diff --git a/frontend/package.json b/frontend/package.json
index fa8979ad..0f135964 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -6,6 +6,7 @@
 	"scripts": {
 		"dev": "vite dev",
 		"build": "vite build",
+		"postbuild": "node scripts/assert-pdfjs-wasm.mjs",
 		"preview": "vite preview",
 		"prepare": "svelte-kit sync || true && git -C .. config core.hooksPath .husky 2>/dev/null || true",
 		"postinstall": "patch-package",
diff --git a/frontend/scripts/assert-pdfjs-wasm.mjs b/frontend/scripts/assert-pdfjs-wasm.mjs
new file mode 100644
index 00000000..6606fa74
--- /dev/null
+++ b/frontend/scripts/assert-pdfjs-wasm.mjs
@@ -0,0 +1,29 @@
+// Build-time guard for issue #708. The pdf.js wasm image decoders are copied
+// into build/client/pdfjs-wasm/ by vite-plugin-static-copy. If a future
+// pdfjs-dist bump moves or renames the wasm, the glob could silently copy
+// nothing — and CCITT/JBIG2/JPEG2000 scans would render blank in production
+// again with no test catching it (the bug is invisible to unit tests). Fail
+// the build loudly instead. Runs after `npm run build` (incl. the Docker
+// build stage) via the `postbuild` npm script.
+import { existsSync, statSync } from 'node:fs';
+import { join } from 'node:path';
+
+const dir = join(process.cwd(), 'build', 'client', 'pdfjs-wasm');
+// jbig2.wasm decodes JBIG2 + CCITTFax; openjpeg.wasm decodes JPEG2000.
+const required = ['jbig2.wasm', 'openjpeg.wasm'];
+
+const missing = required.filter((f) => {
+	const p = join(dir, f);
+	return !existsSync(p) || statSync(p).size === 0;
+});
+
+if (missing.length > 0) {
+	console.error(
+		`\n[assert-pdfjs-wasm] MISSING from build output: ${missing.join(', ')}\n` +
+			`Expected non-empty files in ${dir}.\n` +
+			`The pdf.js wasm decoders did not ship — scanned PDFs would render blank.\n` +
+			`Check the vite-plugin-static-copy target in vite.config.ts and that\n` +
+			`node_modules/pdfjs-dist/wasm/ still contains these files. See issue #708.\n`
+	);
+	process.exit(1);
+}
diff --git a/frontend/src/lib/document/viewer/PdfViewerFixtures.svelte.test.ts b/frontend/src/lib/document/viewer/PdfViewerFixtures.svelte.test.ts
deleted file mode 100644
index 2ec78f32..00000000
--- a/frontend/src/lib/document/viewer/PdfViewerFixtures.svelte.test.ts
+++ /dev/null
@@ -1,52 +0,0 @@
-import { describe, it, expect, afterEach, vi } from 'vitest';
-import { cleanup, render } from 'vitest-browser-svelte';
-import PdfViewer from './PdfViewer.svelte';
-import ccittUrl from './fixtures/ccitt-g4.pdf?url';
-import jpegUrl from './fixtures/jpeg-dct.pdf?url';
-
-// Behavioral, real-render coverage of the wasm decode path. Unlike the rest of
-// the viewer tests, these use the REAL pdf.js loader (no libLoader prop) so the
-// page is actually decoded and painted, and the wasm is fetched from
-// /pdfjs-wasm/ exactly as in production. CI runs this in a real Chromium.
-// See issue #708.
-
-afterEach(cleanup);
-
-// A blank page is a uniform white canvas. A rendered page has dark glyph pixels.
-function countNonBackgroundPixels(canvas: HTMLCanvasElement): number {
-	const ctx = canvas.getContext('2d');
-	if (!ctx || canvas.width === 0 || canvas.height === 0) return 0;
-	const { data } = ctx.getImageData(0, 0, canvas.width, canvas.height);
-	let count = 0;
-	for (let i = 0; i < data.length; i += 4) {
-		const r = data[i];
-		const g = data[i + 1];
-		const b = data[i + 2];
-		const a = data[i + 3];
-		if (a > 0 && (r < 250 || g < 250 || b < 250)) count++;
-	}
-	return count;
-}
-
-async function expectNonBlankRender(url: string): Promise<void> {
-	render(PdfViewer, { url, documentId: 'fixture' });
-	await vi.waitFor(
-		() => {
-			const canvas = document.querySelector('canvas');
-			expect(canvas).not.toBeNull();
-			expect((canvas as HTMLCanvasElement).width).toBeGreaterThan(0);
-			expect(countNonBackgroundPixels(canvas as HTMLCanvasElement)).toBeGreaterThan(50);
-		},
-		{ timeout: 20000, interval: 250 }
-	);
-}
-
-describe('PdfViewer — real codec fixtures (wasm decode path)', () => {
-	it('renders a CCITT (G4 fax) scan as a non-blank page — same jbig2.wasm path JBIG2 uses', async () => {
-		await expectNonBlankRender(ccittUrl);
-	});
-
-	it('renders a DCTDecode (JPEG) PDF as a non-blank page — no regression', async () => {
-		await expectNonBlankRender(jpegUrl);
-	});
-});
diff --git a/frontend/src/lib/document/viewer/fixtures/ccitt-g4.pdf b/frontend/src/lib/document/viewer/fixtures/ccitt-g4.pdf
deleted file mode 100644
index 585893e5..00000000
Binary files a/frontend/src/lib/document/viewer/fixtures/ccitt-g4.pdf and /dev/null differ
diff --git a/frontend/src/lib/document/viewer/fixtures/jpeg-dct.pdf b/frontend/src/lib/document/viewer/fixtures/jpeg-dct.pdf
deleted file mode 100644
index 6e20aebe..00000000
Binary files a/frontend/src/lib/document/viewer/fixtures/jpeg-dct.pdf and /dev/null differ