Fix responses funtion call output

src/llm/apis/openai_responses.cpp

@@ -167,6 +167,47 @@ static FunctionCallFields readFunctionCallFields(const rapidjson::Value& item) {
     return out;
 }
 
+static absl::StatusOr<std::string> normalizeFunctionCallOutput(const rapidjson::Value& outputValue) {
+    if (outputValue.IsString()) {
+        return std::string(outputValue.GetString());
+    }
+    if (!outputValue.IsArray()) {
+        return absl::InvalidArgumentError("function_call_output.output must be a string or array");
+    }
+
+    std::string textOnlyOutput;
+    bool hasAnyText = false;
+    for (const auto& contentItem : outputValue.GetArray()) {
+        if (!contentItem.IsObject()) {
+            continue;
+        }
+        auto contentObj = contentItem.GetObject();
+        auto typeIt = contentObj.FindMember("type");
+        auto textIt = contentObj.FindMember("text");
+        if (typeIt == contentObj.MemberEnd() || !typeIt->value.IsString() ||
+            textIt == contentObj.MemberEnd() || !textIt->value.IsString()) {
+            continue;
+        }
+        const std::string contentType = typeIt->value.GetString();
+        if (contentType != "input_text" && contentType != "output_text") {
+            continue;
+        }
+        if (hasAnyText) {
+            textOnlyOutput += "\n";
+        }
+        textOnlyOutput += textIt->value.GetString();
+        hasAnyText = true;
+    }
+    if (hasAnyText) {
+        return textOnlyOutput;
+    }
+
+    rapidjson::StringBuffer buffer;
+    rapidjson::Writer<rapidjson::StringBuffer> writer(buffer);
+    outputValue.Accept(writer);
+    return std::string(buffer.GetString());
+}
+
 // Reject function_call items that would translate to a syntactically valid but
 // semantically broken assistant.tool_calls entry (missing identifier, name, or
 // arguments). The call_id/id mismatch is also what breaks tool_call_id linkage
@@ -321,10 +362,13 @@ class ResponsesInputBuilder {
         auto callIdIt = itemObj.FindMember("call_id");
         if (callIdIt != itemObj.MemberEnd() && callIdIt->value.IsString())
             callId = callIdIt->value.GetString();
-        std::string output;
         auto outputIt = itemObj.FindMember("output");
-        if (outputIt != itemObj.MemberEnd() && outputIt->value.IsString())
-            output = outputIt->value.GetString();
+        if (outputIt == itemObj.MemberEnd())
+            return absl::InvalidArgumentError("function_call_output item is missing required output field");
+        auto outputStatus = normalizeFunctionCallOutput(outputIt->value);
+        if (!outputStatus.ok())
+            return outputStatus.status();
+        std::string output = outputStatus.value();
         sink.emitToolMessage(callId, output);
         return absl::OkStatus();
     }