diff --git a/relay/channel/deepseek/adaptor.go b/relay/channel/deepseek/adaptor.go
index 9b89957..ed828b7 100644
--- a/relay/channel/deepseek/adaptor.go
+++ b/relay/channel/deepseek/adaptor.go
@@ -26,7 +26,7 @@ func (a *Adaptor) Init(info *common.RelayInfo) {
 }
 
 // GetRequestURL 构建上游请求 URL。
-// Completions(FIM) 模式使用 /beta/completions 端点，Responses 使用 /v1/responses，其余走标准 OpenAI 路径。
+// Completions(FIM) 模式使用 /beta/completions 端点，Responses 视渠道开关直连 /v1/responses 或转 chat，其余走标准 OpenAI 路径。
 func (a *Adaptor) GetRequestURL(info *common.RelayInfo) (string, error) {
 	baseURL := strings.TrimSuffix(info.ChannelMeta.BaseURL, "/")
 
@@ -41,8 +41,16 @@ func (a *Adaptor) GetRequestURL(info *common.RelayInfo) (string, error) {
 		return baseURL + "/v1/chat/completions", nil
 	case constant.RelayModeClaudeMessages:
 		return baseURL + "/anthropic/v1/messages", nil
-	case constant.RelayModeResponses:
-		return baseURL + "/v1/responses", nil
+	case constant.RelayModeResponses, constant.RelayModeResponsesCompact:
+		// 上游原生支持 Responses 协议（渠道开启 supports_responses）：直连 Responses 端点
+		if info.ChannelMeta.UpstreamSpeaksResponses() {
+			if constant.RelayMode(info.RelayMode) == constant.RelayModeResponsesCompact {
+				return baseURL + "/v1/responses/compact", nil
+			}
+			return baseURL + "/v1/responses", nil
+		}
+		// 兜底（chat-only 上游）：请求体先转 Chat Completions 格式再发送（与 openai.Adaptor 行为对齐）
+		return baseURL + "/v1/chat/completions", nil
 	case constant.RelayModeEmbeddings:
 		return baseURL + "/v1/embeddings", nil
 	default:
@@ -65,10 +73,14 @@ func (a *Adaptor) ConvertRequest(ctx context.Context, info *common.RelayInfo, re
 		return convertClaudeRequestForDeepSeek(requestBody, info)
 	}
 
-	// Responses 模式：处理 DeepSeek V4 的 reasoning_effort 映射
+	// Responses 模式：上游原生支持时保持 Responses 格式（模型映射 + reasoning.effort 注入）；
+	// chat-only 上游（渠道未开 supports_responses）先转 Chat 格式，再叠加 DeepSeek 特有适配
 	if constant.RelayMode(info.RelayMode) == constant.RelayModeResponses ||
 		constant.RelayMode(info.RelayMode) == constant.RelayModeResponsesCompact {
-		return convertResponsesRequestForDeepSeek(requestBody, info)
+		if info.ChannelMeta.UpstreamSpeaksResponses() {
+			return convertResponsesRequestForDeepSeek(requestBody, info)
+		}
+		return convertResponsesToChatForDeepSeek(requestBody, info)
 	}
 
 	// 非 OpenAI 格式先转换为 OpenAI
@@ -295,6 +307,35 @@ func convertResponsesRequestForDeepSeek(requestBody []byte, info *common.RelayIn
 	return bytes.NewReader(result), nil
 }
 
+// convertResponsesToChatForDeepSeek chat-only 上游兜底：将 Responses 请求转换为 Chat Completions 格式，
+// 再叠加 DeepSeek 特有适配（stream_options / 思考参数注入）。
+// 模型映射与 ResponsesRequest 快照（响应侧合成 Responses 格式时 echo 请求参数）由
+// ConvertResponsesToOpenAI 完成；思考后缀经 chat 侧 reasoning_effort 映射注入。
+func convertResponsesToChatForDeepSeek(requestBody []byte, info *common.RelayInfo) (io.Reader, error) {
+	converted, err := openai.ConvertResponsesToOpenAI(requestBody, info)
+	if err != nil {
+		return nil, err
+	}
+	chatBody, err := io.ReadAll(converted)
+	if err != nil {
+		return nil, fmt.Errorf("read converted chat body failed: %w", err)
+	}
+
+	var rawMap map[string]json.RawMessage
+	if err := json.Unmarshal(chatBody, &rawMap); err != nil {
+		return bytes.NewReader(chatBody), nil
+	}
+
+	rawMap = injectStreamOptions(rawMap, info)
+	rawMap = injectThinkingParams(rawMap, info)
+
+	result, err := json.Marshal(rawMap)
+	if err != nil {
+		return nil, fmt.Errorf("marshal converted request failed: %w", err)
+	}
+	return bytes.NewReader(result), nil
+}
+
 // injectResponsesReasoningEffort 为 Responses API 请求注入 DeepSeek reasoning.effort 参数。
 //
 // Responses API 用 reasoning.effort 而非 Chat API 的 reasoning_effort 顶层字段：
diff --git a/relay/channel/deepseek/adaptor_test.go b/relay/channel/deepseek/adaptor_test.go
new file mode 100644
index 0000000..6b3a24f
--- /dev/null
+++ b/relay/channel/deepseek/adaptor_test.go
@@ -0,0 +1,141 @@
+package deepseek
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"strings"
+	"testing"
+
+	"github.com/qianfree/team-api/relay/common"
+	"github.com/qianfree/team-api/relay/constant"
+)
+
+// deepseekResponsesInfo 构造 responses 入站的 DeepSeek 渠道 RelayInfo，
+// supportsResponses 控制渠道是否声明上游原生支持 Responses 协议。
+func deepseekResponsesInfo(supportsResponses bool) *common.RelayInfo {
+	return &common.RelayInfo{
+		RelayMode:       int(constant.RelayModeResponses),
+		IsStream:        true,
+		InboundFormat:   constant.RelayFormatResponses,
+		ClientFormat:    constant.RelayFormatResponses,
+		OriginModelName: "deepseek-v4-flash",
+		StreamStatus:    common.NewStreamStatus(),
+		ChannelMeta: &common.ChannelMeta{
+			ChannelType:       int(constant.ProviderDeepSeek),
+			BaseURL:           "https://api.deepseek.example.com",
+			UpstreamModelName: "deepseek-v4-flash",
+			IsModelMapped:     false,
+			SupportsResponses: supportsResponses,
+		},
+	}
+}
+
+// TestGetRequestURL_ResponsesFlagRouting responses 模式按渠道开关路由：
+// 开 → /v1/responses（compact → /v1/responses/compact），关 → /v1/chat/completions 兜底。
+func TestGetRequestURL_ResponsesFlagRouting(t *testing.T) {
+	cases := []struct {
+		name             string
+		mode             constant.RelayMode
+		supportsResponse bool
+		want             string
+	}{
+		{"responses_on", constant.RelayModeResponses, true, "https://api.deepseek.example.com/v1/responses"},
+		{"responses_compact_on", constant.RelayModeResponsesCompact, true, "https://api.deepseek.example.com/v1/responses/compact"},
+		{"responses_off", constant.RelayModeResponses, false, "https://api.deepseek.example.com/v1/chat/completions"},
+		{"responses_compact_off", constant.RelayModeResponsesCompact, false, "https://api.deepseek.example.com/v1/chat/completions"},
+	}
+	for _, c := range cases {
+		a := &Adaptor{}
+		info := deepseekResponsesInfo(c.supportsResponse)
+		info.RelayMode = int(c.mode)
+		got, err := a.GetRequestURL(info)
+		if err != nil {
+			t.Fatalf("GetRequestURL(%s) error: %v", c.name, err)
+		}
+		if got != c.want {
+			t.Errorf("GetRequestURL(%s) = %q, want %q", c.name, got, c.want)
+		}
+	}
+}
+
+const deepseekResponsesRequestBody = `{"model":"deepseek-v4-flash","instructions":"You are helpful.","input":[{"type":"message","role":"user","content":[{"type":"input_text","text":"你好"}]}],"stream":true}`
+
+// TestConvertRequest_ResponsesChatFallback 渠道未开 supports_responses 时，
+// Responses 请求必须转换为 Chat 格式（instructions→system、input→messages、stream 保留），
+// 不能再以 Responses 体直发 chat-only 上游。
+func TestConvertRequest_ResponsesChatFallback(t *testing.T) {
+	a := &Adaptor{}
+	info := deepseekResponsesInfo(false)
+	out, err := a.ConvertRequest(context.Background(), info, []byte(deepseekResponsesRequestBody))
+	if err != nil {
+		t.Fatalf("ConvertRequest error: %v", err)
+	}
+	raw, _ := io.ReadAll(out)
+	var m map[string]json.RawMessage
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatalf("converted body is not json: %v, body: %s", err, raw)
+	}
+
+	// Responses 专属字段必须消失，chat 专属字段必须存在
+	if _, ok := m["input"]; ok {
+		t.Error("input field should be converted to messages")
+	}
+	msgsRaw, ok := m["messages"]
+	if !ok {
+		t.Fatalf("messages field missing: %s", raw)
+	}
+
+	// instructions → system 消息，input → user 消息
+	var msgs []struct {
+		Role    string          `json:"role"`
+		Content json.RawMessage `json:"content"`
+	}
+	if err := json.Unmarshal(msgsRaw, &msgs); err != nil {
+		t.Fatalf("unmarshal messages: %v", err)
+	}
+	if len(msgs) != 2 {
+		t.Fatalf("messages len = %d, want 2 (system + user): %s", len(msgs), raw)
+	}
+	if msgs[0].Role != "system" || strings.TrimSpace(string(msgs[0].Content)) != `"You are helpful."` {
+		t.Errorf("first message should be system with instructions, got role=%s content=%s", msgs[0].Role, msgs[0].Content)
+	}
+	if msgs[1].Role != "user" || !strings.Contains(string(msgs[1].Content), "你好") {
+		t.Errorf("second message should be user with input text, got role=%s content=%s", msgs[1].Role, msgs[1].Content)
+	}
+
+	// stream 保留 + 注入 stream_options（usage 计费需要）
+	if string(m["stream"]) != "true" {
+		t.Errorf("stream should be preserved as true, got %s", m["stream"])
+	}
+	if _, ok := m["stream_options"]; !ok {
+		t.Errorf("stream_options should be injected for stream request: %s", raw)
+	}
+
+	// ResponsesRequest 快照需落 RelayInfo，供响应侧合成 Responses 格式时 echo
+	if info.ResponsesRequest == nil {
+		t.Error("info.ResponsesRequest snapshot should be stashed by conversion")
+	}
+}
+
+// TestConvertRequest_ResponsesUpstreamPassthrough 渠道开启 supports_responses 时，
+// 保持 Responses 格式直连（仅模型映射 + reasoning 注入），不得转成 chat 体。
+func TestConvertRequest_ResponsesUpstreamPassthrough(t *testing.T) {
+	a := &Adaptor{}
+	info := deepseekResponsesInfo(true)
+	out, err := a.ConvertRequest(context.Background(), info, []byte(deepseekResponsesRequestBody))
+	if err != nil {
+		t.Fatalf("ConvertRequest error: %v", err)
+	}
+	raw, _ := io.ReadAll(out)
+	var m map[string]json.RawMessage
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatalf("converted body is not json: %v, body: %s", err, raw)
+	}
+	if _, ok := m["input"]; !ok {
+		t.Errorf("input field should be preserved for responses-native upstream: %s", raw)
+	}
+	if _, ok := m["messages"]; ok {
+		t.Errorf("messages field should not appear for responses-native upstream: %s", raw)
+	}
+}
diff --git a/relay/channel/openai/adaptor_responses_test.go b/relay/channel/openai/adaptor_responses_test.go
index fd797a2..87d9b90 100644
--- a/relay/channel/openai/adaptor_responses_test.go
+++ b/relay/channel/openai/adaptor_responses_test.go
@@ -698,9 +698,90 @@ func TestAdaptor_DoResponse_ResponsesInboundStream_EmbeddedErrorMidStream(t *tes
 	}
 }
 
+// TestAdaptor_DoResponse_ResponsesInboundStream_UpstreamResponsesSSE
+// 上游返回 Responses 格式 SSE（渠道误配为 chat-only 但上游实际说 Responses 的典型形态）：
+// 每个 data 行都能解析为"空 chat chunk"，绝不能静默合成空 response.completed 假成功，
+// 必须返回 502 upstream error（此时已发过前置事件，无法回写错误体）。
+func TestAdaptor_DoResponse_ResponsesInboundStream_UpstreamResponsesSSE(t *testing.T) {
+	ss := strings.Join([]string{
+		`data: {"type":"response.created","response":{"id":"resp_1"}}`,
+		"",
+		`data: {"type":"response.output_text.delta","item_id":"msg_1","delta":"Hi"}`,
+		"",
+		`data: {"type":"response.completed","response":{"id":"resp_1","usage":{"input_tokens":10,"output_tokens":5,"total_tokens":15}}}`,
+		"",
+	}, "\n")
+	resp := &http.Response{
+		StatusCode: http.StatusOK,
+		Header:     http.Header{"Content-Type": {"text/event-stream"}},
+		Body:       io.NopCloser(strings.NewReader(ss)),
+	}
+
+	info := responsesInboundInfo(true)
+	rec := httptest.NewRecorder()
+	a := &Adaptor{}
+	usage, err := a.DoResponse(context.Background(), resp, info, rec)
+	if err == nil {
+		t.Fatal("non-chat upstream stream should return an upstream error, got nil")
+	}
+	if usage == nil {
+		t.Fatal("usage should be non-nil for error path")
+	}
+	var relayErr *constant.RelayError
+	if !errors.As(err, &relayErr) {
+		t.Fatalf("error should be *constant.RelayError, got %T", err)
+	}
+	if relayErr.StatusCode != http.StatusBadGateway {
+		t.Errorf("status code = %d, want %d", relayErr.StatusCode, http.StatusBadGateway)
+	}
+	out := rec.Body.String()
+	// 首个"空 chunk"触发的 created 系列事件可以保留，但不得合成假成功、不得转发 Responses delta
+	if strings.Contains(out, "response.completed") {
+		t.Errorf("should not synthesize empty response.completed:\n%s", out)
+	}
+	if strings.Contains(out, `"delta":"Hi"`) {
+		t.Errorf("upstream responses delta must not be forwarded as chat delta:\n%s", out)
+	}
+}
+
+// TestAdaptor_DoResponse_ResponsesInboundStream_NonSSEJSONBody
+// 上游 200 但返回非流式 JSON 体（无 data: 行）：应向客户端写入 502 错误并返回 upstream error，
+// 而不是合成空 response.completed。
+func TestAdaptor_DoResponse_ResponsesInboundStream_NonSSEJSONBody(t *testing.T) {
+	body := `{"id":"chatcmpl-1","object":"chat.completion","choices":[{"message":{"role":"assistant","content":"Hi"}}],"usage":{"prompt_tokens":5,"completion_tokens":2,"total_tokens":7}}`
+	resp := &http.Response{
+		StatusCode: http.StatusOK,
+		Header:     http.Header{"Content-Type": {"application/json"}},
+		Body:       io.NopCloser(strings.NewReader(body)),
+	}
+
+	info := responsesInboundInfo(true)
+	rec := httptest.NewRecorder()
+	a := &Adaptor{}
+	_, err := a.DoResponse(context.Background(), resp, info, rec)
+	if err == nil {
+		t.Fatal("non-SSE upstream body should return an upstream error, got nil")
+	}
+	var relayErr *constant.RelayError
+	if !errors.As(err, &relayErr) {
+		t.Fatalf("error should be *constant.RelayError, got %T", err)
+	}
+	if !relayErr.ResponseWritten {
+		t.Error("ResponseWritten should be true after writing error body to client")
+	}
+	// SetEventStreamHeaders 已提前提交 HTTP 200，状态码无法改写为 502；
+	// 但错误体必须写入（客户端可见明确错误而非空 SSE 流）
+	if !strings.Contains(rec.Body.String(), "upstream_protocol_mismatch") {
+		t.Errorf("error body should contain protocol mismatch code: %s", rec.Body.String())
+	}
+	if strings.Contains(rec.Body.String(), "response.completed") {
+		t.Errorf("should not synthesize empty response.completed: %s", rec.Body.String())
+	}
+}
+
 // TestAdaptor_DoResponse_ResponsesInboundStream_UnparseableChunks
 // 上游 data 行全部无法解析为 chat chunk（如返回了非 chat 格式）：
-// 保持既有兜底行为（合成空 response.completed、不报错），但不再静默无痕。
+// 不再合成空 response.completed 假成功，必须返回 upstream error 并向客户端写入错误体。
 func TestAdaptor_DoResponse_ResponsesInboundStream_UnparseableChunks(t *testing.T) {
 	ss := strings.Join([]string{
 		"data: {invalid json",
@@ -718,13 +799,23 @@ func TestAdaptor_DoResponse_ResponsesInboundStream_UnparseableChunks(t *testing.
 	rec := httptest.NewRecorder()
 	a := &Adaptor{}
 	usage, err := a.DoResponse(context.Background(), resp, info, rec)
-	if err != nil {
-		t.Fatalf("unparseable chunks keep fallback behavior, unexpected error: %v", err)
-	}
-	if !strings.Contains(rec.Body.String(), "response.completed") {
-		t.Errorf("fallback response.completed missing:\n%s", rec.Body.String())
+	if err == nil {
+		t.Fatal("unparseable non-chat stream should return an upstream error, got nil")
 	}
 	if usage == nil {
 		t.Fatal("usage should be non-nil")
 	}
+	var relayErr *constant.RelayError
+	if !errors.As(err, &relayErr) {
+		t.Fatalf("error should be *constant.RelayError, got %T", err)
+	}
+	if !relayErr.ResponseWritten {
+		t.Error("ResponseWritten should be true after writing error body to client")
+	}
+	if strings.Contains(rec.Body.String(), "response.completed") {
+		t.Errorf("should not synthesize empty response.completed:\n%s", rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), "upstream_protocol_mismatch") {
+		t.Errorf("error body should contain protocol mismatch code: %s", rec.Body.String())
+	}
 }
diff --git a/relay/channel/openai/converter.go b/relay/channel/openai/converter.go
index 36a1d78..705ae24 100644
--- a/relay/channel/openai/converter.go
+++ b/relay/channel/openai/converter.go
@@ -714,6 +714,9 @@ type r2cInputItem struct {
 	CallID  string          `json:"call_id,omitempty"`
 	Output  string          `json:"output,omitempty"`
 	Text    string          `json:"text,omitempty"`
+	// function_call 项字段（Responses 历史中的助手工具调用）
+	Name      string `json:"name,omitempty"`
+	Arguments string `json:"arguments,omitempty"`
 }
 
 type r2cContentPart struct {
@@ -749,6 +752,16 @@ func r2cConvertInputToMessages(input json.RawMessage) ([]map[string]any, error)
 		return nil, fmt.Errorf("input must be string or array: %w", err)
 	}
 	messages := make([]map[string]any, 0, len(items))
+	// 连续的 function_call 项聚合为一条 assistant 消息（chat 协议的 tool_calls 数组语义），
+	// 其后的 function_call_output 转为引用对应 tool_call_id 的 tool 消息
+	var pendingToolCalls []map[string]any
+	flushToolCalls := func() {
+		if len(pendingToolCalls) == 0 {
+			return
+		}
+		messages = append(messages, map[string]any{"role": "assistant", "content": nil, "tool_calls": pendingToolCalls})
+		pendingToolCalls = nil
+	}
 	for _, raw := range items {
 		var item r2cInputItem
 		if err := json.Unmarshal(raw, &item); err != nil {
@@ -756,12 +769,31 @@ func r2cConvertInputToMessages(input json.RawMessage) ([]map[string]any, error)
 		}
 		switch item.Type {
 		case "message":
+			flushToolCalls()
 			if msg := r2cConvertMessage(item); msg != nil {
 				messages = append(messages, msg)
 			}
+		case "function_call":
+			// 历史中的助手工具调用：转为 assistant.tool_calls 条目，id 用 call_id（与 tool 消息的 tool_call_id 对应）
+			if item.CallID == "" && item.Name == "" {
+				continue
+			}
+			pendingToolCalls = append(pendingToolCalls, map[string]any{
+				"id":   item.CallID,
+				"type": "function",
+				"function": map[string]any{
+					"name":      item.Name,
+					"arguments": item.Arguments,
+				},
+			})
 		case "function_call_output":
+			flushToolCalls()
 			messages = append(messages, map[string]any{"role": "tool", "tool_call_id": item.CallID, "content": item.Output})
+		case "reasoning":
+			// reasoning 项（含加密思考内容）无 chat 协议对应物，跳过
+			continue
 		default:
+			flushToolCalls()
 			if item.Role != "" {
 				if msg := r2cConvertMessage(item); msg != nil {
 					messages = append(messages, msg)
@@ -769,6 +801,7 @@ func r2cConvertInputToMessages(input json.RawMessage) ([]map[string]any, error)
 			}
 		}
 	}
+	flushToolCalls()
 	return messages, nil
 }
 
@@ -777,6 +810,11 @@ func r2cConvertMessage(item r2cInputItem) map[string]any {
 	if role == "" {
 		role = "user"
 	}
+	// Responses 的 developer 角色（OpenAI 新式系统提示，codex 等客户端常用）
+	// 多数第三方 chat 上游不识别（serde 严格校验直接拒绝），统一映射为 system
+	if role == "developer" {
+		role = "system"
+	}
 	if len(item.Content) == 0 {
 		return nil
 	}
diff --git a/relay/channel/openai/converter_test.go b/relay/channel/openai/converter_test.go
index cab7c47..699976f 100644
--- a/relay/channel/openai/converter_test.go
+++ b/relay/channel/openai/converter_test.go
@@ -436,6 +436,89 @@ func TestConvertResponsesToOpenAI_InputAudioAndFile(t *testing.T) {
 	}
 }
 
+// TestConvertResponsesToOpenAI_DeveloperRoleMappedToSystem codex 等客户端会在 input 中
+// 发送 developer 角色消息（新式系统提示）；第三方 chat 上游（serde 严格校验）不识别该角色，
+// 必须映射为 system，否则上游直接拒绝整个请求体。
+func TestConvertResponsesToOpenAI_DeveloperRoleMappedToSystem(t *testing.T) {
+	info := &common.RelayInfo{ChannelMeta: &common.ChannelMeta{}}
+	body := []byte(`{"model":"deepseek-v4-flash","instructions":"You are helpful.",` +
+		`"input":[{"type":"message","role":"developer","content":[{"type":"input_text","text":"You are a coding agent."}]},` +
+		`{"type":"message","role":"user","content":[{"type":"input_text","text":"hi"}]}],"stream":true}`)
+	out, err := ConvertResponsesToOpenAI(body, info)
+	if err != nil {
+		t.Fatalf("ConvertResponsesToOpenAI: %v", err)
+	}
+	raw, _ := io.ReadAll(out)
+	var m map[string]any
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatalf("bad json: %v\n%s", err, raw)
+	}
+	msgs, _ := m["messages"].([]any)
+	if len(msgs) != 3 {
+		t.Fatalf("messages = %v, want 3 (instructions→system + developer→system + user)", msgs)
+	}
+	for i, want := range []string{"system", "system", "user"} {
+		msg := msgs[i].(map[string]any)
+		if got := msg["role"]; got != want {
+			t.Errorf("messages[%d].role = %v, want %q", i, got, want)
+		}
+	}
+}
+
+// TestConvertResponsesToOpenAI_FunctionCallHistory codex 多轮会把历史 function_call /
+// function_call_output / reasoning 项放进 input：function_call 需聚合为 assistant.tool_calls
+// （其后的 tool 消息才有对应的 tool_call_id），reasoning 项直接跳过。
+func TestConvertResponsesToOpenAI_FunctionCallHistory(t *testing.T) {
+	info := &common.RelayInfo{ChannelMeta: &common.ChannelMeta{}}
+	body := []byte(`{"model":"deepseek-v4-flash","input":[` +
+		`{"type":"message","role":"user","content":[{"type":"input_text","text":"list files"}]},` +
+		`{"type":"reasoning","summary":[]},` +
+		`{"type":"function_call","call_id":"call_a","name":"shell","arguments":"{\"cmd\":\"ls\"}"},` +
+		`{"type":"function_call","call_id":"call_b","name":"read","arguments":"{\"path\":\"a.go\"}"},` +
+		`{"type":"function_call_output","call_id":"call_a","output":"a.go b.go"},` +
+		`{"type":"function_call_output","call_id":"call_b","output":"package main"}` +
+		`]}`)
+	out, err := ConvertResponsesToOpenAI(body, info)
+	if err != nil {
+		t.Fatalf("ConvertResponsesToOpenAI: %v", err)
+	}
+	raw, _ := io.ReadAll(out)
+	var m map[string]any
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatalf("bad json: %v\n%s", err, raw)
+	}
+	msgs, _ := m["messages"].([]any)
+	if len(msgs) != 4 {
+		t.Fatalf("messages = %v, want 4 (user + assistant[2 calls] + tool + tool)", msgs)
+	}
+
+	// 连续两条 function_call 聚合为一条 assistant 消息
+	assistant := msgs[1].(map[string]any)
+	if assistant["role"] != "assistant" {
+		t.Fatalf("messages[1].role = %v, want assistant", assistant["role"])
+	}
+	calls, _ := assistant["tool_calls"].([]any)
+	if len(calls) != 2 {
+		t.Fatalf("tool_calls = %v, want 2 aggregated calls", calls)
+	}
+	first, _ := calls[0].(map[string]any)
+	if first["id"] != "call_a" || first["type"] != "function" {
+		t.Errorf("tool_calls[0] = %v", first)
+	}
+	fn, _ := first["function"].(map[string]any)
+	if fn["name"] != "shell" || fn["arguments"] != `{"cmd":"ls"}` {
+		t.Errorf("tool_calls[0].function = %v", fn)
+	}
+
+	// function_call_output → tool 消息，tool_call_id 与聚合条目对应
+	for i, wantID := range []string{"call_a", "call_b"} {
+		tool := msgs[2+i].(map[string]any)
+		if tool["role"] != "tool" || tool["tool_call_id"] != wantID {
+			t.Errorf("messages[%d] = %v, want tool with tool_call_id=%s", 2+i, tool, wantID)
+		}
+	}
+}
+
 // TestConvertOpenAIToResponses_TextFormatUnpack chat response_format 转 Responses
 // text.format：json_schema 需解包为扁平结构（不能原样塞入嵌套形状）。
 func TestConvertOpenAIToResponses_TextFormatUnpack(t *testing.T) {
diff --git a/relay/channel/openai/responses.go b/relay/channel/openai/responses.go
index 625ed09..84ee7e8 100644
--- a/relay/channel/openai/responses.go
+++ b/relay/channel/openai/responses.go
@@ -233,6 +233,7 @@ func (a *Adaptor) handleResponsesInboundStream(ctx context.Context, resp *http.R
 	sentCreated := false
 	sentTextDone := false
 	parsedChunks := 0
+	sawChoices := false
 	outputIndex := 0
 	contentIndex := 0
 	toolCallIndexByID := make(map[string]int)
@@ -297,6 +298,9 @@ func (a *Adaptor) handleResponsesInboundStream(ctx context.Context, resp *http.R
 			continue
 		}
 		parsedChunks++
+		if len(chunk.Choices) > 0 {
+			sawChoices = true
+		}
 
 		// 第一个 chunk：发送 response.created + output_item.added + content_part.added
 		if !sentCreated {
@@ -549,12 +553,32 @@ func (a *Adaptor) handleResponsesInboundStream(ctx context.Context, resp *http.R
 		}
 	}
 
-	// 上游零有效 chunk 时不再静默合成空响应：记录告警便于定位
-	// （上游返回非 SSE 体 / 非 chat 格式 / 空 body / 纯 [DONE] 等异常都会走到这里）
-	if !sentCreated {
+	// 上游流始终不是 chat 格式（全程无 choices 且无内容/工具调用/usage）时不再静默合成空响应：
+	// 典型形态包括 Responses/Claude 格式 SSE（JSON 能解析为空 chat chunk）、非流式 JSON 体、空 body 等。
+	// 假成功的空 response.completed 会让客户端"成功但无内容"，必须报错驱动重试换渠道/健康上报。
+	if !sawChoices && contentBuilder.Len() == 0 && len(toolCallIndexByID) == 0 && usage.TotalTokens == 0 {
+		errUpstream := fmt.Errorf("upstream stream is not chat completions format: %d chunks parsed, none contained choices", parsedChunks)
 		g.Log().Warningf(ctx,
-			"[OpenAI.handleResponsesInboundStream] upstream stream yielded no parseable chat chunks (parsed=%d), synthesizing empty response.completed: channel=%d(%s) model=%s request_id=%s",
-			parsedChunks, info.ChannelMeta.ChannelID, info.ChannelMeta.ChannelName, info.OriginModelName, info.RequestID)
+			"[OpenAI.handleResponsesInboundStream] %v: channel=%d(%s) model=%s request_id=%s",
+			errUpstream, info.ChannelMeta.ChannelID, info.ChannelMeta.ChannelName, info.OriginModelName, info.RequestID)
+		info.StreamStatus.SetEndReason(common.StreamEndReasonError, errUpstream)
+		if !sentCreated {
+			// 尚未向客户端发送任何事件：写入错误响应（与 SSE 开始前的非 200 分支行为一致）
+			errBody, _ := json.Marshal(map[string]any{
+				"error": map[string]any{
+					"message": "upstream returned a non-chat-completions stream",
+					"type":    "upstream_error",
+					"param":   nil,
+					"code":    "upstream_protocol_mismatch",
+				},
+			})
+			writeUpstreamErrorResponse(writer, http.StatusBadGateway, errBody)
+			upstreamErr := constant.NewUpstreamError(http.StatusBadGateway, string(errBody), nil)
+			upstreamErr.ResponseWritten = true
+			return &usage, upstreamErr
+		}
+		// 已发送部分事件：流已污染无法回写错误体，直接返回错误终止处理
+		return &usage, constant.NewUpstreamError(http.StatusBadGateway, errUpstream.Error(), nil)
 	}
 
 	// 估算 usage（正常结束 4 字符/token；scanner 异常等部分传输场景 2 字符/token）