diff --git a/src/client/ollama.rs b/src/client/ollama.rs
index 332fb2b..ba4a51b 100644
--- a/src/client/ollama.rs
+++ b/src/client/ollama.rs
@@ -92,10 +92,11 @@ impl OllamaClient {
             let status = response.status().as_u16();
             let body = response.text().await.unwrap_or_default();
             error!("Ollama chat failed with status {}: {}", status, body);
-            return Err(NodeTokenError::Ollama(format!(
-                "Chat failed: HTTP {} - {}",
-                status, body
-            )));
+            // 用 HttpError 保留 status code, 让 executor 据此判断 is_client_error (B1 修复支撑)
+            return Err(NodeTokenError::HttpError {
+                status,
+                message: body,
+            });
         }
 
         let chat_response: OllamaChatResponse = response.json().await.map_err(|e| {
diff --git a/src/protocol/types.rs b/src/protocol/types.rs
index 9b6a08c..47aa55a 100644
--- a/src/protocol/types.rs
+++ b/src/protocol/types.rs
@@ -202,6 +202,10 @@ pub enum NodeTaskResult {
         code: String,
         /// 错误消息
         message: String,
+        /// 该失败是否由请求本身的问题引起(如模型不支持、参数非法)。
+        /// 老 server 忽略该字段时仍按通常失败处理, 保留向后兼容。
+        #[serde(default)]
+        is_client_error: bool,
     },
 }
 
@@ -709,6 +713,7 @@ mod tests {
             result: NodeTaskResult::Failed {
                 code: "ollama_error".to_string(),
                 message: "Model not found".to_string(),
+                is_client_error: false,
             },
         };
         let json = serde_json::to_string(&req).unwrap();
@@ -718,9 +723,14 @@ mod tests {
         assert_eq!(parsed.protocol_version, "node.v1");
         assert_eq!(parsed.task_id, task_id);
         match parsed.result {
-            NodeTaskResult::Failed { code, message } => {
+            NodeTaskResult::Failed {
+                code,
+                message,
+                is_client_error,
+            } => {
                 assert_eq!(code, "ollama_error");
                 assert_eq!(message, "Model not found");
+                assert!(!is_client_error);
             }
             NodeTaskResult::Succeeded { .. } => panic!("Expected Failed variant"),
         }
diff --git a/src/runtime/executor.rs b/src/runtime/executor.rs
index 9834de3..3ee8c82 100644
--- a/src/runtime/executor.rs
+++ b/src/runtime/executor.rs
@@ -86,10 +86,7 @@ impl TaskExecutor {
             }
             Err(e) => {
                 error!("Task {} execution failed: {}", task_id, e);
-                NodeTaskResult::Failed {
-                    code: "ollama_error".to_string(),
-                    message: e.to_string(),
-                }
+                classify_ollama_error(&e)
             }
         };
 
@@ -307,6 +304,32 @@ impl TaskExecutor {
     }
 }
 
+/// 把 Ollama 调用错误分类成 NodeTaskResult, 携带 is_client_error 标志:
+/// - Ollama 4xx (如 "model does not support chat") → is_client_error=true
+///   服务端会立即 terminal failed, 不计入 node failure_count
+/// - Ollama 5xx / 网络错 → is_client_error=false (默认行为, requeue + 失败计数)
+fn classify_ollama_error(err: &NodeTokenError) -> NodeTaskResult {
+    let (code, message, is_client_error) = match err {
+        NodeTokenError::HttpError { status, message } if (400..500).contains(status) => (
+            format!("ollama_http_{}", status),
+            message.clone(),
+            true,
+        ),
+        NodeTokenError::HttpError { status, message } => (
+            format!("ollama_http_{}", status),
+            message.clone(),
+            false,
+        ),
+        NodeTokenError::Network(e) => ("ollama_network".to_string(), e.to_string(), false),
+        other => ("ollama_error".to_string(), other.to_string(), false),
+    };
+    NodeTaskResult::Failed {
+        code,
+        message,
+        is_client_error,
+    }
+}
+
 // 实现 Clone 以便在 tokio::spawn 中使用
 impl Clone for TaskExecutor {
     fn clone(&self) -> Self {
@@ -604,18 +627,59 @@ mod tests {
         let result = NodeTaskResult::Failed {
             code: "ollama_error".to_string(),
             message: error_msg.to_string(),
+            is_client_error: false,
         };
 
         // 验证结果结构
         match result {
-            NodeTaskResult::Failed { code, message } => {
+            NodeTaskResult::Failed {
+                code,
+                message,
+                is_client_error,
+            } => {
                 assert_eq!(code, "ollama_error");
                 assert_eq!(message, error_msg);
+                assert!(!is_client_error);
             }
             NodeTaskResult::Succeeded { .. } => panic!("Expected Failed variant"),
         }
     }
 
+    /// B1 修复回归: HTTP 4xx 应被分类为 is_client_error=true
+    #[test]
+    fn test_classify_ollama_4xx_is_client_error() {
+        let err = NodeTokenError::HttpError {
+            status: 400,
+            message: "model does not support chat".to_string(),
+        };
+        match classify_ollama_error(&err) {
+            NodeTaskResult::Failed {
+                is_client_error,
+                code,
+                ..
+            } => {
+                assert!(is_client_error, "4xx must mark is_client_error=true");
+                assert_eq!(code, "ollama_http_400");
+            }
+            _ => panic!("expected Failed"),
+        }
+    }
+
+    /// HTTP 5xx 应是节点错, is_client_error=false (保持现有 retry 行为)
+    #[test]
+    fn test_classify_ollama_5xx_is_not_client_error() {
+        let err = NodeTokenError::HttpError {
+            status: 503,
+            message: "service unavailable".to_string(),
+        };
+        match classify_ollama_error(&err) {
+            NodeTaskResult::Failed {
+                is_client_error, ..
+            } => assert!(!is_client_error),
+            _ => panic!("expected Failed"),
+        }
+    }
+
     #[test]
     /// 验证任务 deadline 和 grace period 的计算逻辑
     fn test_task_deadline_and_grace_period() {
diff --git a/tests/integration_error_scenarios.rs b/tests/integration_error_scenarios.rs
index 2664999..ebd8de3 100644
--- a/tests/integration_error_scenarios.rs
+++ b/tests/integration_error_scenarios.rs
@@ -109,7 +109,7 @@ async fn test_ollama_connection_failure() {
     // 验证连接失败
     assert!(result.is_err(), "Ollama 连接应该失败");
 
-    // 验证错误信息（可能是 Ollama 错误或 HTTP 错误）
+    // 验证错误信息（HttpError / Ollama / 状态码任一种描述都接受）
     let error_msg = format!("{:?}", result.unwrap_err());
     assert!(
         error_msg.contains("connection")
@@ -117,7 +117,9 @@ async fn test_ollama_connection_failure() {
             || error_msg.contains("Connection")
             || error_msg.contains("Ollama")
             || error_msg.contains("503")
-            || error_msg.contains("HTTP"),
+            || error_msg.contains("502")
+            || error_msg.contains("HTTP")
+            || error_msg.contains("HttpError"),
         "错误信息应该包含 Ollama 或连接失败描述: {}",
         error_msg
     );