Proof Driven Development Kit (PDD Kit) is a research preview from Microsoft Research, introduced with GitHub Next, for teams that need a check on code written by agents. It turns a plan into a formal specification, then uses the Verus verifier to prove the Rust implementation meets that spec for every input. Where a proof cannot be completed, it falls back to tests and computer-use agents. The kit is integrated with Chopin, GitHub Next's real-time multiplayer planning prototype, so a team can write the plan together and carry an approved spec into a pull request. The launch walkthrough follows an app login flow from intent to a verified pull request. PDD Kit discusses the code, infers intent as it goes, and proposes a specification in Verus, a proof language for Rust. A person approves the spec before the verifier runs. It works on Rust today, with no new language to learn and no change to how the underlying code is produced. The stated aim is a workflow in which engineers review specifications, and agent-written code is checked against those specifications before it ships. GitHub describes Chopin plus PDD Kit as a way to ship that code with stronger assurance than code review and testing alone. GitHub Next is a team of researchers and engineers at GitHub that prototypes tools for how software is built. They are showing the work at GitHub Universe on October 28 and 29, 2026. The release is aimed at teams whose agents now write more code than anyone can review line by line, and who want a check that covers every input the spec describes, not only the cases a test suite happens to include. PDD Kit is in research preview.