From 76ca201bb91caba6e638bab9fa6f6e0002a1e13f Mon Sep 17 00:00:00 2001
From: Gustavo Madeira Santana <gumadeiras@gmail.com>
Date: Thu, 12 Mar 2026 08:42:37 +0000
Subject: [PATCH] Matrix: defer sender lookups until needed

---
 extensions/matrix/src/matrix/monitor/handler.test.ts | 8 ++++++--
 extensions/matrix/src/matrix/monitor/handler.ts      | 9 ++++++++-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/extensions/matrix/src/matrix/monitor/handler.test.ts b/extensions/matrix/src/matrix/monitor/handler.test.ts
index ce166af5968..50c4ecbd9bb 100644
--- a/extensions/matrix/src/matrix/monitor/handler.test.ts
+++ b/extensions/matrix/src/matrix/monitor/handler.test.ts
@@ -255,13 +255,14 @@ describe("matrix monitor handler pairing account scope", () => {
 
   it("skips media downloads for unmentioned group media messages", async () => {
     const downloadContent = vi.fn(async () => Buffer.from("image"));
+    const getMemberDisplayName = vi.fn(async () => "sender");
     const { handler, resolveAgentRoute } = createMatrixHandlerTestHarness({
       client: {
         downloadContent,
       },
       isDirectMessage: false,
       mentionRegexes: [/@bot/i],
-      getMemberDisplayName: async () => "sender",
+      getMemberDisplayName,
     });
 
     await handler("!room:example.org", {
@@ -281,6 +282,7 @@ describe("matrix monitor handler pairing account scope", () => {
     } as MatrixRawEvent);
 
     expect(downloadContent).not.toHaveBeenCalled();
+    expect(getMemberDisplayName).not.toHaveBeenCalled();
     expect(resolveAgentRoute).not.toHaveBeenCalled();
   });
 
@@ -304,6 +306,7 @@ describe("matrix monitor handler pairing account scope", () => {
       nextBatch: null,
       prevBatch: null,
     }));
+    const getMemberDisplayName = vi.fn(async () => "sender");
     const { handler, resolveAgentRoute } = createMatrixHandlerTestHarness({
       client: {
         getEvent,
@@ -311,7 +314,7 @@ describe("matrix monitor handler pairing account scope", () => {
       },
       isDirectMessage: false,
       mentionRegexes: [/@bot/i],
-      getMemberDisplayName: async () => "sender",
+      getMemberDisplayName,
     });
 
     await handler("!room:example.org", {
@@ -332,6 +335,7 @@ describe("matrix monitor handler pairing account scope", () => {
 
     expect(getEvent).not.toHaveBeenCalled();
     expect(getRelations).not.toHaveBeenCalled();
+    expect(getMemberDisplayName).not.toHaveBeenCalled();
     expect(resolveAgentRoute).not.toHaveBeenCalled();
   });
 
diff --git a/extensions/matrix/src/matrix/monitor/handler.ts b/extensions/matrix/src/matrix/monitor/handler.ts
index 1854390a054..8b052956772 100644
--- a/extensions/matrix/src/matrix/monitor/handler.ts
+++ b/extensions/matrix/src/matrix/monitor/handler.ts
@@ -294,7 +294,11 @@ export function createMatrixRoomMessageHandler(params: MatrixMonitorHandlerParam
         }
       }
 
-      const senderName = await getMemberDisplayName(roomId, senderId);
+      let senderNamePromise: Promise<string> | null = null;
+      const getSenderName = async (): Promise<string> => {
+        senderNamePromise ??= getMemberDisplayName(roomId, senderId).catch(() => senderId);
+        return await senderNamePromise;
+      };
       const storeAllowFrom = await readStoreAllowFrom();
       const roomUsers = roomConfig?.users ?? [];
       const accessState = resolveMatrixMonitorAccessState({
@@ -324,6 +328,7 @@ export function createMatrixRoomMessageHandler(params: MatrixMonitorHandlerParam
           const allowMatchMeta = formatAllowlistMatchMeta(directAllowMatch);
           if (!directAllowMatch.allowed) {
             if (!isReactionEvent && dmPolicy === "pairing") {
+              const senderName = await getSenderName();
               const { code, created } = await core.channel.pairing.upsertPairingRequest({
                 channel: "matrix",
                 id: senderId,
@@ -400,6 +405,7 @@ export function createMatrixRoomMessageHandler(params: MatrixMonitorHandlerParam
       }
 
       if (isReactionEvent) {
+        const senderName = await getSenderName();
         await handleInboundMatrixReaction({
           client,
           core,
@@ -541,6 +547,7 @@ export function createMatrixRoomMessageHandler(params: MatrixMonitorHandlerParam
       if (!bodyText) {
         return;
       }
+      const senderName = await getSenderName();
 
       const messageId = event.event_id ?? "";
       const replyToEventId = content["m.relates_to"]?.["m.in_reply_to"]?.event_id;