# Development Journal

This journal tracks significant feature additions, bug fixes, and architectural decisions in the crawl4ai project. It serves as both documentation and a historical record of the project's evolution.

## [2025-04-09] Added MHTML Capture Feature

**Feature:** MHTML snapshot capture of crawled pages

**Changes Made:**
1. Added `capture_mhtml: bool = False` parameter to `CrawlerRunConfig` class
2. Added `mhtml: Optional[str] = None` field to `CrawlResult` model
3. Added `mhtml_data: Optional[str] = None` field to `AsyncCrawlResponse` class
4. Implemented `capture_mhtml()` method in `AsyncPlaywrightCrawlerStrategy` class to capture MHTML via CDP
5. Modified the crawler to capture MHTML when enabled and pass it to the result

**Implementation Details:**
- MHTML capture uses Chrome DevTools Protocol (CDP) via Playwright's CDP session API
- The implementation waits for page to fully load before capturing MHTML content
- Enhanced waiting for JavaScript content with requestAnimationFrame for better JS content capture
- We ensure all browser resources are properly cleaned up after capture

**Files Modified:**
- `crawl4ai/models.py`: Added the mhtml field to CrawlResult
- `crawl4ai/async_configs.py`: Added capture_mhtml parameter to CrawlerRunConfig
- `crawl4ai/async_crawler_strategy.py`: Implemented MHTML capture logic
- `crawl4ai/async_webcrawler.py`: Added mapping from AsyncCrawlResponse.mhtml_data to CrawlResult.mhtml

**Testing:**
- Created comprehensive tests in `tests/20241401/test_mhtml.py` covering:
  - Capturing MHTML when enabled
  - Ensuring mhtml is None when disabled explicitly
  - Ensuring mhtml is None by default
  - Capturing MHTML on JavaScript-enabled pages

**Challenges:**
- Had to improve page loading detection to ensure JavaScript content was fully rendered
- Tests needed to be run independently due to Playwright browser instance management
- Modified test expected content to match actual MHTML output

**Why This Feature:**
The MHTML capture feature allows users to capture complete web pages including all resources (CSS, images, etc.) in a single file. This is valuable for:
1. Offline viewing of captured pages
2. Creating permanent snapshots of web content for archival
3. Ensuring consistent content for later analysis, even if the original site changes

**Future Enhancements to Consider:**
- Add option to save MHTML to file
- Support for filtering what resources get included in MHTML
- Add support for specifying MHTML capture options