connectrpc-codegen - library for generating ConnectRPC Rust bindings.

This crate provides programmatic code generation from compiled proto descriptors: buffa message types + ConnectRPC service traits, extension traits, and typed clients.

Most users will not use this crate directly. Use either:

• protoc-gen-connect-rust - protoc/buf plugin binary (generates checked-in service stubs via buf generate)
• connectrpc-build - build.rs integration (generates unified message types + service stubs into $OUT_DIR)

Two generation modes

[codegen::generate_files] - unified output. Buffa message types and ConnectRPC service stubs in one file per proto, with super::-relative type paths. Used by connectrpc-build.

[codegen::generate_services] - service stubs only. Message types are referenced via absolute paths configured via [codegen::CodeGenConfig::extern_paths], so the output compiles standalone against a separately-generated buffa module or crate. Used by the protoc-gen-connect-rust plugin.

Library usage

use connectrpc_codegen::codegen::{generate_services, Options};

let mut options = Options::default();
options.buffa.extern_paths.push((".".into(), "crate::proto".into()));
let files = generate_services(&descriptors, &files_to_generate, &options)?;
for f in files {
    std::fs::write(out_dir.join(&f.name), f.content)?;
}