PDF

PDF Workflows

This skill covers PDF creation, inspection, extraction, page operations, forms, and visual QA in Canvas Notebook. It is a clean-room Canvas skill; do not copy vendor skill material, hidden prompts, or proprietary helper code into this folder.

Core Contract

• Use CANVAS_AGENT_TEMP_DIR for scripts, working copies, extracted assets, page renderings, and validation output. Promote only the requested final PDF to the workspace with copy_path or move_path.
• Treat rendered pages as the source of truth for layout-sensitive tasks.
• Use text extraction for content discovery, not as proof that a PDF looks correct.
• Keep source PDFs immutable unless the user explicitly asks to overwrite them.
• Return only the final requested artifact unless the user asks for extracted intermediates.
• Use deterministic scripts for repeated operations and keep those scripts in scratch unless the user explicitly requests them as deliverables.

Recommended Tools

• pypdf for merge, split, rotate, metadata, encryption, simple form filling, and page-level operations.
• pdfplumber for text, coordinates, tables, and layout-aware inspection.
• The Canvas PDF gateway, when exposed in the active runtime, for supported PDF operations. Discover it with search, inspect the selected operation with describe, then use call.
• HTML plus bundled headless Chromium for creating new PDFs when no suitable gateway operation exists.
• Poppler tools such as pdfinfo, pdftoppm, and pdftocairo for rendering and page diagnostics.
• OCR tools only when available and required; if OCR dependencies are missing, explain the blocker instead of pretending scanned text was read.

Workflow

1. Classify the task: read/review, generate, page operation, form filling, extraction, redaction, OCR, or repair.
2. Make a working copy for destructive operations.
3. Use the simplest reliable library for the operation. Avoid manipulating raw PDF bytes manually.
4. Render updated pages to PNG and inspect alignment, margins, clipping, legibility, form values, signatures/watermarks, and page order.
5. If a visual issue appears, repair the source operation and re-render.

Common Tasks

• Extract text: start with pdfplumber; preserve page numbers and note extraction uncertainty for scanned or complex PDFs.
• Extract tables: use pdfplumber table strategies and validate against rendered pages.
• Create a PDF: use a supported PDF gateway operation or generate structured HTML and print it with headless Chromium; define margins, fonts, section hierarchy, tables, and pagination explicitly.
• Merge or split: use pypdf; verify page count and order with pdfinfo and rendered thumbnails.
• Fill forms: inspect AcroForm fields first, write a copy, flatten only if requested or necessary, then render filled pages.
• Redact: do not cover text with a black rectangle alone. Remove or rewrite underlying content where possible, then verify extraction and rendering.

Final Checks

• Latest rendered pages match the requested content and order.
• Text is readable at normal zoom and no content is clipped.
• Page size, orientation, margins, headers, footers, and numbering are correct.
• Any extraction, OCR, or redaction limitations are stated clearly.