refactor(z-task-modal): implement custom filter for employee selection to prevent reselect of the same employee

app/src/plugins/tm@modal/task/z-task-modal.vue

@@ -102,7 +102,7 @@
             :timeblocks="getEmployeeTimeblocks(subtask.employee_id)"
             :all-timeblocks="timeblocks"
             :deleted-timeblock-ids="deletedTimeblockIds"
-            :custom-filter="getEmployeeCustomFilter(subtask.employee_id)"
+            :custom-filter="customFilterWithEmployeeFilter"
             @update:timeblocks="
               updateEmployeeTimeblocks($event, subtask.employee_id)
             "
@@ -122,7 +122,7 @@
               :timeblocks="getEmployeeTimeblocks(employee.id)"
               :all-timeblocks="timeblocks"
               :deleted-timeblock-ids="deletedTimeblockIds"
-              :custom-filter="getEmployeeCustomFilter(employee.id)"
+              :custom-filter="customFilterWithEmployeeFilter"
               :required="index === 0"
               @update:timeblocks="updateEmployeeTimeblocks($event, employee.id)"
               @clear-employee="() => removeEmployeeAtIndex(index)"
@@ -521,6 +521,33 @@ export default {
   },
 
   methods: {
+    customFilterWithEmployeeFilter(item, input, itemObject) {
+      const shouldShowItem = this.customFilter(item, input);
+
+      if (!shouldShowItem) return false;
+      if (!itemObject?.value) return false;
+
+      const employeeId = itemObject.value;
+
+      if (!this.subtask.id) {
+        // New subtask with multiple employees support or edit of draft with multiple employees
+        return (
+          shouldShowItem &&
+          !this.timeblocks.some((tb) => tb.employee_id === employeeId)
+        );
+      } else if (this.subtask.is_draft) {
+        // Edit draft subtask with multiple employees support
+        return (
+          shouldShowItem &&
+          !this.subtask.employees.some(
+            (employee) => Number(employee.id) === employeeId,
+          )
+        );
+      } else {
+        // Saved standard subtask, allow "re-select" for better UX
+        return shouldShowItem;
+      }
+    },
     toggleEditMode() {
       if (this.subtask.type == 'office365')
         return this.$events.emit('show-unable-to-edit-office-task-modal', {
@@ -564,45 +591,6 @@ export default {
       return this.timeblocks.filter((tb) => tb.employee_id == employeeId);
     },
 
-    // Custom filter for employee select to prevent selecting the same employee twice
-    // currentEmployeeId: the ID of the employee currently selected in this dropdown (can be null)
-    getEmployeeCustomFilter(currentEmployeeId) {
-      return (itemText, queryText, item) => {
-        // Get all selected employee IDs except the current one
-        const selectedEmployeeIds = new Set();
-
-        if (this.isDraftWithMultipleEmployees && this.subtask?.employees) {
-          // In multi-employee mode, collect all selected employee IDs except current
-          this.subtask.employees.forEach((emp) => {
-            if (emp.id && emp.id !== currentEmployeeId) {
-              selectedEmployeeIds.add(emp.id);
-            }
-          });
-        } else if (
-          this.subtask?.employee_id &&
-          this.subtask.employee_id !== currentEmployeeId
-        ) {
-          // In single employee edit mode
-          selectedEmployeeIds.add(this.subtask.employee_id);
-        }
-
-        // Filter out already selected employees (but allow current selection)
-        if (selectedEmployeeIds.has(item.id)) {
-          return false;
-        }
-
-        // Apply default text filtering (from AutocompleteMixin)
-        if (this.customFilter) {
-          return this.customFilter(itemText, queryText, item);
-        }
-
-        // Default case-insensitive text match
-        const searchText = queryText.toString().toLowerCase();
-        const text = itemText.toString().toLowerCase();
-        return text.indexOf(searchText) > -1;
-      };
-    },
-
     updateEmployeeTimeblocks(updatedTimeblocks, employeeId) {
       // Track deleted timeblocks (saved timeblocks that are no longer in the updated list)
       const updatedIds = new Set(