tools/server: support refusal content for Responses API (ggml-org#20285)

* Support refusal content for Responses API

* Update tools/server/server-common.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update tools/server/server-common.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

Author: pwilkin

tools/server/server-common.cpp

@@ -1273,17 +1273,27 @@ json convert_responses_to_chatcmpl(const json & response_body) {
 
                 for (const auto & output_text : item.at("content")) {
                     const std::string type = json_value(output_text, "type", std::string());
-                    if (type != "output_text") {
-                        throw std::invalid_argument("'type' must be 'output_text'");
-                    }
-                    if (!exists_and_is_string(output_text, "text")) {
-                        throw std::invalid_argument("'Output text' requires 'text'");
+                    if (type == "output_text") {
+                        if (!exists_and_is_string(output_text, "text")) {
+                            throw std::invalid_argument("'Output text' requires 'text'");
+                            // Ignore annotations and logprobs for now
+                            chatcmpl_content.push_back({
+                                {"text", output_text.at("text")},
+                                {"type", "text"},
+                            });
+                        }
+                    } else if (type == "refusal") {
+                        if (!exists_and_is_string(output_text, "refusal")) {
+                            throw std::invalid_argument("'Refusal' requires 'refusal'");
+                            // Ignore annotations and logprobs for now
+                            chatcmpl_content.push_back({
+                                {"refusal", output_text.at("refusal")},
+                                {"type", "refusal"},
+                            });
+                        }
+                    } else {
+                        throw std::invalid_argument("'type' must be one of 'output_text' or 'refusal'");
                     }
-                    // Ignore annotations and logprobs for now
-                    chatcmpl_content.push_back({
-                        {"text", output_text.at("text")},
-                        {"type", "text"},
-                    });
                 }
 
                 if (merge_prev) {