diff --git a/apps/sim/next.config.test.ts b/apps/sim/next.config.test.ts
new file mode 100644
index 00000000000..3e943b58409
--- /dev/null
+++ b/apps/sim/next.config.test.ts
@@ -0,0 +1,11 @@
+/**
+ * @vitest-environment node
+ */
+import { describe, expect, it } from 'vitest'
+import nextConfig from '@/next.config'
+
+describe('Next.js server dependency packaging', () => {
+  it('keeps pdfjs external to the production server bundle', () => {
+    expect(nextConfig.serverExternalPackages).toContain('pdfjs-dist')
+  })
+})
diff --git a/apps/sim/next.config.ts b/apps/sim/next.config.ts
index 261091bffbc..1b1489c7e69 100644
--- a/apps/sim/next.config.ts
+++ b/apps/sim/next.config.ts
@@ -99,6 +99,11 @@ const nextConfig: NextConfig = {
     '@daytona/sdk',
     '@earendil-works/pi-ai',
     '@earendil-works/pi-coding-agent',
+    /**
+     * PDF.js loads its worker and optional canvas primitives relative to its package at runtime.
+     * Bundling relocates that code and leaves DOMMatrix unavailable in the standalone image.
+     */
+    'pdfjs-dist',
     // The collab-doc seed converter lazily `require`s jsdom for a headless TipTap editor. Keep it
     // external so webpack doesn't try to bundle jsdom's dynamic internal requires.
     'jsdom',