PyLazarus: Resurrecting 15 Years of Abandoned Python Code with Open-Weight AI & WebAssembly

Description and use

PyLazarus resurrects legacy Python‑2 tools by deterministically repairing syntax, retrieving archived API schemas, patching dependencies with local AI, and running the results client‑side in Pyodide WebAssembly, all with zero server compute cost.

Problem

Python 2 legacy tools from 2005‑2015 became unusable after Python 2 end‑of‑life and API deprecation, leaving many projects as digital ghosts.

Outcome

PyLazarus resurrects 94.4% of legacy Python 2 tools, enabling them to run in the browser with zero server cost and strict security guarantees.

Workflow

• Clone pylazarus repository
• Install dependencies with pip
• Start backend with uvicorn
• Open http://127.0.0.1:8000 to access Living Crypt
• Select a legacy repo
• Run AST syntax transpiler
• Fetch archived API schemas via Wayback Machine
• Patch missing dependencies with local Gemma 4
• Gatekeeper verifies symbol preservation and security
• Execute tool in Pyodide WebAssembly

Evidence

When I first loaded ascii-dungeon-2009 into PyLazarus and watched the WebAssembly terminal render a glowing green procedural dungeon in under 18 milliseconds

Source

The 3-Stage Deterministic Resurrection Pipeline: Models read and draft; deterministic code decides. Python's native ast engine resolves mechanical syntax in $<15\text{ms}$ with zero LLM calls

Source

In our benchmark, raw Gemma 4 silently deleted functions in 4 out of 18 repositories

Source