From 78fe3e4df345fdc7c8d61728fb236c4cc6096592 Mon Sep 17 00:00:00 2001
From: Mohamed Boudra <boudra.moha@gmail.com>
Date: Mon, 4 May 2026 10:13:44 +0700
Subject: [PATCH] Drop subagent task notifications from parent timeline

Subagent task_notification system messages arrive without
parent_tool_use_id but with tool_use_id pointing at the parent's Task
call, so they slip past the sidechain router and render as top-level
"Task Notification" rows in the parent's timeline. Skip them when the
referenced tool_use is a Task call; parent-level background bash
notifications still flow through.
---
 .../server/src/server/agent/providers/claude-agent.ts  | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/packages/server/src/server/agent/providers/claude-agent.ts b/packages/server/src/server/agent/providers/claude-agent.ts
index 38c90daa5..74efbdf6d 100644
--- a/packages/server/src/server/agent/providers/claude-agent.ts
+++ b/packages/server/src/server/agent/providers/claude-agent.ts
@@ -2975,6 +2975,16 @@ class ClaudeAgentSession implements AgentSession {
       return;
     }
     if (message.subtype === "task_notification") {
+      // TODO: subagent timelines are best-effort. Subagent task_notifications
+      // arrive without parent_tool_use_id but with tool_use_id pointing at the
+      // parent's Task call, so they slip past the sidechain router and pollute
+      // the parent timeline. Drop them here; eventually thread them into the
+      // parent Task tool call's sub_agent log instead.
+      const taskUseId = message.tool_use_id;
+      const cachedTool = taskUseId ? this.toolUseCache.get(taskUseId) : undefined;
+      if (cachedTool?.name === "Task") {
+        return;
+      }
       const taskNotificationItem = mapTaskNotificationSystemRecordToToolCall(message);
       if (taskNotificationItem) {
         events.push({