diff --git a/src/auto-reply/reply/agent-runner-payloads.test.ts b/src/auto-reply/reply/agent-runner-payloads.test.ts
index de7cd69eb4a..3ffbf1812bb 100644
--- a/src/auto-reply/reply/agent-runner-payloads.test.ts
+++ b/src/auto-reply/reply/agent-runner-payloads.test.ts
@@ -490,6 +490,63 @@ describe("buildReplyPayloads media filter integration", () => {
     expect(replyPayloads).toHaveLength(0);
   });
 
+  it("suppresses final text payloads already covered by partial preview streaming", async () => {
+    const { replyPayloads } = await buildReplyPayloads({
+      ...baseParams,
+      previewStreamedText: "First block\n\nSecond block",
+      payloads: [{ text: "First block" }, { text: "Second block" }],
+    });
+
+    expect(replyPayloads).toHaveLength(0);
+  });
+
+  it("keeps final text that was not covered by partial preview streaming", async () => {
+    const { replyPayloads } = await buildReplyPayloads({
+      ...baseParams,
+      previewStreamedText: "Working...",
+      payloads: [{ text: "Done." }],
+    });
+
+    expect(replyPayloads).toHaveLength(1);
+    expectFields(replyPayloads[0], { text: "Done." });
+  });
+
+  it("does not suppress short final text just because it appears inside preview text", async () => {
+    const { replyPayloads } = await buildReplyPayloads({
+      ...baseParams,
+      previewStreamedText: "Working on item 3",
+      payloads: [{ text: "3" }],
+    });
+
+    expect(replyPayloads).toHaveLength(1);
+    expectFields(replyPayloads[0], { text: "3" });
+  });
+
+  it("preserves media while removing duplicate preview-streamed caption text", async () => {
+    const { replyPayloads } = await buildReplyPayloads({
+      ...baseParams,
+      previewStreamedText: "Here is the chart",
+      payloads: [{ text: "Here is the chart", mediaUrl: "file:///tmp/chart.png" }],
+    });
+
+    expect(replyPayloads).toHaveLength(1);
+    expectFields(replyPayloads[0], {
+      text: undefined,
+      mediaUrl: "file:///tmp/chart.png",
+    });
+  });
+
+  it("preserves errors even when their text appears in partial preview streaming", async () => {
+    const { replyPayloads } = await buildReplyPayloads({
+      ...baseParams,
+      previewStreamedText: "Agent couldn't generate a response. Please try again.",
+      payloads: [{ text: "Agent couldn't generate a response. Please try again.", isError: true }],
+    });
+
+    expect(replyPayloads).toHaveLength(1);
+    expectFields(replyPayloads[0], { isError: true });
+  });
+
   it("drops all final payloads when block pipeline streamed successfully", async () => {
     const pipeline: Parameters<typeof buildReplyPayloads>[0]["blockReplyPipeline"] = {
       didStream: () => true,
diff --git a/src/auto-reply/reply/agent-runner-payloads.ts b/src/auto-reply/reply/agent-runner-payloads.ts
index 0ef83994a7f..1a77b2df6f2 100644
--- a/src/auto-reply/reply/agent-runner-payloads.ts
+++ b/src/auto-reply/reply/agent-runner-payloads.ts
@@ -158,6 +158,7 @@ export async function buildReplyPayloads(params: {
   blockStreamingEnabled: boolean;
   blockReplyPipeline: BlockReplyPipeline | null;
   /** Payload keys sent directly (not via pipeline) during tool flush. */
+  previewStreamedText?: string;
   directlySentBlockKeys?: Set<string>;
   replyToMode: ReplyToMode;
   replyToChannel?: OriginatingChannelType;
@@ -323,6 +324,54 @@ export async function buildReplyPayloads(params: {
     : mediaFilteredPayloads;
   const isDirectlySentBlockPayload = (payload: ReplyPayload) =>
     Boolean(params.directlySentBlockKeys?.has(createBlockReplyContentKey(payload)));
+  const normalizePreviewDedupeText = (value: string | undefined): string =>
+    (value ?? "").replace(/\s+/g, " ").trim();
+  const buildPreviewDedupeTextSet = (value: string | undefined): Set<string> => {
+    const dedupeText = new Set<string>();
+    const normalizedWhole = normalizePreviewDedupeText(value);
+    if (normalizedWhole) {
+      dedupeText.add(normalizedWhole);
+    }
+    for (const block of (value ?? "").split(/\n{2,}/u)) {
+      const normalizedBlock = normalizePreviewDedupeText(block);
+      if (normalizedBlock) {
+        dedupeText.add(normalizedBlock);
+      }
+    }
+    return dedupeText;
+  };
+  const previewStreamedText = buildPreviewDedupeTextSet(params.previewStreamedText);
+  const isPreviewStreamedTextPayload = (payload: ReplyPayload): boolean => {
+    if (previewStreamedText.size === 0 || payload.isError) {
+      return false;
+    }
+    const text = normalizePreviewDedupeText(payload.text);
+    return Boolean(text && previewStreamedText.has(text));
+  };
+  const preserveUnsentMediaAfterPreviewStream = (payload: ReplyPayload): ReplyPayload | null => {
+    if (!isPreviewStreamedTextPayload(payload)) {
+      return payload;
+    }
+    const reply = resolveSendableOutboundReplyParts(payload);
+    if (!reply.hasMedia) {
+      return null;
+    }
+    return copyReplyPayloadMetadata(payload, {
+      ...payload,
+      text: undefined,
+      audioAsVoice: payload.audioAsVoice || undefined,
+    });
+  };
+  const suppressPreviewStreamedPayloads = (payloads: ReplyPayload[]): ReplyPayload[] => {
+    const unsent: ReplyPayload[] = [];
+    for (const payload of payloads) {
+      const next = preserveUnsentMediaAfterPreviewStream(payload);
+      if (next) {
+        unsent.push(next);
+      }
+    }
+    return unsent;
+  };
   const preserveUnsentMediaAfterBlockStream = (payload: ReplyPayload): ReplyPayload | null => {
     if (payload.isError || payload.isFallbackNotice) {
       return payload;
@@ -383,7 +432,9 @@ export async function buildReplyPayloads(params: {
             }
             return unsent;
           })()
-        : dedupedPayloads;
+        : previewStreamedText.size > 0
+          ? suppressPreviewStreamedPayloads(dedupedPayloads)
+          : dedupedPayloads;
   const blockSentMediaUrls = params.blockStreamingEnabled
     ? await normalizeSentMediaUrlsForDedupe({
         sentMediaUrls: params.blockReplyPipeline?.getSentMediaUrls() ?? [],
diff --git a/src/auto-reply/reply/agent-runner.runreplyagent.e2e.test.ts b/src/auto-reply/reply/agent-runner.runreplyagent.e2e.test.ts
index 32518ca1ba1..ff9b89a4e6f 100644
--- a/src/auto-reply/reply/agent-runner.runreplyagent.e2e.test.ts
+++ b/src/auto-reply/reply/agent-runner.runreplyagent.e2e.test.ts
@@ -622,6 +622,27 @@ describe("runReplyAgent typing (heartbeat)", () => {
     }
   });
 
+  it("suppresses final text blocks already delivered through partial preview streaming", async () => {
+    const onPartialReply = vi.fn();
+    state.runEmbeddedPiAgentMock.mockImplementationOnce(async (params: AgentRunParams) => {
+      await params.onPartialReply?.({ text: "First block\n\nSecond block" });
+      return {
+        payloads: [{ text: "First block" }, { text: "Second block" }],
+        meta: {},
+      };
+    });
+
+    const { run } = createMinimalRun({
+      opts: { onPartialReply },
+      typingMode: "message",
+    });
+
+    const result = await run();
+
+    expect(onPartialReply).toHaveBeenCalledWith({ text: "First block\n\nSecond block" });
+    expect(result).toBeUndefined();
+  });
+
   it("suppresses narrated silent-turn partials, block replies, and final payloads", async () => {
     const onPartialReply = vi.fn();
     const onBlockReply = vi.fn();
diff --git a/src/auto-reply/reply/agent-runner.ts b/src/auto-reply/reply/agent-runner.ts
index 23653db7cb7..27d3b953c2b 100644
--- a/src/auto-reply/reply/agent-runner.ts
+++ b/src/auto-reply/reply/agent-runner.ts
@@ -1277,6 +1277,20 @@ export async function runReplyAgent(params: {
       : null;
 
   const replySessionKey = sessionKey ?? followupRun.run.sessionKey;
+  let latestPreviewStreamedText: string | undefined;
+  const effectiveOpts = opts?.onPartialReply
+    ? {
+        ...opts,
+        onPartialReply: async (
+          payload: Parameters<NonNullable<GetReplyOptions["onPartialReply"]>>[0],
+        ) => {
+          if (typeof payload.text === "string" && payload.text.trim()) {
+            latestPreviewStreamedText = payload.text;
+          }
+          await opts.onPartialReply?.(payload);
+        },
+      }
+    : opts;
   let replyOperation: ReplyOperation;
   try {
     replyOperation =
@@ -1459,7 +1473,7 @@ export async function runReplyAgent(params: {
         sessionCtx,
         replyThreading: replyThreadingOverride ?? sessionCtx.ReplyThreading,
         replyOperation,
-        opts,
+        opts: effectiveOpts,
         typingSignals,
         blockReplyPipeline,
         blockStreamingEnabled,
@@ -1737,6 +1751,7 @@ export async function runReplyAgent(params: {
       silentExpected: followupRun.run.silentExpected,
       blockStreamingEnabled,
       blockReplyPipeline,
+      previewStreamedText: latestPreviewStreamedText,
       directlySentBlockKeys,
       replyToMode,
       replyToChannel,