pdf

name	pdf
description	Use when the user asks to create, combine, split, preview, or extract content from PDF files. Triggers include "markdown to pdf", "mermaid in pdf", "merge PDFs", "split a PDF", "extract text from pdf", "fill AcroForm", "preview pdf as image", and similar PDF generation or manipulation tasks.
tier	2
version	1
license	LicenseRef-Proprietary

pdf skill

Purpose: Give the agent a small, deterministic set of CLIs for the common PDF operations: render Markdown to a well-typeset PDF, merge PDFs, split them by page range or into individual pages, and (via references) extract text or fill forms. Picking the right library on the fly is the single biggest source of PDF bugs; delegating to scripts that embed those choices removes the variance.

1. Red Flags (Anti-Rationalization)

STOP and READ THIS if you are thinking:

• "I'll use pypdf to extract the text." → WRONG for layout-dependent content. pypdf's text extraction is famously unreliable on anything with columns or complex layout; use pdfplumber. See references/library-selection.md.
• "I'll reach for playwright for Markdown → PDF because it handles everything." → WRONG. Playwright pulls a 200 MB Chromium install. weasyprint handles 95% of Markdown/HTML inputs with a fraction of the footprint.
• "I'll fill this XFA form with pypdf." → WRONG. pypdf doesn't fill XFA — only AcroForm. Detect the form type first (see references/forms.md) and fail loudly if it's XFA rather than silently writing an unchanged file.
• "I'll skip checking exit codes from pdf_merge.py." → WRONG. Missing an input file produces exit 1 and the output is absent — silently assuming success ships a broken deliverable.

2. Capabilities

• Render Markdown (+ optional custom CSS) to a typeset PDF via weasyprint. Fenced ```mermaid blocks pre-render to PNG via mmdc; bundled scripts/mermaid-config.json ships an office-friendly Cyrillic-capable font stack (override with --mermaid-config PATH, opt out with --no-mermaid-config).
• Render HTML / web archives to PDF via html2pdf.py — same weasyprint pipeline, natively handles .html/.htm, .mhtml/.mht, and .webarchive. Validated across Fern (OpenRouter), Mintlify (Anthropic Claude Code, Discord, Berachain), GitBook (Hyperliquid), Confluence (Atlassian wikis), Хабр, vc.ru and generic blogs — 34/34 fixtures pass in both modes. Bundled stylesheet on by default; --no-default-css for fully-styled inputs (BI dashboards, branded reports); --css EXTRA.css stacks on top. --reader-mode extracts the main article body (Safari Reader View parity). --timeout 180 SIGALRM watchdog with $HTML2PDF_TIMEOUT override. Universal preprocessing handles draw.io/Confluence SVG diagrams, table-based code blocks (Fern/Mintlify shiki), Tailwind/FontAwesome icon strip, ARIA-role tables (GitBook), ad-network removal, and pathological-CSS protection (Хабр content-drop bug, vc.ru CPU-loop bug). Full pipeline + flag semantics + per-platform notes documented in references/html-conversion.md.
• Merge multiple PDFs into one preserving bookmarks (pdf_merge.py).
• Split a PDF by explicit page ranges, one-per-page, or fixed-size chunks (pdf_split.py).
• Stamp a text or image watermark on every (or selected) page via pdf_watermark.py (drafts, "CONFIDENTIAL", brand stamps). --position center|top-left|top-right|bottom-left|bottom-right|diagonal, --opacity, --rotation, --pages "1-5,8". Builds one overlay per unique page mediabox, so heterogeneous decks (Letter+A4) keep correct proportions.
• Detect, inspect, and fill AcroForm fields via pdf_fill_form.py — three modes: --check (form-type triage with exit codes 0/11/12 = AcroForm/XFA/none), --extract-fields (dump field schema as JSON for editing), and fill mode (INPUT.pdf DATA.json -o OUT.pdf [--flatten]). XFA forms are detected and refused with a clear message.
• Extract text, tables, and layout via pdfplumber (documented; inline usage from the agent is fine).
• Render any .pdf (or peer-skill .docx/.xlsx/.pptx) into a single PNG-grid preview via preview.py (uses Poppler directly for .pdf; LibreOffice + Poppler for OOXML).
• Emit failures as machine-readable JSON to stderr with --json-errors (uniform across all four office skills).

3. Execution Mode

• Mode: script-first for the bundled operations, prompt-first with library references for extraction and form filling.
• Why this mode: The bundled operations (render, merge, split) are stable recipes. Extraction and form filling depend heavily on the specific document and deserve inspection before running — the references guide the inline work.

4. Script Contract

• Commands:
  • python3 scripts/md2pdf.py INPUT.md OUTPUT.pdf [--page-size letter|a4|legal] [--css EXTRA.css] [--base-url DIR] [--no-mermaid] [--strict-mermaid] [--mermaid-config PATH | --no-mermaid-config]
  • python3 scripts/html2pdf.py INPUT OUTPUT.pdf [--page-size letter|a4|legal] [--css EXTRA.css] [--base-url DIR] [--no-default-css] [--reader-mode] [--archive-frame N|main|all|auto] [--list-frames] [--timeout SECONDS] [--engine weasyprint|chrome] [--chrome-js] — INPUT may be .html/.htm, .mhtml/.mht, or .webarchive; sub-resources in archives are extracted to a temp dir automatically. --reader-mode extracts the main article content (Confluence-priority candidate list with body-ratio guard for <main>; longest-match per selector handles archive pages with multiple .entry divs and Disqus comment threads + title-match LCS bonus for multi-article feed pages), stripping navigation, ads, sidebars, and SPA chrome (ARIA role=navigation\|complementary\|banner\|contentinfo + semantic <aside>/<nav>/<footer> + shallow <header>) — ideal for browser-saved news/blog/docs pages and hydrated SPAs. --archive-frame N|main|all|auto (pdf-8, 2026-05-05): selects which inner frame in webarchive/MHTML to render — main (default) = main resource only; N (1-indexed) = specific inner frame; all = concat all "substantial" frames (≥ 1 KB + 0 <script> + ≥ 30 chars text + not single-<img>-only) with <hr><h2>Frame N</h2> separators + per-frame namespace + sha1 image-dedup + encoding parity; auto = deterministic (0 substantial → main, 1 → that frame with main-dominance guard, 2+ → all). Vendor-agnostic: validated on 9 real fixtures across Angular/Closure/Framer/bare-DOM SPA stacks without a single vendor name in the heuristic. --list-frames (pdf-8): prints inner-frame inventory (index/kind/substantial/bytes/scripts/text-len/url) and exits without rendering — for picking N deterministically. --timeout (default 180s, $HTML2PDF_TIMEOUT env, 0 disables) caps weasyprint render via signal.SIGALRM for pathological inputs. Exit 1 with RenderTimeout envelope on watchdog fire; exit 2 with NoSubstantialFrames / FrameIndexOutOfRange envelopes for archive-frame errors. --engine weasyprint|chrome (pdf-11, 2026-05-05): render engine selector. weasyprint (default) — pure-Python typeset PDF, no browser runtime. chrome — opt-in headless Chromium via Playwright (~150 MB, install with bash install.sh --with-chrome). Use chrome when weasyprint produces broken output: Material 3 calc/var bugs (Gmail-class), Framer infinite layout loops, ELMA365 inline.py assertion, JS-hydrated content, <canvas> charts. Chrome path skips weasyprint preprocess (calc-strip, font-face-strip, NORMALIZE_CSS) — those are weasyprint workarounds Chrome doesn't need; reader-mode and --css EXTRA.css remain engine-agnostic. Chrome render hardenings (universal layout strategy, post-VDD-iter-8 — 8 adversarial iterations): <script> strip from HTML + JS-enabled at context level (page can't run own JS → no Gmail self-destruct, no Angular half-hydration; we keep page.evaluate for surgical DOM normalization; --chrome-js opts page-JS back in for canvas/hydration); <base href> stripped (webarchives carry <base href="https://orig-site/"> which would route every relative URL to the offline-blocked origin); media forced to screen (default print triggers nav-hiding @media print rules in SPAs); 1280×1024 viewport (desktop CSS); layout-normalize CSS — high-specificity body release, icon-font ligature suppression with :not(:has(*)) leaf-only guard (avoids font-size:0 cascading through CSS inheritance to children), [class~="spinner"] exact-word match (not substring — avoids hiding class="spinner-class-banner" and similar), image cap (200px), avatar-image cap (48×48 only on ... img, not bare class so containers aren't shrunk); JS-based DOM normalize via page.evaluate — width-gate offsetWidth ≥ 200 for overflow release (narrow icon-sidebars at 64px stay clipped, no label leak), substantial-modal release (position:fixed → static only when wide AND tall AND text-rich), modal-portal hide (when modal released, hide non-portal body children to remove underlying CRM page); scale-to-fit page.pdf(scale = pdf_usable / viewport_width) ≈ 0.561 so 1280 px layout fits A4's ~718 px usable width without right-edge cutoff. Validated on 3 SPA archive shapes × 2 modes (Gmail Closure email, ELMA365 Angular dashboard, Yandex Cloud Console marketplace) — all 6 combinations produce full content with no overlap, no cutoff, no chrome-icon ligatures, no underlying-page noise. Recommended composition: --engine chrome --reader-mode for email/newsletter/article archives (cleaner article-only render); --engine chrome alone for dashboards/registries/structured UIs (preserves card layout). Exit 1 with ChromeEngineUnavailable envelope if Playwright not installed.
  • python3 scripts/pdf_merge.py OUTPUT.pdf INPUT1.pdf INPUT2.pdf [INPUT3.pdf ...]
  • python3 scripts/pdf_split.py INPUT.pdf --ranges "1-5:part1.pdf,6-10:part2.pdf"
  • python3 scripts/pdf_split.py INPUT.pdf --each-page OUTDIR/
  • python3 scripts/pdf_split.py INPUT.pdf --every N OUTDIR/
  • python3 scripts/pdf_watermark.py INPUT.pdf OUTPUT.pdf (--text "DRAFT" | --image STAMP.png) [--opacity 0.3] [--position center|top-left|top-right|bottom-left|bottom-right|diagonal] [--rotation 45] [--font-size 60] [--color "#888"] [--scale 0.5] [--pages "all"|"1-5,8,12-end"]
  • python3 scripts/pdf_fill_form.py --check INPUT.pdf — exit 0/11/12 = AcroForm/XFA/none. (Custom codes start at 10 to leave 0–9 for argparse / shell convention.)
  • python3 scripts/pdf_fill_form.py --extract-fields INPUT.pdf -o fields.json
  • python3 scripts/pdf_fill_form.py INPUT.pdf DATA.json -o OUTPUT.pdf [--flatten]
  • python3 scripts/preview.py INPUT OUTPUT.jpg [--cols 3] [--dpi 110] [--gap 12] [--padding 24] [--label-font-size 14] [--soffice-timeout 240] [--pdftoppm-timeout 60]
  • All scripts above accept --json-errors to emit failures as a single line of JSON on stderr ({v, error, code, type?, details?}). The schema version v is currently 1; argparse usage errors are routed through the same envelope (type:"UsageError").
• Inputs: positional paths; optional flags per command.
• Outputs: single PDF files (md2pdf, pdf_merge) or multiple PDFs under a directory (pdf_split). All stdout goes to the output path list.
• Failure semantics: non-zero exit on missing inputs, invalid range specs, or library errors. Error detail to stderr.
• Idempotency: all three scripts overwrite their outputs on re-run.
• Dry-run support: not applicable.

5. Safety Boundaries

• Allowed scope: only paths named on the command line.
• Default exclusions: do not fetch remote resources unless the user explicitly provides URLs; md2pdf.py --base-url defaults to the input's directory.
• Destructive actions: all three scripts overwrite their outputs without prompting.
• Optional artifacts: custom CSS via md2pdf.py --css is optional; defaults produce a reasonable layout.

6. Validation Evidence

• Local verification:
  • python3 -m venv .venv && source .venv/bin/activate && pip install -r scripts/requirements.txt — installs pypdf, pdfplumber, weasyprint, markdown2, reportlab.
  • bash scripts/tests/test_e2e.sh — runs the end-to-end smoke suite (md2pdf, merge, split, fill-form, mermaid). Includes the html2pdf regression battery: ~37 unit tests for html2pdf_lib/ helpers + data-driven fixture battery (6 synthetic micro-fixtures + 6 hand-stripped real-platform slices + N tmp/ originals when present on disk; per-fixture page-count / size / required+forbidden-needle assertions, see tests/battery_signatures.json).
  • Adding a new platform fixture (e.g. you found a Notion/Stripe page that breaks): drop the .webarchive/.html/.mhtml file into tmp/, run python3 scripts/tests/capture_signatures.py (auto-captures page count + needles + size band; only ADDs new fixtures unless --refresh is passed), hand-add chrome strings to forbidden_needles in battery_signatures.json, commit the JSON delta. Total ~5 min per new site. Detailed in references/html-conversion.md §Regression coverage.
  • python3 scripts/md2pdf.py examples/fixture.md /tmp/invoice.pdf --page-size letter — produces a non-empty PDF.
  • python3 -c "from pypdf import PdfReader; r=PdfReader('/tmp/invoice.pdf'); print(len(r.pages))" — returns at least 1.
  • python3 scripts/pdf_merge.py /tmp/merged.pdf /tmp/invoice.pdf /tmp/invoice.pdf && python3 -c "from pypdf import PdfReader; print(len(PdfReader('/tmp/merged.pdf').pages))" — 2× the page count.
  • python3 scripts/pdf_split.py /tmp/invoice.pdf --each-page /tmp/pages/ — produces /tmp/pages/invoice-001.pdf.
• Expected evidence: /tmp/invoice.pdf, /tmp/merged.pdf, /tmp/pages/invoice-001.pdf.
• CI signal: python3 ../../.claude/skills/skill-creator/scripts/validate_skill.py skills/pdf — exit 0.

7. Instructions

7.1 Pick the library, not the script first

Extraction and form filling are not in the bundled scripts deliberately.

1. Check references/library-selection.md for which library matches the task.
2. For extraction: write inline pdfplumber code in your response.
3. For form filling: follow references/forms.md — detect AcroForm vs XFA first.

7.2 Creating PDFs from Markdown

1. python3 scripts/md2pdf.py input.md output.pdf covers the common case.
2. Pass --css custom.css when the user provides brand styling.
3. For images referenced with relative paths, either put them next to the Markdown file or pass --base-url /absolute/image/root.
4. For HTML-heavy inputs (embedded <style>, flexbox, columns), weasyprint handles those in the script — no extra work needed.

7.3 Merging PDFs

1. Order matters: python3 scripts/pdf_merge.py out.pdf file1.pdf file2.pdf file3.pdf appends in that order.
2. Bookmarks from each input are preserved and nested under a parent named after the source's stem.

7.4 Splitting PDFs

Three modes, exclusive:

• --ranges "1-3:intro.pdf,4-8:body.pdf,9-12:appendix.pdf"
• --each-page OUTDIR/ — one PDF per input page, zero-padded filenames.
• --every N OUTDIR/ — chunks of N pages each.

Page numbers are 1-indexed and inclusive. Invalid ranges exit 1.

7.5 Setup

1. MUST run bash scripts/install.sh once. It creates scripts/.venv/ locally, installs requirements.txt, probes whether weasyprint can find its native libraries, and prints install hints if not. Idempotent.
2. External system libraries (checked by install.sh, installed manually per project plan §3.3 "внешние инструменты — не бандлятся"):
   • pango, cairo, gdk-pixbuf — weasyprint native runtime; required by md2pdf.py. macOS: brew install pango gdk-pixbuf libffi. Debian: sudo apt install libpango-1.0-0 libpangoft2-1.0-0 libharfbuzz0b libcairo2 libgdk-pixbuf2.0-0. See references/weasyprint-setup.md for fuller notes. Commands that need them fail with a clear error until installed.

8. Workflows (Optional)

Markdown-driven PDF:

- [ ] Draft the Markdown content
- [ ] `python3 scripts/md2pdf.py doc.md doc.pdf`
- [ ] Open the PDF, check layout (orphans/widows, table page breaks)
- [ ] Iterate on CSS if needed (`--css brand.css`)

Merge + split for distribution:

- [ ] `python3 scripts/pdf_merge.py combined.pdf intro.pdf body.pdf appendix.pdf`
- [ ] `python3 scripts/pdf_split.py combined.pdf --each-page out/`  (if per-page delivery is needed)
- [ ] Verify page count with pypdf or Preview

Extract text (inline, no bundled script):

- [ ] Read references/library-selection.md, pick pdfplumber
- [ ] Inline: open the file, call page.extract_text(layout=True)
- [ ] For tables, page.extract_tables() with appropriate snap_tolerance

9. Best Practices & Anti-Patterns

DO THIS	DO NOT DO THIS
Use weasyprint for Markdown/HTML → PDF.	Reach for playwright unless you actually need JS/modern CSS.
Use pdfplumber for text/table extraction.	Trust pypdf.extract_text() on column layouts — output is often garbled.
Detect AcroForm vs XFA before filling.	Try to fill XFA with pypdf and ship an unchanged file.
Pass --base-url so relative images resolve.	Assume weasyprint reads relative paths the same way your shell does.
Check exit codes of the bundled scripts.	Assume success because no exception was raised.

Rationalization Table

Agent Excuse	Reality / Counter-Argument
"All PDFs can be read with the same library."	Reading vs creation vs editing vs rendering are four different problem spaces; pick per task.
"The Markdown renderer doesn't matter, they're all similar."	weasyprint supports @page and page-break-inside; markdown-pdf and mdpdf don't.
"My script worked on one PDF, it'll work on all of them."	PDFs are wildly heterogeneous — scanned, image-only, XFA, flattened. Always test on the actual file.

10. Quick Reference

Task	Command
Markdown → PDF	python3 scripts/md2pdf.py doc.md doc.pdf --page-size letter
Markdown → PDF with custom mermaid theme	python3 scripts/md2pdf.py doc.md doc.pdf --mermaid-config theme.json
HTML → PDF	python3 scripts/html2pdf.py report.html report.pdf
HTML → PDF (skip bundled CSS, only embedded styles)	python3 scripts/html2pdf.py dashboard.html out.pdf --no-default-css
Web page / archive → PDF (reader mode, strips nav/ads)	python3 scripts/html2pdf.py page.webarchive article.pdf --reader-mode
List inner frames in webarchive/MHTML (pdf-8)	python3 scripts/html2pdf.py --list-frames email-thread.webarchive
Render only inner frame N (1-indexed, e.g. one email from a thread)	python3 scripts/html2pdf.py --archive-frame 1 thread.webarchive single.pdf
Render all "substantial" inner frames concatenated (e.g. full email thread)	python3 scripts/html2pdf.py --archive-frame all thread.webarchive thread.pdf
Auto-pick frame strategy (0 substantial → main, 1 → that, 2+ → all)	python3 scripts/html2pdf.py --archive-frame auto archive.webarchive out.pdf
HTML → PDF with custom render deadline	python3 scripts/html2pdf.py page.html out.pdf --timeout 300 (or HTML2PDF_TIMEOUT=300 python3 …)
HTML → PDF, watchdog disabled (large book webarchive)	HTML2PDF_TIMEOUT=0 python3 scripts/html2pdf.py book.webarchive book.pdf
HTML → PDF via headless Chrome — for dashboards/registries (pdf-11; install with bash install.sh --with-chrome)	python3 scripts/html2pdf.py registry.webarchive out.pdf --engine chrome
Chrome + reader-mode — recommended for email/newsletter/article archives	python3 scripts/html2pdf.py email.webarchive out.pdf --engine chrome --reader-mode
Chrome engine with JavaScript on (rare; for canvas charts or pre-hydration HTML)	python3 scripts/html2pdf.py page.webarchive out.pdf --engine chrome --chrome-js
Merge PDFs	python3 scripts/pdf_merge.py out.pdf a.pdf b.pdf c.pdf
Split by ranges	python3 scripts/pdf_split.py in.pdf --ranges "1-5:intro.pdf,6-10:body.pdf"
Split one-per-page	python3 scripts/pdf_split.py in.pdf --each-page pages/
Split in chunks of N	python3 scripts/pdf_split.py in.pdf --every N out/
Text watermark on every page	python3 scripts/pdf_watermark.py in.pdf out.pdf --text "DRAFT"
Image watermark, bottom-right corner	python3 scripts/pdf_watermark.py in.pdf out.pdf --image stamp.png --position bottom-right --scale 0.2
Watermark only specific pages	python3 scripts/pdf_watermark.py in.pdf out.pdf --text CONFIDENTIAL --pages "1-5,8"
Inspect AcroForm fields	python3 scripts/pdf_fill_form.py --check form.pdf
Extract field schema as JSON	python3 scripts/pdf_fill_form.py --extract-fields form.pdf -o fields.json
Fill AcroForm from JSON	python3 scripts/pdf_fill_form.py form.pdf data.json -o filled.pdf [--flatten]
Preview as PNG-grid	python3 scripts/preview.py file.pdf preview.jpg [--cols 3] [--dpi 110]
Machine-readable failures	append --json-errors to any of the above

11. Examples (Few-Shot)

Fixture: examples/fixture.md.

Input — user request:

Turn this invoice Markdown into a letter-sized PDF.

Output — agent action:

python3 scripts/md2pdf.py invoice.md invoice.pdf --page-size letter

Input — user request:

Join these three quarterly reports into one annual PDF.

Output — agent action:

python3 scripts/pdf_merge.py annual.pdf q1.pdf q2.pdf q3.pdf q4.pdf

Input — user request:

Split the 120-page handbook into chapters of roughly 10 pages each.

Output — agent action:

python3 scripts/pdf_split.py handbook.pdf --every 10 chapters/

Input — user request:

Convert this Confluence-export HTML report to PDF.

Output — agent action:

python3 scripts/html2pdf.py q1-report.html q1-report.pdf --base-url ./q1-report_files/

Input — user request:

Stamp every page of this draft contract with "DRAFT" diagonally.

Output — agent action:

python3 scripts/pdf_watermark.py contract.pdf contract-draft.pdf --text "DRAFT"

12. Resources

• references/library-selection.md — which PDF library for which task, installation shortcuts.
• references/forms.md — AcroForm vs XFA, filling with pypdf, flattening, visual overlay fallback.
• references/weasyprint-setup.md — install platform notes, @page recipes, font embedding, page breaks.
• references/html-conversion.md — html2pdf.py deep dive: 10-step preprocessing pipeline, _NORMALIZE_CSS rules, reader-mode candidate list with body-ratio guard, render-time hardening (offline URL fetcher + SIGALRM watchdog), per-platform notes (Fern / Mintlify / GitBook / Confluence / Хабр / vc.ru), honest-scope limitations.
• scripts/md2pdf.py — Markdown → PDF via weasyprint + markdown2; mermaid blocks pre-rendered to PNG via mmdc.
• scripts/html2pdf.py — HTML → PDF via the same weasyprint pipeline; reuses md2pdf's default stylesheet (opt-out via --no-default-css).
• scripts/pdf_merge.py — bookmark-preserving merger via pypdf.
• scripts/pdf_split.py — range, per-page, or fixed-chunk splitter.
• scripts/pdf_watermark.py — text/image watermark overlay via reportlab + pypdf; per-mediabox overlay caching for heterogeneous decks; cross-7 same-path guard.
• scripts/pdf_fill_form.py — AcroForm inspect/extract/fill/flatten via pypdf; XFA forms detected and refused.
• scripts/preview.py — universal INPUT → PNG-grid renderer for .pdf (via Poppler) and .docx/.xlsx/.pptx (via LibreOffice + Poppler). Byte-identical across all four office skills.
• scripts/mermaid-config.json — bundled office-friendly mermaid config (Cyrillic-capable font stack, auto-applied unless overridden via --mermaid-config).
• scripts/_errors.py — --json-errors envelope helper (schema v=1).