diff --git a/src/features/background-agent/manager.ts b/src/features/background-agent/manager.ts
index 5282c99..bf0678e 100644
--- a/src/features/background-agent/manager.ts
+++ b/src/features/background-agent/manager.ts
@@ -10,6 +10,7 @@ import {
   findNearestMessageWithFields,
   MESSAGE_STORAGE,
 } from "../hook-message-injector"
+import { subagentSessions } from "../claude-code-session-state"
 
 type OpencodeClient = PluginInput["client"]
 
@@ -82,6 +83,7 @@ export class BackgroundManager {
     }
 
     const sessionID = createResult.data.id
+    subagentSessions.add(sessionID)
 
     const task: BackgroundTask = {
       id: `bg_${crypto.randomUUID().slice(0, 8)}`,
@@ -236,6 +238,7 @@ export class BackgroundManager {
 
       this.tasks.delete(task.id)
       this.clearNotificationsForTask(task.id)
+      subagentSessions.delete(sessionID)
     }
   }
 
diff --git a/src/hooks/session-notification.ts b/src/hooks/session-notification.ts
index d9ff5a8..04acc59 100644
--- a/src/hooks/session-notification.ts
+++ b/src/hooks/session-notification.ts
@@ -1,5 +1,6 @@
 import type { PluginInput } from "@opencode-ai/plugin"
 import { platform } from "os"
+import { subagentSessions } from "../features/claude-code-session-state"
 
 interface Todo {
   content: string
@@ -219,6 +220,8 @@ export function createSessionNotification(
       const sessionID = props?.sessionID as string | undefined
       if (!sessionID) return
 
+      if (subagentSessions.has(sessionID)) return
+
       if (notifiedSessions.has(sessionID)) return
       if (pendingTimers.has(sessionID)) return