Fix edge case with sent indicator being drawn when it shouldn't be

src/components/structures/MessagePanel.tsx

@@ -633,7 +633,7 @@ export default class MessagePanel extends React.Component<IProps, IState> {
 
         const userId = MatrixClientPeg.safeGet().getSafeUserId();
 
-        let foundLastSuccessfulWeSent = false;
+        let foundLastSuccessfulEvent = false;
         let lastShownNonLocalEchoIndex = -1;
         // Find the indices of the last successful event we sent and the last non-local-echo events shown
         for (let i = events.length - 1; i >= 0; i--) {
@@ -646,16 +646,21 @@ export default class MessagePanel extends React.Component<IProps, IState> {
                 lastShownEvent = event;
             }
 
-            if (!foundLastSuccessfulWeSent && this.isSentState(event) && isEligibleForSpecialReceipt(event, userId)) {
-                events[i].lastSuccessfulWeSent = true;
-                foundLastSuccessfulWeSent = true;
+            if (!foundLastSuccessfulEvent && this.isSentState(event) && isEligibleForSpecialReceipt(event)) {
+                foundLastSuccessfulEvent = true;
+                // If we are not sender of this last successful event eligible for special receipt then we stop here
+                // As we do not want to render our sent receipt if there are more receipts below it and events sent
+                // by other users get a synthetic read receipt for their sent events.
+                if (event.getSender() === userId) {
+                    events[i].lastSuccessfulWeSent = true;
+                }
             }
 
             if (lastShownNonLocalEchoIndex < 0 && !event.status) {
                 lastShownNonLocalEchoIndex = i;
             }
 
-            if (lastShownNonLocalEchoIndex >= 0 && foundLastSuccessfulWeSent) {
+            if (lastShownNonLocalEchoIndex >= 0 && foundLastSuccessfulEvent) {
                 break;
             }
         }

src/components/views/rooms/EventTile.tsx

@@ -251,10 +251,7 @@ interface IState {
  * This could be a 'sending' or 'sent' receipt, for example.
  * @returns {boolean}
  */
-export function isEligibleForSpecialReceipt(event: MatrixEvent, myUserId: string): boolean {
-    // Check to see if the event was sent by us. If it wasn't, it won't qualify for special read receipts.
-    if (event.getSender() !== myUserId) return false;
-
+export function isEligibleForSpecialReceipt(event: MatrixEvent): boolean {
     // Determine if the type is relevant to the user.
     // This notably excludes state events and pretty much anything that can't be sent by the composer as a message.
     // For those we rely on local echo giving the impression of things changing, and expect them to be quick.
@@ -332,7 +329,9 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
         // Quickly check to see if the event was sent by us. If it wasn't, it won't qualify for
         // special read receipts.
         const myUserId = MatrixClientPeg.safeGet().getSafeUserId();
-        return isEligibleForSpecialReceipt(this.props.mxEvent, myUserId);
+        // Check to see if the event was sent by us. If it wasn't, it won't qualify for special read receipts.
+        if (this.props.mxEvent.getSender() !== myUserId) return false;
+        return isEligibleForSpecialReceipt(this.props.mxEvent);
     }
 
     private get shouldShowSentReceipt(): boolean {

test/components/structures/MessagePanel-test.tsx

@@ -20,6 +20,7 @@ import { EventEmitter } from "events";
 import { MatrixEvent, Room, RoomMember } from "matrix-js-sdk/src/matrix";
 import { render } from "@testing-library/react";
 import { Thread } from "matrix-js-sdk/src/models/thread";
+import { ReceiptType } from "matrix-js-sdk/src/@types/read_receipts";
 
 import MessagePanel, { shouldFormContinuation } from "../../../src/components/structures/MessagePanel";
 import SettingsStore from "../../../src/settings/SettingsStore";
@@ -757,12 +758,44 @@ describe("MessagePanel", function () {
         ];
         const { container } = render(getComponent({ events, showReadReceipts: true }));
 
-        // just check we have the right number of tiles for now
         const tiles = container.getElementsByClassName("mx_EventTile");
         expect(tiles.length).toEqual(2);
         expect(tiles[0].querySelector(".mx_EventTile_receiptSent")).toBeTruthy();
         expect(tiles[1].querySelector(".mx_EventTile_receiptSent")).toBeFalsy();
     });
+
+    it("should set lastSuccessful=false on non-last event if last event has a receipt from someone else", () => {
+        client.getRoom.mockImplementation((id) => (id === room.roomId ? room : null));
+        const events = [
+            TestUtilsMatrix.mkMessage({
+                event: true,
+                room: room.roomId,
+                user: client.getSafeUserId(),
+                ts: 1000,
+            }),
+            TestUtilsMatrix.mkMessage({
+                event: true,
+                room: room.roomId,
+                user: "@other:user",
+                ts: 1001,
+            }),
+        ];
+        room.addReceiptToStructure(
+            events[1].getId()!,
+            ReceiptType.Read,
+            "@other:user",
+            {
+                ts: 1001,
+            },
+            true,
+        );
+        const { container } = render(getComponent({ events, showReadReceipts: true }));
+
+        const tiles = container.getElementsByClassName("mx_EventTile");
+        expect(tiles.length).toEqual(2);
+        expect(tiles[0].querySelector(".mx_EventTile_receiptSent")).toBeFalsy();
+        expect(tiles[1].querySelector(".mx_EventTile_receiptSent")).toBeFalsy();
+    });
 });
 
 describe("shouldFormContinuation", () => {