fix: support bare Node built-ins and .wasm/font files in Netlify edge functions

.changeset/quiet-bees-copy.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-netlify': patch
+---
+
+fix: support bare Node built-in imports and `.wasm`/font files in edge functions

packages/adapter-netlify/index.js

@@ -402,7 +402,9 @@ function to_import_specifier(path) {
 
 /** @satisfies {import('rolldown').BuildOptions} */
 const rolldown_config = {
-	platform: 'browser',
+	// Mirror Netlify's edge-bundler behaviour for externalising Node.js built-ins
+	// see https://github.com/netlify/build/blob/main/packages/edge-bundler/node/npm_dependencies.ts#L289-L309
+	platform: 'node',
 	output: {
 		sourcemap: true,
 		codeSplitting: false
@@ -412,9 +414,19 @@ const rolldown_config = {
 	},
 	// Node built-ins are allowed, but must be prefixed with `node:`
 	// https://docs.netlify.com/edge-functions/api/#runtime-environment
-	external: builtinModules.map((id) => `node:${id}`),
 	resolve: {
-		alias: Object.fromEntries(builtinModules.map((id) => [id, `node:${id}`]))
+		alias: Object.fromEntries(builtinModules.map((id) => [id, `node:${id}`])),
+		mainFields: ['module', 'browser', 'main']
+	},
+	// Rolldown's default does not handle these files automatically
+	// see https://github.com/rolldown/rolldown/blob/main/crates/rolldown/src/utils/prepare_build_context.rs#L320-L336
+	moduleTypes: {
+		'.wasm': 'copy',
+		'.woff': 'copy',
+		'.woff2': 'copy',
+		'.ttf': 'copy',
+		'.eot': 'copy',
+		'.otf': 'copy'
 	}
 };
 

packages/adapter-netlify/test/apps/edge/_test_dependencies/wasm-lib/index.js

@@ -0,0 +1,10 @@
+// imports a .wasm file directly, like resvg/satori-based packages
+/**
+ * @param {number} a
+ * @param {number} b
+ * @returns {Promise<number>}
+ */
+export async function add(a, b) {
+	const wasm = await import('./add.wasm');
+	return wasm.add(a, b);
+}

packages/adapter-netlify/test/apps/edge/_test_dependencies/wasm-lib/package.json

@@ -0,0 +1,7 @@
+{
+	"name": "e2e-test-dep-wasm",
+	"version": "1.0.0",
+	"private": true,
+	"type": "module",
+	"exports": "./index.js"
+}

packages/adapter-netlify/test/apps/edge/build.test.js

@@ -35,3 +35,13 @@ test('treeshakes component from the server bundle if SSR is turned off', () => {
 	const edge_function = fs.readFileSync(edge_function_path, 'utf-8');
 	expect(edge_function).not.toContain('this should never appear in the server bundle');
 });
+
+test('.wasm files are copied alongside the edge function', () => {
+	const edge_function = fs.readFileSync(edge_function_path, 'utf-8');
+	const wasm_import = edge_function.match(/import\(["'](\.\/[^"']+\.wasm)["']\)/)?.[1];
+
+	expect(wasm_import).toBeDefined();
+	expect(fs.existsSync(path.resolve(path.dirname(edge_function_path), wasm_import ?? ''))).toBe(
+		true
+	);
+});

packages/adapter-netlify/test/apps/edge/package.json

@@ -12,6 +12,7 @@
 	"devDependencies": {
 		"@sveltejs/kit": "workspace:^",
 		"@sveltejs/vite-plugin-svelte": "catalog:",
+		"e2e-test-dep-wasm": "file:./_test_dependencies/wasm-lib",
 		"svelte": "catalog:",
 		"vite": "catalog:",
 		"vitest": "catalog:"

packages/adapter-netlify/test/apps/edge/src/routes/node-builtin/+server.js

@@ -0,0 +1,6 @@
+// a bare (non `node:`-prefixed) built-in import, as found in many dependencies
+import { createHash } from 'crypto';
+
+export function GET() {
+	return new Response(createHash('sha256').update('hello').digest('hex'));
+}

packages/adapter-netlify/test/apps/edge/src/routes/wasm/+server.js

@@ -0,0 +1,5 @@
+import { add } from 'e2e-test-dep-wasm';
+
+export async function GET() {
+	return new Response(String(await add(1, 2)));
+}

packages/adapter-netlify/test/apps/edge/test/test.js

@@ -33,3 +33,15 @@ test('page renders on the client if SSR is turned off', async ({ page }) => {
 	await page.goto('/treeshake-server');
 	await expect(page.locator('p')).toHaveText('this should never appear in the server bundle');
 });
+
+test('bare Node built-in imports work', async ({ request }) => {
+	const response = await request.get('/node-builtin');
+	expect(await response.text()).toBe(
+		'2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824'
+	);
+});
+
+test('.wasm imports work', async ({ request }) => {
+	const response = await request.get('/wasm');
+	expect(await response.text()).toBe('3');
+});