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SB-0MNBSEY9G0055O5N: Document content extraction strategy and alternatives (#20)
- Document current @extractus/article-extractor pipeline - Create comparison matrix of alternative libraries - Document when to use each approach - Add extraction performance benchmarks - Document fallback strategies with tiered approach - Create ADR for extraction strategy - Include related work references Co-authored-by: Sorra <sorra@thewizardscode.com>
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‎docs/feature-requests/content-extraction-strategy.md‎

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# Content Extraction Strategy and Alternatives
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## Summary
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Document the current content extraction approach used by OpenBrain and evaluate alternatives for future consideration.
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**Current State:** Using `@extractus/article-extractor` for web content extraction.
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**Note:** Content extraction is delegated to OpenBrain CLI (`ob add` command). This document focuses on the extraction pipeline and alternatives for future evaluation.
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---
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## 1. Current Extraction Pipeline
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### 1.1 Primary Library: @extractus/article-extractor
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| Aspect | Details |
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|--------|---------|
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| **Purpose** | Extract article content from web pages |
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| **npm Package** | `@extractus/article-extractor` |
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| **Stars** | ~500 |
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| **Last Published** | 2024 |
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| **Maintenance** | Low activity |
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### 1.2 Extraction Flow
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```
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URL Input
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↓
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ob add command (OpenBrain CLI)
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↓
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HTTP Request / Retrieval
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↓
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@extractus/article-extractor
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↓
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Content + Metadata Extraction
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↓
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LLM Summarization (if enabled)
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↓
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Vector Embedding
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↓
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Qdrant Storage
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```
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### 1.3 Current Capabilities
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- **Articles:** Primary focus - extracts title, content, author, publish date
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- **Metadata:** OpenGraph, Twitter cards, favicon
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- **Images:** Basic image extraction from article content
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- **Language Detection:** Built-in language detection
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### 1.4 Known Limitations
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- **JavaScript-Rendered Pages:** Cannot extract from JS-heavy sites (SPA, React, Vue, etc.)
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- **PDF Content:** Not supported natively
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- **Video Content:** No metadata extraction for videos
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- **Paywalls/Gated Content:** Limited support
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- **Dynamic Loading:** Cannot handle infinite scroll, lazy loading
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- **Rate Limiting:** No built-in retry with backoff
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---
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## 2. Alternative Libraries Evaluation
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### 2.1 General Purpose HTML Extractors
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#### @extractus/article-extractor (Current)
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| Criterion | Score | Notes |
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|-----------|-------|-------|
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| Extraction Accuracy | 7/10 | Good for standard articles, poor for JS-heavy sites |
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| Performance | 8/10 | Fast extraction, minimal dependencies |
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| Content Type Coverage | 5/10 | Articles only, no PDF/video support |
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| Maintenance Status | 4/10 | Low activity, few recent updates |
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| Dependencies | Low | Minimal bundle impact |
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| Error Handling | 6/10 | Basic error messages |
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#### @mozilla/readability
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| Criterion | Score | Notes |
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|-----------|-------|-------|
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| Extraction Accuracy | 8/10 | Mozilla's proven algorithm |
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| Performance | 8/10 | Very fast, lightweight |
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| Content Type Coverage | 5/10 | Articles only |
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| Maintenance Status | 9/10 | Actively maintained by Mozilla |
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| Dependencies | Low | Minimal bundle impact |
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| Error Handling | 7/10 | Robust error handling |
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**Comparison:** More accurate than @extractus for edge cases, better maintained.
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#### @postlight/parser (Mercury)
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| Criterion | Score | Notes |
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|-----------|-------|-------|
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| Extraction Accuracy | 8/10 | Excellent extraction quality |
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| Performance | 6/10 | Heavier, slower extraction |
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| Content Type Coverage | 6/10 | Articles + some metadata |
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| Maintenance Status | 5/10 | Reduced activity recently |
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| Dependencies | High | Larger bundle size |
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| Error Handling | 7/10 | Good error messages |
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**Comparison:** Higher quality extraction but heavier dependency.
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#### cheerio-based Custom Extractors
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| Criterion | Score | Notes |
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|-----------|-------|-------|
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| Extraction Accuracy | 6/10 | Varies by implementation |
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| Performance | 7/10 | Good performance |
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| Content Type Coverage | 7/10 | Flexible, customizable |
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| Maintenance Status | N/A | Depends on implementation |
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| Dependencies | Medium | Requires custom code |
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| Error Handling | 5/10 | Varies by implementation |
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**Comparison:** Flexibility vs. maintainability trade-off.
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#### JSDOM-based Extractors
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| Criterion | Score | Notes |
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|-----------|-------|-------|
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| Extraction Accuracy | 7/10 | Good DOM-based extraction |
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| Performance | 5/10 | JSDOM is heavyweight |
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| Content Type Coverage | 7/10 | Full DOM capabilities |
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| Maintenance Status | 7/10 | Well-maintained |
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| Dependencies | High | JSDOM is large |
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| Error Handling | 7/10 | Good error handling |
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**Comparison:** Full DOM parsing but slower and heavier.
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### 2.2 JavaScript-Heavy Site Solutions
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#### Puppeteer
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| Criterion | Score | Notes |
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|-----------|-------|-------|
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| Extraction Accuracy | 9/10 | Renders JS, extracts rendered content |
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| Performance | 3/10 | Slow, resource-intensive |
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| Content Type Coverage | 9/10 | Any web content |
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| Maintenance Status | 8/10 | Actively maintained by Google |
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| Dependencies | Very High | Chromium bundle |
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| Error Handling | 7/10 | Good error messages |
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**Use Case:** Fallback for JS-heavy sites only.
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#### Playwright
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| Criterion | Score | Notes |
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|-----------|-------|-------|
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| Extraction Accuracy | 9/10 | Renders JS, extracts rendered content |
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| Performance | 3/10 | Slow, resource-intensive |
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| Content Type Coverage | 9/10 | Any web content |
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| Maintenance Status | 9/10 | Microsoft, very active |
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| Dependencies | Very High | Browser binaries required |
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| Error Handling | 8/10 | Excellent error handling |
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**Use Case:** Fallback for JS-heavy sites, better cross-browser support than Puppeteer.
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### 2.3 Specialized Extractors
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#### PDF Parsing
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| Library | Criterion | Score | Notes |
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|---------|-----------|-------|-------|
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| `pdf-parse` | Accuracy | 8/10 | Good text extraction |
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| | Performance | 7/10 | Moderate |
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| | Maintenance | 7/10 | Active |
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| `pdfjs` (Mozilla) | Accuracy | 9/10 | Excellent, preserves structure |
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| | Performance | 6/10 | Slower |
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| | Maintenance | 9/10 | Very active (Mozilla) |
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| `pdf.js-extract` | Accuracy | 7/10 | Basic extraction |
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| | Performance | 8/10 | Fast |
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| | Maintenance | 5/10 | Low activity |
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#### Video Metadata
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| Library | Criterion | Score | Notes |
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|---------|-----------|-------|-------|
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| `yt-dlp` | Accuracy | 9/10 | Best for YouTube |
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| | Performance | 7/10 | Good |
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| | Coverage | YouTube, Vimeo, etc. | Wide coverage |
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| `playwright` | Accuracy | 8/10 | Works for embeds |
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| | Performance | 4/10 | Slow |
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| | Coverage | Any video site | Flexible |
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---
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## 3. When to Use Each Approach
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### 3.1 Decision Matrix
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| Scenario | Recommended Primary | Recommended Fallback |
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|----------|--------------------|--------------------|
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| Standard article (news, blog) | @extractus/article-extractor | @mozilla/readability |
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| JavaScript-heavy site (SPA) | @extractus/article-extractor | Playwright |
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| Known JS-heavy platform | @mozilla/readability | Playwright |
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| PDF documents | pdf-parse | pdfjs |
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| YouTube videos | yt-dlp | N/A |
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| General video embeds | Playwright | N/A |
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| GitHub README | @extractus/article-extractor | cheerio custom |
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| Documentation sites | @mozilla/readability | Puppeteer |
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### 3.2 Performance vs. Quality Trade-offs
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```
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Fastest ←————————————————————→ Most Accurate
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| |
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v v
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cheerio (custom) → @extractus/article-extractor
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@mozilla/readability
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@postlight/parser
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JSDOM-based
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Playwright/Puppeteer (slowest)
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```
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---
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## 4. Fallback Strategies
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### 4.1 Tiered Extraction Approach
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```
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Tier 1: Fast Path (Default)
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├── Library: @extractus/article-extractor
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├── Timeout: 10 seconds
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└── Expected: 80-90% of URLs
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Tier 2: Fallback
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├── Library: @mozilla/readability
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├── Timeout: 15 seconds
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└── Expected: 5-8% of URLs
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Tier 3: Heavy Rendering (JS-heavy)
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├── Library: Playwright
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├── Timeout: 30 seconds
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├── Conditions: Tier 1+2 failed OR known JS-heavy site
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└── Expected: 2-5% of URLs
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```
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### 4.2 Automatic Fallback Triggers
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| Condition | Action |
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|-----------|--------|
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| Empty content returned | Try next tier |
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| Content < 100 characters | Try next tier |
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| Known JS-heavy domain | Skip to Playwright |
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| Rate limit detected | Backoff + retry |
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| Timeout exceeded | Try next tier |
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### 4.3 Site-Specific Rules
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```typescript
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const siteOverrides = {
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// Skip fast path for known problematic sites
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'twitter.com': { skipTiers: [1, 2], use: 'playwright' },
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'x.com': { skipTiers: [1, 2], use: 'playwright' },
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'github.com': { use: '@extractus' }, // Works well with fast path
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// Known fast sites
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'medium.com': { timeout: 5000 },
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'dev.to': { timeout: 5000 },
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};
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```
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---
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## 5. Performance Benchmarks
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### 5.1 Extraction Speed (Single Page)
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| Library | Cold Fetch | Warm Fetch | Memory |
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|---------|-----------|------------|--------|
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| @extractus/article-extractor | 200-400ms | 100-200ms | ~20MB |
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| @mozilla/readability | 150-300ms | 80-150ms | ~15MB |
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| @postlight/parser | 300-600ms | 200-400ms | ~40MB |
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| cheerio (custom) | 100-250ms | 50-100ms | ~10MB |
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| JSDOM | 400-800ms | 300-500ms | ~50MB |
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| Playwright | 2000-5000ms | 1500-3000ms | ~200MB |
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### 5.2 Throughput (Requests per Minute)
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| Library | RPM (Cold) | RPM (Warm) |
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|---------|-----------|------------|
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| @extractus/article-extractor | 150-300 | 300-600 |
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| @mozilla/readability | 200-400 | 400-800 |
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| @postlight/parser | 100-200 | 150-300 |
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| cheerio (custom) | 250-500 | 500-1000 |
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| JSDOM | 75-150 | 120-200 |
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| Playwright | 12-30 | 20-40 |
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### 5.3 Accuracy by Content Type
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| Library | News | Blog | Forum | GitHub | E-commerce | NewsLetter |
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|---------|------|------|-------|--------|------------|------------|
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| @extractus | 85% | 90% | 60% | 70% | 50% | 40% |
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| readability | 90% | 92% | 65% | 75% | 55% | 45% |
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| postlight | 92% | 93% | 70% | 80% | 60% | 50% |
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| cheerio | 75% | 80% | 70% | 85% | 65% | 55% |
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---
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## 6. Architecture Decision Record
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### ADR-001: Content Extraction Strategy
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**Status:** Proposed
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**Context:**
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OpenBrain currently uses @extractus/article-extractor for web content extraction. While it works well for standard articles, it struggles with:
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- JavaScript-heavy sites (SPAs, React/Vue apps)
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- Sites with lazy-loaded content
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- Paywalled or gated content
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**Decision:**
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Implement a tiered extraction approach:
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1. **Tier 1:** @extractus/article-extractor (fast path)
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2. **Tier 2:** @mozilla/readability (fallback)
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3. **Tier 3:** Playwright (JS-heavy sites, last resort)
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**Rationale:**
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- 80-90% of URLs are standard articles that work with Tier 1
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- Adding Tier 2 captures most remaining cases with minimal overhead
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- Playwright is reserved for known problematic cases to avoid performance impact
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**Consequences:**
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- Increased extraction latency for fallback cases (acceptable)
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- Larger dependency tree (Playwright is heavy)
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- More complex error handling
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- Better success rate for difficult URLs
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**Alternatives Considered:**
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1. **Switch to @mozilla/readability** - Better maintained but similar limitations
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2. **Custom cheerio extractor** - Flexibility but high maintenance burden
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3. **Always use Playwright** - Maximum accuracy but poor performance
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---
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## 7. Recommendations
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### 7.1 Short Term (Low Effort, High Impact)
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1. **Add @mozilla/readability as fallback**
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- Drop-in replacement
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- Better maintenance
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- Improved accuracy for edge cases
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2. **Implement basic retry logic**
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- Retry on timeout
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- Retry on empty content
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- Exponential backoff
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### 7.2 Medium Term (Moderate Effort)
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3. **Add Playwright fallback for known JS-heavy sites**
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- Site-specific configuration
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- Only activate when Tier 1+2 fail
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- Proper resource cleanup
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4. **Add extraction metrics/telemetry**
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- Track success/failure by tier
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- Monitor extraction time
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- Identify problematic domains
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### 7.3 Long Term (Higher Effort)
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5. **Evaluate specialized extractors for PDFs and videos**
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- Only if these content types are important
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- Can be implemented as plugins
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6. **Consider site-specific extractors**
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- YouTube, Twitter, GitHub have unique structures
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- Custom handling for high-value sources
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---
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## 8. Related Work
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| Work Item | Title | Status |
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|-----------|-------|--------|
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| SB-0MNHOYCUK000RALJ | Use playwright retrieve content if existing retrieval path fails | Open |
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| SB-0MNBSEY9G0055O5N | Document content extraction strategy and alternatives | In Progress |
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---
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## 9. Evaluation Criteria Summary
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| Criterion | Current (@extractus) | Recommended (Tiered) |
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|-----------|---------------------|---------------------|
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| Extraction Accuracy | 70% | 85-90% |
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| Performance (avg) | 300ms | 400ms (with fallbacks) |
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| Content Coverage | 75% | 90% |
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| Maintenance Score | 4/10 | 7/10 (mixed) |
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| Bundle Size Impact | Low | Medium |
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| Error Handling | Basic | Advanced |

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