Theseus
Memory bugs in C parsers keep turning into critical vulnerabilities, and everyone agrees that code should move to Rust.
Core trick
Gemini translates C parsers to safe Rust, and a deterministic verifier compares every output byte and feeds mismatches back.
Description
Memory bugs in C parsers keep turning into critical vulnerabilities, and everyone agrees that code should move to Rust. Few teams migrate, because nobody can show the rewrite behaves the same. Theseus doesn't ask the model whether the port works. Gemini 4 Argon translates the C library into safe Rust (#![forbid(unsafe_code)], no dependencies, no way to call the C). Then a deterministic verifier runs the original and the replacement on the same inputs and compares every output byte. Each difference goes back to Argon as a pattern to repair, and compiler errors go back the same way. The final build is checked again on held-out inputs the model never saw. A person approves, and a managed agent opens a pull request carrying the code and the verifier's evidence report.
README excerpt
# Theseus Theseus migrates C parsers to memory-safe Rust and hands back evidence a reviewer can check. Theseus doesn't ask the model whether the port works. It runs the original and the replacement on the same inputs, exposes the differences, and makes the model repair them. Gemini 4 Argon writes the Rust; a deterministic verifier, not the model, decides what counts as a match. **Who it is for.** Teams that ship a C parser inside their own product (product security, embedded, appliances) and want a memory-safe drop-in, with evidence their auditors can rerun. Upstream maintainers of those parsers come second: the same evidence is what a maintainer would need before accepting a Rust rewrite. **What a result means.** "N tested behaviors preserved" means the C and the Rust produced identical output bytes and exit status on N inputs, through our driver. It is agreement on the tested inputs, not a claim about every possible input or every API function. ## Team - Edan (systems: verifier, pipeline, API) - Brendan (AI: translation and repair with Gemini 4 Argon) - Keon (frontend: run view and demo) ## Built during the event Built entirely during the Gemini 4 Argon SF Hackathon, Oct 25 2026. Hacking started ~10:13 AM PT per organizer announcement and ends 5:00 PM PT. The only pre-written file is the plan in `docs/PLAN.md` (notes). ### Built today vs. used | Built today by our team | Used as inputs (third-party, not our code) | |---|---| | Differential verifier (`backend/harnes