Translate Book (Parallel Subagents) Skill by 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

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: ebook-convert --version pandoc --version python3 -c "import pypandoc; print('pypandoc ok')" Installation Option A: npx (recommended) npx skills add deusyu/translate-book -a claude-code -g Option B: ClawHub clawhub install translate-book Option C: Git clone 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 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)

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 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 with floating TOC book.docx Word document book.epub E-book format book.pdf Print-ready PDF Project Structure translate-book/ ├── SKILL.md # Claude Code skill definition (orchestrator) ├── scripts/ │ ├── convert.py # PDF/DOCX/EPUB → Markdown chunks via Calibre HTMLZ │ ├── manifest.py # SHA-256 chunk tracking and merge validation │ ├── merge_and_build.py # Merge chunks → HTML → DOCX/EPUB/PDF │ ├── calibre_html_publish.py # Calibre wrapper for format conversion │ ├── template.html # Web HTML template with floating TOC │ └── template_ebook.html # Ebook HTML template └── README.md How Manifest Validation Works

scripts/manifest.py (conceptual usage)

During convert.py — records source hashes

manifest

{ "chunk0001.md" : "sha256:abc123..." , "chunk0002.md" : "sha256:def456..." ,

...

}

During merge_and_build.py — validates before merging

1. Check every chunk has a corresponding output_chunk

2. Re-hash source chunks and compare against manifest

3. Reject if any hash mismatches (stale/corrupt output)

4. Reject if any output file is empty

If validation fails, the script auto-deletes stale output.md and re-merges from valid chunk outputs. Real-World Example: Translate a Technical Book

1. Install the skill

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

2. Open Claude Code in your working directory

cd ~/books

3. Say in Claude Code:

"translate clean-code.pdf to Chinese"

Claude Code will:

- Run convert.py to split into chunks

- Launch 8 parallel subagents per batch

- Each subagent translates one chunk

- Validate all outputs via manifest

- Merge and build all formats

4. Outputs appear in:

ls clean-code_temp/

chunk0001.md chunk0002.md ... (source)

output_chunk0001.md ... (translated)

manifest.json

output.md

book.html

book.docx

book.epub

book.pdf

Resuming an Interrupted Translation

If translation is interrupted, just re-run the same command:

"translate clean-code.pdf to Chinese"

The skill detects existing output_chunk*.md files

and skips already-translated chunks automatically.

Only missing or failed chunks are retried.

Changing Output Metadata After Translation If you need to update the title, author, template, or image assets without re-translating:

Delete only the final artifacts (keeps translated chunks)

cd book_name_temp/ rm -f output.md book*.html book.docx book.epub book.pdf

Re-run merge step

python3 .. /scripts/merge_and_build.py \ --temp-dir . \ --title "《New Title》" Do NOT delete chunk files — those are your translated content. Only delete final artifacts when changing metadata. Troubleshooting Problem Solution Calibre ebook-convert not found Install Calibre; ensure ebook-convert is in $PATH Manifest validation failed Source chunks changed — re-run convert.py Missing source chunk Source file deleted — re-run convert.py to regenerate Incomplete translation Re-run the skill — resumes from last valid chunk Changed title/template but output unchanged Delete output.md , book*.html , book.docx , book.epub , book.pdf then re-run merge_and_build.py output.md exists but manifest invalid Script auto-deletes stale output and re-merges PDF generation fails Verify Calibre has PDF output support; try ebook-convert --help Empty output chunks Retry failed chunks; check API rate limits Diagnosing Chunk Issues

Check which chunks are missing translation

ls book_temp/chunk*.md | wc -l

total source chunks

ls book_temp/output_chunk*.md | wc -l

translated chunks so far

Find missing output chunks

for f in book_temp/chunk*.md ; do base = $( basename " $f " .md ) out = "book_temp/output_ ${base} .md" if [ ! -f " $out " ] || [ ! -s " $out " ] ; then echo "Missing: $out " fi done

Check manifest

cat book_temp/manifest.json | python3 -m json.tool | head -30 Configuration Tips Chunk size: ~6000 chars per chunk is the default. Smaller chunks = more parallelism but more API calls. Concurrency: Default is 8 parallel subagents per batch. Adjust in SKILL.md if hitting rate limits. Languages: Add new language codes to the skill triggers and translation prompt in SKILL.md . Templates: Customize scripts/template.html and scripts/template_ebook.html for different HTML/ebook styling. Key Design Principles Isolated context per chunk — each subagent starts fresh, preventing context overflow on long books Hash-based integrity — SHA-256 tracking catches stale or corrupt translated chunks before merging Resumable at chunk granularity — never re-translate what's already done Format-agnostic input — Calibre handles PDF/DOCX/EPUB normalization before the pipeline begins Multiple output formats — single pipeline produces HTML, DOCX, EPUB, and PDF simultaneously