PDF Verification

PDF Verification Skill

Purpose

After generating PDF files, always verify page counts and file integrity programmatically before declaring task completion. This catches formatting issues, empty pages, and corrupted files early.

When to Use

• After any PDF generation task
• When specific page counts are required
• Before marking a PDF-related task as complete

Verification Steps

1. Install PyPDF2 (if needed)

pip install PyPDF2

2. Verify Page Count and Integrity

Use run_shell to execute a Python verification script:

python -c "
from PyPDF2 import PdfReader
import sys

def verify_pdf(filepath, expected_pages=None):
    try:
        reader = PdfReader(filepath)
        actual_pages = len(reader.pages)
        print(f'✓ {filepath}: {actual_pages} pages')
        
        if expected_pages and actual_pages != expected_pages:
            print(f'✗ Page count mismatch: expected {expected_pages}, got {actual_pages}')
            return False
        
        # Check file is not empty/corrupted
        if actual_pages == 0:
            print(f'✗ Empty PDF: {filepath}')
            return False
        
        return True
    except Exception as e:
        print(f'✗ Error reading {filepath}: {e}')
        return False

# Verify each PDF
results = []
results.append(verify_pdf('output.pdf', expected_pages=2))
print(f'All checks passed: {all(results)}')
sys.exit(0 if all(results) else 1)
"

3. Verify Multiple PDFs

For tasks with multiple PDFs, verify each one:

python -c "
from PyPDF2 import PdfReader

pdfs = {
    'listings.pdf': 2,
    'map.pdf': 1,
    'summary.pdf': 1
}

all_passed = True
for filepath, expected in pdfs.items():
    try:
        reader = PdfReader(filepath)
        actual = len(reader.pages)
        status = '✓' if actual == expected else '✗'
        print(f'{status} {filepath}: {actual}/{expected} pages')
        if actual != expected:
            all_passed = False
    except Exception as e:
        print(f'✗ {filepath}: {e}')
        all_passed = False

print(f'Verification: {\"PASSED\" if all_passed else \"FAILED\"}')
"

4. Check File Size (Optional)

Add file size validation to catch empty or near-empty files:

python -c "
import os
from PyPDF2 import PdfReader

filepath = 'output.pdf'
min_size = 1000  # minimum bytes

file_size = os.path.getsize(filepath)
if file_size < min_size:
    print(f'✗ File too small: {file_size} bytes')
else:
    reader = PdfReader(filepath)
    print(f'✓ {filepath}: {len(reader.pages)} pages, {file_size} bytes')
"

Best Practices

1. Verify immediately after generation - Don't wait until the end of the task
2. Check all required PDFs - Verify each file meets specifications
3. Fail fast - If verification fails, regenerate before proceeding
4. Log results - Print verification results for debugging
5. Set reasonable minimums - Use file size checks to catch empty outputs

Common Issues Caught

• Wrong page counts (extra blank pages, missing content)
• Corrupted or unreadable PDF files
• Empty PDFs (0 pages)
• Files that appear generated but contain no actual content

Example Task Completion Check

# Final verification before marking task complete
python -c "
from PyPDF2 import PdfReader
import sys

required = {'listings.pdf': 2, 'map.pdf': 1}
passed = True

for f, pages in required.items():
    try:
        actual = len(PdfReader(f).pages)
        if actual != pages:
            print(f'FAIL: {f} has {actual} pages, expected {pages}')
            passed = False
    except Exception as e:
        print(f'FAIL: Cannot read {f}: {e}')
        passed = False

if passed:
    print('SUCCESS: All PDFs verified')
    sys.exit(0)
else:
    sys.exit(1)
"