Microsoft's agent migration recipe: approve the rules, not the fixes, and let a differential test grade the result

Mon, 26 Oct 2026 16:03:00 +0000

The hard part of an agent-driven migration stopped being the translation a while ago. It’s the review. A migration that touches 400 files produces 400 diffs, and a human who reads them one at a time either gives up around file 60 or starts approving on rhythm. Microsoft’s Command Line publication published the first post of a series on this on 26 October 2026 , covering how its teams use agents to move very large codebases to new toolchains and from legacy C and C++ to Rust. Its answer to the review problem is worth copying at a much smaller scale.

Differential-Testing on Tokenise

Microsoft's agent migration recipe: approve the rules, not the fixes, and let a differential test grade the result