Translate Book Parallel

# Translate Book (Parallel Subagents)

> Skill by [ara.so](https://ara.so) — Daily 2026 Skills collection.

A Claude Code skill that translates entire books (PDF/DOCX/EPUB) into any language using parallel subagents. Each chunk gets an isolated context window — preventing truncation and context accumulation that plague single-session translation.

## Pipeline Overview

```
Input (PDF/DOCX/EPUB)
  │
  ▼
Calibre ebook-convert → HTMLZ → HTML → Markdown
  │
  ▼
Split into chunks (~6000 chars each)
  │  manifest.json tracks SHA-256 hashes
  ▼
Parallel subagents (8 concurrent by default)
  │  each: read chunk → translate → write output_chunk*.md
  ▼
Validate (manifest hash check, 1:1 source↔output match)
  │
  ▼
Merge → Pandoc → HTML (with TOC) → Calibre → DOCX / EPUB / PDF
```

## Prerequisites

```bash
# 1. Calibre (provides ebook-convert)
# macOS
brew install --cask calibre
# Linux
sudo apt-get install calibre
# Or download from https://calibre-ebook.com/

# 2. Pandoc
brew install pandoc        # macOS
sudo apt-get install pandoc # Linux

# 3. Python dependencies
pip install pypandoc beautifulsoup4
```

Verify all tools are available:

```bash
ebook-convert --version
pandoc --version
python3 -c "import pypandoc; print('pypandoc ok')"
```

## Installation

**Option A: npx (recommended)**

```bash
npx skills add deusyu/translate-book -a claude-code -g
```

**Option B: ClawHub**

```bash
clawhub install translate-book
```

**Option C: Git clone**

```bash
git clone https://github.com/deusyu/translate-book.git ~/.claude/skills/translate-book
```

## Usage in Claude Code

Once the skill is installed, use natural language inside Claude Code:

```
translate /path/to/book.pdf to Chinese
```

```
translate ~/Downloads/mybook.epub to Japanese
```

```
/translate-book translate /path/to/book.docx to French
```

The skill orchestrates the full pipeline automatically.

## Supported Languages

| Code | Language   |
|------|-----------|
| `zh` | Chinese    |
| `en` | English    |
| `ja` | Japanese   |
| `ko` | Korean     |
| `fr` | French     |
| `de` | German     |
| `es` | Spanish    |

Language codes are extensible — add new ones in the skill definition.

## Running Pipeline Steps Manually

### Step 1: Convert to Markdown Chunks

```bash
python3 scripts/convert.py /path/to/book.pdf --olang zh
```

This produces inside `{book_name}_temp/`:
- `chunk0001.md`, `chunk0002.md`, ... (source chunks, ~6000 chars each)
- `manifest.json` (SHA-256 hashes for validation)

```bash
# For EPUB input
python3 scripts/convert.py /path/to/book.epub --olang ja

# For DOCX input
python3 scripts/convert.py /path/to/book.docx --olang fr
```

### Step 2: Translate (Parallel Subagents)

The skill handles this step — it launches 8 concurrent subagents per batch, each translating one chunk independently:

```
# Each subagent receives exactly this task:
Read chunk0042.md → translate to target language → write output_chunk0042.md
```

**Resumable:** Already-translated chunks (valid `output_chunk*.md` files) are skipped on re-run.

### Step 3: Merge and Build All Formats

```bash
python3 scripts/merge_and_build.py \
  --temp-dir book_name_temp \
  --title "《Book Title in Target Language》"
```

Before merging, validation checks:
- Every source chunk has a matching output file (1:1)
- Source chunk hashes match `manifest.json` (no stale outputs)
- No output files are empty

Outputs produced:

| File | Description |
|------|-------------|
| `output.md` | Merged translated Markdown |
| `book.html` | Web version wit