---

name: batch-translate description: Batch process books through the complete pipeline - generate cropped images for split pages, OCR all pages, then translate with context. Use when asked to process, OCR, translate, or batch process one or more books.

Batch Book Translation Workflow

Process books through the complete pipeline: Crop → OCR → Translate

Roadmap Reference

See .claude/ROADMAP.md for the translation priority list.

Priority 1 = UNTRANSLATED - These are highest priority for processing:

• Kircher encyclopedias (Oedipus, Musurgia, Ars Magna Lucis)
• Fludd: Utriusque Cosmi Historia
• Theatrum Chemicum, Musaeum Hermeticum
• Cardano: De Subtilitate
• Della Porta: Magia Naturalis
• Lomazzo, Poliziano, Landino

# Get roadmap with priorities
curl -s "https://sourcelibrary.org/api/books/roadmap" | jq '.books[] | select(.priority == 1) | {title, notes}'

Roadmap source: src/app/api/books/roadmap/route.ts

Overview

This workflow handles the full processing pipeline for historical book scans:

1. Generate Cropped Images - For split two-page spreads, extract individual pages
2. OCR - Extract text from page images using Gemini vision
3. Translate - Translate OCR'd text with prior page context for continuity

API Endpoints

Endpoint	Purpose
GET /api/books	List all books
GET /api/books/BOOK_ID	Get book with all pages
POST /api/jobs/queue-books	Queue pages for Lambda worker processing (primary path)
GET /api/jobs	List processing jobs
POST /api/jobs/JOB_ID/retry	Retry failed pages in a job
POST /api/jobs/JOB_ID/cancel	Cancel a running job
POST /api/books/BOOK_ID/batch-ocr-async	Submit Gemini Batch API OCR job (50% cheaper, ~24h)
POST /api/books/BOOK_ID/batch-translate-async	Submit Gemini Batch API translation job

Processing Options

Option 1: Lambda Workers via Job System (Primary Path)

The primary processing path uses AWS Lambda workers via SQS queues. Each page is processed independently with automatic job tracking.

# Queue OCR for a book's pages
curl -s -X POST "https://sourcelibrary.org/api/jobs/queue-books" \
  -H "Content-Type: application/json" \
  -d '{"bookIds": ["BOOK_ID"], "action": "ocr"}'

# Queue translation
curl -s -X POST "https://sourcelibrary.org/api/jobs/queue-books" \
  -H "Content-Type: application/json" \
  -d '{"bookIds": ["BOOK_ID"], "action": "translation"}'

# Queue image extraction
curl -s -X POST "https://sourcelibrary.org/api/jobs/queue-books" \
  -H "Content-Type: application/json" \
  -d '{"bookIds": ["BOOK_ID"], "action": "image_extraction"}'

IMPORTANT: Always use gemini-3-flash-preview for all OCR and translation tasks. Do NOT use gemini-2.5-flash.

Option 2: Gemini Batch API (50% Cheaper, Automated Pipeline)

The post-import-pipeline cron uses Gemini Batch API for automated processing of newly imported books. Results arrive in ~24 hours at 50% cost.

Job Type	API	Model	Cost
Single page	Realtime (Lambda)	gemini-3-flash-preview	Full price
batch_ocr	Batch API	gemini-3-flash-preview	50% off
batch_translate	Batch API	gemini-3-flash-preview	50% off

OCR Output Format

OCR uses Markdown output with semantic tags:

Markdown Formatting

• # ## ### for headings (bigger text = bigger heading)
• **bold**, *italic* for emphasis
• ->centered text<- for centered lines (NOT for headings)
• > blockquotes for quotes/prayers
• --- for dividers
• Tables only for actual tabular data

Metadata Tags (hidden from readers)

Tag	Purpose
<lang>X</lang>	Detected language
<page-num>N</page-num>	Page/folio number
<header>X</header>	Running headers
<sig>X</sig>	Printer's marks (A2, B1)
<meta>X</meta>	Hidden metadata
<warning>X</warning>	Quality issues
<vocab>X</vocab>	Key terms for indexing

Inline Annotations (visible to readers)

Tag	Purpose
<margin>X</margin>	Marginal notes (before paragraph)
<gloss>X</gloss>	Interlinear annotations
<insert>X</insert>	Boxed text, additions
<unclear>X</unclear>	Illegible readings
<note>X</note>	Interpretive notes
<term>X</term>	Technical vocabulary
<image-desc>X</image-desc>	Describe illustrations

Critical OCR Rules

1. Preserve original spelling, capitalization, punctuation
2. Page numbers/headers/signatures go in metadata tags only
3. IGNORE partial text at edges (from facing page in spread)
4. Describe images/diagrams with <image-desc>, never tables
5. End with <vocab>key terms, names, concepts</vocab>

Step 1: Analyze Book Status

First, check what work is needed for a book:

# Get book and analyze page status
curl -s "https://sourcelibrary.org/api/books/BOOK_ID" > /tmp/book.json

# Count pages by status (IMPORTANT: check length > 0, not just existence - empty strings are truthy!)
jq '{
  title: .title,
  total_pages: (.pages | length),
  split_pages: [.pages[] | select(.crop)] | length,
  needs_crop: [.pages[] | select(.crop) | select(.cropped_photo | not)] | length,
  has_ocr: [.pages[] | select((.ocr.data // "") | length > 0)] | length,
  needs_ocr: [.pages[] | select((.ocr.data // "") | length == 0)] | length,
  has_translation: [.pages[] | select((.translation.data // "") | length > 0)] | length,
  needs_translation: [.pages[] | select((.ocr.data // "") | length > 0) | select((.translation.data // "") | length == 0)] | length
}' /tmp/book.json

Detecting Bad OCR

Pages that were OCR'd before cropped images were generated have incorrect OCR (contains both pages of the spread). Detect these:

# Find pages with crop data + OCR but missing cropped_photo at OCR time
# These often contain "two-page" or "spread" in the OCR text
jq '[.pages[] | select(.crop) | select(.ocr.data) |
  select(.ocr.data | test("two-page|spread"; "i"))] | length' /tmp/book.json

Step 2: Generate Cropped Images

For books with split two-page spreads, generate individual page images:

# Get page IDs needing crops
CROP_IDS=$(jq '[.pages[] | select(.crop) | select(.cropped_photo | not) | .id]' /tmp/book.json)

# Create crop job
curl -s -X POST "https://sourcelibrary.org/api/jobs" \
  -H "Content-Type: application/json" \
  -d "{
    \"type\": \"generate_cropped_images\",
    \"book_id\": \"BOOK_ID\",
    \"book_title\": \"BOOK_TITLE\",
    \"page_ids\": $CROP_IDS
  }"

Process the job:

# Trigger processing (40 pages per request, auto-continues)
curl -s -X POST "https://sourcelibrary.org/api/jobs/JOB_ID/process"

Step 3: OCR Pages

Option A: Using Job System (for large batches)

# Get page IDs needing OCR (check for empty strings, not just null)
OCR_IDS=$(jq '[.pages[] | select((.ocr.data // "") | length == 0) | .id]' /tmp/book.json)

# Create OCR job
curl -s -X POST "https://sourcelibrary.org/api/jobs" \
  -H "Content-Type: application/json" \
  -d "{
    \"type\": \"batch_ocr\",
    \"book_id\": \"BOOK_ID\",
    \"book_title\": \"BOOK_TITLE\",
    \"model\": \"gemini-3-flash-preview\",
    \"language\": \"Latin\",
    \"page_ids\": $OCR_IDS
  }"

Option B: Using Lambda Workers with Page IDs

# OCR specific pages (including overwrite)
curl -s -X POST "https://sourcelibrary.org/api/jobs/queue-books" \
  -H "Content-Type: application/json" \
  -d '{
    "bookIds": ["BOOK_ID"],
    "action": "ocr",
    "pageIds": ["PAGE_ID_1", "PAGE_ID_2"],
    "overwrite": true
  }'

Lambda workers automatically use cropped_photo when available.

Step 4: Translate Pages

Option A: Using Job System

# Get page IDs needing translation (must have OCR content, check for empty strings)
TRANS_IDS=$(jq '[.pages[] | select((.ocr.data // "") | length > 0) | select((.translation.data // "") | length == 0) | .id]' /tmp/book.json)

# Create translation job
curl -s -X POST "https://sourcelibrary.org/api/jobs" \
  -H "Content-Type: application/json" \
  -d "{
    \"type\": \"batch_translate\",
    \"book_id\": \"BOOK_ID\",
    \"book_title\": \"BOOK_TITLE\",
    \"model\": \"gemini-3-flash-preview\",
    \"language\": \"Latin\",
    \"page_ids\": $TRANS_IDS
  }"

Option B: Using Lambda Workers (Recommended)

Lambda FIFO queue automatically provides previous page context for translation continuity:

# Queue translation for pages that have OCR but no translation
curl -s -X POST "https://sourcelibrary.org/api/jobs/queue-books" \
  -H "Content-Type: application/json" \
  -d '{"bookIds": ["BOOK_ID"], "action": "translation"}'

The translation Lambda worker processes pages sequentially via FIFO queue and fetches the previous page's translation for context.

Complete Book Processing Script

Process a single book through the full pipeline using Lambda workers:

#!/bin/bash
BOOK_ID="YOUR_BOOK_ID"
BASE_URL="https://sourcelibrary.org"

# 1. Fetch book data
echo "Fetching book..."
BOOK=$(curl -s "$BASE_URL/api/books/$BOOK_ID")
TITLE=$(echo "$BOOK" | jq -r '.title[0:40]')
echo "Processing: $TITLE"

# 2. Queue OCR (Lambda workers handle all pages automatically)
NEEDS_OCR=$(echo "$BOOK" | jq '[.pages[] | select((.ocr.data // "") | length == 0)] | length')
if [ "$NEEDS_OCR" != "0" ]; then
  echo "Queueing OCR for $NEEDS_OCR pages..."
  curl -s -X POST "$BASE_URL/api/jobs/queue-books" \
    -H "Content-Type: application/json" \
    -d "{\"bookIds\": [\"$BOOK_ID\"], \"action\": \"ocr\"}"
  echo "OCR job queued!"
fi

# 3. Queue translation (after OCR completes — check /jobs page)
NEEDS_TRANS=$(echo "$BOOK" | jq '[.pages[] | select((.ocr.data // "") | length > 0) | select((.translation.data // "") | length == 0)] | length')
if [ "$NEEDS_TRANS" != "0" ]; then
  echo "Queueing translation for $NEEDS_TRANS pages..."
  curl -s -X POST "$BASE_URL/api/jobs/queue-books" \
    -H "Content-Type: application/json" \
    -d "{\"bookIds\": [\"$BOOK_ID\"], \"action\": \"translation\"}"
  echo "Translation job queued!"
fi

echo "Jobs queued! Monitor progress at $BASE_URL/jobs"

Fixing Bad OCR

When pages were OCR'd before cropped images existed, they contain text from both pages. Fix with:

# 1. Generate cropped images first (Step 2 above)

# 2. Find pages with bad OCR
BAD_OCR_IDS=$(jq '[.pages[] | select(.crop) | select(.ocr.data) |
  select(.ocr.data | test("two-page|spread"; "i")) | .id]' /tmp/book.json)

# 3. Re-OCR with overwrite via Lambda workers
curl -s -X POST "https://sourcelibrary.org/api/jobs/queue-books" \
  -H "Content-Type: application/json" \
  -d "{\"bookIds\": [\"BOOK_ID\"], \"action\": \"ocr\", \"pageIds\": $BAD_OCR_IDS, \"overwrite\": true}"

Processing All Books

Use the Lambda worker job system for bulk processing:

#!/bin/bash
BASE_URL="https://sourcelibrary.org"

# Get all book IDs
BOOK_IDS=$(curl -s "$BASE_URL/api/books" | jq -r '[.[].id]')

# Queue OCR for all books (Lambda workers handle parallelism and rate limiting)
curl -s -X POST "$BASE_URL/api/jobs/queue-books" \
  -H "Content-Type: application/json" \
  -d "{\"bookIds\": $BOOK_IDS, \"action\": \"ocr\"}"

# After OCR completes, queue translation
curl -s -X POST "$BASE_URL/api/jobs/queue-books" \
  -H "Content-Type: application/json" \
  -d "{\"bookIds\": $BOOK_IDS, \"action\": \"translation\"}"

Monitor progress at https://sourcelibrary.org/jobs

Monitoring Progress

Check overall library status:

curl -s "https://sourcelibrary.org/api/books" | jq '[.[] | {
  title: .title[0:30],
  pages: .pages_count,
  ocr: .ocr_count,
  translated: .translation_count
}] | sort_by(-.pages)'

Troubleshooting

Empty Strings vs Null (CRITICAL)

In jq, empty strings "" are truthy! This means:

• select(.ocr.data) matches pages with "" (WRONG)
• select(.ocr.data | not) does NOT match pages with "" (WRONG)
• Use select((.ocr.data // "") | length == 0) to find missing/empty OCR
• Use select((.ocr.data // "") | length > 0) to find pages WITH OCR content

Rate Limits (429 errors)

Gemini API Tiers

Tier	RPM	How to Qualify
Free	15	Default
Tier 1	300	Enable billing + $50 spend
Tier 2	1000	$250 spend
Tier 3	2000	$1000 spend

Optimal Sleep Times by Tier

Tier	Max RPM	Safe Sleep Time	Effective Rate
Free	15	4.0s	~15/min
Tier 1	300	0.4s	~150/min
Tier 2	1000	0.12s	~500/min
Tier 3	2000	0.06s	~1000/min

Note: Use ~50% of max rate to leave headroom for bursts.

API Key Rotation

The system supports multiple API keys for higher throughput:

• Set GEMINI_API_KEY (primary)
• Set GEMINI_API_KEY_2, GEMINI_API_KEY_3, ... up to GEMINI_API_KEY_10
• Keys rotate automatically with 60s cooldown after rate limit

With N keys at Tier 1, you get N × 300 RPM = N × 150 safe req/min

Function Timeouts

• Jobs have maxDuration=300s for Vercel Pro
• If hitting timeouts, reduce CROP_CHUNK_SIZE in job processing

Missing Cropped Photos

• Check if crop job completed successfully
• Verify page has crop data with xStart and xEnd
• Re-run crop generation for specific pages

Bad OCR Detection

Look for these patterns in OCR text indicating wrong image was used:

• "two-page spread"
• "left page" / "right page" descriptions
• Duplicate text blocks
• References to facing pages