# Publish Ebook Preview

> Build and validate EPUB packages and preview websites for ebook publishing projects, especially simple HTML/CSS/JS + Markdown book repos. Use when the user asks to regenerate an EPUB for Google Books/Google Play Books review, document the EPUB build process, publish a web preview using the first half of chapters, or add a final-page Google Books purchase link/CTA to online chapter pages.

- Skill: `j945935cy/publish-ebook-preview` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add j945935cy/publish-ebook-preview`
- Raw SKILL.md: https://api.skillmd.com/api/skills/j945935cy/publish-ebook-preview/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: j945935cy (https://skillmd.com/u/j945935cy)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/j945935cy/publish-ebook-preview

---


# Publish Ebook Preview

## Overview

Use this skill to prepare an ebook project for EPUB upload and web preview publishing. Favor simple, reproducible build steps, clean EPUB packaging, and a restrained preview site that shows only the first half of the book while linking readers to Google Books for purchase.

## Workflow

1. Inspect the repository structure before editing.
   - Look for `src/` Markdown chapters, `web/` static site files, `epub/` EPUB source tree, and `tools/build_epub.py` or equivalent scripts.
   - Read project instructions such as `AGENTS.md`, `BOOK_STRUCTURE.md`, and validation scripts.
   - Check `git status --short` and preserve unrelated user changes.

2. Rebuild the EPUB deterministically.
   - Prefer an existing build script, usually `python tools/build_epub.py`.
   - Keep the first ZIP entry as `mimetype`, uncompressed, with content exactly `application/epub+zip`.
   - Keep the EPUB package minimal: top-level entries should normally be only `mimetype`, `META-INF/`, and `OEBPS/`.
   - Include every `OEBPS/` resource in `content.opf` manifest.
   - Prefer PNG/JPG cover images for Google Books compatibility. Avoid relying on SVG-only covers.
   - Ensure `cover.xhtml`, `content.opf`, `nav.xhtml`, and `toc.ncx` all point to the same cover resource.
   - Use a stable `dc:identifier` when regenerating a revised version of the same book.

3. Build the web preview with the first half of chapters.
   - If the book has 10 chapters, expose chapters 1-5 as the preview.
   - If chapter count differs, use the first `ceil(total / 2)` chapters unless the user gives a specific preview range.
   - Keep later chapters visible only as locked/listed items or omit their content, depending on the existing site pattern.
   - Do not duplicate full paid-book content into the free preview site.

4. Add the Google Books purchase link at the end of chapter pages.
   - Put the CTA after the visible chapter content, effectively on the last page/last section of each web chapter view.
   - Use the project's existing CTA style and wording when present.
   - The link should point directly to the Google Books purchase/detail URL supplied by the user or already used in the project.
   - If no URL is available, leave a clear placeholder constant in the code and tell the user it needs the final Google Books URL.

5. Validate before finishing.
   - Run the project validator if present, for example `python tools/validate_project.py`.
   - Parse XML/XHTML files in the EPUB when possible: `.xml`, `.opf`, `.ncx`, `.xhtml`.
   - Confirm ZIP contents do not include source-only files such as root-level cover source images.
   - Confirm the web preview limit is implemented in code or data.
   - If `epubcheck` is installed, run it on the final `.epub`. If it is unavailable, state that clearly.

## EPUB Build Notes

When writing or editing a build script:

```python
with ZipFile(output_path, "w") as epub_zip:
    epub_zip.write(epub_dir / "mimetype", "mimetype", compress_type=ZIP_STORED)
    for file_path in sorted(epub_dir.rglob("*")):
        if file_path.is_dir() or file_path.name in {output_path.name, "mimetype"}:
            continue
        epub_zip.write(file_path, file_path.relative_to(epub_dir).as_posix(), compress_type=ZIP_DEFLATED)
```

Add explicit exclusions for source-only assets, for example an original `cover1.png` copied into `OEBPS/Images/cover.png`.

For Google Books review, prefer:

- `OEBPS/Images/cover.png`
- OPF manifest item: `media-type="image/png" properties="cover-image"`
- `meta name="cover" content="cover-image"`
- `cover.xhtml` with `<img src="../Images/cover.png" .../>`

## Web Preview Pattern

For JavaScript-driven static sites, look for code like:

```javascript
const previewChapters = chapters.slice(0, 5);
```

Adjust `5` to the first half of the chapter count. If possible, compute it:

```javascript
const previewCount = Math.ceil(chapters.length / 2);
const previewChapters = chapters.slice(0, previewCount);
```

Place the Google Books CTA after rendered chapter content, not before the reader reaches the chapter ending.

## Final Response

Report:

- The final EPUB path and whether the filename was reused.
- The preview range, such as chapters 1-5 of 10.
- The Google Books link location in the web chapter flow.
- Validation commands run and whether `epubcheck` was available.