diff --git a/server/src/test/java/com/rocketmq/studio/cluster/client/ClientControllerTest.java b/server/src/test/java/com/rocketmq/studio/cluster/client/ClientControllerTest.java
new file mode 100644
index 00000000..43e0a110
--- /dev/null
+++ b/server/src/test/java/com/rocketmq/studio/cluster/client/ClientControllerTest.java
@@ -0,0 +1,104 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.rocketmq.studio.cluster.client;
+
+import com.rocketmq.studio.common.domain.enums.ClientLanguage;
+import com.rocketmq.studio.common.domain.enums.ClientType;
+import com.rocketmq.studio.common.domain.enums.Protocol;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.test.web.servlet.MockMvc;
+
+import java.time.LocalDateTime;
+import java.util.List;
+
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+@WebMvcTest(ClientController.class)
+@AutoConfigureMockMvc(addFilters = false)
+class ClientControllerTest {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @MockBean
+    private ClientService clientService;
+
+    @Test
+    void listConnectionsShouldReturnProtocolAwareClientRows() throws Exception {
+        ClientConnectionVO grpcClient = ClientConnectionVO.builder()
+                .clientId("grpc-client-001")
+                .type(ClientType.Consumer)
+                .groupOrTopic("cg-order")
+                .protocol(Protocol.gRPC)
+                .address("10.0.0.1:8081")
+                .language(ClientLanguage.Java)
+                .version("5.1.0")
+                .connectedAt(LocalDateTime.of(2026, 1, 1, 12, 0))
+                .clusterName("production-cluster")
+                .build();
+        ClientConnectionVO remotingClient = ClientConnectionVO.builder()
+                .clientId("remoting-client-001")
+                .type(ClientType.Producer)
+                .groupOrTopic("order-topic")
+                .protocol(Protocol.Remoting)
+                .address("10.0.0.2:10911")
+                .language(ClientLanguage.Go)
+                .version("4.9.8")
+                .connectedAt(LocalDateTime.of(2026, 1, 1, 12, 5))
+                .clusterName("production-cluster")
+                .build();
+        when(clientService.listConnections(null, null)).thenReturn(List.of(grpcClient, remotingClient));
+
+        mockMvc.perform(get("/api/clients"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.code").value(200))
+                .andExpect(jsonPath("$.data").isArray())
+                .andExpect(jsonPath("$.data[0].clientId").value("grpc-client-001"))
+                .andExpect(jsonPath("$.data[0].type").value("Consumer"))
+                .andExpect(jsonPath("$.data[0].protocol").value("gRPC"))
+                .andExpect(jsonPath("$.data[0].language").value("Java"))
+                .andExpect(jsonPath("$.data[0].version").value("5.1.0"))
+                .andExpect(jsonPath("$.data[1].clientId").value("remoting-client-001"))
+                .andExpect(jsonPath("$.data[1].type").value("Producer"))
+                .andExpect(jsonPath("$.data[1].protocol").value("Remoting"));
+
+        verify(clientService).listConnections(null, null);
+    }
+
+    @Test
+    void listConnectionsShouldPassClusterAndTypeFilters() throws Exception {
+        when(clientService.listConnections("production-cluster", "Consumer")).thenReturn(List.of());
+
+        mockMvc.perform(get("/api/clients")
+                        .param("clusterId", "production-cluster")
+                        .param("type", "Consumer"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.code").value(200))
+                .andExpect(jsonPath("$.data").isArray())
+                .andExpect(jsonPath("$.data").isEmpty());
+
+        verify(clientService).listConnections("production-cluster", "Consumer");
+    }
+}