diff --git a/src/features/background-agent/manager.test.ts b/src/features/background-agent/manager.test.ts
index 385f85da6..bf722c5c5 100644
--- a/src/features/background-agent/manager.test.ts
+++ b/src/features/background-agent/manager.test.ts
@@ -32,6 +32,7 @@ type PendingParentWakeForTest = {
   promptContext: Record<string, unknown>
   notifications: string[]
   shouldReply: boolean
+  dispatchedAt?: number
 }
 
 class MockBackgroundManager {
@@ -5168,6 +5169,71 @@ describe("BackgroundManager.handleEvent - session.error", () => {
     manager.shutdown()
   })
 
+  test("does not requeue dispatched parent wake when session history already contains assistant output after the wake", async () => {
+    //#given
+    const promptCalls: Array<{ path: { id: string }; body: Record<string, unknown> }> = []
+    const client = {
+      session: {
+        status: async () => ({ data: { "parent-session-wake": { type: "idle" } } }),
+        messages: async () => [
+          {
+            info: {
+              role: "assistant",
+              time: { created: Date.now() },
+            },
+            parts: [{ type: "text", text: "wake was already accepted" }],
+          },
+        ],
+        promptAsync: async (args: { path: { id: string }; body: Record<string, unknown> }) => {
+          promptCalls.push(args)
+          return {}
+        },
+        abort: async () => ({}),
+      },
+    }
+    const manager = new BackgroundManager({ pluginContext: createPluginInput(client) })
+    const managerInternals = cast<{
+      queuePendingParentWake: (
+        sessionID: string,
+        notification: string,
+        promptContext: Record<string, unknown>,
+        shouldReply: boolean,
+        delayMs?: number,
+      ) => void
+      flushPendingParentWake: (sessionID: string) => Promise<void>
+    }>(manager)
+    managerInternals.queuePendingParentWake(
+      "parent-session-wake",
+      "<system-reminder>done</system-reminder>",
+      { agent: "sisyphus" },
+      true,
+      0,
+    )
+    await managerInternals.flushPendingParentWake("parent-session-wake")
+    const wake = getDispatchedParentWakes(manager).get("parent-session-wake")
+    if (!wake) {
+      throw new Error("Missing dispatched parent wake")
+    }
+    wake.dispatchedAt = Date.now() - 1_000
+
+    //#when
+    manager.handleEvent({
+      type: "session.error",
+      properties: {
+        sessionID: "parent-session-wake",
+        error: { name: "UnknownError", message: "late provider failure" },
+      },
+    })
+    await flushBackgroundNotifications()
+
+    //#then
+    expect(promptCalls).toHaveLength(1)
+    expect(getDispatchedParentWakes(manager).has("parent-session-wake")).toBe(false)
+    expect(getPendingParentWakes(manager).has("parent-session-wake")).toBe(false)
+
+    manager.shutdown()
+  })
+
   test("terminates task on session.error when session is gone", async () => {
     //#given
     const manager = createBackgroundManager()
diff --git a/src/features/background-agent/manager.ts b/src/features/background-agent/manager.ts
index 579033be0..d0b50677f 100644
--- a/src/features/background-agent/manager.ts
+++ b/src/features/background-agent/manager.ts
@@ -108,6 +108,23 @@ type PendingParentWake = {
   promptContext: ParentWakePromptContext
   notifications: string[]
   shouldReply: boolean
+  dispatchedAt?: number
+}
+
+type ParentWakeSessionMessage = {
+  info?: {
+    role?: string
+    finish?: string
+    time?: { created?: unknown }
+  }
+  role?: string
+  finish?: string
+  time?: { created?: unknown }
+  parts?: Array<{
+    type?: string
+    text?: string
+    content?: unknown
+  }>
 }
 
 type ResumeTaskSnapshot = {
@@ -127,6 +144,7 @@ type ResumeTaskSnapshot = {
 
 const PENDING_PARENT_WAKE_RETRY_MS = 1_000
 const PENDING_PARENT_WAKE_DEBOUNCE_MS = 100
+const PARENT_WAKE_ACCEPTED_MESSAGE_SKEW_MS = 5_000
 
 interface MessagePartInfo {
   id?: string
@@ -1358,6 +1376,7 @@ The fallback retry session is now created and can be inspected directly.
       },
       notifications: [...wake.notifications],
       shouldReply: wake.shouldReply,
+      ...(wake.dispatchedAt !== undefined ? { dispatchedAt: wake.dispatchedAt } : {}),
     }
   }
 
@@ -1372,7 +1391,9 @@ The fallback retry session is now created and can be inspected directly.
 
   private trackDispatchedParentWake(sessionID: string, wake: PendingParentWake): void {
     this.clearDispatchedParentWake(sessionID)
-    this.dispatchedParentWakes.set(sessionID, this.cloneParentWake(wake))
+    const dispatchedWake = this.cloneParentWake(wake)
+    dispatchedWake.dispatchedAt = Date.now()
+    this.dispatchedParentWakes.set(sessionID, dispatchedWake)
     const timer = setTimeout(() => {
       this.dispatchedParentWakeTimers.delete(sessionID)
       this.dispatchedParentWakes.delete(sessionID)
@@ -1380,12 +1401,21 @@ The fallback retry session is now created and can be inspected directly.
     this.dispatchedParentWakeTimers.set(sessionID, timer)
   }
 
-  private requeueDispatchedParentWake(sessionID: string, reason: string): boolean {
+  private async requeueDispatchedParentWake(sessionID: string, reason: string): Promise<boolean> {
     const wake = this.dispatchedParentWakes.get(sessionID)
     if (!wake) {
       return false
     }
 
+    if (await this.hasAcceptedMessageAfterDispatchedParentWake(sessionID, wake)) {
+      this.clearDispatchedParentWake(sessionID)
+      log("[background-agent] Ignored late parent wake failure after assistant output:", {
+        sessionID,
+        reason,
+      })
+      return false
+    }
+
     this.clearDispatchedParentWake(sessionID)
     const pendingWake = this.pendingParentWakes.get(sessionID)
     if (pendingWake) {
@@ -1403,6 +1433,136 @@ The fallback retry session is now created and can be inspected directly.
     return true
   }
 
+  private async loadParentWakeSessionMessages(sessionID: string): Promise<ParentWakeSessionMessage[]> {
+    try {
+      const messagesResp = await messagesInDirectory(this.client, {
+        path: { id: sessionID },
+      }, this.directory)
+      return normalizeSDKResponse(messagesResp, [] as ParentWakeSessionMessage[])
+    } catch (error) {
+      log("[background-agent] Failed to inspect parent session messages for wake safety:", {
+        sessionID,
+        error,
+      })
+      return []
+    }
+  }
+
+  private getParentWakeMessageRole(message: ParentWakeSessionMessage): string | undefined {
+    return message.info?.role ?? message.role
+  }
+
+  private getParentWakeMessageFinish(message: ParentWakeSessionMessage): string | undefined {
+    return message.info?.finish ?? message.finish
+  }
+
+  private getParentWakeMessageCreatedAt(message: ParentWakeSessionMessage): number | undefined {
+    const value = message.info?.time?.created ?? message.time?.created
+    if (typeof value === "number" && Number.isFinite(value)) {
+      return value
+    }
+    if (typeof value === "string") {
+      const parsed = Date.parse(value)
+      return Number.isFinite(parsed) ? parsed : undefined
+    }
+    if (value instanceof Date) {
+      return value.getTime()
+    }
+    return undefined
+  }
+
+  private latestAssistantTurnIsWaitingOnTools(messages: ParentWakeSessionMessage[]): boolean {
+    for (let index = messages.length - 1; index >= 0; index--) {
+      const message = messages[index]
+      if (!message) {
+        continue
+      }
+      const role = this.getParentWakeMessageRole(message)
+      if (role === "assistant") {
+        return this.getParentWakeMessageFinish(message) === "tool-calls"
+      }
+      if (role === "user") {
+        return false
+      }
+    }
+    return false
+  }
+
+  private parentWakeMessageHasOutput(message: ParentWakeSessionMessage): boolean {
+    const role = this.getParentWakeMessageRole(message)
+    if (role !== "assistant" && role !== "tool") {
+      return false
+    }
+    if (!message.parts || message.parts.length === 0) {
+      return role === "assistant"
+    }
+    return message.parts.some((part) => {
+      if (part.type === "text" || part.type === "reasoning") {
+        return typeof part.text === "string" && part.text.trim().length > 0
+      }
+      if (part.type === "tool" || part.type === "tool_result") {
+        return true
+      }
+      if (part.content !== undefined) {
+        if (typeof part.content === "string") {
+          return part.content.trim().length > 0
+        }
+        if (Array.isArray(part.content)) {
+          return part.content.length > 0
+        }
+        return true
+      }
+      return false
+    })
+  }
+
+  private parentWakeMessageContainsNotification(
+    message: ParentWakeSessionMessage,
+    wake: PendingParentWake,
+  ): boolean {
+    if (this.getParentWakeMessageRole(message) !== "user") {
+      return false
+    }
+    return message.parts?.some((part) =>
+      typeof part.text === "string" && wake.notifications.some((notification) => part.text?.includes(notification))
+    ) ?? false
+  }
+
+  private async shouldDeferParentWakeForSessionHistory(sessionID: string): Promise<boolean> {
+    const messages = await this.loadParentWakeSessionMessages(sessionID)
+    if (!this.latestAssistantTurnIsWaitingOnTools(messages)) {
+      return false
+    }
+    log("[background-agent] Deferred parent wake because latest assistant turn is waiting on tool results:", {
+      sessionID,
+    })
+    return true
+  }
+
+  private async hasAcceptedMessageAfterDispatchedParentWake(
+    sessionID: string,
+    wake: PendingParentWake,
+  ): Promise<boolean> {
+    if (wake.dispatchedAt === undefined) {
+      return false
+    }
+    const dispatchedAt = wake.dispatchedAt
+    const messages = await this.loadParentWakeSessionMessages(sessionID)
+    return messages.some((message) => {
+      const createdAt = this.getParentWakeMessageCreatedAt(message)
+      if (createdAt === undefined) {
+        return false
+      }
+      if (
+        createdAt >= dispatchedAt - PARENT_WAKE_ACCEPTED_MESSAGE_SKEW_MS
+        && this.parentWakeMessageContainsNotification(message, wake)
+      ) {
+        return true
+      }
+      return createdAt >= dispatchedAt && this.parentWakeMessageHasOutput(message)
+    })
+  }
+
   private clearSessionOutputObserved(sessionID: string): void {
     this.observedOutputSessions.delete(sessionID)
   }
@@ -1599,7 +1759,9 @@ The fallback retry session is now created and can be inspected directly.
 
       const resolved = this.resolveTaskAttemptBySession(sessionID)
       if (!resolved?.isCurrent) {
-        this.requeueDispatchedParentWake(sessionID, "session.error")
+        void this.requeueDispatchedParentWake(sessionID, "session.error").catch((error) => {
+          log("[background-agent] Failed to requeue dispatched parent wake:", { sessionID, error })
+        })
         return
       }
 
@@ -2534,6 +2696,11 @@ The task was re-queued on a fallback model after a retryable failure.
       return
     }
 
+    if (await this.shouldDeferParentWakeForSessionHistory(sessionID)) {
+      this.schedulePendingParentWakeFlush(sessionID)
+      return
+    }
+
     const latestWake = this.pendingParentWakes.get(sessionID)
     if (!latestWake) {
       return
diff --git a/src/features/background-agent/task-completion-cleanup.test.ts b/src/features/background-agent/task-completion-cleanup.test.ts
index 943dabc41..5a6494bb9 100644
--- a/src/features/background-agent/task-completion-cleanup.test.ts
+++ b/src/features/background-agent/task-completion-cleanup.test.ts
@@ -18,6 +18,15 @@ type PromptAsyncCall = {
   }
 }
 
+type SessionMessageForTest = {
+  info?: {
+    role?: string
+    finish?: string
+    time?: { created?: number }
+  }
+  parts?: Array<{ type?: string }>
+}
+
 type FakeTimers = {
   getDelay: (timer: ReturnType<typeof setTimeout>) => number | undefined
   run: (timer: ReturnType<typeof setTimeout>) => void
@@ -61,6 +70,7 @@ function createManager(
   enableParentSessionNotifications: boolean,
   sessionStatuses?: Record<string, { type: string }>,
   promptAsyncImpl?: (call: PromptAsyncCall) => Promise<unknown>,
+  sessionMessages: SessionMessageForTest[] = [],
 ): {
   manager: BackgroundManager
   promptAsyncCalls: PromptAsyncCall[]
@@ -68,7 +78,7 @@ function createManager(
   const promptAsyncCalls: PromptAsyncCall[] = []
   const client = {
     session: {
-      messages: async () => [],
+      messages: async () => sessionMessages,
       status: async () => ({ data: sessionStatuses ?? {} }),
       prompt: async () => ({}),
       promptAsync: async (call: PromptAsyncCall) => {
@@ -401,6 +411,41 @@ describe("BackgroundManager.notifyParentSession cleanup scheduling", () => {
       expect(notificationPayload).toContain(taskB.id)
     })
 
+    test("#when parent status is idle but latest assistant turn is still waiting on tool results #then background completion does not fork a reply", async () => {
+      // given
+      const sessionStatuses: Record<string, { type: string }> = {
+        "parent-1": { type: "idle" },
+      }
+      const sessionMessages: SessionMessageForTest[] = [
+        {
+          info: { role: "user", time: { created: 1778819814009 } },
+          parts: [{ type: "text" }],
+        },
+        {
+          info: { role: "assistant", finish: "tool-calls", time: { created: 1778819997535 } },
+          parts: [{ type: "tool" }],
+        },
+      ]
+      const { manager, promptAsyncCalls } = createManager(true, sessionStatuses, undefined, sessionMessages)
+      managerUnderTest = manager
+      const task = createTask({
+        id: "task-a",
+        parentSessionId: "parent-1",
+        description: "task A",
+        status: "completed",
+        completedAt: new Date("2026-05-15T13:40:19.368Z"),
+      })
+      getTasks(manager).set(task.id, task)
+      getPendingByParent(manager).set(task.parentSessionId, new Set([task.id]))
+
+      // when
+      await notifyParentSessionForTest(manager, task)
+      await waitForCoalescedFlush()
+
+      // then
+      expect(promptAsyncCalls).toHaveLength(0)
+    })
+
     test("#when all-complete notification wakes parent #then prompt stays in the same OpenCode directory instance", async () => {
       // given
       const { manager, promptAsyncCalls } = createManager(true)