During January 2025, this developer contributed to the com-lihaoyi/mill repository by implementing a new ScalaPB feature that enables Scala 3 syntax generation for Protocol Buffers. The work involved adding a scala3_sources option to the ScalaPB plugin, integrating it into ScalaPBModule.scala, and ensuring proper compiler argument wiring. They updated documentation and introduced new test coverage to validate the Scala 3 syntax generation path. Utilizing skills in Scala, build tooling, and plugin development, the developer focused on simplifying protobuf usage for Mill users, thereby supporting safer cross-version builds and reducing migration friction for teams adopting Scala 3.