⏳ FuncUndo: The Semantic Code Time Machine

Stop undoing files. Start reverting logic.

FuncUndo (internally Chronos) is a function-level version control system for VS Code. While Git tracks raw text lines, FuncUndo understands Abstract Syntax Trees (AST). It tracks changes to your logic blocks silently in the background, allowing you to "time travel" individual functions without affecting the rest of your file.

🧐 Why FuncUndo?

Git is a blunt instrument for local, exploratory coding. When you’re deep in a "flow state," you don't want to commit every 2 minutes, but you also don't want to lose that brilliant version of a function you wrote an hour ago.

Feature	Git / Standard Undo	FuncUndo
Granularity	File or Line-level	Function & Method-level
Context	Raw text differences	Semantic logic changes
Safety	Blind reversion	Dependency risk assessment
Noise	Tracks whitespace/formatting	Ignores non-logic changes

✨ Key Superpowers

🧠 AST-Aware Tracking: Hashes code based on structural logic. If you only changed a comment or added whitespace, FuncUndo knows the logic is the same and won't clutter your history.
🕸️ The Risk Engine: Features a real-time Directed Acyclic Graph (DAG) of your call stack. It warns you before a revert if the change will break active dependent functions.
🔒 100% Local & Private: Your code never leaves your machine. History is stored in a high-performance SQLite WASM binary within your workspace.
⚡ Zero-Lag Architecture: Heavy lifting is offloaded to Node.js Worker Threads. Your VS Code UI stays at a flawless 60fps while we parse your AST in the background.
🌐 WASM-Powered: Built on web-tree-sitter and sql.js for zero native dependencies. It works out-of-the-box on Windows, Mac, Linux, and even VS Code for the Web.

🏗 System Architecture

We strictly decouple the Compiler Track (Heavy Processing) from the UI Track (User Interaction) to ensure your editor never stutters.

graph TD
    subgraph Client["VS Code IDE"]
        Editor["Active Text Editor"]
        UI["React Webview Sidebar"]
    end

    subgraph ExtensionHost["Main Node.js Process"]
        EventLoop["Event Orchestrator & Debouncer"]
        WorkspaceEdit["Reversion Engine"]
        RiskEngine["Risk & Dependency Engine"]
    end

    subgraph Worker["Background Node Worker"]
        Parser["Tree-sitter WASM Parser"]
        ASTExtractor["AST Structural Hasher"]
    end

    subgraph Storage["Local File System"]
        DB[("sql.js WASM Database")]
        VFile[".vscode/semantic-history.sqlite"]
    end

    Editor -- "onDidSave" --> EventLoop
    EventLoop -- "Raw Text (IPC)" --> Parser
    Parser --> ASTExtractor
    ASTExtractor -- "ExtractedFunctions[]" --> EventLoop
    EventLoop -- "Compare Hash & Insert" --> DB
    UI <--> |RPC| RiskEngine
    UI -- "Trigger Revert" --> WorkspaceEdit
    WorkspaceEdit -- "Surgical AST Diff" --> Editor

🔄 The "Safe Revert" Lifecycle

The Silent Loop: Every time you save, a background worker parses the file into an AST.
Logic Fingerprinting: We generate a unique hash for every function body. If the hash changes, we store a new "version" in SQLite.
Blast Radius Analysis: When you click "Revert," the Risk Engine queries the DB: "Who calls this function?" If dependents exist, we show a DANGER modal.
Surgical Patching: Instead of a full file overwrite, we use vscode.WorkspaceEdit to replace only the specific character coordinates of the function, followed by a programmatic format to match your style.

🛠 Tech Stack

Parser: web-tree-sitter (Compiled to WebAssembly)
Database: sql.js with Kysely ORM for type-safe SQL.
Frontend: React 18 + Zustand for state + VS Code Webview UI Toolkit.
Concurrency: Node.js worker_threads for non-blocking AST parsing.

💻 Local Development

Prerequisites

Node.js v18+
VS Code

Installation

Clone the repo:

git clone https://github.com/SemanticCodeTools/chronos-extension.git
cd chronos-extension

Install & Build:

    npm install
    npm run compile # Compiles TS and copies WASM binaries
    ```
3.  **Launch:**
    Press `F5` in VS Code to open the **Extension Development Host**.

📂 Project Structure

chronos-extension/
├── src/
│   ├── engine/       # Track A: The Compiler (WASM Parser & Workers)
│   ├── storage/      # Track B: The Database (Kysely Schema & SQLite)
│   ├── webview/      # Track B: The UI (React App & Components)
│   ├── extension.ts  # The Orchestrator
│   └── shared/       # Shared Types & Contracts
├── wasm-binaries/    # Pre-compiled Tree-sitter & SQLite targets
└── esbuild.js        # Lightning fast build script

🔮 Future Roadmap

Phase 2: Support for Python, Go, and Rust (via additional Tree-sitter WASM grammars).
Phase 3: Visual Churn Heatmap—See which functions are the most "unstable" over time.
Phase 4: AI-Generated summaries of what changed between two function versions.

🤝 The Team

Jatin Jain - The Event Loop & Orchestration
Mankirat Singh Nanda - Storage Engine
Mayur Nanda - Parser Engine

Found a bug? Open an issue. Want to contribute? Check out CONTRIBUTING.md.

FuncUndo

Mankirat Singh