document-generation-pdf

---
name: document-generation-pdf
description: Generate, fill, and assemble PDF documents at scale. Handles legal forms, contracts, invoices, certificates. Supports form filling (pdf-lib), template rendering (Puppeteer, LaTeX), digital
license: MIT
---

# Document Generation & PDF Automation

Expert in generating, filling, and assembling PDF documents programmatically for legal, HR, and business workflows.

## When to Use

✅ **Use for**:
- Legal form automation (expungement, immigration, contracts)
- Invoice/receipt generation at scale
- Certificate creation (completion, participation, awards)
- Contract assembly from templates
- Government form filling (IRS, court filings)
- Multi-document packet creation

❌ **NOT for**:
- Simple PDF viewing (use browser or pdf.js)
- Basic file conversion (use online tools)
- OCR text extraction (use Tesseract.js or AWS Textract)
- PDF editing by hand (use Adobe Acrobat)

---

## Technology Selection

### pdf-lib vs Puppeteer vs LaTeX

| Feature | pdf-lib | Puppeteer | LaTeX |
|---------|---------|-----------|-------|
| Form filling | ✅ Native | ❌ Complex | ❌ No |
| Template rendering | ❌ No | ✅ HTML/CSS | ✅ Templates |
| Performance (1000 PDFs) | 5s | 60s | 30s |
| File size | Small | Medium | Small |
| Signature fields | ✅ Yes | ❌ No | ❌ No |
| Best for | Government forms | Invoices, reports | Academic papers |

**Timeline**:
- 2000s: LaTeX for academic documents
- 2010: PDFKit (Node.js) for generation
- 2017: Puppeteer for HTML → PDF
- 2019: pdf-lib for pure JS form filling
- 2024: pdf-lib is gold standard for forms

**Decision tree**:
```
Need to fill existing form? → pdf-lib
Need complex layouts? → Puppeteer (HTML/CSS)
Need academic formatting? → LaTeX
Need to merge PDFs? → pdf-lib
Need digital signatures? → pdf-lib + DocuSign API
```

---

## Common Anti-Patterns

### Anti-Pattern 1: Using Puppeteer for Simple Form Filling

**Novice thinking**: "I'll use Puppeteer for everything, it's versatile"

**Problem**: 12x slower, 10x more memory, can't preserve form fields.

**Wrong approach**:
```typescript
// ❌ Puppeteer for simple form filling (SLOW!)
import puppeteer from 'puppeteer';

async function fillForm(data: FormData): Promise<Buffer> {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();

  // Load PDF in browser
  await page.goto(`file://${pdfPath}`);

  // Somehow fill form fields? (hacky)
  await page.evaluate((data) => {
    // Can't easily access PDF form fields from DOM
    // Would need to convert PDF → HTML first
  }, data);

  const pdf = await page.pdf();
  await browser.close();

  return pdf;
}
```

**Why wrong**:
- Browser overhead (200MB+ RAM per instance)
- Can't access native PDF form fields
- Loses interactive form capabilities
- 12x slower than pdf-lib

**Correct approach**:
```typescript
// ✅ pdf-lib for form filling (FAST!)
import { PDFDocument } from 'pdf-lib';

async function fillForm(templatePath: string, data: FormData): Promise<Uint8Array> {
  // Load existing PDF form
  const existingPdfBytes = await fs.readFile(templatePath);
  const pdfDoc = await PDFDocument.load(existingPdfBytes);

  // Get form
  const form = pdfDoc.getForm();

  // Fill text fields
  form.getTextField('applicant_name').setText(data.name);
  form.getTextField('case_number').setText(data.caseNumber);
  form.getTextField('date_of_birth').setText(data.dob);

  // Fill checkboxes
  if (data.hasPriorConvictions) {
    form.getCheckBox('prior_convictions').check();
  }

  // Fill dropdowns
  form.getDropdown('state').select(data.state);

  // Flatten form (make non-editable)
  form.flatten();

  // Save
  return await pdfDoc.save();
}
```

**Performance comparison** (1000 PDFs):
- Puppeteer: 60 seconds, 4GB RAM
- pdf-lib: 5 seconds, 200MB RAM

**Timeline context**:
- 2017: Puppeteer released, everyone used it for PDFs
- 2019: pdf-lib released, proper form handling
- 2024: pdf-lib is standard for government forms

---

### Anti-Pattern 2: Not Flattening Forms

**Problem**: Users can edit filled forms, causing data inconsistencies.

**Wrong approach**:
```typescript
// ❌ Don't flatten - form stays editable
const pdfDoc = await PDFDocument.load(existingPdfBytes);
const form = pdfDoc.getForm();

form.getTextField('name').setText('John Doe');

const pdfBytes = await pdfDoc.save();
// User can open PDF and change "John Doe" to anything!
```

**Why wrong**:
- User can modify official documents
- Data doesn't match database
- Violates document integrity

**Correct approach**:
```typescript
// ✅ Flatten form after filling
const pdfDoc = await PDFDocument.load(existingPdfBytes);
const form = pdfDoc.getForm();

form.getTextField('name').setText('John Doe');

// Flatten (convert fields to static text)
form.flatten();

const pdfBytes = await pdfDoc.save();
// User can't edit filled values ✅
```

**When NOT to flatten**:
- Draft documents (user needs to review/edit)
- Multi-step workflows (partial completion)
- Templates for users to fill manually

---

### Anti-Pattern 3: Generating PDFs from HTML Without Page Breaks

**Novice thinking**: "HTML → PDF is easy with Puppeteer"

**Problem**: Content splits mid-sentence across pages.

**Wrong approach**:
```typescript
// ❌ No page break control
const html = `
  <div class="contract">
    <h1>Mutual Agreement</h1>
    <p>Long paragraph that might split across pages...</p>
    <section>
      <h2>Terms and Conditions</h2>
      <ol>
        <li>Term 1 that could get cut off...</li>
        <li>Term 2...</li>
      </ol>
    </section>
  </div>
`;

const pdf = await page.pdf({ format: 'A4' });
// Result: Ugly page breaks in middle of sections
```

**Correct approach**:
```typescript
// ✅ Explicit page break control with CSS
const html = `
  <style>
    @media print {
      .page-break { page-break-after: always; }
      .avoid-break { page-break-inside: avoid; }

      h1, h2, h3 {
        page-break-after: avoid;
        page-break-inside: avoid;
      }

      section {
        page-break-inside: avoid;
      }
    }
  </style>

  <div class="contract">
    <section class="avoid-break">
      <h1>Mutual Agreement</h1>
      <p>This entire section stays together...</p>
    </section>

    <div class="page-break"></div>

    <section class="avoid-break">
      <h2>Terms and Conditions</h2>
      <ol>
        <li>Term 1</li>
        <li>Term 2</li>
      </ol>
    </section>
  </div>
`;

const pdf = await page.pdf({
  format: 'A4',
  printBackground: true,
  margin: {
    top: '1in',
    right: '1in',
    bottom: '1in',
    left: '1in'
  }
});
```

**CSS print properties**:
- `page-break-before: always` - Force new page before element
- `page-break-after: always` - Force new page after element
- `page-break-inside: avoid` - Keep element together

---

### Anti-Pattern 4: Not Handling Signature Fields

**Problem**: Signature fields aren't clickable in generated PDFs.

**Wrong approach**:
```typescript
// ❌ Add signature as image (not a real signature field)
const pdfDoc = await PDFDocument.load(existingPdfBytes);

const signatureImage = await pdfDoc.embedPng(signaturePngBytes);
const page = pdfDoc.getPage(0);

page.drawImage(signatureImage, {
  x: 100,
  y: 100,
  width: 200,
  height: 50
});

await pdfDoc.save();
// Not a real signature field - can't be signed digitally
```

**Why wrong**:
- Not legally recognized (just an image)
- Can't use DocuSign/Adobe Sign
- No signature metadata (who, when)

**Correct approach 1**: Create signature field (for DocuSign)
```typescript
// ✅ Create signature field for electronic signing
const pdfDoc = await PDFDocument.load(existingPdfBytes);
const form = pdfDoc.getForm();

// Create signature field
const signatureField = form.createTextField('applicant_signature');
signatureField.addToPage(pdfDoc.getPage(0), {
  x: 100,
  y: 100,
  width: 200,
  height: 50
});

// Mark as signature field (metadata)
signatureField.updateWidgets({
  borderWidth: 1,
  borderColor: { type: 'RGB', red: 0, green: 0, blue: 0 }
});

await pdfDoc.save();
// DocuSign can now detect and fill this field ✅
```

**Correct approach 2**: DocuSign API integration
```typescript
// ✅ Send to DocuSign for e-signature
import { ApiClient, EnvelopesApi } from 'docusign-esign';

async function sendForSignature(pdfBytes: Uint8Array, signerEmail: string) {
  const apiClient = new ApiClient();
  apiClient.setBasePath('https://demo.docusign.net/restapi');

  const envelopesApi = new EnvelopesApi(apiClient);

  const envelope = {
    emailSubject: 'Please sign: Expungement Petition',
    documents: [{
      documentBase64: Buffer.from(pdfBytes).toString('base64'),
      name: 'Petition.pdf',
      fileExtension: 'pdf',
      documentId: '1'
    }],
    recipients: {
      signers: [{
        email: signerEmail,
        name: 'John Doe',
        recipientId: '1',
        tabs: {
          signHereTabs: [{
            documentId: '1',
            pageNumber: '1',
            xPosition: '100',
            yPosition: '100'
          }]
        }
      }]
    },
    status: 'sent'
  };

  return await envelopesApi.createEnvelope(accountId, { envelopeDefinition: envelope });
}
```

---

### Anti-Pattern 5: Storing Filled PDFs Without Encryption

**Problem**: Sensitive legal documents stored in plain text.

**Wrong approach**:
```typescript
// ❌ Save PDF to disk unencrypted
const pdfBytes = await pdfDoc.save();
await fs.writeFile(`./documents/${caseId}.pdf`, pdfBytes);
// Sensitive data accessible to anyone with file system access
```

**Why wrong**:
- Legal/medical data exposed
- HIPAA/GDPR violations
- Data breach liability

**Correct approach 1**: Encrypt at rest
```typescript
// ✅ Encrypt PDF with user password
const pdfBytes = await pdfDoc.save({
  userPassword: generateSecurePassword(),
  ownerPassword: process.env.PDF_OWNER_PASSWORD,
  permissions: {
    printing: 'highResolution',
    modifying: false,
    copying: false,
    annotating: false,
    fillingForms: false,
    contentAccessibility: true,
    documentAssembly: false
  }
});

await fs.writeFile(`./documents/${caseId}.pdf`, pdfBytes);
```

**Correct approach 2**: Store in encrypted storage (S3 with SSE)
```typescript
// ✅ Upload to S3 with server-side encryption
import { S3Client, PutObjectCommand } from '@aws-sdk/client-s3';

const s3Client = new S3Client({ region: 'us-east-1' });

await s3Client.send(new PutObjectCommand({
  Bucket: 'expungement-documents',
  Key: `cases/${caseId}/petition.pdf`,
  Body: pdfBytes,
  ServerSideEncryption: 'AES256',
  Metadata: {
    caseId: caseId,
    documentType: 'petition',
    generatedAt: new Date().toISOString()
  },
  ACL: 'private'  // Not publicly accessible
}));

// Store S3 URL in database (encrypted)
await db.documents.insert({
  case_id: caseId,
  s3_url: encrypt(`s3://expungement-documents/cases/${caseId}/petition.pdf`),
  created_at: new Date()
});
```

**Compliance requirements**:
- HIPAA: Encryption at rest + in transit, access logging
- GDPR: Right to deletion, data minimization
- State bar rules: Attorney-client privilege protection

---

## Production Checklist

```
□ Form fields filled correctly (test with validation)
□ Forms flattened after filling (non-editable)
□ Page breaks controlled (no mid-sentence splits)
□ Signature fields created (for DocuSign/Adobe Sign)
□ PDFs encrypted at rest (S3 SSE or user password)
□ Access logged (who viewed/downloaded)
□ Auto-deletion scheduled (retention policy)
□ Fonts embedded (cross-platform compatibility)
□ File size optimized (&lt;5MB per document)
□ Batch generation tested (1000+ PDFs)
```

---

## When to Use vs Avoid

| Scenario | Appropriate? |
|----------|--------------|
| Fill 50+ government forms | ✅ Yes - automate with pdf-lib |
| Generate invoices from template | ✅ Yes - Puppeteer from HTML |
| Create certificates at scale | ✅ Yes - pdf-lib or LaTeX |
| Assemble multi-doc packets | ✅ Yes - pdf-lib merge |
| View PDFs in browser | ❌ No - use pdf.js or browser |
| Edit PDF by hand | ❌ No - use Adobe Acrobat |
| Extract text with OCR | ❌ No - use Tesseract/Textract |

---

## Flat PDF Overlay at Scale (Government Forms)

Many government court forms are **flat PDFs** (no fillable fields). You MUST overlay text at precise X,Y coordinates. Never generate forms from scratch - courts will reject them.

### The Three-Tier Strategy

```
1. FILLABLE PDF → Use form.getTextField().setText() (best)
2. FLAT PDF + COORDINATES → Draw text overlays at X,Y positions (this section)
3. NO TEMPLATE EXISTS → Emergency fallback with warning banner (worst)
```

### Anti-Pattern 6: Generating Forms from Scratch

**Novice thinking**: "The PDF doesn't have form fields, I'll just create a new PDF"

**Problem**: Courts reject non-official forms. Your custom layout won't match official documents.

**Wrong approach**:
```typescript
// ❌ NEVER DO THIS - courts reject custom forms
const pdfDoc = await PDFDocument.create();
const page = pdfDoc.addPage([612, 792]);

page.drawText('IN THE CIRCUIT COURT OF...', { x: 200, y: 720 });
page.drawText(`Defendant: ${data.name}`, { x: 100, y: 600 });
// Result: Court clerk says "This isn't our form" and rejects filing
```

**Correct approach**: Draw on top of official template
```typescript
// ✅ Load official form, draw text in blank spaces
const templateBytes = await fs.readFile('public/forms/OR-set-aside-motion.pdf');
const pdfDoc = await PDFDocument.load(templateBytes);
const page = pdfDoc.getPage(3); // Page 4 is the form
const font = await pdfDoc.embedFont(StandardFonts.Helvetica);

// Draw in blank spaces at measured coordinates
page.drawText(data.county.toUpperCase(), { x: 310, y: 700, size: 11, font });
page.drawText(data.caseNumber, { x: 432, y: 655, size: 10, font });
page.drawText(data.fullName, { x: 72, y: 568, size: 11, font });
```

---

### Measuring Coordinates at Scale

**Problem**: Manually measuring X,Y for 50 states × 10+ forms = impossible.

**Solution 1: Visual Coordinate Picker Tool**

Use [pdf-coordinates](https://github.com/jol333/pdf-coordinates) - click on PDF to capture X,Y:
- Upload PDF, click on blank fields
- Select coordinate system: **Bottom-Left** (PDF standard)
- Export annotated PDF with coordinate labels
- Works offline, no data upload

**Solution 2: JSON Configuration (Zerodha Pattern)**

Define coordinates in JSON config, not code:
```typescript
// field-mappings/oregon-set-aside.json
{
  "templatePath": "/forms/or/OR-criminal-set-aside.pdf",
  "pageIndex": 3,
  "fields": [
    {
      "name": "county",
      "x": 310,
      "y": 700,
      "fontSize": 11,
      "maxWidth": 120,
      "transform": "uppercase"
    },
    {
      "name": "caseNumber",
      "x": 432,
      "y": 655,
      "fontSize": 10,
      "maxWidth": 100,
      "maxChars": 12
    },
    {
      "name": "fullName",
      "x": 72,
      "y": 568,
      "fontSize": 11,
      "maxWidth": 250,
      "shrinkToFit": true
    }
  ]
}
```

**Solution 3: Debug Grid Overlay**

Add temporary grid during development:
```typescript
async function drawDebugGrid(page: PDFPage, font: PDFFont) {
  const { width, height } = page.getSize();

  // Draw grid every 50 points
  for (let x = 0; x <= width; x += 50) {
    page.drawLine({
      start: { x, y: 0 },
      end: { x, y: height },
      thickness: 0.2,
      color: rgb(0.9, 0.9, 0.9),
    });
    if (x % 100 === 0) {
      page.drawText(String(x), { x: x + 2, y: 5, size: 6, font });
    }
  }
  // Same for horizontal lines...
}
```

---

### Text Overflow Handling

**Problem**: Long names overflow into adjacent fields or get cut off.

**Three overflow strategies**:

```typescript
// 1. Truncate with ellipsis
function truncate(text: string, maxChars: number): string {
  if (text.length <= maxChars) return text;
  return text.slice(0, maxChars - 2) + '..';
}

// 2. Shrink font to fit (min 7pt for readability)
function shrinkToFit(text: string, maxWidthPts: number, startSize: number): number {
  let fontSize = startSize;
  const charWidth = (size: number) => size * 0.52; // Helvetica avg

  while (fontSize > 7 && text.length * charWidth(fontSize) > maxWidthPts) {
    fontSize -= 0.5;
  }
  return fontSize;
}

// 3. Multi-line wrap (for addresses)
page.drawText(longAddress, {
  x: 100,
  y: 500,
  size: 9,
  font,
  maxWidth: 200, // pdf-lib auto-wraps at this width
  lineHeight: 12,
});
```

**Field input constraints** - Prevent overflow at data collection:
```typescript
export const FIELD_CONSTRAINTS = {
  fullName: { maxLength: 35 },
  county: { maxLength: 12 },
  caseNumber: { maxLength: 12 },
  agency: { maxLength: 28 },
  charges: { maxLength: 45 },
} as const;
```

---

### Production Workflow for Multi-State Forms

```
1. DOWNLOAD official forms
   └─ Store in /public/forms/{state}/ with metadata.json

2. INSPECT each form
   └─ Run pdf-lib inspection to check: fillable? how many fields?

3. CATEGORIZE forms
   ├─ Fillable → Map field names in field-mappings/{state}.ts
   └─ Flat → Measure coordinates with pdf-coordinates tool

4. CREATE JSON config for flat PDFs
   └─ One JSON file per form with all X,Y coordinates

5. TEST with debug grid
   └─ Generate test PDF with colored text + coordinate labels

6. QA visual verification
   └─ Compare filled PDF against original blank form

7. DOCUMENT constraints
   └─ Export maxLength/maxWidth limits for form inputs
```

---

### Legal Filing Requirements

**Court e-filing systems require**:
- ✅ Flattened forms (no interactive fields)
- ✅ No digital signature metadata (DocuSign breaks e-filing)
- ✅ Standard fonts embedded (Helvetica, Times)
- ✅ File under 10MB
- ✅ Exact match to official form layout

**Flattening for courts**:
```typescript
// If form had fields, flatten them
const form = pdfDoc.getForm();
if (form.getFields().length > 0) {
  form.flatten(); // Converts to static text
}

// For overlay text, it's already static - no flattening needed
const pdfBytes = await pdfDoc.save();
```

---

### Coordinate System Reference

```
PDF coordinate system (pdf-lib default):
- Origin: Bottom-left corner (0, 0)
- X increases: Left → Right
- Y increases: Bottom → Top
- Units: Points (72 points = 1 inch)
- Letter size: 612 x 792 points (8.5" x 11")

To convert from top-left origin (e.g., Adobe Acrobat display):
  y_pdf = 792 - y_topLeft

Common positions (Letter size):
- Top margin: y = 720-750
- Header area: y = 700-750
- Body start: y = 650-700
- Left margin: x = 50-72
- Right edge: x = 540-560
- Bottom margin: y = 50-72
```

---

## References

- `/references/pdf-lib-guide.md` - Form filling, field types, flattening, encryption
- `/references/puppeteer-templates.md` - HTML templates, page breaks, styling for print
- `/references/document-assembly.md` - Merging PDFs, packet creation, watermarks
- [pdf-coordinates](https://github.com/jol333/pdf-coordinates) - Visual X,Y coordinate picker
- [Zerodha pdf_text_overlay](https://github.com/zerodha/pdf_text_overlay) - JSON config pattern

## Scripts

- `scripts/form_filler.ts` - Fill PDF forms from JSON data, batch processing
- `scripts/document_assembler.ts` - Merge multiple PDFs, add cover pages, watermarks
- `scripts/generate-test-overlay-pdf.ts` - Test overlay coordinates with debug grid

---

**This skill guides**: PDF generation | Form filling | Document automation | Digital signatures | pdf-lib | Puppeteer | LaTeX | DocuSign | **Flat PDF overlay** | **Coordinate mapping**