ params }) {
-	return {
-		body: JSON.stringify(params)
-	};
+	return Response.json(params);
 }
diff --git a/packages/astro/test/fixtures/ssr-prerender-get-static-paths/src/pages/data/[slug].json.ts b/packages/astro/test/fixtures/ssr-prerender-get-static-paths/src/pages/data/[slug].json.ts
index d969873c5..7a1b6af28 100644
--- a/packages/astro/test/fixtures/ssr-prerender-get-static-paths/src/pages/data/[slug].json.ts
+++ b/packages/astro/test/fixtures/ssr-prerender-get-static-paths/src/pages/data/[slug].json.ts
@@ -1,16 +1,14 @@
 export const prerender = true;
 
 export async function getStaticPaths() {
-    return [
+	return [
         { params: { slug: 'thing1' } },
         { params: { slug: 'thing2' } }
     ];
 }
 
 export async function GET() {
-    return {
-        body: JSON.stringify({
-            title: '[slug]'
-        }, null, 4)
-    };
+	return Response.json({
+		title: '[slug]',
+	});
 }
diff --git a/packages/astro/test/fixtures/static-build/src/pages/company.json.ts b/packages/astro/test/fixtures/static-build/src/pages/company.json.ts
index 08f45a7b8..6a08cc939 100644
--- a/packages/astro/test/fixtures/static-build/src/pages/company.json.ts
+++ b/packages/astro/test/fixtures/static-build/src/pages/company.json.ts
@@ -1,8 +1,6 @@
-export async function GET() {
-    return {
-        body: JSON.stringify({
-            name: 'Astro Technology Company',
-            url: 'https://astro.build/'
-        })
-    }
+export function GET() {
+	return Response.json({
+		name: 'Astro Technology Company',
+		url: 'https://astro.build/',
+	});
 }
diff --git a/packages/astro/test/fixtures/static-build/src/pages/data/[slug].json.ts b/packages/astro/test/fixtures/static-build/src/pages/data/[slug].json.ts
index 2fa13ac18..2c78812ec 100644
--- a/packages/astro/test/fixtures/static-build/src/pages/data/[slug].json.ts
+++ b/packages/astro/test/fixtures/static-build/src/pages/data/[slug].json.ts
@@ -6,11 +6,9 @@ export async function getStaticPaths() {
 }
 
 export async function GET({ params }) {
-    return {
-        body: JSON.stringify({
-            slug: params.slug,
-            name: 'Astro Technology Company',
-            url: 'https://astro.build/'
-        })
-    }
+    return Response.json({
+        slug: params.slug,
+        name: 'Astro Technology Company',
+        url: 'https://astro.build/'
+    });
 }
diff --git a/packages/astro/test/fixtures/static-build/src/pages/posts.json.js b/packages/astro/test/fixtures/static-build/src/pages/posts.json.js
index aefbbffff..b72a000d9 100644
--- a/packages/astro/test/fixtures/static-build/src/pages/posts.json.js
+++ b/packages/astro/test/fixtures/static-build/src/pages/posts.json.js
@@ -15,8 +15,5 @@ async function fetchPosts() {
 
 export async function GET() {
     const posts = await fetchPosts();
-
-    return {
-        body: JSON.stringify(posts, null, 4),
-    };
+    return Response.json(posts);
 }
diff --git a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/[slug].json.ts b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/[slug].json.ts
index 783031605..3c1408300 100644
--- a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/[slug].json.ts
+++ b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/[slug].json.ts
@@ -6,10 +6,8 @@ export async function getStaticPaths() {
 }
 
 export async function GET({ params }) {
-    return {
-        body: JSON.stringify({
-            slug: params.slug,
-            title: '[slug]'
-        })
-    };
+    return Response.json({
+        slug: params.slug,
+        title: '[slug]'
+    });
 }
diff --git a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/data/[slug].json.ts b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/data/[slug].json.ts
index 707c39fa9..26cd9b065 100644
--- a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/data/[slug].json.ts
+++ b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/data/[slug].json.ts
@@ -6,10 +6,8 @@ export async function getStaticPaths() {
 }
 
 export async function GET({ params }) {
-    return {
-        body: JSON.stringify({
-            slug: params.slug,
-            title: 'data [slug]'
-        })
-    };
+    return Response.json({
+        slug: params.slug,
+        title: 'data [slug]'
+    });
 }
diff --git a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/home.json.ts b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/home.json.ts
index 5eaac42f1..2bee50a8e 100644
--- a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/home.json.ts
+++ b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/home.json.ts
@@ -1,7 +1,3 @@
 export async function GET() {
-    return {
-        body: JSON.stringify({
-            title: 'home'
-        })
-    };
+	return Response.json({ title: 'home' });
 }
diff --git a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/[image].svg.ts b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/[image].svg.ts
index c6fa88711..cef9dd608 100644
--- a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/[image].svg.ts
+++ b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/[image].svg.ts
@@ -1,14 +1,16 @@
 export async function getStaticPaths() {
-	return [
-			{ params: { image: 1 } },
-			{ params: { image: 2 } },
-	];
+	return [{ params: { image: 1 } }, { params: { image: 2 } }];
 }
 
 export async function GET({ params }) {
-	return {
-			body: `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 300 200">
+	return new Response(
+		`<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 300 200">
 	<title>${params.image}</title>
-</svg>`
-	};
+</svg>`,
+		{
+			headers: {
+				'content-type': 'image/svg+xml',
+			},
+		}
+	);
 }
diff --git a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/hex.ts b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/hex.ts
index 84dd6dcaa..c258c3091 100644
--- a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/hex.ts
+++ b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/hex.ts
@@ -1,9 +1,6 @@
-import { readFileSync } from "node:fs";
+import { readFile } from 'node:fs/promises';
 
-export async function GET({ params, request }) {
-  const buffer = readFileSync(new URL('../../astro.png', import.meta.url));
-  return {
-    body: buffer.toString('hex'),
-    encoding: 'hex',
-  };
+export async function GET() {
+	const buffer = await readFile(new URL('../../astro.png', import.meta.url));
+	return new Response(buffer.buffer);
 }
diff --git a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/static.svg.ts b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/static.svg.ts
index 93fcf4022..423f258f8 100644
--- a/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/static.svg.ts
+++ b/packages/astro/test/fixtures/with-endpoint-routes/src/pages/images/static.svg.ts
@@ -1,7 +1,12 @@
-export async function GET() {
-	return {
-			body: `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 300 200">
+export function GET() {
+	return new Response(
+		`<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 300 200">
 	<title>Static SVG</title>
-</svg>`
-	};
+</svg>`,
+		{
+			headers: {
+				'content-type': 'image/svg+xml',
+			},
+		}
+	);
 }
diff --git a/packages/astro/test/non-html-pages.test.js b/packages/astro/test/non-html-pages.test.js
index 2cf581104..9f050ae96 100644
--- a/packages/astro/test/non-html-pages.test.js
+++ b/packages/astro/test/non-html-pages.test.js
@@ -15,12 +15,6 @@ describe('Non-HTML Pages', () => {
 			expect(json).to.have.property('name', 'Astro');
 			expect(json).to.have.property('url', 'https://astro.build/');
 		});
-
-		it('should match contents (deprecated object form)', async () => {
-			const json = JSON.parse(await fixture.readFile('/about-object.json'));
-			expect(json).to.have.property('name', 'Astro');
-			expect(json).to.have.property('url', 'https://astro.build/');
-		});
 	});
 
 	describe('png', () => {
@@ -40,22 +34,5 @@ describe('Non-HTML Pages', () => {
 				'iVBORw0KGgoAAAANSUhEUgAAAGQAAACWCAMAAAAfZt10AAAABlBMVEXd3d3+/v7B/CFgAAAA3UlEQVR42u3ZMQ7DIBQFQeb+l06bNgUbG/5eYApLFjzWNE3TNE3TNE035av9AhAQEBBQGAQEFAaFQWFQGBQGhUGCKAwKgwQpDJ6JECgCRYIEikH8YAyCRyEGyRCDvBWRIPNNBpm/8G6kUM45EhXKlQfuFSHFpbFH+jt2j/S7xwqUYvBaCRIozZy6X2km7v1K8uwQIIWBwkBAQEBg3Tyj3z4LnzRBKgwKg8KgMEgQhaEwSBCFQWBEiMIgQQqDBCkMEqQw+APixYgcsa0TERs7D/F6xGmIAxCD/Iw4AvEB92Ec3ZAPdlMAAAAASUVORK5CYII='
 			);
 		});
-
-		it('should not have had its encoding mangled (deprecated object form)', async () => {
-			const buffer = await fixture.readFile('/placeholder-object.png', 'base64');
-
-			// Sanity check the first byte
-			const hex = Buffer.from(buffer, 'base64').toString('hex');
-			const firstHexByte = hex.slice(0, 2);
-			// If we accidentally utf8 encode the png, the first byte (in hex) will be 'c2'
-			expect(firstHexByte).to.not.equal('c2');
-			// and if correctly encoded in binary, it should be '89'
-			expect(firstHexByte).to.equal('89');
-
-			// Make sure the whole buffer (in base64) matches this snapshot
-			expect(buffer).to.equal(
-				'iVBORw0KGgoAAAANSUhEUgAAAGQAAACWCAMAAAAfZt10AAAABlBMVEXd3d3+/v7B/CFgAAAA3UlEQVR42u3ZMQ7DIBQFQeb+l06bNgUbG/5eYApLFjzWNE3TNE3TNE035av9AhAQEBBQGAQEFAaFQWFQGBQGhUGCKAwKgwQpDJ6JECgCRYIEikH8YAyCRyEGyRCDvBWRIPNNBpm/8G6kUM45EhXKlQfuFSHFpbFH+jt2j/S7xwqUYvBaCRIozZy6X2km7v1K8uwQIIWBwkBAQEBg3Tyj3z4LnzRBKgwKg8KgMEgQhaEwSBCFQWBEiMIgQQqDBCkMEqQw+APixYgcsa0TERs7D/F6xGmIAxCD/Iw4AvEB92Ec3ZAPdlMAAAAASUVORK5CYII='
-			);
-		});
 	});
 });
diff --git a/packages/astro/test/ssr-api-route.test.js b/packages/astro/test/ssr-api-route.test.js
index fbaafc822..e15993b88 100644
--- a/packages/astro/test/ssr-api-route.test.js
+++ b/packages/astro/test/ssr-api-route.test.js
@@ -33,17 +33,6 @@ describe('API routes in SSR', () => {
 		expect(body.length).to.equal(3);
 	});
 
-	it('Can load the API route too (deprecated object form)', async () => {
-		const app = await fixture.loadTestAdapterApp();
-		const request = new Request('http://example.com/food-object.json');
-		const response = await app.render(request);
-		expect(response.status).to.equal(200);
-		expect(response.headers.get('Content-Type')).to.equal('application/json;charset=utf-8');
-		expect(response.headers.get('Content-Length')).to.not.be.empty;
-		const body = await response.json();
-		expect(body.length).to.equal(3);
-	});
-
 	it('Has valid api context', async () => {
 		const app = await fixture.loadTestAdapterApp();
 		const request = new Request('http://example.com/context/any');
@@ -96,13 +85,6 @@ describe('API routes in SSR', () => {
 			expect(res.status).to.equal(200);
 		});
 
-		it('Infer content type with charset for { body } shorthand (deprecated object form)', async () => {
-			const response = await fixture.fetch('/food-object.json', {
-				method: 'GET',
-			});
-			expect(response.headers.get('Content-Type')).to.equal('application/json;charset=utf-8');
-		});
-
 		it('Can set multiple headers of the same type', async () => {
 			const response = await new Promise((resolve) => {
 				let { port } = devServer.address;
diff --git a/packages/integrations/markdoc/test/fixtures/content-collections/src/pages/collection.json.js b/packages/integrations/markdoc/test/fixtures/content-collections/src/pages/collection.json.js
index 6f389f0a7..cb3c84652 100644
--- a/packages/integrations/markdoc/test/fixtures/content-collections/src/pages/collection.json.js
+++ b/packages/integrations/markdoc/test/fixtures/content-collections/src/pages/collection.json.js
@@ -4,7 +4,5 @@ import { stripAllRenderFn } from '../../utils.js';
 
 export async function GET() {
 	const posts = await getCollection('blog');
-	return {
-		body: stringify(stripAllRenderFn(posts))
-	};
+	return new Response(stringify(stripAllRenderFn(posts)));
 }
diff --git a/packages/integrations/markdoc/test/fixtures/content-collections/src/pages/entry.json.js b/packages/integrations/markdoc/test/fixtures/content-collections/src/pages/entry.json.js
index aa24117ab..53dd17013 100644
--- a/packages/integrations/markdoc/test/fixtures/content-collections/src/pages/entry.json.js
+++ b/packages/integrations/markdoc/test/fixtures/content-collections/src/pages/entry.json.js
@@ -4,7 +4,5 @@ import { stripRenderFn } from '../../utils.js';
 
 export async function GET() {
 	const post = await getEntryBySlug('blog', 'post-1');
-	return {
-		body: stringify(stripRenderFn(post)),
-	};
+	return new Response(stringify(stripRenderFn(post)));
 }
diff --git a/packages/integrations/mdx/test/fixtures/mdx-frontmatter-injection/src/pages/glob.json.js b/packages/integrations/mdx/test/fixtures/mdx-frontmatter-injection/src/pages/glob.json.js
index 3423bc634..63248dc56 100644
--- a/packages/integrations/mdx/test/fixtures/mdx-frontmatter-injection/src/pages/glob.json.js
+++ b/packages/integrations/mdx/test/fixtures/mdx-frontmatter-injection/src/pages/glob.json.js
@@ -1,6 +1,6 @@
 export async function GET() {
 	const docs = await import.meta.glob('./*.mdx', { eager: true });
-	return {
-		body: JSON.stringify(Object.values(docs).map(doc => doc.frontmatter)),
-	}
+	return new Response(
+		JSON.stringify(Object.values(docs).map(doc => doc.frontmatter))
+	);
 }
diff --git a/packages/integrations/mdx/test/fixtures/mdx-frontmatter/src/pages/glob.json.js b/packages/integrations/mdx/test/fixtures/mdx-frontmatter/src/pages/glob.json.js
index 9a10127b7..d82d9f770 100644
--- a/packages/integrations/mdx/test/fixtures/mdx-frontmatter/src/pages/glob.json.js
+++ b/packages/integrations/mdx/test/fixtures/mdx-frontmatter/src/pages/glob.json.js
@@ -1,9 +1,6 @@
 export async function GET() {
 	const mdxPages = await import.meta.glob('./*.mdx', { eager: true });
-
-	return {
-		body: JSON.stringify({
-			titles: Object.values(mdxPages ?? {}).map(v => v?.frontmatter?.title),
-		})
-	}
+	return Response.json({
+		titles: Object.values(mdxPages ?? {}).map((v) => v?.frontmatter?.title),
+	});
 }
diff --git a/packages/integrations/mdx/test/fixtures/mdx-get-headings/src/pages/pages.json.js b/packages/integrations/mdx/test/fixtures/mdx-get-headings/src/pages/pages.json.js
index de65e50e0..e57192c61 100644
--- a/packages/integrations/mdx/test/fixtures/mdx-get-headings/src/pages/pages.json.js
+++ b/packages/integrations/mdx/test/fixtures/mdx-get-headings/src/pages/pages.json.js
@@ -1,11 +1,8 @@
 export async function GET() {
 	const mdxPages = await import.meta.glob('./*.mdx', { eager: true });
-
-	return {
-		body: JSON.stringify({
-			headingsByPage: Object.fromEntries(
-				Object.entries(mdxPages ?? {}).map(([k, v]) => [k, v?.getHeadings()])
-			),
-		}),
-	}
+	return Response.json({
+		headingsByPage: Object.fromEntries(
+			Object.entries(mdxPages ?? {}).map(([k, v]) => [k, v?.getHeadings()])
+		),
+	});
 }
diff --git a/packages/integrations/mdx/test/fixtures/mdx-url-export/src/pages/pages.json.js b/packages/integrations/mdx/test/fixtures/mdx-url-export/src/pages/pages.json.js
index 93bf31be2..02cff64a8 100644
--- a/packages/integrations/mdx/test/fixtures/mdx-url-export/src/pages/pages.json.js
+++ b/packages/integrations/mdx/test/fixtures/mdx-url-export/src/pages/pages.json.js
@@ -1,9 +1,6 @@
 export async function GET() {
 	const mdxPages = await import.meta.glob('./*.mdx', { eager: true });
-
-	return {
-		body: JSON.stringify({
-			urls: Object.values(mdxPages ?? {}).map(v => v?.url),
-		})
-	}
+	return Response.json({
+		urls: Object.values(mdxPages ?? {}).map((v) => v?.url),
+	});
 }
diff --git a/packages/integrations/mdx/test/fixtures/mdx-vite-env-vars/src/pages/frontmatter.json.js b/packages/integrations/mdx/test/fixtures/mdx-vite-env-vars/src/pages/frontmatter.json.js
index 91654c392..152285b9c 100644
--- a/packages/integrations/mdx/test/fixtures/mdx-vite-env-vars/src/pages/frontmatter.json.js
+++ b/packages/integrations/mdx/test/fixtures/mdx-vite-env-vars/src/pages/frontmatter.json.js
@@ -1,7 +1,5 @@
 import { frontmatter } from './vite-env-vars.mdx';
 
 export function GET() {
-	return {
-		body: JSON.stringify(frontmatter),
-	}
+	return Response.json(frontmatter);
 }
diff --git a/packages/integrations/node/test/fixtures/node-middleware/src/pages/ssr.ts b/packages/integrations/node/test/fixtures/node-middleware/src/pages/ssr.ts
index 67f32eafa..423db341a 100644
--- a/packages/integrations/node/test/fixtures/node-middleware/src/pages/ssr.ts
+++ b/packages/integrations/node/test/fixtures/node-middleware/src/pages/ssr.ts
@@ -1,9 +1,7 @@
 export async function GET() {
 	let number = Math.random();
-	return {
-		body: JSON.stringify({
-			number,
-			message: `Here's a random number: ${number}`,
-		}),
-	};
+	return Response.json({
+		number,
+		message: `Here's a random number: ${number}`,
+	});
 }