feat(agents): add pdf skill

Author: leonidgrishenkov

agents/.agents/skills/pdf/SKILL.md

@@ -0,0 +1,336 @@
+---
+name: pdf
+description:
+  Extract text/tables from PDFs, merge/split documents, create new PDFs, fill forms, and OCR scanned files. Use when
+  working with PDF files or when user mentions PDFs, forms, or document extraction.
+---
+
+# PDF Processing Guide
+
+## Overview
+
+This guide covers essential PDF processing operations using Python libraries and command-line tools. For advanced
+features, JavaScript libraries, and detailed examples, see [reference.md](reference.md). If you need to fill out a PDF
+form, read [forms.md](forms.md) and follow its instructions.
+
+## Quick Start
+
+```python
+from pypdf import PdfReader, PdfWriter
+
+# Read a PDF
+reader = PdfReader("document.pdf")
+print(f"Pages: {len(reader.pages)}")
+
+# Extract text
+text = ""
+for page in reader.pages:
+    text += page.extract_text()
+```
+
+## Python Libraries
+
+### pypdf - Basic Operations
+
+#### Merge PDFs
+
+```python
+from pypdf import PdfWriter, PdfReader
+
+writer = PdfWriter()
+for pdf_file in ["doc1.pdf", "doc2.pdf", "doc3.pdf"]:
+    reader = PdfReader(pdf_file)
+    for page in reader.pages:
+        writer.add_page(page)
+
+with open("merged.pdf", "wb") as output:
+    writer.write(output)
+```
+
+#### Split PDF
+
+```python
+reader = PdfReader("input.pdf")
+for i, page in enumerate(reader.pages):
+    writer = PdfWriter()
+    writer.add_page(page)
+    with open(f"page_{i+1}.pdf", "wb") as output:
+        writer.write(output)
+```
+
+#### Extract Metadata
+
+```python
+reader = PdfReader("document.pdf")
+meta = reader.metadata
+print(f"Title: {meta.title}")
+print(f"Author: {meta.author}")
+print(f"Subject: {meta.subject}")
+print(f"Creator: {meta.creator}")
+```
+
+#### Rotate Pages
+
+```python
+reader = PdfReader("input.pdf")
+writer = PdfWriter()
+
+page = reader.pages[0]
+page.rotate(90)  # Rotate 90 degrees clockwise
+writer.add_page(page)
+
+with open("rotated.pdf", "wb") as output:
+    writer.write(output)
+```
+
+### pdfplumber - Text and Table Extraction
+
+#### Extract Text with Layout
+
+```python
+import pdfplumber
+
+with pdfplumber.open("document.pdf") as pdf:
+    for page in pdf.pages:
+        text = page.extract_text()
+        print(text)
+```
+
+#### Extract Tables
+
+```python
+with pdfplumber.open("document.pdf") as pdf:
+    for i, page in enumerate(pdf.pages):
+        tables = page.extract_tables()
+        for j, table in enumerate(tables):
+            print(f"Table {j+1} on page {i+1}:")
+            for row in table:
+                print(row)
+```
+
+#### Advanced Table Extraction
+
+```python
+import pandas as pd
+
+with pdfplumber.open("document.pdf") as pdf:
+    all_tables = []
+    for page in pdf.pages:
+        tables = page.extract_tables()
+        for table in tables:
+            if table:  # Check if table is not empty
+                df = pd.DataFrame(table[1:], columns=table[0])
+                all_tables.append(df)
+
+# Combine all tables
+if all_tables:
+    combined_df = pd.concat(all_tables, ignore_index=True)
+    combined_df.to_excel("extracted_tables.xlsx", index=False)
+```
+
+### reportlab - Create PDFs
+
+#### Basic PDF Creation
+
+```python
+from reportlab.lib.pagesizes import letter
+from reportlab.pdfgen import canvas
+
+c = canvas.Canvas("hello.pdf", pagesize=letter)
+width, height = letter
+
+# Add text
+c.drawString(100, height - 100, "Hello World!")
+c.drawString(100, height - 120, "This is a PDF created with reportlab")
+
+# Add a line
+c.line(100, height - 140, 400, height - 140)
+
+# Save
+c.save()
+```
+
+#### Create PDF with Multiple Pages
+
+```python
+from reportlab.lib.pagesizes import letter
+from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, PageBreak
+from reportlab.lib.styles import getSampleStyleSheet
+
+doc = SimpleDocTemplate("report.pdf", pagesize=letter)
+styles = getSampleStyleSheet()
+story = []
+
+# Add content
+title = Paragraph("Report Title", styles['Title'])
+story.append(title)
+story.append(Spacer(1, 12))
+
+body = Paragraph("This is the body of the report. " * 20, styles['Normal'])
+story.append(body)
+story.append(PageBreak())
+
+# Page 2
+story.append(Paragraph("Page 2", styles['Heading1']))
+story.append(Paragraph("Content for page 2", styles['Normal']))
+
+# Build PDF
+doc.build(story)
+```
+
+#### Subscripts and Superscripts
+
+**IMPORTANT**: Never use Unicode subscript/superscript characters (₀₁₂₃₄₅₆₇₈₉, ⁰¹²³⁴⁵⁶⁷⁸⁹) in ReportLab PDFs. The
+built-in fonts do not include these glyphs, causing them to render as solid black boxes.
+
+Instead, use ReportLab's XML markup tags in Paragraph objects:
+
+```python
+from reportlab.platypus import Paragraph
+from reportlab.lib.styles import getSampleStyleSheet
+
+styles = getSampleStyleSheet()
+
+# Subscripts: use <sub> tag
+chemical = Paragraph("H<sub>2</sub>O", styles['Normal'])
+
+# Superscripts: use <super> tag
+squared = Paragraph("x<super>2</super> + y<super>2</super>", styles['Normal'])
+```
+
+For canvas-drawn text (not Paragraph objects), manually adjust font the size and position rather than using Unicode
+subscripts/superscripts.
+
+## Command-Line Tools
+
+### pdftotext (poppler-utils)
+
+```bash
+# Extract text
+pdftotext input.pdf output.txt
+
+# Extract text preserving layout
+pdftotext -layout input.pdf output.txt
+
+# Extract specific pages
+pdftotext -f 1 -l 5 input.pdf output.txt  # Pages 1-5
+```
+
+### qpdf
+
+```bash
+# Merge PDFs
+qpdf --empty --pages file1.pdf file2.pdf -- merged.pdf
+
+# Split pages
+qpdf input.pdf --pages . 1-5 -- pages1-5.pdf
+qpdf input.pdf --pages . 6-10 -- pages6-10.pdf
+
+# Rotate pages
+qpdf input.pdf output.pdf --rotate=+90:1  # Rotate page 1 by 90 degrees
+
+# Remove password
+qpdf --password=mypassword --decrypt encrypted.pdf decrypted.pdf
+```
+
+### pdftk (if available)
+
+```bash
+# Merge
+pdftk file1.pdf file2.pdf cat output merged.pdf
+
+# Split
+pdftk input.pdf burst
+
+# Rotate
+pdftk input.pdf rotate 1east output rotated.pdf
+```
+
+## Common Tasks
+
+### Extract Text from Scanned PDFs
+
+```python
+# Requires: pip install pytesseract pdf2image
+import pytesseract
+from pdf2image import convert_from_path
+
+# Convert PDF to images
+images = convert_from_path('scanned.pdf')
+
+# OCR each page
+text = ""
+for i, image in enumerate(images):
+    text += f"Page {i+1}:\n"
+    text += pytesseract.image_to_string(image)
+    text += "\n\n"
+
+print(text)
+```
+
+### Add Watermark
+
+```python
+from pypdf import PdfReader, PdfWriter
+
+# Create watermark (or load existing)
+watermark = PdfReader("watermark.pdf").pages[0]
+
+# Apply to all pages
+reader = PdfReader("document.pdf")
+writer = PdfWriter()
+
+for page in reader.pages:
+    page.merge_page(watermark)
+    writer.add_page(page)
+
+with open("watermarked.pdf", "wb") as output:
+    writer.write(output)
+```
+
+### Extract Images
+
+```bash
+# Using pdfimages (poppler-utils)
+pdfimages -j input.pdf output_prefix
+
+# This extracts all images as output_prefix-000.jpg, output_prefix-001.jpg, etc.
+```
+
+### Password Protection
+
+```python
+from pypdf import PdfReader, PdfWriter
+
+reader = PdfReader("input.pdf")
+writer = PdfWriter()
+
+for page in reader.pages:
+    writer.add_page(page)
+
+# Add password
+writer.encrypt("userpassword", "ownerpassword")
+
+with open("encrypted.pdf", "wb") as output:
+    writer.write(output)
+```
+
+## Quick Reference
+
+| Task               | Best Tool                       | Command/Code               |
+| ------------------ | ------------------------------- | -------------------------- |
+| Merge PDFs         | pypdf                           | `writer.add_page(page)`    |
+| Split PDFs         | pypdf                           | One page per file          |
+| Extract text       | pdfplumber                      | `page.extract_text()`      |
+| Extract tables     | pdfplumber                      | `page.extract_tables()`    |
+| Create PDFs        | reportlab                       | Canvas or Platypus         |
+| Command line merge | qpdf                            | `qpdf --empty --pages ...` |
+| OCR scanned PDFs   | pytesseract                     | Convert to image first     |
+| Fill PDF forms     | pdf-lib or pypdf (see forms.md) | See forms.md               |
+
+## Next Steps
+
+- For advanced pypdfium2 usage, see [reference.md](reference.md)
+- For JavaScript libraries (pdf-lib), see [reference.md](reference.md)
+- If you need to fill out a PDF form, follow the instructions in [forms.md](forms.md)
+- For troubleshooting guides, see [reference.md](reference.md)