Borrowing it
Nothing to install: this file belongs to lowtidebuild/ebook-writer. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/lowtidebuild/ebook-writer/main/.claude/skills/web-viewer-builder/SKILL.mdgit clone --depth 1 https://github.com/lowtidebuild/ebook-writerWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/lowtidebuild/ebook-writer/web-viewer-builder)<a href="https://agentmods.dev/skills/lowtidebuild/ebook-writer/web-viewer-builder"><img src="https://agentmods.dev/badge/skills/lowtidebuild/ebook-writer/web-viewer-builder.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00000 | $0.00877 |
| Opus 5 | $0.00000 | $0.00439 |
| Sonnet 5 | $0.00000 | $0.00175 |
| Haiku 4.5 | $0.00000 | $0.00088 |
Grade A, and why
web-viewer-builder scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 82 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Web Viewer Builder Skill
Purpose
Generate a PDF.js-based web ebook viewer from the typeset PDFs. The viewer renders the actual PDF pages with a two-page book spread layout, page-turn animation, chapter navigation sidebar, and bilingual language toggle. Deployable to GitHub Pages.
When to Use
Step 8 of the ebook pipeline — after PDFs have been generated in Step 7. This skill takes the finalized PDF files and produces a deployable web viewer.
Script
scripts/build_viewer.py
Usage
.venv/bin/python3 .claude/skills/web-viewer-builder/scripts/build_viewer.py \
--pdf-primary output/final/book_ko.pdf \
--pdf-secondary output/final/book_en.pdf \
--output output/web-viewer/ \
--template .claude/skills/web-viewer-builder/references/viewer_template.html \
--title "Book Title" \
--title-secondary "Book Title (EN)" \
--primary-lang ko \
--secondary-lang en
Arguments
| Argument | Required | Description |
|---|---|---|
--pdf-primary |
Yes | Path to primary language PDF |
--pdf-secondary |
No | Path to secondary language PDF; omit for a single-language viewer |
--output |
Yes | Output directory for the web viewer |
--template |
Yes | Path to viewer_template.html |
--title |
Yes | Book title (primary language) |
--title-secondary |
No | Book title (secondary language) |
--primary-lang |
No | Primary language code, default ko |
--secondary-lang |
No | Secondary language code, default en |
How It Works
- Build time: PyMuPDF scans both PDFs for chapter headings (font size >= 14pt in top 40% of page)
- Build time: Chapter-to-page mapping is extracted and embedded as JSON in the HTML
- Runtime: PDF.js loads and renders the PDF pages on canvas elements
- Runtime: Sidebar is populated instantly from the embedded JSON (no client-side scanning)
- Single-language mode: When
--pdf-secondaryis omitted or missing, the language toggle is hidden instead of pointing both buttons at the primary PDF
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 82 lines · 0 tokens per session scan A c00cb2d728f1
web-viewer-builder is a skill published in the GitHub repository lowtidebuild/ebook-writer (5 stars, last pushed 2mo ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 877 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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