fix(background-agent): allow disabling parent session reminders

src/features/background-agent/manager.test.ts

@@ -981,6 +981,52 @@ describe("BackgroundManager.notifyParentSession - aborted parent", () => {
   })
 })
 
+describe("BackgroundManager.notifyParentSession - notifications toggle", () => {
+  test("should skip parent prompt injection when notifications are disabled", async () => {
+    //#given
+    let promptCalled = false
+    const promptMock = async () => {
+      promptCalled = true
+      return {}
+    }
+    const client = {
+      session: {
+        prompt: promptMock,
+        promptAsync: promptMock,
+        abort: async () => ({}),
+        messages: async () => ({ data: [] }),
+      },
+    }
+    const manager = new BackgroundManager(
+      { client, directory: tmpdir() } as unknown as PluginInput,
+      undefined,
+      { enableParentSessionNotifications: false },
+    )
+    const task: BackgroundTask = {
+      id: "task-no-parent-notification",
+      sessionID: "session-child",
+      parentSessionID: "session-parent",
+      parentMessageID: "msg-parent",
+      description: "task notifications disabled",
+      prompt: "test",
+      agent: "explore",
+      status: "completed",
+      startedAt: new Date(),
+      completedAt: new Date(),
+    }
+    getPendingByParent(manager).set("session-parent", new Set([task.id]))
+
+    //#when
+    await (manager as unknown as { notifyParentSession: (task: BackgroundTask) => Promise<void> })
+      .notifyParentSession(task)
+
+    //#then
+    expect(promptCalled).toBe(false)
+
+    manager.shutdown()
+  })
+})
+
 function buildNotificationPromptBody(
   task: BackgroundTask,
   currentMessage: CurrentMessage | null

src/features/background-agent/manager.ts

@@ -93,6 +93,7 @@ export class BackgroundManager {
   private completionTimers: Map<string, ReturnType<typeof setTimeout>> = new Map()
   private idleDeferralTimers: Map<string, ReturnType<typeof setTimeout>> = new Map()
   private notificationQueueByParent: Map<string, Promise<void>> = new Map()
+  private enableParentSessionNotifications: boolean
   readonly taskHistory = new TaskHistory()
 
   constructor(
@@ -102,6 +103,7 @@ export class BackgroundManager {
       tmuxConfig?: TmuxConfig
       onSubagentSessionCreated?: OnSubagentSessionCreated
       onShutdown?: () => void
+      enableParentSessionNotifications?: boolean
     }
   ) {
     this.tasks = new Map()
@@ -114,6 +116,7 @@ export class BackgroundManager {
     this.tmuxEnabled = options?.tmuxConfig?.enabled ?? false
     this.onSubagentSessionCreated = options?.onSubagentSessionCreated
     this.onShutdown = options?.onShutdown
+    this.enableParentSessionNotifications = options?.enableParentSessionNotifications ?? true
     this.registerProcessCleanup()
   }
 
@@ -1186,14 +1189,17 @@ export class BackgroundManager {
       allComplete = true
     }
 
+    const completedTasks = allComplete
+      ? Array.from(this.tasks.values())
+        .filter(t => t.parentSessionID === task.parentSessionID && t.status !== "running" && t.status !== "pending")
+      : []
+
+    if (this.enableParentSessionNotifications) {
       const statusText = task.status === "completed" ? "COMPLETED" : task.status === "interrupt" ? "INTERRUPTED" : "CANCELLED"
       const errorInfo = task.error ? `\n**Error:** ${task.error}` : ""
 
       let notification: string
-    let completedTasks: BackgroundTask[] = []
       if (allComplete) {
-      completedTasks = Array.from(this.tasks.values())
-        .filter(t => t.parentSessionID === task.parentSessionID && t.status !== "running" && t.status !== "pending")
         const completedTasksText = completedTasks
           .map(t => `- \`${t.id}\`: ${t.description}`)
           .join("\n")
@@ -1285,6 +1291,12 @@ Use \`background_output(task_id="${task.id}")\` to retrieve this result when rea
         }
         log("[background-agent] Failed to send notification:", error)
       }
+    } else {
+      log("[background-agent] Parent session notifications disabled, skipping prompt injection:", {
+        taskId: task.id,
+        parentSessionID: task.parentSessionID,
+      })
+    }
 
     if (allComplete) {
       for (const completedTask of completedTasks) {