fix(openai): 保留 Responses Lite namespace 调用

backend/internal/service/openai_responses_namespace.go

@@ -78,8 +78,9 @@ func shouldStripOpenAIResponsesInputNamespaces(account *Account, transport OpenA
 //   - compact 端点的 schema 不含该字段，携带即 400 `Unknown parameter:
 //     input[N].namespace`（issue #4761 正文），故 compact 一律清理。
 //   - API Key 出口默认按标准 Responses API 处理并清理该字段；但当请求本身声明
-//     namespace 工具时，上游显然使用了 namespace 扩展，此时必须保留调用项上的
-//     namespace，否则声明与历史调用会失配并触发 Missing namespace。
+//     namespace 工具时（包括 Responses Lite 的 input[].additional_tools），上游显然
+//     使用了 namespace 扩展，此时必须保留调用项上的 namespace，否则声明与历史
+//     调用会失配并触发 Missing namespace。
 //   - 摊平模式下调用项已被改写成平名，残留 namespace 指向的声明已不存在，一律清理。
 func shouldKeepOpenAIResponsesToolCallNamespaces(
 	account *Account,
@@ -104,13 +105,39 @@ func shouldKeepOpenAIResponsesToolCallNamespaces(
 }
 
 func hasOpenAIResponsesNamespaceToolDeclaration(body []byte) bool {
-	tools := gjson.GetBytes(body, "tools")
-	if !tools.IsArray() {
+	hasNamespaceTool := func(tools gjson.Result) bool {
+		if !tools.IsArray() {
+			return false
+		}
+		found := false
+		tools.ForEach(func(_, tool gjson.Result) bool {
+			if strings.EqualFold(strings.TrimSpace(tool.Get("type").String()), "namespace") {
+				found = true
+				return false
+			}
+			return true
+		})
+		return found
+	}
+
+	if hasNamespaceTool(gjson.GetBytes(body, "tools")) {
+		return true
+	}
+
+	// Responses Lite moves private namespace declarations out of top-level
+	// tools and into an input.additional_tools carrier. API-key requests are
+	// intentionally not rewritten by normalizeOpenAIResponsesLiteTools, so the
+	// declaration can arrive here only in this form.
+	input := gjson.GetBytes(body, "input")
+	if !input.IsArray() {
 		return false
 	}
 	found := false
-	tools.ForEach(func(_, tool gjson.Result) bool {
-		if strings.EqualFold(strings.TrimSpace(tool.Get("type").String()), "namespace") {
+	input.ForEach(func(_, item gjson.Result) bool {
+		if !strings.EqualFold(strings.TrimSpace(item.Get("type").String()), "additional_tools") {
+			return true
+		}
+		if hasNamespaceTool(item.Get("tools")) {
 			found = true
 			return false
 		}

backend/internal/service/openai_responses_namespace_forward_test.go

@@ -89,6 +89,41 @@ func TestOpenAIGatewayService_APIKeyPreservesDeclaredNamespaceToolCalls(t *testi
 	require.False(t, gjson.GetBytes(forwarded, "input.1.namespace").Exists())
 }
 
+// Responses Lite 把 namespace 声明放在 input.additional_tools，而不是顶层 tools。
+// OpenAI API Key 走该请求形态时也必须保留历史 function_call.namespace。
+func TestOpenAIGatewayService_APIKeyPreservesLiteDeclaredNamespaceToolCalls(t *testing.T) {
+	body := []byte(`{
+		"model":"gpt-5.6-terra",
+		"stream":false,
+		"input":[
+			{"type":"function_call","namespace":"mcp__cua_repl","name":"js","call_id":"call_js","arguments":"{}"},
+			{"type":"message","role":"user","namespace":"leftover","content":[{"type":"input_text","text":"hello"}]},
+			{"type":"additional_tools","role":"developer","tools":[
+				{"type":"namespace","name":"mcp__cua_repl","tools":[{"type":"function","name":"js","parameters":{"type":"object"}}]}
+			]}
+		]
+	}`)
+	upstream := &httpUpstreamRecorder{responses: []*http.Response{
+		newOpenAIRejectedFieldTestResponse(http.StatusOK, namespaceForwardOKResponse),
+	}}
+	c := newOpenAIRejectedFieldTestContext(body)
+	c.Request.Header.Set(responsesLiteHeader, "true")
+
+	result, err := newOpenAIRejectedFieldTestService(upstream).Forward(
+		context.Background(), c, newOpenAIRejectedFieldTestAccount(), body,
+	)
+
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.Len(t, upstream.bodies, 1)
+	forwarded := upstream.bodies[0]
+
+	require.True(t, gjson.GetBytes(forwarded, `input.#(type=="additional_tools").tools.#(type=="namespace")`).Exists())
+	require.Equal(t, "mcp__cua_repl", gjson.GetBytes(forwarded, "input.0.namespace").String())
+	require.Equal(t, "js", gjson.GetBytes(forwarded, "input.0.name").String())
+	require.False(t, gjson.GetBytes(forwarded, "input.1.namespace").Exists())
+}
+
 // compact 端点 schema 更窄：input[].namespace 会 400 Unknown parameter（issue #4761），
 // 且没有证据表明它接受 namespace 工具声明。compact 只做历史摘要、不需要模型寻址工具，
 // 因此保持既有的摊平 + 全量清理行为，不随默认值翻转扩大风险面。

backend/internal/service/openai_responses_namespace_test.go

@@ -98,6 +98,9 @@ func TestShouldKeepOpenAIResponsesToolCallNamespaces(t *testing.T) {
 		{name: "apikey_without_namespace_tool_strips", account: apiKey, transport: OpenAIUpstreamTransportHTTPSSE, want: false},
 		{name: "apikey_with_namespace_tool_keeps", account: apiKey, transport: OpenAIUpstreamTransportHTTPSSE, body: []byte(`{"tools":[{"type":"namespace","name":"mcp__codex_app","tools":[]}]}`), want: true},
 		{name: "apikey_with_mixed_case_namespace_tool_keeps", account: apiKey, transport: OpenAIUpstreamTransportHTTPSSE, body: []byte(`{"tools":[{"type":" Namespace ","name":"mcp__codex_app","tools":[]}]}`), want: true},
+		{name: "apikey_with_lite_additional_namespace_tool_keeps", account: apiKey, transport: OpenAIUpstreamTransportHTTPSSE, body: []byte(`{"input":[{"type":"additional_tools","role":"developer","tools":[{"type":"namespace","name":"mcp__cua_repl","tools":[{"type":"function","name":"js"}]}]}]}`), want: true},
+		{name: "apikey_with_mixed_case_lite_carrier_keeps", account: apiKey, transport: OpenAIUpstreamTransportHTTPSSE, body: []byte(`{"input":[{"type":" Additional_Tools ","tools":[{"type":" Namespace ","name":"mcp__cua_repl","tools":[]}]}]}`), want: true},
+		{name: "apikey_with_lite_function_only_strips", account: apiKey, transport: OpenAIUpstreamTransportHTTPSSE, body: []byte(`{"input":[{"type":"additional_tools","tools":[{"type":"function","name":"js","namespace":"mcp__cua_repl"}]}]}`), want: false},
 		{name: "apikey_function_tool_with_namespace_field_strips", account: apiKey, transport: OpenAIUpstreamTransportHTTPSSE, body: []byte(`{"tools":[{"type":"function","name":"automation_update","namespace":"mcp__codex_app"}]}`), want: false},
 		{name: "apikey_compact_with_namespace_tool_strips", account: apiKey, transport: OpenAIUpstreamTransportHTTPSSE, compactPath: true, body: []byte(`{"tools":[{"type":"namespace","name":"mcp__codex_app","tools":[]}]}`), want: false},
 		{name: "setup_token_keeps", account: setupToken, transport: OpenAIUpstreamTransportHTTPSSE, want: true},