Zero-copy protobuf and ConnectRPC for Rust

Anthropic open-sourced two Rust crates: buffa, a pure-Rust Protocol Buffers implementation with editions support and zero-copy message views, and connect-rust, a Tower-based ConnectRPC implementation supporting Connect, gRPC, and gRPC-Web. Both pass full upstream conformance suites and are already in production at Anthropic, built in six weeks with Claude Opus 4.6 doing most of the coding. The post details Rust-specific design decisions including protobuf editions mapping, zero-copy view trade-offs, and gaps the conformance suites missed.