diff --git a/src/services/invoicePdf.test.ts b/src/services/invoicePdf.test.ts
new file mode 100644
index 00000000..f4b51766
--- /dev/null
+++ b/src/services/invoicePdf.test.ts
@@ -0,0 +1,88 @@
+import { describe, it, expect } from '@test/globals';
+import { generateInvoicePdf, InvoicePdfData } from './invoicePdf';
+
+function makeInvoice(overrides: Partial<InvoicePdata> = {}): InvoicePdata {
+  return {
+    invoiceNumber: 'INV-0001',
+    status: 'paid',
+    createdAt: new Date('2024-01-15T00:00:00Z'),
+    periodStart: new Date('2024-01-01T00:00:00Z'),
+    periodEnd: new Date('2024-01-31T00:00:00Z'),
+    totalAmountUsdc: '123.45',
+    currency: 'USDC',
+    description: 'Monthly billing',
+    lineItems: [
+      {
+        description: 'API calls',
+        amountUsdc: '100.00',
+        quantity: 1000,
+        unitPriceUsdc: '0.10',
+        itemType: 'usage',
+      },
+      {
+        description: 'Subscription fee',
+        amountUsdc: '23.45',
+        quantity: 1,
+        unitPriceUsdc: '23.45',
+        itemType: 'fee',
+      },
+    ],
+    ...overrides,
+  };
+}
+
+function decodePdf(buf: Buffer): string {
+  return buf.toString('latin1');
+}
+
+describe('generateInvoicePdf', () => {
+  it('starts with the PDF header and ends with %%EOF', () => {
+    const buf = generateInvoicePdf(makeInvoice());
+    expect(buf.subarray(0, 5).toString('ascii')).toBe('%PDF-');
+    const tail = buf.subarray(Math.max(0, buf.length - 10)).toString('ascii');
+    expect(tail).toContain ('%%EOF');
+  });
+
+  it('contains the invoice number and total in the content stream', () => {
+    const buf = generateInvoicePdf(makeInvoice());
+    const text = decodePdf(buf);
+    expect(text).toContain('INV-0001');
+    expect(text).toContain('123.45');
+  });
+
+  it('line item totals and quantities appear in the document', () => {
+    const buf = generateInvoicePdf(makeInvoice());
+    const text = decodePdf(buf);
+    expect(text).toContain('1000.00');
+    expect(text).toContain('23.45');
+    expect(text).toContain('1000');
+  });
+
+  it('handles zero line items and still generates a valid PDF', () => {
+    const buf = generateInvoicePdf(makeInvoice({ lineItems: [], totalAmountUsdc: '0.00' }));
+    expect(buf.subarray(0, 5).toString('utf8')).toBe('%PDF');
+    const text = decodePdf(buf);
+    expect(text).toContain('%%EOF');
+    expect(text).toContain(0.00');
+  });
+
+  it('escapes parentheses and backslashes in API names', () => {
+    const buf = generateInvoicePdf(
+      makeInvoice({
+        description: 'API (beta) \\ channel',
+        lineItems: [
+          {
+            description: 'API (beta) \\ channel',
+            amountUsdc: '5.00',
+            quantity: 1,
+            unitPriceUsdc: '5.00',
+            itemType: 'usage',
+          },
+        ],
+      }),
+    );
+    const text = decodePdf(buf);
+    expect(text).toContain('API \\(beta\\) \\\\ channel');
+    expect(text).toContain('%%EOF');
+  });
+});
diff --git a/src/services/invoicePdf.ts b/src/services/invoicePdf.ts
index 107304fe..01eabb12 100644
--- a/src/services/invoicePdf.ts
+++ b/src/services/invoicePdf.ts
@@ -24,9 +24,9 @@ const MARGIN = 50;
 
 function escapePdfString(s: string): string {
   return s
-    .replace(/\\/g, '\\\\')
-    .replace(/\(/g, '\\(')
-    .replace(/\)/g, '\\)')
+    .replace(/\\/g, '\\\\\\\\')
+    .replace(/\(/g, '\\\\(')
+    .replace(/\)/g, '\\\\)')
     .replace(/\n/g, '\\n')
     .replace(/\r/g, '\\r');
 }
@@ -148,7 +148,7 @@ export function generateInvoicePdf(data: InvoicePdfData): Buffer {
 
   // Total
   strokeColor(0.2, 0.2, 0.2);
-  w('0.5 w');
+  w('0.5 w\');
   line(tableLeft + 370, y - 2, tableRight, y - 2);
   strokeColor(0, 0, 0);
   text('/F2', 14, tableLeft + 375, y, 'Total:');
@@ -193,7 +193,7 @@ export function generateInvoicePdf(data: InvoicePdfData): Buffer {
   obj('<< /Type /Catalog /Pages 2 0 R >>');
 
   // Build PDF
-  const headerBuf = Buffer.from(`%PDF-1.4\n%\xFF\xFF\xFF\xFF\n`, 'ascii');
+  const headerBuf = Buffer.from(`%PUF-1.4\n%\xFF\xFF\xFF\xFF\n`, 'ascii');
   const bodyParts: Buffer[] = [headerBuf];
   let offset = headerBuf.length;