From caebc75456f8e3ec9f3bfda1c83c81b45901bad9 Mon Sep 17 00:00:00 2001
From: Gustavo Madeira Santana <gumadeiras@gmail.com>
Date: Sat, 14 Mar 2026 02:58:53 +0000
Subject: [PATCH] Matrix: keep SAS notices in the verification DM

---
 .../matrix/src/matrix/monitor/events.test.ts  | 68 +++++++++++++++++++
 .../src/matrix/monitor/verification-events.ts | 29 ++++++++
 2 files changed, 97 insertions(+)

diff --git a/extensions/matrix/src/matrix/monitor/events.test.ts b/extensions/matrix/src/matrix/monitor/events.test.ts
index c3a73ba9ba8..54db8ad4f7f 100644
--- a/extensions/matrix/src/matrix/monitor/events.test.ts
+++ b/extensions/matrix/src/matrix/monitor/events.test.ts
@@ -391,6 +391,74 @@ describe("registerMatrixMonitorEvents verification routing", () => {
     expect(body).toContain("SAS decimal: 4321 8765 2109");
   });
 
+  it("prefers the most recent verification DM over the canonical active DM for unmapped SAS summaries", async () => {
+    const { sendMessage, roomEventListener, verificationSummaryListener } = createHarness({
+      joinedMembersByRoom: {
+        "!dm-active:example.org": ["@alice:example.org", "@bot:example.org"],
+        "!dm-current:example.org": ["@alice:example.org", "@bot:example.org"],
+      },
+    });
+    if (!verificationSummaryListener) {
+      throw new Error("verification.summary listener was not registered");
+    }
+
+    roomEventListener("!dm-current:example.org", {
+      event_id: "$start-current",
+      sender: "@alice:example.org",
+      type: "m.key.verification.start",
+      origin_server_ts: Date.now(),
+      content: {
+        "m.relates_to": { event_id: "$req-current" },
+      },
+    });
+
+    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("Matrix verification started with"))).toBe(true);
+    });
+
+    verificationSummaryListener({
+      id: "verification-current-room",
+      otherUserId: "@alice:example.org",
+      isSelfVerification: false,
+      initiatedByMe: false,
+      phase: 3,
+      phaseName: "started",
+      pending: true,
+      methods: ["m.sas.v1"],
+      canAccept: false,
+      hasSas: true,
+      sas: {
+        decimal: [2468, 1357, 9753],
+        emoji: [
+          ["🔔", "Bell"],
+          ["📁", "Folder"],
+          ["🐴", "Horse"],
+        ],
+      },
+      hasReciprocateQr: false,
+      completed: false,
+      createdAt: new Date("2026-02-25T21:42:54.000Z").toISOString(),
+      updatedAt: new Date("2026-02-25T21:42:55.000Z").toISOString(),
+    });
+
+    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 decimal: 2468 1357 9753"))).toBe(true);
+    });
+    const calls = sendMessage.mock.calls as unknown[][];
+    const sasCall = calls.find((call) =>
+      String((call[1] as { body?: string } | undefined)?.body ?? "").includes(
+        "SAS decimal: 2468 1357 9753",
+      ),
+    );
+    expect((sasCall?.[0] ?? "") as string).toBe("!dm-current:example.org");
+  });
+
   it("retries SAS notice lookup when start arrives before SAS payload is available", async () => {
     vi.useFakeTimers();
     const verifications: Array<{
diff --git a/extensions/matrix/src/matrix/monitor/verification-events.ts b/extensions/matrix/src/matrix/monitor/verification-events.ts
index 0e5d3573652..cc6a38d120c 100644
--- a/extensions/matrix/src/matrix/monitor/verification-events.ts
+++ b/extensions/matrix/src/matrix/monitor/verification-events.ts
@@ -310,6 +310,7 @@ export function createMatrixVerificationEventRouter(params: {
   const routedVerificationSasFingerprints = new Set<string>();
   const routedVerificationStageNotices = new Set<string>();
   const verificationFlowRooms = new Map<string, string>();
+  const verificationUserRooms = new Map<string, string>();
 
   function rememberVerificationRoom(roomId: string, event: MatrixRawEvent, flowId: string | null) {
     for (const candidate of resolveVerificationFlowCandidates({ event, flowId })) {
@@ -323,6 +324,22 @@ export function createMatrixVerificationEventRouter(params: {
     }
   }
 
+  function rememberVerificationUserRoom(remoteUserId: string, roomId: string): void {
+    const normalizedUserId = trimMaybeString(remoteUserId);
+    const normalizedRoomId = trimMaybeString(roomId);
+    if (!normalizedUserId || !normalizedRoomId) {
+      return;
+    }
+    verificationUserRooms.delete(normalizedUserId);
+    verificationUserRooms.set(normalizedUserId, normalizedRoomId);
+    if (verificationUserRooms.size > MAX_TRACKED_VERIFICATION_EVENTS) {
+      const oldest = verificationUserRooms.keys().next().value;
+      if (typeof oldest === "string") {
+        verificationUserRooms.delete(oldest);
+      }
+    }
+  }
+
   async function resolveSummaryRoomId(
     summary: MatrixVerificationSummaryLike,
   ): Promise<string | null> {
@@ -340,6 +357,17 @@ export function createMatrixVerificationEventRouter(params: {
     if (!remoteUserId) {
       return null;
     }
+    const recentRoomId = trimMaybeString(verificationUserRooms.get(remoteUserId));
+    if (
+      recentRoomId &&
+      (await isStrictDirectRoom({
+        client: params.client,
+        roomId: recentRoomId,
+        remoteUserId,
+      }))
+    ) {
+      return recentRoomId;
+    }
     const inspection = await inspectMatrixDirectRooms({
       client: params.client,
       remoteUserId,
@@ -406,6 +434,7 @@ export function createMatrixVerificationEventRouter(params: {
         );
         return;
       }
+      rememberVerificationUserRoom(senderId, roomId);
       if (!trackBounded(routedVerificationEvents, sourceFingerprint)) {
         return;
       }