Yesterday GitHub Next and Microsoft Research announced the Proof-Driven Development Kit (PDD Kit), now in research preview. The pitch, in GitHub Next's own words: "How do you guarantee your agent's code is correct? You prove it." Instead of a human reading an agent-generated diff line by line, a verifier reads a formal specification and checks the code against it for every input. I spend most of my time making coding agents behave inside config rules, so a tool that moves trust from "I read the diff" to "the spec checked the code" is exactly my kind of news. Here is what the kit actually does, the research it sits on, and the three places it stops working.

What the PDD Kit actually does

The workflow GitHub Next laid out, using a sample login flow, runs in five steps:

Plan. A team plans the feature together inside Chopin, GitHub Next's multiplayer agentic planning tool.

Spec.…