diff --git a/extensions/matrix/src/matrix/monitor/events.test.ts b/extensions/matrix/src/matrix/monitor/events.test.ts
index 54db8ad4f7f..03035f17521 100644
--- a/extensions/matrix/src/matrix/monitor/events.test.ts
+++ b/extensions/matrix/src/matrix/monitor/events.test.ts
@@ -118,6 +118,56 @@ function createHarness(params?: {
 }
 
 describe("registerMatrixMonitorEvents verification routing", () => {
+  it("does not repost historical verification completions during startup catch-up", async () => {
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date("2026-03-14T13:10:00.000Z"));
+    try {
+      const { sendMessage, roomEventListener } = createHarness();
+
+      roomEventListener("!room:example.org", {
+        event_id: "$done-old",
+        sender: "@alice:example.org",
+        type: "m.key.verification.done",
+        origin_server_ts: Date.now() - 10 * 60 * 1000,
+        content: {
+          "m.relates_to": { event_id: "$req-old" },
+        },
+      });
+
+      await vi.runAllTimersAsync();
+      expect(sendMessage).not.toHaveBeenCalled();
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it("still posts fresh verification completions", async () => {
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date("2026-03-14T13:10:00.000Z"));
+    try {
+      const { sendMessage, roomEventListener } = createHarness();
+
+      roomEventListener("!room:example.org", {
+        event_id: "$done-fresh",
+        sender: "@alice:example.org",
+        type: "m.key.verification.done",
+        origin_server_ts: Date.now(),
+        content: {
+          "m.relates_to": { event_id: "$req-fresh" },
+        },
+      });
+
+      await vi.waitFor(() => {
+        expect(sendMessage).toHaveBeenCalledTimes(1);
+      });
+      expect(getSentNoticeBody(sendMessage)).toContain(
+        "Matrix verification completed with @alice:example.org.",
+      );
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
   it("forwards reaction room events into the shared room handler", async () => {
     const { onRoomMessage, sendMessage, roomEventListener } = createHarness();
 
diff --git a/extensions/matrix/src/matrix/monitor/verification-events.ts b/extensions/matrix/src/matrix/monitor/verification-events.ts
index cc6a38d120c..b7e951e82d9 100644
--- a/extensions/matrix/src/matrix/monitor/verification-events.ts
+++ b/extensions/matrix/src/matrix/monitor/verification-events.ts
@@ -11,6 +11,7 @@ import {
 
 const MAX_TRACKED_VERIFICATION_EVENTS = 1024;
 const SAS_NOTICE_RETRY_DELAY_MS = 750;
+const VERIFICATION_EVENT_STARTUP_GRACE_MS = 30_000;
 
 type MatrixVerificationStage = "request" | "ready" | "start" | "cancel" | "done" | "other";
 
@@ -306,12 +307,24 @@ export function createMatrixVerificationEventRouter(params: {
   client: MatrixClient;
   logVerboseMessage: (message: string) => void;
 }) {
+  const routerStartedAtMs = Date.now();
   const routedVerificationEvents = new Set<string>();
   const routedVerificationSasFingerprints = new Set<string>();
   const routedVerificationStageNotices = new Set<string>();
   const verificationFlowRooms = new Map<string, string>();
   const verificationUserRooms = new Map<string, string>();
 
+  function shouldEmitVerificationEventNotice(event: MatrixRawEvent): boolean {
+    const eventTs =
+      typeof event.origin_server_ts === "number" && Number.isFinite(event.origin_server_ts)
+        ? event.origin_server_ts
+        : null;
+    if (eventTs === null) {
+      return true;
+    }
+    return eventTs >= routerStartedAtMs - VERIFICATION_EVENT_STARTUP_GRACE_MS;
+  }
+
   function rememberVerificationRoom(roomId: string, event: MatrixRawEvent, flowId: string | null) {
     for (const candidate of resolveVerificationFlowCandidates({ event, flowId })) {
       verificationFlowRooms.set(candidate, roomId);
@@ -420,6 +433,12 @@ export function createMatrixVerificationEventRouter(params: {
     rememberVerificationRoom(roomId, event, signal.flowId);
 
     void (async () => {
+      if (!shouldEmitVerificationEventNotice(event)) {
+        params.logVerboseMessage(
+          `matrix: ignoring historical verification event room=${roomId} id=${event.event_id ?? "unknown"} type=${event.type ?? "unknown"}`,
+        );
+        return;
+      }
       const flowId = signal.flowId;
       const sourceEventId = trimMaybeString(event?.event_id);
       const sourceFingerprint = sourceEventId ?? `${senderId}:${event.type}:${flowId ?? "none"}`;