arborlogic/openzerocode/pdf-official

PDF skill

An Apache-2.0 toolkit for reading, composing, transforming, and filling PDF files. Written from scratch on top of permissively-licensed open-source libraries (pypdf, pdfplumber, pypdfium2, reportlab, pdf-lib, qpdf) so this can be embedded in commercial projects without special agreement.

Route the task

Pick the sub-guide by the verb of the request.

If a task mixes several of these, follow the order: probe → plan → extract or compose → validate.

Every path starts with a probe. scripts/survey.py returns page count, whether the file is encrypted, whether it has an AcroForm, and whether page 1 looks like a scan.

First install

Python-only path (all BSD / MIT / Apache) — covers 95% of tasks:

python3 -m pip install --upgrade pypdf pdfplumber pypdfium2 reportlab Pillow

Add these external binaries only when you actually need them:

# qpdf — merge/split/encrypt/repair, Apache-2.0
brew install qpdf                # macOS
apt-get install -y qpdf          # Debian / Ubuntu
 
# Tesseract — OCR for scanned PDFs, Apache-2.0
brew install tesseract
python3 -m pip install pytesseract pdf2image
apt-get install -y tesseract-ocr
 
# Poppler — pdftotext / pdftoppm / pdfimages, GPL-2.0
# Optional. Only install if you accept a GPL dependency at CLI level.
brew install poppler
apt-get install -y poppler-utils

Every script under scripts/ uses argparse. Exit codes: 0 OK · 1 runtime failure · 2 bad arguments · 3 validation failure (apply_values.py / overlay_text.py; sanity_check.py reports findings with exit 1). Any single script can be lifted into another project — none imports from a shared framework.

One-command triage

scripts/survey.py path/to/file.pdf --pretty

Sample output:

{
  "path": "/abs/path/file.pdf",
  "page_count": 12,
  "is_locked": false,
  "form_field_count": 34,
  "looks_scanned": false,
  "metadata": {"Title": "...", "Author": "...", "Producer": "..."}
}

Route by the flags:

• is_locked: true → unlock first (qpdf --password=… --decrypt). Almost

every reader library refuses locked files.

• form_field_count > 0 → widgets path in `interactive.md` §1.
• form_field_count == 0 AND you need to fill it → overlay path

in `interactive.md` §2.

• looks_scanned: true → skip pypdf text extraction, go straight to OCR

(`extract.md` §5).

Which library for which task

Common gotchas

1. PDF origin is bottom-left, image origin is top-left. Every "off by a

few points" bug is one of these two systems misapplied. Coordinate conversion is in one place: `interactive.md` §2.c.

1. `pypdf.extract_text()` returns nothing for scans. That's not a bug —

there's no text stream. Use the looks_scanned flag and route to OCR.

1. **Unicode subscripts / superscripts render as black rectangles in

reportlab** because Helvetica/Times/Courier don't ship those glyphs. Use <sub> / <super> XML in Paragraph, or move the pen manually on canvas. See `compose.md` §5.

1. XFA forms are not AcroForms. If probe_fields.py returns [] on a

PDF that clearly has widgets in Adobe Reader, it's XFA — flatten it in Acrobat first.

1. `writer.encrypt(pw)` in pypdf uses RC4 by default. For real AES-256,

pass algorithm="AES-256", or use qpdf --encrypt … 256 --.

What's next

Open the sub-guide from the routing table and work through it end to end. Each sub-guide has a Validation section at the bottom describing how to confirm the result.