Fix cannot create task for new user via [] method

src/libs/ReportUtils.ts

@@ -293,6 +293,7 @@ type OptimisticChatReport = Pick<
     | 'writeCapability'
     | 'avatarUrl'
     | 'invoiceReceiver'
+    | 'isHidden'
 > & {
     isOptimisticReport: true;
 };

src/libs/actions/Task.ts

@@ -650,6 +650,27 @@ function setAssigneeChatReport(chatReport: OnyxTypes.Report) {
     Onyx.merge(ONYXKEYS.TASK, {assigneeChatReport: chatReport});
 }
 
+function setNewOptimisticAssignee(assigneeLogin: string, assigneeAccountID: number | undefined = undefined) {
+    const currentAssigneeAccountID = assigneeAccountID ?? UserUtils.generateAccountID(assigneeLogin);
+    const report: ReportUtils.OptimisticChatReport = ReportUtils.buildOptimisticChatReport([currentAssigneeAccountID]);
+
+    // When assigning a task to a new user, by default we share the task in their DM
+    // However, the DM doesn't exist yet - and will be created optimistically once the task is created
+    // We don't want to show the new DM yet, because if you select an assignee and then change the assignee, the previous DM will still be shown
+    // So here, we create it optimistically to share it with the assignee, but we have to hide it until the task is created
+    report.isHidden = true;
+    Onyx.set(`${ONYXKEYS.COLLECTION.REPORT}${report.reportID}`, report);
+
+    const optimisticPersonalDetailsListAction: OnyxTypes.PersonalDetails = {
+        accountID: currentAssigneeAccountID,
+        avatar: allPersonalDetails?.[currentAssigneeAccountID]?.avatar ?? UserUtils.getDefaultAvatarURL(currentAssigneeAccountID),
+        displayName: allPersonalDetails?.[currentAssigneeAccountID]?.displayName ?? assigneeLogin,
+        login: assigneeLogin,
+    };
+    Onyx.merge(ONYXKEYS.PERSONAL_DETAILS_LIST, {[currentAssigneeAccountID]: optimisticPersonalDetailsListAction});
+    return {assignee: optimisticPersonalDetailsListAction, assigneeReport: report};
+}
+
 /**
  * Sets the assignee value for the task and checks for an existing chat with the assignee
  * If there is no existing chat, it creates an optimistic chat report
@@ -670,26 +691,7 @@ function setAssigneeValue(
         }
         // If chat report is still not found we need to build new optimistic chat report
         if (!report) {
-            report = ReportUtils.buildOptimisticChatReport([assigneeAccountID]);
-            report.isOptimisticReport = true;
-
-            // When assigning a task to a new user, by default we share the task in their DM
-            // However, the DM doesn't exist yet - and will be created optimistically once the task is created
-            // We don't want to show the new DM yet, because if you select an assignee and then change the assignee, the previous DM will still be shown
-            // So here, we create it optimistically to share it with the assignee, but we have to hide it until the task is created
-            if (report) {
-                report.isHidden = true;
-            }
-            Onyx.set(`${ONYXKEYS.COLLECTION.REPORT}${report.reportID}`, report);
-
-            // If this is an optimistic report, we likely don't have their personal details yet so we set it here optimistically as well
-            const optimisticPersonalDetailsListAction = {
-                accountID: assigneeAccountID,
-                avatar: allPersonalDetails?.[assigneeAccountID]?.avatar ?? UserUtils.getDefaultAvatarURL(assigneeAccountID),
-                displayName: allPersonalDetails?.[assigneeAccountID]?.displayName ?? assigneeEmail,
-                login: assigneeEmail,
-            };
-            Onyx.merge(ONYXKEYS.PERSONAL_DETAILS_LIST, {[assigneeAccountID]: optimisticPersonalDetailsListAction});
+            report = setNewOptimisticAssignee(assigneeEmail, assigneeAccountID).assigneeReport;
         }
 
         // The optimistic field may not exist in the existing report and it can be overridden by the optimistic field of previous report data when merging the assignee chat report
@@ -1051,6 +1053,7 @@ export {
     getTaskAssigneeAccountID,
     clearTaskErrors,
     canModifyTask,
+    setNewOptimisticAssignee,
 };
 
 export type {PolicyValue, Assignee, ShareDestination};

src/pages/home/report/ReportFooter.tsx

@@ -110,10 +110,16 @@ function ReportFooter({
             const mentionWithDomain = ReportUtils.addDomainToShortMention(mention ?? '') ?? mention;
 
             let assignee: OnyxTypes.PersonalDetails | EmptyObject = {};
+            let assigneeChatReport;
             if (mentionWithDomain) {
                 assignee = Object.values(allPersonalDetails).find((value) => value?.login === mentionWithDomain) ?? {};
+                if (!Object.keys(assignee).length) {
+                    const optimisticDataForNewAssignee = Task.setNewOptimisticAssignee(mentionWithDomain);
+                    assignee = optimisticDataForNewAssignee.assignee;
+                    assigneeChatReport = optimisticDataForNewAssignee.assigneeReport;
+                }
             }
-            Task.createTaskAndNavigate(report.reportID, title, '', assignee?.login ?? '', assignee.accountID, undefined, report.policyID);
+            Task.createTaskAndNavigate(report.reportID, title, '', assignee?.login ?? '', assignee.accountID, assigneeChatReport, report.policyID);
             return true;
         },
         [allPersonalDetails, report.policyID, report.reportID],