diff --git a/src/agent/async-agent.test.ts b/src/agent/async-agent.test.ts
index cd7f3c32..b4dd4276 100644
--- a/src/agent/async-agent.test.ts
+++ b/src/agent/async-agent.test.ts
@@ -143,4 +143,46 @@ describe("AsyncAgent internal flow", () => {
 
     agent.close();
   });
+
+  it("forwards only assistant message_end events when writeInternal opts in", async () => {
+    let resolveRunInternal: ((value: { text: string; thinking: undefined; error: undefined }) => void) | undefined;
+    runInternalMock.mockImplementationOnce(
+      () => new Promise((resolve) => {
+        resolveRunInternal = resolve as typeof resolveRunInternal;
+      }),
+    );
+
+    const agent = new AsyncAgent();
+    const iter = agent.read()[Symbol.asyncIterator]();
+    const streamCallback = subscribeCallbacks[0];
+    expect(streamCallback).toBeDefined();
+
+    agent.writeInternal("announce", { forwardAssistant: true });
+    await Promise.resolve();
+
+    internalRunState.value = true;
+    streamCallback!({
+      type: "message_end",
+      message: { role: "user", content: [{ type: "text", text: "hidden internal prompt" }] },
+    });
+    streamCallback!({
+      type: "message_end",
+      message: { role: "assistant", content: [{ type: "text", text: "visible summary" }] },
+    });
+
+    const first = await nextWithTimeout(iter);
+    expect(first).not.toBe("timeout");
+    if (first !== "timeout") {
+      expect((first as { type: string }).type).toBe("message_end");
+      expect((first as { message: { role: string } }).message.role).toBe("assistant");
+    }
+
+    const second = await nextWithTimeout(iter);
+    expect(second).toBe("timeout");
+
+    resolveRunInternal!({ text: "", thinking: undefined, error: undefined });
+    await agent.waitForIdle();
+    internalRunState.value = false;
+    agent.close();
+  });
 });
diff --git a/src/agent/async-agent.ts b/src/agent/async-agent.ts
index 514a57e7..fc7fb15b 100644
--- a/src/agent/async-agent.ts
+++ b/src/agent/async-agent.ts
@@ -10,12 +10,18 @@ const devNull = { write: () => true } as unknown as NodeJS.WritableStream;
 /** Discriminated union of legacy Message, raw AgentEvent, and MulticaEvent */
 export type ChannelItem = Message | AgentEvent | MulticaEvent;
 
+export interface WriteInternalOptions {
+  /** Forward assistant message_end events to realtime stream during internal runs */
+  forwardAssistant?: boolean | undefined;
+}
+
 export class AsyncAgent {
   private readonly agent: Agent;
   private readonly channel = new Channel<ChannelItem>();
   private _closed = false;
   private queue: Promise<void> = Promise.resolve();
   private closeCallbacks: Array<() => void> = [];
+  private forwardInternalAssistant = false;
   readonly sessionId: string;
 
   constructor(options?: AgentOptions) {
@@ -29,7 +35,7 @@ export class AsyncAgent {
     // Suppress forwarding during internal runs to avoid leaking
     // orchestration messages to the frontend/real-time stream.
     this.agent.subscribeAll((event: AgentEvent | MulticaEvent) => {
-      if (this.agent.isInternalRun) return;
+      if (!this.shouldForwardEvent(event)) return;
       this.channel.send(event);
     });
   }
@@ -63,19 +69,26 @@ export class AsyncAgent {
   /**
    * Write an internal message to agent (non-blocking, serialized queue).
    * Messages are persisted with `internal: true` and rolled back from
-   * in-memory state. Events are suppressed from the real-time stream.
+   * in-memory state. Events are suppressed from the real-time stream by default.
    */
-  writeInternal(content: string): void {
+  writeInternal(content: string, options?: WriteInternalOptions): void {
     if (this._closed) throw new Error("Agent is closed");
+    const forwardAssistant = options?.forwardAssistant === true;
 
     this.queue = this.queue
       .then(async () => {
         if (this._closed) return;
-        const result = await this.agent.runInternal(content);
-        await this.agent.flushSession();
-        if (result.error) {
-          // Internal run errors are for diagnostics only; do not leak to user stream.
-          console.error(`[AsyncAgent] Internal run error: ${result.error}`);
+        const prevForward = this.forwardInternalAssistant;
+        this.forwardInternalAssistant = forwardAssistant;
+        try {
+          const result = await this.agent.runInternal(content);
+          await this.agent.flushSession();
+          if (result.error) {
+            // Internal run errors are for diagnostics only; do not leak to user stream.
+            console.error(`[AsyncAgent] Internal run error: ${result.error}`);
+          }
+        } finally {
+          this.forwardInternalAssistant = prevForward;
         }
       })
       .catch((err) => {
@@ -98,7 +111,7 @@ export class AsyncAgent {
   subscribe(callback: (event: AgentEvent | MulticaEvent) => void): () => void {
     console.log(`[AsyncAgent] Adding subscriber for agent: ${this.sessionId}`);
     const unsubscribe = this.agent.subscribeAll((event) => {
-      if (this.agent.isInternalRun) return;
+      if (!this.shouldForwardEvent(event)) return;
       console.log(`[AsyncAgent] Event received: ${event.type}`);
       callback(event);
     });
@@ -113,6 +126,16 @@ export class AsyncAgent {
     return this.queue;
   }
 
+  private shouldForwardEvent(event: AgentEvent | MulticaEvent): boolean {
+    if (!this.agent.isInternalRun) return true;
+    if (!this.forwardInternalAssistant) return false;
+    if (event.type !== "message_end") return false;
+
+    const maybeMessage = (event as { message?: unknown }).message;
+    if (!maybeMessage || typeof maybeMessage !== "object") return false;
+    return (maybeMessage as { role?: unknown }).role === "assistant";
+  }
+
   /** Register a callback to be invoked when the agent is closed */
   onClose(callback: () => void): void {
     if (this._closed) {
diff --git a/src/agent/subagent/announce.ts b/src/agent/subagent/announce.ts
index fff82b7e..8809efdb 100644
--- a/src/agent/subagent/announce.ts
+++ b/src/agent/subagent/announce.ts
@@ -260,7 +260,7 @@ export function runCoalescedAnnounceFlow(
       return false;
     }
 
-    parentAgent.writeInternal(message);
+    parentAgent.writeInternal(message, { forwardAssistant: true });
     return true;
   } catch (err) {
     console.error(`[SubagentAnnounce] Failed to coalesced-announce to parent:`, err);
@@ -308,7 +308,7 @@ export function runSubagentAnnounceFlow(params: SubagentAnnounceParams): boolean
       return false;
     }
 
-    parentAgent.writeInternal(message);
+    parentAgent.writeInternal(message, { forwardAssistant: true });
     return true;
   } catch (err) {
     console.error(`[SubagentAnnounce] Failed to announce to parent:`, err);