feat(files): add Markdown PDF download

Author: Bill Leoutsakos

apps/sim/app/api/files/export/[id]/markdown-pdf.test.ts

@@ -0,0 +1,60 @@
+/**
+ * @vitest-environment node
+ */
+import { PDFDocument } from 'pdf-lib'
+import sharp from 'sharp'
+import { describe, expect, it } from 'vitest'
+import { renderMarkdownPdf } from '@/app/api/files/export/[id]/markdown-pdf'
+
+describe('Markdown PDF rendering', () => {
+  it('creates a valid multi-page PDF with GFM and an embedded image', async () => {
+    const image = await sharp({
+      create: {
+        width: 120,
+        height: 60,
+        channels: 3,
+        background: '#4f46e5',
+      },
+    })
+      .png()
+      .toBuffer()
+    const repeatedParagraphs = Array.from(
+      { length: 70 },
+      (_, index) => `Paragraph ${index + 1} with **bold**, _italic_, and \`inline code\`.`
+    ).join('\n\n')
+    const markdown = `# Export title
+
+> A useful blockquote with a [link](https://sim.ai).
+
+Smart quotes “work”, Greek Ω stays readable, and unsupported emoji 🚀 falls back safely.
+
+- First item
+- Second item
+
+| Name | Value |
+| --- | ---: |
+| Alpha | 1 |
+| Beta | 2 |
+
+\`\`\`ts
+const exported = true
+\`\`\`
+
+![Embedded image](/api/files/view/image-1)
+
+${repeatedParagraphs}`
+
+    const buffer = await renderMarkdownPdf({
+      markdown,
+      title: 'Export title',
+      images: new Map([['image-1', image]]),
+    })
+
+    expect(buffer.subarray(0, 4).toString()).toBe('%PDF')
+    expect(buffer.length).toBeGreaterThan(1_000)
+
+    const document = await PDFDocument.load(buffer)
+    expect(document.getTitle()).toBe('Export title')
+    expect(document.getPageCount()).toBeGreaterThan(1)
+  })
+})