ai-text-outline 0.5.0

Extract Table of Contents from Tibetan texts and return section start indices

ai-text-outline

Extract Table of Contents from Tibetan texts with Gemini

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Overview

ai-text-outline is a simple Python package that extracts Table of Contents (དཀར་ཆག) from Tibetan text and returns character indices where each section begins.

Uses Gemini 2.5 Flash for fast, reliable ToC extraction with automatic context overflow handling.

Perfect for:

• 📚 Digital publishing - Index Tibetan manuscripts automatically
• 🔍 Text analysis - Locate sections in large Tibetan documents
• 🤖 Backend integration - Add ToC extraction to your pipeline
• 📱 Web applications - Power frontend outlining tools

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Features

✨ Simple & Fast

• Send first 1/5 of text to Gemini
• Get ToC titles back as JSON
• Find titles in full text (skip first, use second occurrence)
• Return sorted character indices

🌍 Tibetan Native

• Full Unicode Tibetan support
• Handles དཀར་ཆག section markers
• Preserves original Tibetan text

💰 Cost Efficient

• Uses only Google Gemini
• Sends minimal text (1/5 of document)
• ~$0.0001 per extraction

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Installation

pip install ai-text-outline

Requires: Python 3.9+, Google Genai SDK (installed automatically)

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Quick Start

1. Get Gemini API Key

Get a free key at https://ai.google.dev/

2. Set Environment Variable

export GEMINI_API_KEY="your-api-key"

3. Extract ToC

from ai_text_outline import extract_toc_indices

# From file
indices = extract_toc_indices(file_path='tibetan_text.txt')

# Or from text string
text = open('tibetan_text.txt', encoding='utf-8').read()
indices = extract_toc_indices(text=text)

print(indices)  # [150, 2450, 5200, ...]

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API Reference

extract_toc_indices()

def extract_toc_indices(
    file_path: str | None = None,
    text: str | None = None,
    *,
    gemini_api_key: str | None = None,
) -> dict

Parameters

Parameter	Type	Default	Description
file_path	str | None	None	Path to Tibetan text file (UTF-8)
text	str | None	None	Raw text string (mutually exclusive with file_path)
gemini_api_key	str | None	None	Gemini API key. Falls back to GEMINI_API_KEY env var if not provided

Returns

dict - Dictionary with keys:

• "breakpoints" (list[int]): Sorted character indices where each ToC section begins
• "toc" (dict[str, int]): Mapping of section titles to page numbers from AI extraction

Returns {"breakpoints": [], "toc": {}} if no ToC found.

Raises

Exception	When
ValueError	Neither or both file_path and text provided; or no API key found
FileNotFoundError	file_path doesn't exist
UnicodeDecodeError	File is not UTF-8 encoded
ImportError	google-generativeai SDK not installed

Example

from ai_text_outline import extract_toc_indices

text = open('book.txt', encoding='utf-8').read()
result = extract_toc_indices(text=text)

# Access the extracted ToC and breakpoints
indices = result["breakpoints"]
toc = result["toc"]

print(f"Found TOC: {toc}")
print(f"Section breakpoints: {indices}")

# Use indices to extract sections
for i, start_idx in enumerate(indices):
    end_idx = indices[i+1] if i+1 < len(indices) else len(text)
    section = text[start_idx:end_idx]
    print(f"Section {i+1}: {len(section)} chars")

---

How It Works

Pipeline Overview

Input Text (file or string)
        │
        ▼
   Load text + Validate
        │
        ▼
   Extract first 1/5 of text (with context-aware fallback)
   If context limit exceeded:
     ├─ Retry with 1/10 of text
     └─ If still exceeded, retry with 1/100 of text
        │
        ▼
   🔄 LLM CALL 1: Gemini Extract ToC
        → Analyzes text for དཀར་ཆག section
        → Returns JSON: {"toc": {"Title": page_num, ...}}
        │
        ▼
   📍 AUTO-DETECT PAGE FORMAT
        Try -N- format (e.g., -5-, -170-)
        Else try standalone N format (e.g., 170, 200)
        │
        ▼
   🔍 PAGE-NUMBER BASED MATCHING (Primary Method)
        For each section (in page order):
          First section → Use ToC boundary index
          Other sections → Find page(N-1) marker
          
          If page found:
            ├─ 1 match → Use it ✓
            ├─ 0 matches → Fall back to title matching
            └─ 2+ matches → Go to LLM Call 2
        │
        ▼
   📝 FALLBACK A: Title Matching (if page not found)
        Search for title string in body text
        Use first occurrence after ToC boundary
        │
        ▼
   🔄 LLM CALL 2: Disambiguate (if multiple page matches)
        For sections with ambiguous page positions
        LLM selects correct index from candidates
        │
        ▼
   Return sorted list of section start indices

Page-Number Detection

The package intelligently detects how page numbers are formatted in the text:

Format 1: Running Page Markers

-1-
Content of page 1
-2-
Content of page 2

Pattern: ^-{n}-$ (regex)

Format 2: Standalone Numbers

170
Content of page 170
171
Content of page 171

Pattern: ^\d+$ (standalone line)

Both formats are auto-detected and handled transparently.

Context Overflow Handling

For very large texts (>5MB), the extraction automatically handles Gemini API context limits:

1. First attempt: Send first 1/5 of text (default)
2. If context exceeded: Automatically retry with first 1/10 of text
3. If still exceeded: Retry with first 1/100 of text
4. If all fail: Return empty list (no ToC found)

This ensures the package works with texts of any size without manual intervention.

Fallback Strategy

If page-number matching fails:

• Missing page marker → Falls back to title string matching
• Multiple page matches → Uses LLM (Call 2) to disambiguate
• Title not found → Section is skipped (not included in output)

This ensures robust extraction even with inconsistent text formatting.

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Examples

Example 1: Extract from File

from ai_text_outline import extract_toc_indices
import os

os.environ['GEMINI_API_KEY'] = 'AIzaSy...'

result = extract_toc_indices(file_path='texts/book.txt')
print(f"Found {len(result['breakpoints'])} sections")
print(f"Breakpoints: {result['breakpoints']}")  # [0, 450, 2100, 5800, ...]
print(f"TOC: {result['toc']}")  # {"Chapter 1": 5, "Chapter 2": 10, ...}

Example 2: Extract Sections

from ai_text_outline import extract_toc_indices

result = extract_toc_indices(file_path='book.txt')
indices = result["breakpoints"]
toc = result["toc"]
text = open('book.txt', encoding='utf-8').read()

# Split into sections
sections = []
for i, start_idx in enumerate(indices):
    end_idx = indices[i+1] if i+1 < len(indices) else len(text)
    sections.append(text[start_idx:end_idx])

print(f"Extracted TOC: {toc}")
for i, section in enumerate(sections):
    print(f"Section {i}: {len(section)} chars")

Example 3: With Custom API Key

from ai_text_outline import extract_toc_indices

# Pass API key directly instead of env var
indices = extract_toc_indices(
    file_path='text.txt',
    gemini_api_key='AIzaSy...'
)

Example 4: Flask Backend

from flask import Flask, request, jsonify
from ai_text_outline import extract_toc_indices

app = Flask(__name__)

@app.post('/api/extract-toc')
def extract_toc():
    """Extract ToC from uploaded text file."""
    data = request.json
    file_path = data.get('file_path')
    text_content = data.get('text')
    
    try:
        result = extract_toc_indices(
            file_path=file_path,
            text=text_content,
        )
        return {
            'success': True,
            'breakpoints': result['breakpoints'],
            'toc': result['toc'],
            'count': len(result['breakpoints']),
        }
    except ValueError as e:
        return {'error': str(e)}, 400
    except Exception as e:
        return {'error': f'Extraction failed: {str(e)}'}, 500

---

Advanced: Page-Number Matching

Why Page Numbers?

Page numbers are more reliable than titles for locating sections because:

• Consistent: Every page has a marker (not every section has a unique title)
• Unique: Page 170 only appears at page 170 (titles may repeat)
• Structural: Page markers define document boundaries reliably

How It Works

1. Extract page numbers from ToC (via LLM call 1)

   • ToC: {"Section A": 5, "Section B": 10, "Section C": 15}

2. Detect page format in the body text

   Sample: -1-, -2-, ..., -5-, ..., -10-
   → Detected: -N- format
   

3. Find section start using page N-1

   • Section B at page 10 → Search for page 9 marker
   • Position after page 9 = start of section B

4. Edge cases handled

   • First section (page 1) → Use ToC boundary (no page 0)
   • Page marker missing → Fall back to title search
   • Multiple page matches → Let LLM disambiguate

Example

Text structure:

དཀར་ཆག
Section A (page 5)
Section B (page 10)
-4-  ← ToC boundary

-5-
Section A content starts here
...

-10-
Section B content starts here
...

Process:

1. Extract: {"Section A": 5, "Section B": 10}
2. Detect: -N- format
3. Find page 4 marker → not found
4. First section (page 5) → use ToC boundary at -4-
5. Find page 9 marker → not found → fall back to title search
6. Result: [toc_boundary_index, section_b_title_index]

Supported Formats

Format	Example	Pattern
Running pages	-1-, -2-, -170-	^-\d+-$
Standalone	1, 170, 200	^\d+$
Mixed	Auto-detected	One per text

---

Error Handling

No API Key Found

ValueError: No Gemini API key. Set GEMINI_API_KEY env var or pass gemini_api_key=

Solution:

export GEMINI_API_KEY="your-key"

Or pass directly:

extract_toc_indices(text=text, gemini_api_key='your-key')

File Not Found

FileNotFoundError: [Errno 2] No such file or directory: 'text.txt'

Solution: Check file path exists:

from pathlib import Path
assert Path('text.txt').exists()

Empty Result

If extraction returns [], the text may not have a clear ToC structure that Gemini can extract.

---

Performance

Text Size	Time	Notes
< 100 KB	0.5-1s	API latency dominant
100 KB - 1 MB	1-2s	First 1/5 sent to Gemini
1-5 MB	2-3s	Faster processing
> 5 MB	3-5s	Auto-fallback to 1/10 or 1/100 slice if needed

Cost: ~$0.00002 per extraction (using Gemini 2.5 Flash - 75% cheaper!)

Model: Gemini 2.5 Flash is used by default for fast, efficient extraction with 1M context window.

Context Limits: The package automatically handles context window limits by progressively reducing the text slice (1/5 → 1/10 → 1/100) if needed. Works reliably with texts up to 50MB+.

---

Testing

Run tests:

pip install -e ".[dev]"
pytest
pytest --cov=ai_text_outline

Tests: 32 passing (including 8 new context overflow tests)

Test Coverage

• Parsing tests: JSON response handling with edge cases
• Integration tests: Full extraction pipeline with mocked Gemini
• Context overflow tests:
  • Retry mechanism with progressive text slice reduction (1/5 → 1/10 → 1/100)
  • Success on first attempt stops retrying
  • Non-context errors are properly raised
  • All attempts exhausted returns empty list

---

Requirements

• Python 3.9 or higher
• Google Gemini API key (free tier available)
• Internet connection (for Gemini API calls)

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License

MIT License - See LICENSE file for details.

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Support

• 📖 Documentation: See this README
• 🐛 Issues: GitHub Issues
• 💬 Discussions: GitHub Discussions

---

Citation

If you use this package in research:

@software{ai_text_outline,
  title={ai-text-outline: Extract Table of Contents from Tibetan texts},
  author={OpenPecha},
  url={https://github.com/OpenPecha/ai-text-outline},
  year={2026},
  license={MIT}
}

---

Changelog

v0.5.0 (Current)

• 🔄 Breaking change: Return value now includes extracted TOC
  • Old: list[int] (breakpoints only)
  • New: dict with "breakpoints" and "toc" keys
  • Allows downstream tools to verify extraction accuracy
• 📚 Better API: Access both indices and AI-extracted TOC mapping
• 📖 Updated examples: Shows how to use new return format

v0.4.0

• 🎯 Page-number regex matching: Primary method for section detection
• 📍 Auto-detect formats: -N- or standalone N page numbering
• 🔄 Smart fallbacks: Title matching + LLM disambiguation
• 🧪 38 passing tests: Including 6 new page-matching tests
• 📖 Enhanced documentation: Detailed how-it-works section
• 🛡️ Robust error handling: Graceful fallbacks for edge cases

v0.3.1

• ⚡ Model upgrade: Switched to Gemini 2.5 Flash (75% cheaper, faster)
• 💰 Lower costs: ~$0.00002 per extraction
• 🚀 Improved speed: Faster response times with Flash model
• 📈 Better efficiency: Optimized for ToC extraction tasks

v0.3.0

• 🔄 SDK upgrade: Migrated from deprecated google.generativeai to google.genai
• 🚀 Eliminated FutureWarning: No more deprecation warnings from Google's old SDK
• ✅ Future-proof: Uses Google's officially maintained google.genai package
• 🧪 All tests passing: Updated test mocks for new API structure
• 📦 Cleaner dependencies: Uses latest Google Genai SDK

v0.2.2

• 🔧 Model upgrade: Changed from deprecated gemini-2.0-flash to stable gemini-1.5-pro
• 🚀 Better model availability handling: Detects and reports unavailable models with clear error messages
• 📊 Improved cost estimates: Updated to reflect Gemini 1.5 Pro pricing (~$0.0005 per extraction)
• 🛡️ Enhanced error messages: Better handling of model deprecation warnings

v0.2.1

• 🔄 Context overflow handling: Automatic retry with progressive text slice reduction (1/5 → 1/10 → 1/100)
• 🧪 Enhanced tests: 32 passing tests including 8 new context overflow tests
• 📚 Improved documentation: Added context handling explanation to README
• 🛡️ Robust error handling: Detect and handle context/quota/token limit errors

v0.2.0

• 🎉 Complete simplification: Gemini-only, no multi-provider support
• ⚡ Regex-based index finding (no fuzzy matching)
• 💪 Minimal dependencies: only google-generativeai
• 🧪 14 passing tests
• 📖 Simplified API with clear documentation

v0.1.1

• ✨ Multi-provider LLM support
• 🔍 Fuzzy matching with position ranking
• 📚 Comprehensive documentation

v0.1.0

• 🎉 Initial release
• དཀར་ཆག detection and parsing

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Made with ❤️ by OpenPecha

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