docs(cortex-gui): Feature improvement plan comparing to Zed and VSCode

[echobt]

Summary

This PR adds a comprehensive feature improvement plan for Cortex GUI, based on detailed analysis of both Zed (performance-focused Rust editor) and VSCode (feature-rich IDE).

Analysis Conducted

I cloned and analyzed both repositories:

• Zed: 218 crates in Rust, with particular focus on their GPUI framework, rope data structure, sum_tree, edit_prediction system, and multi-buffer editing
• VSCode: Full codebase analysis including workbench, editor, and extension architecture

Key Findings

Cortex GUI Strengths

• Modern tech stack (SolidJS, Tauri, TailwindCSS)
• Already has VirtualList for virtualization
• Good debugger support (27 components)
• Notebook/REPL support
• Git integration

15 Features to Add/Improve

Priority	Feature	Impact
P0	Rope Data Structure	Large file performance
P0	Enhanced Virtualization	UI performance
P1	Edit Predictions	AI-powered editing
P1	Multi-Buffer Editing	Zed's killer feature
P1	Async LSP Operations	No UI freezes
P2	Sum Tree for Display Map	O(log n) operations
P2	Incremental Highlighting	Instant syntax highlighting
P2	Real-Time Collaboration	Multiplayer editing
P2	GPU-Accelerated Rendering	120fps scrolling
P2	Enhanced Test Explorer	Coverage visualization
P2	Tasks System	Problem matchers
P3	Sticky Scroll Headers	Code context
P3	Performance Profiler	Diagnostics
P3	Workspace Trust	Security
P3	Keybinding Editor	UX improvement

Document Contents

• Executive summary of current state
• Detailed implementation guidance for each feature
• Code examples and TypeScript interfaces
• Priority matrix with impact/effort analysis
• Quick wins for immediate improvements

Related

This plan focuses on making Cortex GUI competitive with the best editors:

• Performance matching Zed (the fastest editor available)
• Features matching VSCode (the most comprehensive IDE)
• While maintaining Cortex's unique AI-first approach