use-protobuf

Use Protobuf

Treat Protobuf as the canonical typed contract for gRPC, REST gateway bindings, OpenAPI, generated SDKs, and shared data structures. Model the domain before optimizing generated code.

Workflow

1. Read repository instructions and inspect existing .proto files, packages, versions, imports, generation configuration, and generated output conventions.
2. Classify each service as gRPC-only or HTTP-exposed before adding annotations.
3. Model every RPC, stream packet, enum, error, and reusable message with concrete types.
4. Apply transport-specific validation and documentation rules.
5. Evaluate compatibility according to the package's release state and version.
6. Generate every configured SDK and OpenAPI artifact. Use $use-buf and $use-buf-plugins when available.
7. Run repository tests and inspect generated diffs; never hand-edit generated code.

Define RPC Contracts Explicitly

• Define a dedicated RPC method for every gRPC operation.
• Name unary messages MethodRequest and MethodResponse.
• Keep request and response messages distinct even when their current fields happen to match.
• Use TitleCase service, method, message, and enum names; use lower_snake_case fields and UPPER_SNAKE_CASE enum values.
• Prefer comments that explain semantics, units, identity, presence, ordering, and lifecycle rather than restating the field name.

rpc GetDocument(GetDocumentRequest) returns (GetDocumentResponse);

Model Streaming Without Base Payloads

Use the appropriate gRPC streaming form:

rpc ImportRecords(stream ImportRecordsStreamRequest) returns (ImportRecordsResponse);
rpc WatchJob(WatchJobRequest) returns (stream WatchJobStreamResponse);
rpc Transfer(stream TransferStreamRequest) returns (stream TransferStreamResponse);

MUST NOT create an abstract, generic, inherited, or catch-all base event/base payload for stream requests or responses. Define concrete stream event, step, or packet messages. When several variants may occur, use oneof whose alternatives are separate messages. Use one homogeneous stream message only when every packet genuinely has the same body and semantics, such as fixed-shape file chunks.