Posts tagged with "Legacy Modernization"

GitHub ported the Copilot agent runtime from TypeScript to 832,378 lines of production Rust in about 14.5 weeks for roughly $120,000 in tokens plus three weeks of one developer's time, with a 96.22% prompt-cache hit rate and up to 18x faster in-process session startup. We break down the token bill into reusable unit costs, show why caching kept it around a sixth of the uncached price, and list the preconditions and EU residency checks to settle before budgeting your own agent-driven rewrite.