Log Viewer

# Log Viewer PRD

## Overview
Build a log file viewer that supports pasting or uploading log text, auto-detects log formats, provides syntax highlighting by level, regex search, virtual scrolling for large files, and a simulated live streaming mode.

## Requirements
- Paste log text or upload a log file for viewing
- Auto-detect log format: JSON lines, syslog-style, or custom delimited formats
- Syntax highlighting by log level: debug in gray, info in blue, warn in yellow, error in red, fatal in purple
- Search with full regex support and result highlighting
- Filter by log level with toggleable checkboxes for each level
- Filter by date range with start and end date inputs
- Text wrapping toggle to switch between wrapped and horizontal-scroll modes
- Line numbers displayed alongside each log entry
- Virtual scrolling to efficiently handle 100,000+ lines without performance degradation
- Copy selected lines to clipboard
- Bookmark or pin important lines for quick reference
- JSON log expansion to pretty-print JSON fields inline when clicked
- Auto-scroll mode that follows new log entries as they appear
- Simulated live streaming mode that appends new log lines on an interval
- Column mode view showing timestamp, level, and message in separate columns
- Log statistics summary showing counts per log level
- Export the currently filtered results as a text file
- Dark theme styling throughout
- Responsive layout for desktop and mobile

## Tech Stack
- HTML, CSS, JavaScript (vanilla or any framework)
- No log viewing libraries — build parsing, virtual scrolling, and filtering yourself

## Scoring Criteria
- **Functional (40%)**: Log parsing, level detection, filtering, and search all work correctly
- **Quality (20%)**: Virtual scrolling performs smoothly at scale, clean code, handles malformed log lines gracefully
- **Fidelity (25%)**: All features implemented including streaming mode, bookmarks, JSON expansion, statistics, export
- **Speed (15%)**: Time bonus