REST will return Json instead of ProtoJson

[raphael-goetz]

Resolves: #161

[Copilot]

Pull request overview

Updates the REST adapter response serialization so that protobuf Value payloads are converted into standard JSON output (instead of protobuf’s kind-shaped “proto-json”), addressing issue #161.

Changes:

• Added a pb_value_to_json converter from tucana::shared::Value to serde_json::Value.
• Updated the response payload serialization path to serialize the converted JSON value.

Comments suppressed due to low confidence (1)

adapter/rest/src/main.rs:251

• The successful response path serializes payload to JSON bytes but does not ensure a Content-Type: application/json header is present (unlike json_error). If flows omit this header, clients may not treat the body as JSON; consider adding a default content-type when building the response (without overriding an explicit flow-provided value).

            // payload -> json bytes
            let json_val = pb_value_to_json(payload_val);
            let json = serde_json::to_vec_pretty(&json_val).unwrap_or_else(|err| {
                format!(r#"{{"error":"Serialization failed: {:?}"}}"#, err).into_bytes()
            });

            let status =
                StatusCode::from_u16(code as u16).unwrap_or(StatusCode::INTERNAL_SERVER_ERROR);
            build_response(status, http_headers, json)

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.