feat(task): 优化孙智能体任务消息的发送与工具注册

- 在发送任务消息时增加可选的任务仓库参数支持子任务重发
- 新增 extract_parent_task_id 函数用于提取孙智能体的父任务 ID
- 补发子任务（孙智能体）的 TaskStarted 事件，解决视图重进导致的 navigateToTaskId 丢失
- 判断并附加子任务的父任务 ID，完善日志记录与事件发送
- 在子智能体运行时根据深度排除 task 工具，防止无限嵌套调用
- ToolRegistry 新增 without 方法，可创建排除指定工具的新实例用于子智能体配置

src/gateway/ws.rs

@@ -492,7 +492,7 @@ async fn handle_inbound(
                 if let Some(task_session_id) = response.metadata.get("task_session_id") {
                     // 提前提取 task_id，用于给历史消息打标记
                     let task_id = response.metadata.get("task_id").cloned().unwrap_or_default();
-                    if let Err(e) = send_task_messages(&store, task_session_id, sender, Some(task_id.clone())).await {
+                    if let Err(e) = send_task_messages(&store, task_session_id, sender, Some(task_id.clone()), Some(&state.task_repository)).await {
                         tracing::warn!(error = %e, task_session_id = %task_session_id, "Failed to send task messages");
                     }
 
@@ -570,7 +570,7 @@ async fn handle_inbound(
                         &load_chat_channel,
                         load_chat_id,
                     );
-                    if let Err(e) = send_task_messages(&store, &session_id, sender, None).await {
+                    if let Err(e) = send_task_messages(&store, &session_id, sender, None, None).await {
                         tracing::warn!(
                             error = %e,
                             channel = %load_chat_channel,
@@ -669,9 +669,13 @@ async fn send_topic_history(
 
     for task in running_tasks {
         if task.state == TaskSessionState::Running {
+            // 判断是否为孙智能体：parent_session_id 以 "sub:" 开头表示父会话是子智能体
+            let parent_task_id = extract_parent_task_id(&task);
+
             tracing::info!(
                 task_id = %task.id,
                 description = %task.description,
+                parent_task_id = ?parent_task_id,
                 "Re-sending TaskStarted for running task after topic history load"
             );
             let _ = sender
@@ -680,7 +684,7 @@ async fn send_topic_history(
                     description: task.description.clone(),
                     subagent_type: task.subagent_type.clone(),
                     topic_id: Some(topic_id.to_string()),
-                    parent_task_id: None,
+                    parent_task_id,
                     tool_call_id: None,
                 })
                 .await;
@@ -696,6 +700,7 @@ async fn send_task_messages(
     session_id: &str,
     sender: &mpsc::Sender<WsOutbound>,
     subagent_task_id: Option<String>,
+    task_repository: Option<&Arc<dyn TaskRepository>>,
 ) -> Result<(), Box<dyn std::error::Error>> {
     let messages = store.load_messages(session_id)?;
 
@@ -713,6 +718,37 @@ async fn send_task_messages(
         }
     }
 
+    // 补发子任务（孙智能体）的 TaskStarted 事件
+    // 解决重新进入子智能体视图后 navigateToTaskId 丢失的问题
+    if let (Some(repo), Some(parent_task_id)) = (task_repository, &subagent_task_id) {
+        match repo.list_tasks_for_session(session_id).await {
+            Ok(child_tasks) => {
+                for child in child_tasks {
+                    if child.state == TaskSessionState::Running {
+                        tracing::info!(
+                            child_task_id = %child.id,
+                            parent_task_id = %parent_task_id,
+                            "Re-sending TaskStarted for child task after sub-agent view re-enter"
+                        );
+                        let _ = sender
+                            .send(WsOutbound::TaskStarted {
+                                task_id: child.id.clone(),
+                                description: child.description.clone(),
+                                subagent_type: child.subagent_type.clone(),
+                                topic_id: child.parent_topic_id.clone(),
+                                parent_task_id: Some(parent_task_id.clone()),
+                                tool_call_id: None,
+                            })
+                            .await;
+                    }
+                }
+            }
+            Err(e) => {
+                tracing::warn!(error = %e, session_id = %session_id, "Failed to list child tasks for resend");
+            }
+        }
+    }
+
     Ok(())
 }
 
@@ -737,6 +773,20 @@ fn set_subagent_task_id(outbound: &mut WsOutbound, task_id: &str) {
     }
 }
 
+/// 从 TaskSession 中提取父任务 ID（仅孙智能体有值）。
+/// 孙智能体的 parent_session_id 格式为 "sub:{grandparent_session}:task:{parent_task_uuid}"，
+/// 从中提取 "task:{parent_task_uuid}" 作为 parent_task_id。
+fn extract_parent_task_id(task: &crate::tools::task::types::TaskSession) -> Option<String> {
+    let parent = &task.parent_session_id;
+    // 仅当父会话是子智能体会话时才提取（格式: "sub:...:task:{uuid}"）
+    if parent.starts_with("sub:") {
+        if let Some(pos) = parent.find(":task:") {
+            return Some(parent[pos + 1..].to_string()); // "task:{uuid}"
+        }
+    }
+    None
+}
+
 /// 将 ChatMessage 转换为 WsOutbound 列表
 fn chat_message_to_ws_outbound(msg: &crate::bus::ChatMessage) -> Vec<WsOutbound> {
     use crate::bus::message::ToolMessageState;

src/tools/registry.rs

@@ -73,6 +73,20 @@ impl ToolRegistry {
             .cloned()
             .collect()
     }
+
+    /// 创建一个排除指定工具的新 registry 副本
+    pub fn without(&self, exclude: &[&str]) -> Self {
+        let exclude_set: std::collections::HashSet<&str> = exclude.iter().copied().collect();
+        let tools = self.tools.read().expect("ToolRegistry lock poisoned");
+        let filtered: HashMap<String, Arc<dyn ToolTrait>> = tools
+            .iter()
+            .filter(|(name, _)| !exclude_set.contains(name.as_str()))
+            .map(|(k, v)| (k.clone(), v.clone()))
+            .collect();
+        let new_registry = ToolRegistry::new();
+        *new_registry.tools.write().expect("ToolRegistry lock poisoned") = filtered;
+        new_registry
+    }
 }
 
 impl Default for ToolRegistry {

src/tools/task/runtime.rs

@@ -19,6 +19,7 @@ use crate::tools::{ToolContext, ToolRegistry};
 use super::error::TaskError;
 use super::prompt::{extract_summary, SubagentPromptBuilder};
 use super::repository::TaskRepository;
+use super::tool::TaskTool;
 use super::types::{SubagentDef, SubagentSource, TaskDefinition, TaskSession, TaskToolResult};
 
 /// 子代理运行时配置
@@ -332,9 +333,17 @@ impl DefaultSubAgentRuntime {
     ) -> Result<AgentLoop, TaskError> {
         let prompt_provider = Arc::new(StaticSystemPromptProvider::new(system_prompt));
 
+        // 孙智能体（depth >= 2）不注册 task 工具，防止无限嵌套
+        let child_depth = parent_nesting_depth + 1;
+        let tools = if child_depth >= 2 {
+            Arc::new(self.subagent_tools.without(&[TaskTool::TOOL_NAME]))
+        } else {
+            self.subagent_tools.clone()
+        };
+
         AgentLoop::with_tools_and_system_prompt_provider(
             AgentRuntimeConfig::from(self.provider_config.clone()),
-            self.subagent_tools.clone(),
+            tools,
             prompt_provider,
             None, // 子代理不需要 skill provider
         )

src/tools/task/tool.rs

@@ -15,6 +15,8 @@ pub struct TaskTool {
 }
 
 impl TaskTool {
+    pub const TOOL_NAME: &'static str = "task";
+
     /// 创建 TaskTool
     /// - `max_nesting_depth = None`：无深度限制（主 agent）
     /// - `max_nesting_depth = Some(N)`：允许最多 N 层嵌套（子 agent）
@@ -29,7 +31,7 @@ impl TaskTool {
 #[async_trait]
 impl Tool for TaskTool {
     fn name(&self) -> &str {
-        "task"
+        Self::TOOL_NAME
     }
 
     fn description(&self) -> &str {