Pure WASM Python Execution Library for Go Based on Pydantic Monty 'monty-go' Released

Fugue Labs has released monty-go, a pure Go wrapper library that compiles Pydantic's Monty Python interpreter to WebAssembly and loads it via wazero. This tool embeds a 2.9MB WASM binary into Go binaries to execute LLM-generated Python code in a sandboxed environment without containers, CGO, or subprocesses.

Key Features and How It Works

• External Function Calls (Pause/Resume): When Python code calls an external function, the Monty execution is paused; execution resumes after the Go code handles the function and returns the result. This allows LLMs to handle complex logic with a single Python script instead of sequential tool calls.
• Resource Limits: Limits can be set on memory, execution time, allocations, and recursion depth to safely terminate dangerous code such as infinite loops or memory bombs. Go's context.Context deadlines are also respected.
• OS Call Control: Python's access to the file system and environment variables is controlled via Go callbacks, blocking access to paths outside the allowed list.

Integration with AI Agent Development

This library is designed to power the code-mode of Gollem, a Go-based production agent framework. Previously, LLMs had to call tools sequentially, but with monty-go, LLMs can write Python code to call tools as functions, Monty safely executes them, and Gollem orchestrates the entire process. This aligns with recent AI agent trends such as Anthropic's Programmatic Tool Calling and Code Execution with MCP, and Cloudflare's Code Mode.