diff --git a/extensions/matrix/src/matrix/monitor/events.test.ts b/extensions/matrix/src/matrix/monitor/events.test.ts
index c6d78064ef4..894880abb9c 100644
--- a/extensions/matrix/src/matrix/monitor/events.test.ts
+++ b/extensions/matrix/src/matrix/monitor/events.test.ts
@@ -241,6 +241,68 @@ describe("registerMatrixMonitorEvents verification routing", () => {
     });
   });
 
+  it("retries SAS notice lookup when start arrives before SAS payload is available", async () => {
+    vi.useFakeTimers();
+    const verifications: Array<{
+      id: string;
+      transactionId?: string;
+      otherUserId: string;
+      updatedAt?: string;
+      sas?: {
+        decimal?: [number, number, number];
+        emoji?: Array<[string, string]>;
+      };
+    }> = [
+      {
+        id: "verification-race",
+        transactionId: "$req-race",
+        updatedAt: new Date("2026-02-25T21:42:54.000Z").toISOString(),
+        otherUserId: "@alice:example.org",
+      },
+    ];
+    const { sendMessage, roomEventListener } = createHarness({
+      joinedMembersByRoom: {
+        "!dm:example.org": ["@alice:example.org", "@bot:example.org"],
+      },
+      verifications,
+    });
+
+    try {
+      roomEventListener("!dm:example.org", {
+        event_id: "$start-race",
+        sender: "@alice:example.org",
+        type: "m.key.verification.start",
+        origin_server_ts: Date.now(),
+        content: {
+          "m.relates_to": { event_id: "$req-race" },
+        },
+      });
+
+      await vi.advanceTimersByTimeAsync(500);
+      verifications[0] = {
+        ...verifications[0]!,
+        sas: {
+          decimal: [1234, 5678, 9012],
+          emoji: [
+            ["🚀", "Rocket"],
+            ["🦋", "Butterfly"],
+            ["📕", "Book"],
+          ],
+        },
+      };
+      await vi.advanceTimersByTimeAsync(500);
+
+      await vi.waitFor(() => {
+        const bodies = (sendMessage.mock.calls as unknown[][]).map((call) =>
+          String((call[1] as { body?: string } | undefined)?.body ?? ""),
+        );
+        expect(bodies.some((body) => body.includes("SAS emoji:"))).toBe(true);
+      });
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
   it("ignores verification notices in unrelated non-DM rooms", async () => {
     const { sendMessage, roomEventListener } = createHarness({
       joinedMembersByRoom: {
diff --git a/extensions/matrix/src/matrix/monitor/verification-events.ts b/extensions/matrix/src/matrix/monitor/verification-events.ts
index 672c37c57d6..624fcc4e176 100644
--- a/extensions/matrix/src/matrix/monitor/verification-events.ts
+++ b/extensions/matrix/src/matrix/monitor/verification-events.ts
@@ -9,6 +9,7 @@ import {
 } from "./verification-utils.js";
 
 const MAX_TRACKED_VERIFICATION_EVENTS = 1024;
+const SAS_NOTICE_RETRY_DELAY_MS = 750;
 
 type MatrixVerificationStage = "request" | "ready" | "start" | "cancel" | "done" | "other";
 
@@ -225,6 +226,37 @@ async function resolveVerificationSummaryForSignal(
   return activeByUser.length === 1 ? (activeByUser[0] ?? null) : null;
 }
 
+async function resolveVerificationSasNoticeForSignal(
+  client: MatrixClient,
+  params: {
+    roomId: string;
+    event: MatrixRawEvent;
+    senderId: string;
+    flowId: string | null;
+    stage: MatrixVerificationStage;
+  },
+): Promise<{ summary: MatrixVerificationSummaryLike | null; sasNotice: string | null }> {
+  const summary = await resolveVerificationSummaryForSignal(client, params);
+  const immediateNotice =
+    summary && isActiveVerificationSummary(summary) ? formatVerificationSasNotice(summary) : null;
+  if (immediateNotice || (params.stage !== "ready" && params.stage !== "start")) {
+    return {
+      summary,
+      sasNotice: immediateNotice,
+    };
+  }
+
+  await new Promise((resolve) => setTimeout(resolve, SAS_NOTICE_RETRY_DELAY_MS));
+  const retriedSummary = await resolveVerificationSummaryForSignal(client, params);
+  return {
+    summary: retriedSummary,
+    sasNotice:
+      retriedSummary && isActiveVerificationSummary(retriedSummary)
+        ? formatVerificationSasNotice(retriedSummary)
+        : null,
+  };
+}
+
 function trackBounded(set: Set<string>, value: string): boolean {
   if (!value || set.has(value)) {
     return false;
@@ -298,16 +330,13 @@ export function createMatrixVerificationEventRouter(params: {
       }
 
       const stageNotice = formatVerificationStageNotice({ stage: signal.stage, senderId, event });
-      const summary = await resolveVerificationSummaryForSignal(params.client, {
+      const { summary, sasNotice } = await resolveVerificationSasNoticeForSignal(params.client, {
         roomId,
         event,
         senderId,
         flowId,
-      }).catch(() => null);
-      const sasNotice =
-        summary && isActiveVerificationSummary(summary)
-          ? formatVerificationSasNotice(summary)
-          : null;
+        stage: signal.stage,
+      }).catch(() => ({ summary: null, sasNotice: null }));
 
       const notices: string[] = [];
       if (stageNotice) {