withastro · matthewp · Mar 27, 2026 · Mar 23, 2026 · Mar 23, 2026 · Mar 23, 2026
diff --git a/.changeset/fix-ssr-assets-manifest-middleware.md b/.changeset/fix-ssr-assets-manifest-middleware.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes CSS, fonts, and other assets failing to load when using `@astrojs/node` in middleware mode with a catch-all route. Previously these assets were incorrectly matched by the catch-all instead of being served as static files.
-Fixes CSS, fonts, and other assets failing to load when using `@astrojs/node` in middleware mode with a catch-all route. Previously these assets were incorrectly matched by the catch-all instead of being served as static files.
+Fixes catch-all routes incorrectly intercepting requests for static assets when using the `@astrojs/node` adapter in middleware mode.
-Fixes CSS, fonts, and other assets failing to load when using `@astrojs/node` in middleware mode with a catch-all route. Previously these assets were incorrectly matched by the catch-all instead of being served as static files.
+Fixes catch-all routes incorrectly intercepting requests for static assets when using the `@astrojs/node` adapter in middleware mode.
diff --git a/packages/astro/src/core/build/plugins/plugin-manifest.ts b/packages/astro/src/core/build/plugins/plugin-manifest.ts
@@ -124,6 +124,17 @@ async function createManifest(
 		internals.staticFiles.add(file);
 	}
 
+	// Also include SSR-emitted assets (CSS, fonts, images) tracked in ssrAssetsPerEnvironment.
+	// These assets are moved to the client directory by ssrMoveAssets() later in the pipeline,
+	// so they haven't landed on disk yet when we glob above. Without this, adapters in middleware
+	// mode won't recognize them as static files and will match them against catch-all routes instead.
+	// See: https://github.com/withastro/astro/issues/16039
+	for (const [, ssrAssets] of internals.ssrAssetsPerEnvironment) {
+		for (const asset of ssrAssets) {
+			internals.staticFiles.add(asset);
+		}
+	}
+
 	const staticFiles = internals.staticFiles;
 	const encodedKey = await encodeKey(await buildOpts.key);
 	const manifest = await buildManifest(buildOpts, internals, Array.from(staticFiles), encodedKey);

diff --git a/packages/integrations/node/test/fixtures/ssr-assets-middleware/package.json b/packages/integrations/node/test/fixtures/ssr-assets-middleware/package.json
@@ -0,0 +1,9 @@
+{
+  "name": "@test/ssr-assets-middleware",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "@astrojs/node": "workspace:*",
+    "astro": "workspace:*"
+  }
+}
diff --git a/packages/integrations/node/test/fixtures/ssr-assets-middleware/src/pages/[...path].astro b/packages/integrations/node/test/fixtures/ssr-assets-middleware/src/pages/[...path].astro
@@ -0,0 +1,12 @@
+---
+// Catch-all route — simulates a custom 404 handler.
+// This is intentional: if SSR-emitted assets are missing from manifest.assets,
+// asset requests like /_astro/*.css will match this catch-all instead of being
+// served as static files. See https://github.com/withastro/astro/issues/16039
+const { path } = Astro.params;
+---
+<!DOCTYPE html>
+<html lang="en">
+<head><title>Not Found</title></head>
+<body>catch-all: {path}</body>
+</html>
diff --git a/packages/integrations/node/test/fixtures/ssr-assets-middleware/src/pages/index.astro b/packages/integrations/node/test/fixtures/ssr-assets-middleware/src/pages/index.astro
@@ -0,0 +1,7 @@
+---
+import '../styles/main.css';
+---
+<html lang="en">
+<head><title>home</title></head>
+<body><div>home</div></body>
+</html>
diff --git a/packages/integrations/node/test/fixtures/ssr-assets-middleware/src/styles/main.css b/packages/integrations/node/test/fixtures/ssr-assets-middleware/src/styles/main.css
@@ -0,0 +1,3 @@
+.container {
+  color: red;
+}
diff --git a/packages/integrations/node/test/node-middleware.test.js b/packages/integrations/node/test/node-middleware.test.js
@@ -219,3 +219,67 @@ describe('behavior from middleware, middleware with fastify', () => {
 		assert.equal(body.text().includes('bar'), true);
 	});
 });
+
+// Regression test for https://github.com/withastro/astro/issues/16039
+// SSR-emitted assets (CSS, fonts, images) must appear in manifest.assets so that
+// the Node adapter in middleware mode can identify them as static files and NOT
+// match them against catch-all routes.
+describe('middleware with fastify and catch-all route: SSR assets in manifest', () => {
+	/** @type {import('./test-utils').Fixture} */
+	let fixture;
+	let server;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: './fixtures/ssr-assets-middleware/',
+			output: 'server',
+			adapter: nodejs({ mode: 'middleware' }),
+			vite: {
+				build: {
+					// Prevent CSS/SVG from being inlined so they appear as separate
+					// files in dist/client/_astro/ and are tracked in ssrAssetsPerEnvironment.
+					assetsInlineLimit: 0,
+				},
+			},
+		});
+		await fixture.build();
+		const { handler } = await fixture.loadAdapterEntryModule();
+		const app = Fastify({ logger: false });
+		await app
+			.register(fastifyStatic, {
+				root: fileURLToPath(
+					new URL('./fixtures/ssr-assets-middleware/dist/client', import.meta.url),
+				),
+			})
+			.register(fastifyMiddie);
+		app.use(handler);
+
+		await app.listen({ port: 8890 });
+
+		server = app;
+	});
+
+	after(async () => {
+		server.close();
+		await fixture.clean();
+	});
+
+	it('should serve SSR-emitted CSS assets directly, not the catch-all page', async () => {
+		// First get the index page to find the CSS asset URL
+		const indexRes = await fetch('http://localhost:8890/');
+		assert.equal(indexRes.status, 200);
+		const html = await indexRes.text();
+		const $ = cheerio.load(html);
+
+		// Find the CSS link tag injected by Astro
+		const cssHref = $('link[rel="stylesheet"]').attr('href');
+		assert.ok(cssHref, 'Expected a CSS <link> tag in the page');
+		assert.match(cssHref, /\/_astro\/.*\.css$/);
+
+		// Request the CSS asset — it must be served as CSS, not as the catch-all HTML page
+		const cssRes = await fetch(`http://localhost:8890${cssHref}`);
+		assert.equal(cssRes.status, 200);
+		const contentType = cssRes.headers.get('content-type');
+		assert.ok(contentType?.includes('text/css'), `Expected text/css, got: ${contentType}`);
+	});
+});
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml