feat: add support for read in edge environments

.changeset/old-moons-lick.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-cloudflare': minor
+---
+
+feat: add support for `('$app/server').read`

packages/adapter-cloudflare/index.js

@@ -161,6 +161,9 @@ export default function (options = {}) {
 					return prerender ? emulated.prerender_platform : emulated.platform;
 				}
 			};
+		},
+		supports: {
+			read: () => true
 		}
 	};
 }

packages/adapter-cloudflare/src/worker.js

@@ -19,7 +19,33 @@ export default {
 	async fetch(req, env, context) {
 		await server.init({
 			// @ts-expect-error env contains environment variables and bindings
-			env
+			env,
+			read: (file) =>
+				new ReadableStream({
+					async start(controller) {
+						try {
+							const response = await env.ASSETS.fetch(new URL('/' + file, req.url));
+							if (!response.ok) {
+								throw new Error(`Failed to fetch (${response.status} - ${response.statusText})`);
+							}
+							const reader = response.body.getReader();
+							/** @returns {Promise<void>} */
+							async function pump() {
+								const { done, value } = await reader.read();
+								if (done) {
+									controller.close();
+									return;
+								}
+								controller.enqueue(value);
+								return pump();
+							}
+							return pump();
+						} catch (error) {
+							console.error(`Error reading file ${file}:`, error);
+							controller.error(error);
+						}
+					}
+				})
 		});
 
 		// skip cache if "cache-control: no-cache" in request

packages/adapter-cloudflare/test/apps/pages/src/routes/read/+server.js

@@ -0,0 +1,6 @@
+import { read } from '$app/server';
+import goose from '../../../../goose.jpg';
+
+export function GET() {
+	return read(goose);
+}

packages/adapter-cloudflare/test/apps/pages/test/test.js

@@ -4,3 +4,9 @@ test('worker works', async ({ page }) => {
 	await page.goto('/');
 	await expect(page.locator('h1')).toContainText('Sum: 3');
 });
+
+test("('$app/server').read works", async ({ page }) => {
+	const response = await page.goto('/read');
+	expect(response.status()).toBe(200);
+	expect(response.headers()['content-type']).toBe('image/jpeg');
+});

packages/adapter-cloudflare/test/apps/workers/src/routes/read/+server.js

@@ -0,0 +1,6 @@
+import { read } from '$app/server';
+import goose from '../../../../goose.jpg';
+
+export function GET() {
+	return read(goose);
+}

packages/adapter-cloudflare/test/apps/workers/test/test.js

@@ -4,3 +4,9 @@ test('worker works', async ({ page }) => {
 	await page.goto('/');
 	await expect(page.locator('h1')).toContainText('Sum: 3');
 });
+
+test("('$app/server').read works", async ({ page }) => {
+	const response = await page.goto('/read');
+	expect(response.status()).toBe(200);
+	expect(response.headers()['content-type']).toBe('image/jpeg');
+});