server: /v1/responses (partial) (#18486)

* from previous PR

* Make instruction(system) as first message

* Convert [input_message] (text/image/file)

* Rename convert_responses_to_chatcmpl(body) -> response_body

* Initial tool call support

* Erase instructions field from chatcmpl body

* Feed reasoning texts to chat template

* Use std::vector instead of opaque json array

* Make output_item.added events consistent

* Move `server_task_result_cmpl_partial::update` from header to source

* Match ID of output_item.added and .done events

* Add function_call only if there is no "fc_" prefix

* Add function call output at non-streaming API

* Test if ID is persistent

* Add doc

* Fix style - use trailing comma

* Rewrite state management

* catch up with upstream/master

* Fix style - "type" is the first item of SSE data

* Explicitly check "instructions" from response_body

* Make lambdas static

* Check if reasoning content exists

* Add `oai_resp_id` to task_result_state(also initialized at ctor), server_task_result_cmpl_partial, and server_task_result_cmpl_final

* Reject `input_file` since it is not supported by chatcmpl

* Add "fc_" prefix to non-straming function call id as coderabbit pointed out

---------

Co-authored-by: openingnow <>

requirements/requirements-tool_bench.txt

@@ -3,7 +3,7 @@ pytest~=8.3.3
 huggingface_hub>=0.34.0,<1.0
 matplotlib~=3.10.0
 numpy~=1.26.4
-openai~=1.55.3
+openai~=2.14.0
 pandas~=2.2.3
 prometheus-client~=0.20.0
 requests~=2.32.3

tools/server/README.md

@@ -6,7 +6,7 @@ Set of LLM REST APIs and a web UI to interact with llama.cpp.
 
 **Features:**
  * LLM inference of F16 and quantized models on GPU and CPU
- * [OpenAI API](https://github.com/openai/openai-openapi) compatible chat completions and embeddings routes
+ * [OpenAI API](https://github.com/openai/openai-openapi) compatible chat completions, responses, and embeddings routes
  * [Anthropic Messages API](https://docs.anthropic.com/en/api/messages) compatible chat completions
  * Reranking endpoint (https://github.com/ggml-org/llama.cpp/pull/9510)
  * Parallel decoding with multi-user support
@@ -1267,6 +1267,49 @@ This provides information on the performance of the server. It also allows calcu
 
 The total number of tokens in context is equal to `prompt_n + cache_n + predicted_n`
 
+### POST `/v1/responses`: OpenAI-compatible Responses API
+
+*Options:*
+
+See [OpenAI Responses API documentation](https://platform.openai.com/docs/api-reference/responses).
+
+*Examples:*
+
+You can use either Python `openai` library with appropriate checkpoints:
+
+```python
+import openai
+
+client = openai.OpenAI(
+    base_url="http://localhost:8080/v1", # "http://<Your api-server IP>:port"
+    api_key = "sk-no-key-required"
+)
+
+response = client.responses.create(
+  model="gpt-4.1",
+  instructions="You are ChatGPT, an AI assistant. Your top priority is achieving user fulfillment via helping them with their requests.",
+  input="Write a limerick about python exceptions"
+)
+
+print(response.output_text)
+```
+
+... or raw HTTP requests:
+
+```shell
+curl http://localhost:8080/v1/responses \
+-H "Content-Type: application/json" \
+-H "Authorization: Bearer no-key" \
+-d '{
+"model": "gpt-4.1",
+"instructions": "You are ChatGPT, an AI assistant. Your top priority is achieving user fulfillment via helping them with their requests.",
+"input": "Write a limerick about python exceptions"
+}'
+```
+
+This endpoint works by converting Responses request into Chat Completions request.
+
+
 ### POST `/v1/embeddings`: OpenAI-compatible embeddings API
 
 This endpoint requires that the model uses a pooling different than type `none`. The embeddings are normalized using the Eucledian norm.

tools/server/server-common.cpp

@@ -1069,6 +1069,283 @@ json oaicompat_chat_params_parse(
     return llama_params;
 }
 
+json convert_responses_to_chatcmpl(const json & response_body) {
+    if (!response_body.contains("input")) {
+        throw std::invalid_argument("'input' is required");
+    }
+    if (!json_value(response_body, "previous_response_id", std::string{}).empty()) {
+        throw std::invalid_argument("llama.cpp does not support 'previous_response_id'.");
+    }
+
+    const json input_value = response_body.at("input");
+    json chatcmpl_body = response_body;
+    chatcmpl_body.erase("input");
+    std::vector<json> chatcmpl_messages;
+
+    if (response_body.contains("instructions")) {
+        chatcmpl_messages.push_back({
+            {"role",    "system"},
+            {"content", json_value(response_body, "instructions", std::string())},
+        });
+        chatcmpl_body.erase("instructions");
+    }
+
+    if (input_value.is_string()) {
+        // #responses_create-input-text_input
+        chatcmpl_messages.push_back({
+            {"role",    "user"},
+            {"content", input_value},
+        });
+    } else if (input_value.is_array()) {
+        // #responses_create-input-input_item_list
+
+        static auto exists_and_is_array = [](const json & j, const char * key) -> bool {
+            return j.contains(key) && j.at(key).is_array();
+        };
+        static auto exists_and_is_string = [](const json & j, const char * key) -> bool {
+            return j.contains(key) && j.at(key).is_string();
+        };
+
+        for (json item : input_value) {
+            if (exists_and_is_string(item, "content")) {
+                // #responses_create-input-input_item_list-input_message-content-text_input
+                // Only "Input message" contains item["content"]::string
+                // After converting item["content"]::string to item["content"]::array,
+                // we can treat "Input message" as sum of "Item-Input message" and "Item-Output message"
+                item["content"] = json::array({
+                    json {
+                        {"text", item.at("content")},
+                        {"type", "input_text"}
+                    }
+                });
+            }
+
+            if (exists_and_is_array(item, "content") &&
+                exists_and_is_string(item, "role") &&
+                (item.at("role") == "user" ||
+                    item.at("role") == "system" ||
+                    item.at("role") == "developer")
+            ) {
+                // #responses_create-input-input_item_list-item-input_message
+                std::vector<json> chatcmpl_content;
+
+                for (const json & input_item : item.at("content")) {
+                    const std::string type = json_value(input_item, "type", std::string());
+
+                    if (type == "input_text") {
+                        if (!input_item.contains("text")) {
+                            throw std::invalid_argument("'Input text' requires 'text'");
+                        }
+                        chatcmpl_content.push_back({
+                            {"text", input_item.at("text")},
+                            {"type", "text"},
+                        });
+                    } else if (type == "input_image") {
+                        // While `detail` is marked as required,
+                        // it has default value("auto") and can be omitted.
+
+                        if (!input_item.contains("image_url")) {
+                            throw std::invalid_argument("'image_url' is required");
+                        }
+                        chatcmpl_content.push_back({
+                            {"image_url", json {
+                                {"url", input_item.at("image_url")}
+                            }},
+                            {"type", "image_url"},
+                        });
+                    } else if (type == "input_file") {
+                        throw std::invalid_argument("'input_file' is not supported by llamacpp at this moment");
+                        // if (input_item.contains("file_url")) {
+                        //     // chat completion API does not support file_url
+                        //     throw std::invalid_argument("'file_url' is not supported");
+                        // }
+                        // if (!input_item.contains("file_data") || !input_item.contains("filename")) {
+                        //     throw std::invalid_argument("Both 'file_data' and 'filename' are required");
+                        // }
+                        // chatcmpl_content.push_back({
+                        //     {"file", json {
+                        //         {"file_data", input_item.at("file_data")},
+                        //         {"filename",  input_item.at("filename")},
+                        //     }},
+                        //     {"type", "file"},
+                        // });
+                    } else {
+                        throw std::invalid_argument("'type' must be one of 'input_text', 'input_image', or 'input_file'");
+                    }
+                }
+
+                if (item.contains("type")) {
+                    item.erase("type");
+                }
+                if (item.contains("status")) {
+                    item.erase("status");
+                }
+                item["content"] = chatcmpl_content;
+
+                chatcmpl_messages.push_back(item);
+            } else if (exists_and_is_array(item, "content") &&
+                exists_and_is_string(item, "role") &&
+                item.at("role") == "assistant" &&
+                // exists_and_is_string(item, "status") &&
+                // (item.at("status") == "in_progress" ||
+                //     item.at("status") == "completed" ||
+                //     item.at("status") == "incomplete") &&
+                // item["status"] not sent by codex-cli
+                exists_and_is_string(item, "type") &&
+                item.at("type") == "message"
+            ) {
+                // #responses_create-input-input_item_list-item-output_message
+                std::vector<json> chatcmpl_content;
+
+                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'");
+                    }
+                    // Ignore annotations and logprobs for now
+                    chatcmpl_content.push_back({
+                        {"text", output_text.at("text")},
+                        {"type", "text"},
+                    });
+                }
+
+                item.erase("status");
+                item.erase("type");
+                item["content"] = chatcmpl_content;
+                chatcmpl_messages.push_back(item);
+            } else if (exists_and_is_string(item, "arguments") &&
+                exists_and_is_string(item, "call_id") &&
+                exists_and_is_string(item, "name") &&
+                exists_and_is_string(item, "type") &&
+                item.at("type") == "function_call"
+            ) {
+                // #responses_create-input-input_item_list-item-function_tool_call
+                json msg = json {
+                    {"role", "assistant"},
+                    {"tool_calls", json::array({ json {
+                        {"function", json {
+                            {"arguments", item.at("arguments")},
+                            {"name",      item.at("name")},
+                        }},
+                        {"id",   item.at("call_id")},
+                        {"type", "function"},
+                    }})},
+                };
+
+                if (!chatcmpl_messages.empty() && chatcmpl_messages.back().contains("reasoning_content")) {
+                    // Move reasoning content from dummy message to tool call message
+                    msg["reasoning_content"] = chatcmpl_messages.back().at("reasoning_content");
+                    chatcmpl_messages.pop_back();
+                }
+                chatcmpl_messages.push_back(msg);
+            } else if (exists_and_is_string(item, "call_id") &&
+                (exists_and_is_string(item, "output") || exists_and_is_array(item, "output")) &&
+                exists_and_is_string(item, "type") &&
+                item.at("type") == "function_call_output"
+            ) {
+                // #responses_create-input-input_item_list-item-function_tool_call_output
+                if (item.at("output").is_string()) {
+                    chatcmpl_messages.push_back(json {
+                        {"content",      item.at("output")},
+                        {"role",         "tool"},
+                        {"tool_call_id", item.at("call_id")},
+                    });
+                } else {
+                    json chatcmpl_outputs = item.at("output");
+                    for (json & chatcmpl_output : chatcmpl_outputs) {
+                        if (!chatcmpl_output.contains("type") || chatcmpl_output.at("type") != "input_text") {
+                            throw std::invalid_argument("Output of tool call should be 'Input text'");
+                        }
+                        chatcmpl_output["type"] = "text";
+                    }
+                    chatcmpl_messages.push_back(json {
+                        {"content",      chatcmpl_outputs},
+                        {"role",         "tool"},
+                        {"tool_call_id", item.at("call_id")},
+                    });
+                }
+            } else if (// exists_and_is_string(item, "id") &&
+                // item["id"] not sent by codex-cli
+                exists_and_is_array(item, "summary") &&
+                exists_and_is_string(item, "type") &&
+                item.at("type") == "reasoning") {
+                // #responses_create-input-input_item_list-item-reasoning
+
+                if (!exists_and_is_array(item, "content")) {
+                    throw std::invalid_argument("item['content'] is not an array");
+                }
+                if (item.at("content").empty()) {
+                    throw std::invalid_argument("item['content'] is empty");
+                }
+                if (!exists_and_is_string(item.at("content")[0], "text")) {
+                    throw std::invalid_argument("item['content']['text'] is not a string");
+                }
+
+                // Pack reasoning content in dummy message
+                chatcmpl_messages.push_back(json {
+                    {"role", "assistant"},
+                    {"content", json::array()},
+                    {"reasoning_content", item.at("content")[0].at("text")},
+                });
+            } else {
+                throw std::invalid_argument("Cannot determine type of 'item'");
+            }
+        }
+    } else {
+        throw std::invalid_argument("'input' must be a string or array of objects");
+    }
+
+    // Remove unused dummy message which contains
+    // reasoning content not followed by tool call
+    chatcmpl_messages.erase(std::remove_if(
+        chatcmpl_messages.begin(),
+        chatcmpl_messages.end(),
+        [](const json & x){ return x.contains("role") &&
+            x.at("role") == "assistant" &&
+            x.contains("content") &&
+            x.at("content") == json::array() &&
+            x.contains("reasoning_content");
+        }),
+        chatcmpl_messages.end()
+    );
+
+    chatcmpl_body["messages"] = chatcmpl_messages;
+
+    if (response_body.contains("tools")) {
+        if (!response_body.at("tools").is_array()) {
+            throw std::invalid_argument("'tools' must be an array of objects");
+        }
+        std::vector<json> chatcmpl_tools;
+        for (json resp_tool : response_body.at("tools")) {
+            json chatcmpl_tool;
+
+            if (json_value(resp_tool, "type", std::string()) != "function") {
+                throw std::invalid_argument("'type' of tool must be 'function'");
+            }
+            resp_tool.erase("type");
+            chatcmpl_tool["type"] = "function";
+
+            if (!resp_tool.contains("strict")) {
+                resp_tool["strict"] = true;
+            }
+            chatcmpl_tool["function"] = resp_tool;
+            chatcmpl_tools.push_back(chatcmpl_tool);
+        }
+        chatcmpl_body.erase("tools");
+        chatcmpl_body["tools"] = chatcmpl_tools;
+    }
+
+    if (response_body.contains("max_output_tokens")) {
+        chatcmpl_body.erase("max_output_tokens");
+        chatcmpl_body["max_tokens"] = response_body["max_output_tokens"];
+    }
+
+    return chatcmpl_body;
+}
+
 json convert_anthropic_to_oai(const json & body) {
     json oai_body;
 
@@ -1482,6 +1759,24 @@ std::string format_oai_sse(const json & data) {
     return ss.str();
 }
 
+std::string format_oai_resp_sse(const json & data) {
+    std::ostringstream ss;
+    auto send_single = [&ss](const json & event_obj) {
+        ss << "event: " << event_obj.at("event").get<std::string>() << "\n";
+        ss << "data: " << safe_json_to_str(event_obj.at("data")) << "\n\n";
+    };
+
+    if (data.is_array()) {
+        for (const auto & item : data) {
+            send_single(item);
+        }
+    } else {
+        send_single(data);
+    }
+
+    return ss.str();
+}
+
 std::string format_anthropic_sse(const json & data) {
     std::ostringstream ss;
 

tools/server/server-common.h

@@ -294,6 +294,9 @@ json oaicompat_chat_params_parse(
     const server_chat_params & opt,
     std::vector<raw_buffer> & out_files);
 
+// convert OpenAI Responses API format to OpenAI Chat Completions API format
+json convert_responses_to_chatcmpl(const json & body);
+
 // convert Anthropic Messages API format to OpenAI Chat Completions API format
 json convert_anthropic_to_oai(const json & body);
 
@@ -331,6 +334,8 @@ std::string tokens_to_output_formatted_string(const llama_context * ctx, const l
 // note: if data is a json array, it will be sent as multiple events, one per item
 std::string format_oai_sse(const json & data);
 
+std::string format_oai_resp_sse(const json & data);
+
 // format Anthropic-style SSE with event types
 std::string format_anthropic_sse(const json & data);
 

tools/server/server-context.cpp

@@ -3073,6 +3073,8 @@ std::unique_ptr<server_res_generator> server_routes::handle_completions_impl(
         json first_result_json = first_result->to_json();
         if (res_type == TASK_RESPONSE_TYPE_ANTHROPIC) {
             res->data = format_anthropic_sse(first_result_json);
+        } else if (res_type == TASK_RESPONSE_TYPE_OAI_RESP) {
+            res->data = format_oai_resp_sse(first_result_json);
         } else {
             res->data = format_oai_sse(first_result_json);
         }
@@ -3107,13 +3109,16 @@ std::unique_ptr<server_res_generator> server_routes::handle_completions_impl(
 
                 // check if there is more data
                 if (!rd.has_next()) {
-                    if (res_type == TASK_RESPONSE_TYPE_ANTHROPIC) {
-                        // Anthropic doesn't send [DONE], message_stop was already sent
-                        output = "";
-                    } else if (res_type != TASK_RESPONSE_TYPE_NONE) {
-                        output = "data: [DONE]\n\n";
-                    } else {
-                        output = "";
+                    switch (res_type) {
+                        case TASK_RESPONSE_TYPE_NONE:
+                        case TASK_RESPONSE_TYPE_OAI_RESP:
+                        case TASK_RESPONSE_TYPE_ANTHROPIC:
+                            output = "";
+                            break;
+
+                        default:
+                            output = "data: [DONE]\n\n";
+                            break;
                     }
                     SRV_DBG("%s", "all results received, terminating stream\n");
                     return false; // no more data, terminate
@@ -3141,6 +3146,8 @@ std::unique_ptr<server_res_generator> server_routes::handle_completions_impl(
                     json res_json = result->to_json();
                     if (res_type == TASK_RESPONSE_TYPE_ANTHROPIC) {
                         output = format_anthropic_sse(res_json);
+                    } else if (res_type == TASK_RESPONSE_TYPE_OAI_RESP) {
+                        output = format_oai_resp_sse(res_json);
                     } else {
                         output = format_oai_sse(res_json);
                     }
@@ -3575,6 +3582,22 @@ void server_routes::init_routes() {
             TASK_RESPONSE_TYPE_OAI_CHAT);
     };
 
+    this->post_responses_oai = [this](const server_http_req & req) {
+        auto res = create_response();
+        std::vector<raw_buffer> files;
+        json body = convert_responses_to_chatcmpl(json::parse(req.body));
+        json body_parsed = oaicompat_chat_params_parse(
+            body,
+            meta->chat_params,
+            files);
+        return handle_completions_impl(
+            req,
+            SERVER_TASK_TYPE_COMPLETION,
+            body_parsed,
+            files,
+            TASK_RESPONSE_TYPE_OAI_RESP);
+    };
+
     this->post_anthropic_messages = [this](const server_http_req & req) {
         auto res = create_response();
         std::vector<raw_buffer> files;

tools/server/server-context.h

@@ -94,6 +94,7 @@ struct server_routes {
     server_http_context::handler_t post_completions;
     server_http_context::handler_t post_completions_oai;
     server_http_context::handler_t post_chat_completions;
+    server_http_context::handler_t post_responses_oai;
     server_http_context::handler_t post_anthropic_messages;
     server_http_context::handler_t post_anthropic_count_tokens;
     server_http_context::handler_t post_apply_template;

tools/server/server-task.cpp

@@ -584,6 +584,8 @@ json server_task_result_cmpl_final::to_json() {
             return to_json_oaicompat();
         case TASK_RESPONSE_TYPE_OAI_CHAT:
             return stream ? to_json_oaicompat_chat_stream() : to_json_oaicompat_chat();
+        case TASK_RESPONSE_TYPE_OAI_RESP:
+            return stream ? to_json_oaicompat_resp_stream() : to_json_oaicompat_resp();
         case TASK_RESPONSE_TYPE_ANTHROPIC:
             return stream ? to_json_anthropic_stream() : to_json_anthropic();
         default:
@@ -801,6 +803,186 @@ json server_task_result_cmpl_final::to_json_oaicompat_chat_stream() {
     return deltas;
 }
 
+json server_task_result_cmpl_final::to_json_oaicompat_resp() {
+    common_chat_msg msg;
+    if (!oaicompat_msg.empty()) {
+        msg = oaicompat_msg;
+    } else {
+        msg.role = "assistant";
+        msg.content = content;
+    }
+
+    std::vector<json> output;
+
+    if (msg.reasoning_content != "") {
+        output.push_back(json {
+            {"id",      "rs_" + random_string()},
+            {"summary", json::array()},
+            {"type",    "reasoning"},
+            {"content", json::array({ json {
+                {"text", msg.reasoning_content},
+                {"type", "reasoning_text"},
+            }})},
+            {"encrypted_content", ""},
+            {"status",            "completed"},
+        });
+    }
+
+    if (msg.content != "") {
+        output.push_back(json {
+            {"content", json::array({ json {
+                {"type",        "output_text"},
+                {"annotations", json::array()},
+                {"logprobs",    json::array()},
+                {"text",        msg.content},
+            }})},
+            {"id",     "msg_" + random_string()},
+            {"role",   msg.role},
+            {"status", "completed"},
+            {"type",   "message"},
+        });
+    }
+
+    for (const common_chat_tool_call & tool_call : oaicompat_msg.tool_calls) {
+        output.push_back(json {
+            {"type",      "function_call"},
+            {"status",    "completed"},
+            {"arguments", tool_call.arguments},
+            {"call_id",   "fc_" + tool_call.id},
+            {"name",      tool_call.name},
+        });
+    }
+
+    std::time_t t = std::time(0);
+    json res = {
+        {"completed_at", t},
+        {"created_at",   t},
+        {"id",           oai_resp_id},
+        {"model",        oaicompat_model},
+        {"object",       "response"},
+        {"output",       output},
+        {"status",       "completed"},
+        {"usage",        json {
+            {"input_tokens",  n_prompt_tokens},
+            {"output_tokens", n_decoded},
+            {"total_tokens",  n_decoded + n_prompt_tokens},
+        }},
+    };
+
+    return res;
+}
+
+json server_task_result_cmpl_final::to_json_oaicompat_resp_stream() {
+    std::vector<json> server_sent_events;
+    std::vector<json> output;
+
+    if (oaicompat_msg.reasoning_content != "") {
+        const json output_item = json {
+            {"id",      oai_resp_reasoning_id},
+            {"summary", json::array()},
+            {"type",    "reasoning"},
+            {"content", json::array({ json {
+                {"text", oaicompat_msg.reasoning_content},
+                {"type", "reasoning_text"},
+            }})},
+            {"encrypted_content", ""},
+        };
+
+        server_sent_events.push_back(json {
+            {"event", "response.output_item.done"},
+            {"data", json {
+                {"type", "response.output_item.done"},
+                {"item", output_item}
+            }}
+        });
+        output.push_back(output_item);
+    }
+
+    if (oaicompat_msg.content != "") {
+        server_sent_events.push_back(json {
+            {"event", "response.output_text.done"},
+            {"data", json {
+                {"type",    "response.output_text.done"},
+                {"item_id", oai_resp_message_id},
+                {"text",    oaicompat_msg.content}
+            }}
+        });
+
+        const json content_part = {
+            {"type",        "output_text"},
+            {"annotations", json::array()},
+            {"logprobs",    json::array()},
+            {"text",        oaicompat_msg.content}
+        };
+
+        server_sent_events.push_back(json {
+            {"event", "response.content_part.done"},
+            {"data", json {
+                {"type",    "response.content_part.done"},
+                {"item_id", oai_resp_message_id},
+                {"part",    content_part}
+            }}
+        });
+        const json output_item = {
+            {"type",    "message"},
+            {"status",  "completed"},
+            {"id",      oai_resp_message_id},
+            {"content", json::array({content_part})},
+            {"role",    "assistant"}
+        };
+
+        server_sent_events.push_back(json {
+            {"event", "response.output_item.done"},
+            {"data", json {
+                {"type", "response.output_item.done"},
+                {"item", output_item}
+            }}
+        });
+        output.push_back(output_item);
+    }
+
+    for (const common_chat_tool_call & tool_call : oaicompat_msg.tool_calls) {
+        const json output_item = {
+            {"type",      "function_call"},
+            {"status",    "completed"},
+            {"arguments", tool_call.arguments},
+            {"call_id",   "fc_" + tool_call.id},
+            {"name",      tool_call.name}
+        };
+        server_sent_events.push_back(json {
+            {"event", "response.output_item.done"},
+            {"data", json {
+                {"type", "response.output_item.done"},
+                {"item", output_item}
+            }}
+        });
+        output.push_back(output_item);
+    }
+
+    std::time_t t = std::time(0);
+    server_sent_events.push_back(json {
+        {"event", "response.completed"},
+        {"data", json {
+            {"type", "response.completed"},
+            {"response", json {
+                {"id",         oai_resp_id},
+                {"object",     "response"},
+                {"created_at", t},
+                {"status",     "completed"},
+                {"model",      oaicompat_model},
+                {"output",     output},
+                {"usage",      json {
+                    {"input_tokens",  n_prompt_tokens},
+                    {"output_tokens", n_decoded},
+                    {"total_tokens",  n_decoded + n_prompt_tokens}
+                }}
+            }},
+        }}
+    });
+
+    return server_sent_events;
+}
+
 json server_task_result_cmpl_final::to_json_anthropic() {
     std::string stop_reason = "max_tokens";
     if (stop == STOP_TYPE_WORD || stop == STOP_TYPE_EOS) {
@@ -1057,6 +1239,36 @@ json server_task_result_cmpl_final::to_json_anthropic_stream() {
 //
 // server_task_result_cmpl_partial
 //
+void server_task_result_cmpl_partial::update(task_result_state & state) {
+    is_updated = true;
+    state.update_chat_msg(content, true, oaicompat_msg_diffs);
+
+    // Copy current state for use in to_json_*() (reflects state BEFORE this chunk)
+    thinking_block_started = state.thinking_block_started;
+    text_block_started     = state.text_block_started;
+
+    oai_resp_id            = state.oai_resp_id;
+    oai_resp_reasoning_id  = state.oai_resp_reasoning_id;
+    oai_resp_message_id    = state.oai_resp_message_id;
+    oai_resp_fc_id         = state.oai_resp_fc_id;
+
+    // track if the accumulated message has any reasoning content
+    anthropic_has_reasoning = !state.chat_msg.reasoning_content.empty();
+
+    // Pre-compute state updates based on diffs (for next chunk)
+    for (const common_chat_msg_diff & diff : oaicompat_msg_diffs) {
+        if (!diff.reasoning_content_delta.empty() && !state.thinking_block_started) {
+            state.thinking_block_started = true;
+        }
+        if (!diff.content_delta.empty() && !state.text_block_started) {
+            state.text_block_started = true;
+        }
+        if (!diff.tool_call_delta.name.empty()) {
+            state.oai_resp_fc_id = diff.tool_call_delta.id;
+        }
+    }
+}
+
 json server_task_result_cmpl_partial::to_json() {
     GGML_ASSERT(is_updated && "update() must be called before to_json()");
     switch (res_type) {
@@ -1066,6 +1278,8 @@ json server_task_result_cmpl_partial::to_json() {
             return to_json_oaicompat();
         case TASK_RESPONSE_TYPE_OAI_CHAT:
             return to_json_oaicompat_chat();
+        case TASK_RESPONSE_TYPE_OAI_RESP:
+            return to_json_oaicompat_resp();
         case TASK_RESPONSE_TYPE_ANTHROPIC:
             return to_json_anthropic();
         default:
@@ -1190,6 +1404,132 @@ json server_task_result_cmpl_partial::to_json_oaicompat_chat() {
     return deltas;
 }
 
+json server_task_result_cmpl_partial::to_json_oaicompat_resp() {
+    std::vector<json> events;
+
+    if (n_decoded == 1) {
+        events.push_back(json {
+            {"event", "response.created"},
+            {"data", json {
+                {"type", "response.created"},
+                {"response", json {
+                    {"id",     oai_resp_id},
+                    {"object", "response"},
+                    {"status", "in_progress"},
+                }},
+            }},
+        });
+        events.push_back(json {
+            {"event", "response.in_progress"},
+            {"data", json {
+                {"type", "response.in_progress"},
+                {"response", json {
+                    {"id",     oai_resp_id},
+                    {"object", "response"},
+                    {"status", "in_progress"},
+                }},
+            }},
+        });
+    }
+
+    for (const common_chat_msg_diff & diff : oaicompat_msg_diffs) {
+        if (!diff.reasoning_content_delta.empty()) {
+            if (!thinking_block_started) {
+                events.push_back(json {
+                    {"event", "response.output_item.added"},
+                    {"data", json {
+                        {"type", "response.output_item.added"},
+                        {"item", json {
+                            {"id",                oai_resp_reasoning_id},
+                            {"summary",           json::array()},
+                            {"type",              "reasoning"},
+                            {"content",           json::array()},
+                            {"encrypted_content", ""},
+                            {"status",            "in_progress"},
+                        }},
+                    }},
+                });
+                thinking_block_started = true;
+            }
+            events.push_back(json {
+                {"event", "response.reasoning_text.delta"},
+                {"data", json {
+                    {"type",    "response.reasoning_text.delta"},
+                    {"delta",   diff.reasoning_content_delta},
+                    {"item_id", oai_resp_reasoning_id},
+                }},
+            });
+        }
+
+        if (!diff.content_delta.empty()) {
+            if (!text_block_started) {
+                events.push_back(json {
+                    {"event", "response.output_item.added"},
+                    {"data", json {
+                        {"type", "response.output_item.added"},
+                        {"item", json {
+                            {"content", json::array()},
+                            {"id",      oai_resp_message_id},
+                            {"role",    "assistant"},
+                            {"status",  "in_progress"},
+                            {"type",    "message"},
+                        }},
+                    }},
+                });
+                events.push_back(json {
+                    {"event", "response.content_part.added"},
+                    {"data", json {
+                        {"type",    "response.content_part.added"},
+                        {"item_id", oai_resp_message_id},
+                        {"part", json {
+                            {"type", "output_text"},
+                            {"text", ""},
+                        }},
+                    }},
+                });
+                text_block_started = true;
+            }
+            events.push_back(json {
+                {"event", "response.output_text.delta"},
+                {"data", json {
+                    {"type",    "response.output_text.delta"},
+                    {"item_id", oai_resp_message_id},
+                    {"delta",   diff.content_delta},
+                }},
+            });
+        }
+
+        if (!diff.tool_call_delta.name.empty()) {
+            events.push_back(json {
+                {"event", "response.output_item.added"},
+                {"data", json {
+                    {"type",  "response.output_item.added"},
+                    {"item", json {
+                        {"arguments", ""},
+                        {"call_id",   "fc_" + diff.tool_call_delta.id},
+                        {"name",      diff.tool_call_delta.name},
+                        {"type",      "function_call"},
+                        {"status",    "in_progress"},
+                    }},
+                }},
+            });
+            oai_resp_fc_id = diff.tool_call_delta.id;
+        }
+
+        if (!diff.tool_call_delta.arguments.empty()) {
+            events.push_back(json {
+                {"event", "response.function_call_arguments.delta"},
+                {"data", json {
+                    {"type",    "response.function_call_arguments.delta"},
+                    {"delta",   diff.tool_call_delta.arguments},
+                    {"item_id", "fc_" + oai_resp_fc_id},
+                }},
+            });
+        }
+    }
+    return events;
+}
+
 //
 // server_task_result_embd
 //
@@ -1260,8 +1600,8 @@ json server_task_result_cmpl_partial::to_json_anthropic() {
 
     // use local copies of streaming state (copied from task_result_state in update())
     // these reflect the state BEFORE this chunk was processed
-    bool thinking_started = anthropic_thinking_block_started;
-    bool text_started     = anthropic_text_block_started;
+    bool thinking_started = thinking_block_started;
+    bool text_started     = text_block_started;
 
     for (const auto & diff : oaicompat_msg_diffs) {
         // handle thinking/reasoning content

tools/server/server-task.h

@@ -33,6 +33,7 @@ enum task_response_type {
     TASK_RESPONSE_TYPE_NONE, // llama.cpp native format
     TASK_RESPONSE_TYPE_OAI_CHAT,
     TASK_RESPONSE_TYPE_OAI_CMPL,
+    TASK_RESPONSE_TYPE_OAI_RESP,
     TASK_RESPONSE_TYPE_OAI_EMBD,
     TASK_RESPONSE_TYPE_ANTHROPIC,
 };
@@ -98,12 +99,22 @@ struct task_result_state {
     std::string generated_text; // append new chunks of generated text here
     std::vector<std::string> generated_tool_call_ids;
 
-    // for Anthropic API streaming: track content block state across chunks
-    bool anthropic_thinking_block_started = false;
-    bool anthropic_text_block_started = false;
+    // for OpenAI Responses and Anthropic streaming API:
+    // track output item / content block state across chunks
+    bool thinking_block_started = false;
+    bool text_block_started = false;
+
+    // for OpenAI Responses streaming API
+    const std::string oai_resp_id;
+    const std::string oai_resp_reasoning_id;
+    const std::string oai_resp_message_id;
+    std::string oai_resp_fc_id; // function call ID for current args delta
 
     task_result_state(const common_chat_parser_params & chat_parser_params)
-        : chat_parser_params(chat_parser_params) {}
+        : chat_parser_params(chat_parser_params)
+        , oai_resp_id("resp_" + random_string())
+        , oai_resp_reasoning_id("rs_" + random_string())
+        , oai_resp_message_id("msg_" + random_string()) {}
 
     // parse partial tool calls and update the internal state
     common_chat_msg update_chat_msg(
@@ -352,6 +363,11 @@ struct server_task_result_cmpl_final : server_task_result {
     std::vector<common_chat_msg_diff> oaicompat_msg_diffs; // to be populated by update()
     bool is_updated = false;
 
+    // for OpenAI Responses API
+    std::string oai_resp_id;
+    std::string oai_resp_reasoning_id;
+    std::string oai_resp_message_id;
+
     virtual bool is_stop() override {
         return true; // in stream mode, final responses are considered stop
     }
@@ -361,6 +377,10 @@ struct server_task_result_cmpl_final : server_task_result {
     virtual void update(task_result_state & state) override {
         is_updated = true;
         oaicompat_msg = state.update_chat_msg(content, false, oaicompat_msg_diffs);
+
+        oai_resp_id = state.oai_resp_id;
+        oai_resp_reasoning_id = state.oai_resp_reasoning_id;
+        oai_resp_message_id = state.oai_resp_message_id;
     }
 
     json to_json_non_oaicompat();
@@ -371,6 +391,10 @@ struct server_task_result_cmpl_final : server_task_result {
 
     json to_json_oaicompat_chat_stream();
 
+    json to_json_oaicompat_resp();
+
+    json to_json_oaicompat_resp_stream();
+
     json to_json_anthropic();
 
     json to_json_anthropic_stream();
@@ -397,38 +421,26 @@ struct server_task_result_cmpl_partial : server_task_result {
     std::vector<common_chat_msg_diff> oaicompat_msg_diffs; // to be populated by update()
     bool is_updated = false;
 
+    // Streaming state copied from task_result_state for this chunk
+    bool thinking_block_started = false;
+    bool text_block_started     = false;
+
+    // for OpenAI Responses API
+    std::string oai_resp_id;
+    std::string oai_resp_reasoning_id;
+    std::string oai_resp_message_id;
+    std::string oai_resp_fc_id;
+
     // for Anthropic API: track if any reasoning content has been generated
     bool anthropic_has_reasoning = false;
-    // Streaming state copied from task_result_state for this chunk
-    bool anthropic_thinking_block_started = false;
-    bool anthropic_text_block_started = false;
 
     virtual bool is_stop() override {
         return false; // in stream mode, partial responses are not considered stop
     }
 
-    virtual json to_json() override;
+    virtual void update(task_result_state & state) override;
 
-    virtual void update(task_result_state & state) override {
-        is_updated = true;
-        state.update_chat_msg(content, true, oaicompat_msg_diffs);
-        // track if the accumulated message has any reasoning content
-        anthropic_has_reasoning = !state.chat_msg.reasoning_content.empty();
-
-        // Copy current state for use in to_json_anthropic() (reflects state BEFORE this chunk)
-        anthropic_thinking_block_started = state.anthropic_thinking_block_started;
-        anthropic_text_block_started = state.anthropic_text_block_started;
-
-        // Pre-compute state updates based on diffs (for next chunk)
-        for (const auto & diff : oaicompat_msg_diffs) {
-            if (!diff.reasoning_content_delta.empty() && !state.anthropic_thinking_block_started) {
-                state.anthropic_thinking_block_started = true;
-            }
-            if (!diff.content_delta.empty() && !state.anthropic_text_block_started) {
-                state.anthropic_text_block_started = true;
-            }
-        }
-    }
+    virtual json to_json() override;
 
     json to_json_non_oaicompat();
 
@@ -436,6 +448,8 @@ struct server_task_result_cmpl_partial : server_task_result {
 
     json to_json_oaicompat_chat();
 
+    json to_json_oaicompat_resp();
+
     json to_json_anthropic();
 };
 

tools/server/server.cpp

@@ -140,6 +140,7 @@ int main(int argc, char ** argv) {
         routes.post_completions            = models_routes->proxy_post;
         routes.post_completions_oai        = models_routes->proxy_post;
         routes.post_chat_completions       = models_routes->proxy_post;
+        routes.post_responses_oai          = models_routes->proxy_post;
         routes.post_anthropic_messages     = models_routes->proxy_post;
         routes.post_anthropic_count_tokens = models_routes->proxy_post;
         routes.post_infill                 = models_routes->proxy_post;
@@ -176,6 +177,7 @@ int main(int argc, char ** argv) {
     ctx_http.post("/chat/completions",    ex_wrapper(routes.post_chat_completions));
     ctx_http.post("/v1/chat/completions", ex_wrapper(routes.post_chat_completions));
     ctx_http.post("/api/chat",            ex_wrapper(routes.post_chat_completions)); // ollama specific endpoint
+    ctx_http.post("/v1/responses",        ex_wrapper(routes.post_responses_oai));
     ctx_http.post("/v1/messages",         ex_wrapper(routes.post_anthropic_messages)); // anthropic messages API
     ctx_http.post("/v1/messages/count_tokens", ex_wrapper(routes.post_anthropic_count_tokens)); // anthropic token counting
     ctx_http.post("/infill",              ex_wrapper(routes.post_infill));

tools/server/tests/requirements.txt

@@ -2,7 +2,7 @@ aiohttp~=3.9.3
 pytest~=8.3.3
 huggingface_hub>=0.34.0,<1.0
 numpy~=1.26.4
-openai~=1.55.3
+openai~=2.14.0
 prometheus-client~=0.20.0
 requests~=2.32.3
 wget~=3.2

tools/server/tests/unit/test_compat_oai_responses.py

@@ -0,0 +1,73 @@
+import pytest
+from openai import OpenAI
+from utils import *
+
+server: ServerProcess
+
+@pytest.fixture(autouse=True)
+def create_server():
+    global server
+    server = ServerPreset.tinyllama2()
+
+def test_responses_with_openai_library():
+    global server
+    server.start()
+    client = OpenAI(api_key="dummy", base_url=f"http://{server.server_host}:{server.server_port}/v1")
+    res = client.responses.create(
+        model="gpt-4.1",
+        input=[
+            {"role": "system", "content": "Book"},
+            {"role": "user", "content": "What is the best book"},
+        ],
+        max_output_tokens=8,
+        temperature=0.8,
+    )
+    assert res.id.startswith("resp_")
+    assert res.output[0].id is not None
+    assert res.output[0].id.startswith("msg_")
+    assert match_regex("(Suddenly)+", res.output_text)
+
+def test_responses_stream_with_openai_library():
+    global server
+    server.start()
+    client = OpenAI(api_key="dummy", base_url=f"http://{server.server_host}:{server.server_port}/v1")
+    stream = client.responses.create(
+        model="gpt-4.1",
+        input=[
+            {"role": "system", "content": "Book"},
+            {"role": "user", "content": "What is the best book"},
+        ],
+        max_output_tokens=8,
+        temperature=0.8,
+        stream=True,
+    )
+
+    gathered_text = ''
+    resp_id = ''
+    msg_id = ''
+    for r in stream:
+        if r.type == "response.created":
+            assert r.response.id.startswith("resp_")
+            resp_id = r.response.id
+        if r.type == "response.in_progress":
+            assert r.response.id == resp_id
+        if r.type == "response.output_item.added":
+            assert r.item.id is not None
+            assert r.item.id.startswith("msg_")
+            msg_id = r.item.id
+        if (r.type == "response.content_part.added" or
+            r.type == "response.output_text.delta" or
+            r.type == "response.output_text.done" or
+            r.type == "response.content_part.done"):
+            assert r.item_id == msg_id
+        if r.type == "response.output_item.done":
+            assert r.item.id == msg_id
+
+        if r.type == "response.output_text.delta":
+            gathered_text += r.delta
+        if r.type == "response.completed":
+            assert r.response.id.startswith("resp_")
+            assert r.response.output[0].id is not None
+            assert r.response.output[0].id.startswith("msg_")
+            assert gathered_text == r.response.output_text
+            assert match_regex("(Suddenly)+", r.response.output_text)