🤖 FastMCP Code Copilot

Enterprise Sandboxed Model Context Protocol (MCP) Server for AI-Assisted Engineering

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Filesystem isolation firewall confining agent operations to designated workspace while blocking directory traversal attacks (../, /etc, .env).

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📌 Executive Summary & Enterprise Origin

In strictly regulated enterprise R&D environments (such as Tier-1 automotive and industrial engineering), commercial cloud-based AI code assistants (like commercial GitHub Copilot) are frequently restricted due to proprietary IP leakage, strict network proxy constraints, and compliance mandates.

FastMCP Code Copilot was architected to bridge internal enterprise AI chatbots and desktop assistants (such as Claude Desktop, Cursor, or custom LLM gateways) directly to local codebases with institutional-grade cybersecurity rigor:

• Zero Data Egress: Operates entirely over local network transports (HTTP/SSE or standard I/O) without transmitting repository contents to unverified third parties.
• Hardware-Level Containment: Enforces strict directory containment, symlink escape checks, and path normalization.
• High-Throughput Engineering Context: Delivers 17 granular AST-level inspection and surgical file manipulation tools, cutting token consumption by up to 40% via line-scoped reading and multi-file batching.

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📸 Architectural Showcase

Security Sandbox & Path Containment	Developer Copilot & AST Codebase Tools
Hardened containment firewall: eliminates directory escaping and path injection.	17 specialized code analysis tools: AST parsing, symbol extraction, and ripgrep.

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🏗️ System Architecture & Security Model

The server operates as an asynchronous Starlette application exposing the standard Model Context Protocol (MCP) specification:

flowchart TD
    Client["AI Assistant (Claude Desktop / Cursor / Internal Chatbot)"] -->|JSON-RPC via MCP| Server["Starlette ASGI Application (Uvicorn)"]
    
    subgraph "Security Containment Middleware"
        Server --> CORS["CORS & Request Logging Middleware"]
        CORS --> PathValidator{"Path Sandbox Validator (security.py)"}
        
        PathValidator -->|Absolute Path| Reject1["REJECT: Absolute paths forbidden"]
        PathValidator -->|Traversal Attempt '../'| Reject2["REJECT: Directory traversal detected"]
        PathValidator -->|Symlink Escape| Reject3["REJECT: Target outside PROJECT_ROOT"]
        PathValidator -->|Normalized Safe Relative Path| ToolDispatcher["MCP Tool Dispatcher"]
    end
    
    subgraph "17 High-Performance Developer Tools"
        ToolDispatcher --> T1["File Operations (read, batch, write, modify, undo)"]
        ToolDispatcher --> T2["Code Search & Discovery (grep, regex, AST symbols)"]
        ToolDispatcher --> T3["Diagnostics & Metrics (AST metrics, syntax validation)"]
        ToolDispatcher --> T4["Controlled Command Execution (pytest, git, python)"]
    end
    
    ToolDispatcher --> SandboxWorkspace[("Designated Project Sandbox Root")]

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Institutional Security Invariants:

1. Root Boundary Enclosure: Every operation is strictly relative to the designated PROJECT_ROOT. Attempting to access parent paths (../../) raises an immediate validation exception.
2. Symlink Traversal Protection: Evaluates Path.resolve() against the physical filesystem. If a symlink resolves to an inode outside the project root, access is terminated immediately.
3. Internal Index Concealment: Persistent search indexes (.mcp_index) are excluded from file listings and search queries, preventing search cache data from polluting developer repositories.
4. Controlled Execution Whitelist: Command execution is restricted to safe, verified developer toolchains (pytest, git, python, npm).

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🛠️ Comprehensive 17-Tool Registry

The server implements 17 granular tools categorized across four engineering dimensions:

1. Surgical File Manipulation

• read_file: Reads files safely with optional start_line and end_line slicing to minimize LLM token overhead.
• batch_read_files: Fetches up to 10 files in a single tool call, eliminating latency round-trips.
• write_file: Creates or overwrites files with atomic write guarantees.
• create_file: Creates empty boilerplate or placeholder files safely.
• modify_file: Surgical text-block replacement with bounds validation, whitespace preservation, and staleness detection.
• undo_edit: Single-level rollback reverting the last modified file back to its previous state.

2. Codebase Structure & Exploration

• list_files: Non-recursive and recursive file enumeration with custom glob filters and ignore patterns (.git, node_modules, .venv).
• get_file_structure: Generates an ASCII tree visualization of the project hierarchy with depth limits.
• get_file_info: Retrieves file metadata including size, encoding, language type, and last modification timestamp.

3. Code Search & AST Symbol Intelligence

• search_in_files: Fast regex and substring searches across the workspace.
• grep_search: Ripgrep-like search returning matching lines bundled with configurable preceding and trailing context lines.
• find_function: AST-driven function, method, and class extractor supporting Python, JavaScript, and TypeScript.
• find_references: Scans for identifier references, method invocations, and variable declarations across all project files.

4. Code Diagnostics & Controlled Execution

• analyze_file: Computes cyclomatic complexity estimates, line counts (blank, comment, code), and structural metrics across 15+ languages.
• get_diagnostics: Fast syntax and lint validation for Python (ast.parse), JSON, and JavaScript.
• execute_command: Executes whitelisted commands inside the sandbox (e.g., pytest tests/, git status) with timeout and output truncation guards.
• set_project_root: Dynamically switches the active workspace root at runtime with state reset and index cache reloading.

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📁 Repository Structure

MCP-Code-Copilot/
├── assets/                         # High-resolution architectural figures
│   ├── mcp_primary_sandbox_container.png
│   ├── mcp_secondary_copilot_overview.png
│   └── MCP.png
├── middleware/
│   ├── logging.py                  # Structured request and execution logger
│   └── security.py                 # Path validation, traversal guards, symlink checks
├── tools/
│   └── file_operations.py          # Implementations for all 17 developer tools
├── utils/
│   ├── encoding_detector.py        # Automated chardet charset encoding detector
│   ├── error_handler.py            # Standardized JSON-RPC error formatters
│   └── file_validator.py           # Binary file checks and size validators
├── tests/
│   ├── conftest.py                 # Pytest fixtures and mock workspace setup
│   ├── test_file_operations.py     # End-to-end tool validation tests
│   ├── test_fts5.py                # FTS5 full-text search indexing tests
│   ├── test_gating.py              # Tool visibility and lifecycle gating tests
│   └── test_security.py            # Sandbox boundary & path traversal penetration tests
├── config.py                       # Server configuration constants
├── pyproject.toml                  # Python package specification (v3.0.0)
├── requirements.txt                # Production dependencies
├── server.py                       # FastMCP v2 & Starlette ASGI server entry point
└── README.md                       # Master documentation (this file)

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🚀 Quick Start & Integration Guide

1. Installation

Install the package directly into your Python environment:

# Clone the repository
git clone https://github.com/Vignesh-Manivasakam/MCP-Code-Copilot.git
cd MCP-Code-Copilot

# Install with pip (editable CLI mode)
pip install -e .

2. Launch the Server

Start the server and specify your project workspace:

# Using the installed CLI wrapper:
mcp-code-copilot /path/to/your/project --port 8000

# Or via Python directly:
python server.py /path/to/your/project --port 8000

Console Output:

============================================================
🚀 FastMCP Code Copilot Server  v3.0.0
============================================================
  Project : my-project-workspace
  MCP     : http://127.0.0.1:8000/mcp
  Health  : http://127.0.0.1:8000/health
  Sandbox : ENFORCED (/path/to/your/project)
============================================================

3. Register with Claude Desktop

Add the server definition to your claude_desktop_config.json:

{
  "mcpServers": {
    "fastmcp-code-copilot": {
      "command": "python",
      "args": [
        "-m", "server",
        "D:\\path\\to\\your\\workspace",
        "--port", "8000"
      ]
    }
  }
}

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🧪 Verification & Security Testing

Run the automated test suite to verify sandbox boundary enforcement:

# Run security and path traversal penetration tests
python -m pytest tests/test_security.py tests/test_fts5.py -v

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🛡️ License & Enterprise Compliance Notice

• License: Released under the open-source MIT License.
• Compliance: Engineered to conform with enterprise corporate IT governance guidelines. Eliminates commercial per-seat licensing fees while providing transparent, auditable code interaction logs.
• Author: Vignesh Manivasakam (LinkedIn · GitHub)