diff --git a/src/auto-reply/reply/block-reply-pipeline.multi-message.test.ts b/src/auto-reply/reply/block-reply-pipeline.multi-message.test.ts
new file mode 100644
index 00000000000..3c35699ddec
--- /dev/null
+++ b/src/auto-reply/reply/block-reply-pipeline.multi-message.test.ts
@@ -0,0 +1,61 @@
+import { describe, expect, it } from "vitest";
+import { setReplyPayloadMetadata } from "../reply-payload.js";
+import { createBlockReplyPipeline } from "./block-reply-pipeline.js";
+
+function blockFor(text: string, assistantMessageIndex: number) {
+  return setReplyPayloadMetadata({ text }, { assistantMessageIndex });
+}
+
+describe("block reply pipeline multi-assistant-message suppression", () => {
+  it("recognizes each fully-streamed message across a multi-message turn", async () => {
+    const sent: string[] = [];
+    const pipeline = createBlockReplyPipeline({
+      onBlockReply: async (payload) => {
+        if (payload.text) {
+          sent.push(payload.text);
+        }
+      },
+      timeoutMs: 5000,
+    });
+
+    pipeline.enqueue(blockFor("Alpha one.", 0));
+    pipeline.enqueue(blockFor("Alpha two.", 0));
+    pipeline.enqueue(blockFor("Beta one.", 1));
+    pipeline.enqueue(blockFor("Beta two.", 1));
+    await pipeline.flush({ force: true });
+
+    expect(sent).toEqual(["Alpha one.", "Alpha two.", "Beta one.", "Beta two."]);
+    expect(pipeline.hasSentPayload({ text: "Alpha one. Alpha two." })).toBe(true);
+    expect(pipeline.hasSentPayload({ text: "Beta one. Beta two." })).toBe(true);
+  });
+
+  it("does not treat one message as covering another message's text", async () => {
+    const pipeline = createBlockReplyPipeline({
+      onBlockReply: async () => {},
+      timeoutMs: 5000,
+    });
+
+    pipeline.enqueue(blockFor("Alpha one.", 0));
+    pipeline.enqueue(blockFor("Alpha two.", 0));
+    pipeline.enqueue(blockFor("Beta one.", 1));
+    pipeline.enqueue(blockFor("Beta two.", 1));
+    await pipeline.flush({ force: true });
+
+    expect(pipeline.hasSentPayload({ text: "Alpha one. Alpha two. Beta one. Beta two." })).toBe(
+      false,
+    );
+  });
+
+  it("suppresses a single message split into multiple blocks", async () => {
+    const pipeline = createBlockReplyPipeline({
+      onBlockReply: async () => {},
+      timeoutMs: 5000,
+    });
+
+    pipeline.enqueue(blockFor("Gamma one.", 0));
+    pipeline.enqueue(blockFor("Gamma two.", 0));
+    await pipeline.flush({ force: true });
+
+    expect(pipeline.hasSentPayload({ text: "Gamma one. Gamma two." })).toBe(true);
+  });
+});
diff --git a/src/auto-reply/reply/block-reply-pipeline.ts b/src/auto-reply/reply/block-reply-pipeline.ts
index 08e8ed01833..014f622bda1 100644
--- a/src/auto-reply/reply/block-reply-pipeline.ts
+++ b/src/auto-reply/reply/block-reply-pipeline.ts
@@ -120,7 +120,7 @@ export function createBlockReplyPipeline(params: {
   const bufferedKeys = new Set<string>();
   const bufferedPayloadKeys = new Set<string>();
   const bufferedPayloads: ReplyPayload[] = [];
-  const streamedTextFragments: string[] = [];
+  const streamedTextFragmentsByMessage = new Map<number | undefined, string[]>();
   let bufferedAssistantMessageIndex: number | undefined;
   let sendChain: Promise<void> = Promise.resolve();
   let aborted = false;
@@ -186,7 +186,10 @@ export function createBlockReplyPipeline(params: {
           sentMediaUrls.add(mediaUrl);
         }
         if (!isStatusNotice && reply.trimmedText) {
-          streamedTextFragments.push(reply.trimmedText);
+          const assistantMessageIndex = getReplyPayloadMetadata(payload)?.assistantMessageIndex;
+          const fragments = streamedTextFragmentsByMessage.get(assistantMessageIndex) ?? [];
+          fragments.push(reply.trimmedText);
+          streamedTextFragmentsByMessage.set(assistantMessageIndex, fragments);
         }
         if (!isStatusNotice) {
           didStream = true;
@@ -328,7 +331,7 @@ export function createBlockReplyPipeline(params: {
       if (sentContentKeys.has(payloadKey)) {
         return true;
       }
-      if (!didStream || streamedTextFragments.length === 0) {
+      if (!didStream) {
         return false;
       }
       const reply = resolveSendableOutboundReplyParts(payload);
@@ -336,7 +339,13 @@ export function createBlockReplyPipeline(params: {
         return false;
       }
       const normalize = (text: string) => text.replace(/\s+/g, "");
-      return normalize(streamedTextFragments.join("")) === normalize(reply.trimmedText);
+      const target = normalize(reply.trimmedText);
+      for (const fragments of streamedTextFragmentsByMessage.values()) {
+        if (fragments.length > 0 && normalize(fragments.join("")) === target) {
+          return true;
+        }
+      }
+      return false;
     },
     getSentMediaUrls: () => Array.from(sentMediaUrls),
   };