We ran verify on ourselves
Refactron changed. The product, the site, the pitch: all of it. When a change this big lands, there is only one honest thing a verification company can do with it. Run the gate.
The pivot landed on green. This page is the record of why it was safe.
What we were building
Refactron started as an AI refactoring tool. Point it at your codebase and it would author the changes teams put off for years: framework migrations, API upgrades, the SQLAlchemy 1 to 2 kind of work nobody volunteers for. It worked, and it authored real migrations across real codebases.
What we watched happen
While we were building it, the ground moved. Coding agents got genuinely good. Cursor, Claude Code, Copilot: suddenly everyone had a tool that produces a plausible diff in seconds. Generating the change stopped being the hard part. And in our own migrations we had learned exactly where the hours actually went: not writing the diff, but proving it did not silently break behavior. The failure mode of this era is not broken builds. It is code that compiles fine, passes a glance, and is wrong. Confident, plausible, merged.
The realization
The most valuable thing we had built was never the part that wrote code. It was the gate we had built to trust our own output: the isolated shadow tree, the coverage check, the verdict that refused to say SAFE when the changed lines were never exercised. Every team we talked to had the same question, and it was never “can you write this change?” It was “how do I know this change is safe?”
So we kept the gate and made it the product. Refactron is now the verification layer for AI code change: point it at any diff, your agent's, a codemod's, or your own, and it proves behavior was preserved, with a reproducible record of why.
What this means if you use Refactron
The gate itself is now the whole interface. Two surfaces ship today: a CLI you can point at any diff, and an MCP server your agent calls as verify_change before it lands its own work. The CI gate is designed and is what we build next. Everything that existed only to demonstrate the gate, the transforms and the migration tooling, is gone as of 0.4.0.
Same mission. Same team. New surface. Behavior preserved, and now you can hold us to that the same way we hold every diff to it.
Try it before anyone else
The MCP server and CI gate are being built in the open. Come shape them.
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