LHN-LHN doesn't show the message sent or the system message

src/libs/OptionsListUtils.ts

@@ -857,6 +857,15 @@ function getLastMessageTextForReport(
         lastMessageTextFromReport = getReportActionMessageText(lastReportAction);
     }
 
+    if (reportID) {
+        const chatReport = allReports?.[`${ONYXKEYS.COLLECTION.REPORT}${report?.chatReportID}`];
+        // If the report is a one-transaction report, get the last message text from combined report actions so the LHN can display modifications to the transaction thread or the report itself
+        const transactionThreadReportID = getOneTransactionThreadReportID(report, chatReport, allSortedReportActions[reportID]);
+        if (transactionThreadReportID) {
+            lastMessageTextFromReport = getReportActionMessageText(lastReportAction);
+        }
+    }
+
     return lastMessageTextFromReport || (report?.lastMessageText ?? '');
 }
 

tests/unit/SidebarUtilsTest.ts

@@ -4,7 +4,7 @@ import type {OnyxCollection, OnyxEntry} from 'react-native-onyx';
 import Onyx from 'react-native-onyx';
 import useReportIsArchived from '@hooks/useReportIsArchived';
 import DateUtils from '@libs/DateUtils';
-import {getReportActionMessageText} from '@libs/ReportActionsUtils';
+import {getOriginalMessage, getReportActionMessageText} from '@libs/ReportActionsUtils';
 import {getAllReportErrors} from '@libs/ReportUtils';
 import SidebarUtils from '@libs/SidebarUtils';
 import initOnyxDerivedValues from '@userActions/OnyxDerived';
@@ -13,7 +13,8 @@ import ONYXKEYS from '@src/ONYXKEYS';
 import type {Policy, Report, ReportAction, ReportActions, Transaction, TransactionViolation, TransactionViolations} from '@src/types/onyx';
 import type {ReportCollectionDataSet} from '@src/types/onyx/Report';
 import type {TransactionViolationsCollectionDataSet} from '@src/types/onyx/TransactionViolation';
-import {chatReportR14932} from '../../__mocks__/reportData/reports';
+import {actionR14932 as mockIOUAction} from '../../__mocks__/reportData/actions';
+import {chatReportR14932, iouReportR14932} from '../../__mocks__/reportData/reports';
 import createRandomPolicy from '../utils/collections/policies';
 import createRandomReportAction from '../utils/collections/reportActions';
 import createRandomReport from '../utils/collections/reports';
@@ -1125,6 +1126,69 @@ describe('SidebarUtils', () => {
                     oneTransactionThreadReport: undefined,
                 });
 
+                expect(result?.alternateText).toBe(`You: ${getReportActionMessageText(lastAction)}`);
+            });
+            it('returns the last action message as an alternate text if the expense report is the one expense report', async () => {
+                const IOUTransactionID = `${ONYXKEYS.COLLECTION.TRANSACTION}TRANSACTION_IOU` as const;
+
+                iouReportR14932.reportID = '5';
+                chatReportR14932.reportID = '6';
+                iouReportR14932.lastActorAccountID = undefined;
+
+                const report: Report = {
+                    ...createRandomReport(1),
+                    chatType: 'policyExpenseChat',
+                    pendingAction: null,
+                    isOwnPolicyExpenseChat: true,
+                    parentReportID: iouReportR14932.reportID,
+                    parentReportActionID: mockIOUAction.reportActionID,
+                    lastActorAccountID: undefined,
+                };
+
+                const linkedCreateAction: ReportAction = {
+                    ...mockIOUAction,
+                    originalMessage: {...getOriginalMessage(mockIOUAction), IOUTransactionID},
+                    childReportID: report.reportID,
+                    reportActionID: '3',
+                };
+
+                const lastAction: ReportAction = {
+                    ...createRandomReportAction(1),
+                    message: [
+                        {
+                            type: 'COMMENT',
+                            html: 'test action',
+                            text: 'test action',
+                        },
+                    ],
+                    originalMessage: {
+                        whisperedTo: [],
+                    },
+
+                    created: DateUtils.getDBTime(),
+                    lastModified: DateUtils.getDBTime(),
+                    shouldShow: true,
+                    pendingAction: null,
+                    actionName: CONST.REPORT.ACTIONS.TYPE.ADD_COMMENT,
+                    actorAccountID: undefined,
+                };
+
+                await Onyx.set(`${ONYXKEYS.COLLECTION.REPORT}${iouReportR14932.reportID}`, iouReportR14932);
+                await Onyx.set(`${ONYXKEYS.COLLECTION.REPORT}${chatReportR14932.reportID}`, chatReportR14932);
+                await Onyx.set(`${ONYXKEYS.COLLECTION.REPORT}${report.reportID}`, report);
+                await Onyx.set(`${ONYXKEYS.COLLECTION.REPORT_ACTIONS}${report.reportID}`, {[lastAction.reportActionID]: lastAction});
+                await Onyx.set(`${ONYXKEYS.COLLECTION.REPORT_ACTIONS}${iouReportR14932.reportID}`, {[linkedCreateAction.reportActionID]: linkedCreateAction});
+
+                const result = SidebarUtils.getOptionData({
+                    report: iouReportR14932,
+                    reportAttributes: undefined,
+                    reportNameValuePairs: {},
+                    personalDetails: {},
+                    policy: undefined,
+                    parentReportAction: undefined,
+                    oneTransactionThreadReport: undefined,
+                });
+
                 expect(result?.alternateText).toBe(`You: ${getReportActionMessageText(lastAction)}`);
             });
         });