Method renderGroupedBySubProperty

src/bases/TaskListView.ts:1661–1736

* Render tasks grouped by sub-property (when no primary grouping is configured). * This treats the sub-group property as primary grouping.

(taskNotes: TaskInfo[])

	 * This treats the sub-group property as primary grouping.
	 */
	private async renderGroupedBySubProperty(taskNotes: TaskInfo[]): Promise<void> {
		const visibleProperties = this.getVisibleProperties();

		// Apply search filter
		const filteredTasks = this.applySearchFilter(taskNotes);
		this.setExpandedRelationshipTaskScope(filteredTasks);
		const renderTasks = this.getTopLevelRenderTasks(filteredTasks);
		const candidateTasks = this.getTopLevelRenderTasks(taskNotes);
		this.setCurrentVisibleTaskPaths(renderTasks);

		// Show "no results" if search returned empty but we had tasks
		if (this.isSearchWithNoResults(filteredTasks, taskNotes.length)) {
			this.clearAllTaskElements();
			this.sortScopeTaskPaths.clear();
			this.sortScopeCandidateTaskPaths.clear();
			if (this.itemsContainer) {
				this.renderSearchNoResults(this.itemsContainer);
			}
			return;
		}

		const targetDate = createUTCDateFromLocalCalendarDate(new Date());
		this.currentTargetDate = targetDate;
		const cardOptions = this.getCardOptions(targetDate);

		// Group tasks by sub-property
		const pathToProps = buildTaskListPathProperties(this.dataAdapter.extractDataItems());
		const groupedTasks = groupTasksByTaskListSubProperty(
			renderTasks,
			this.subGroupPropertyId!,
			pathToProps
		);
		const allGroupedTasks = groupTasksByTaskListSubProperty(
			candidateTasks,
			this.subGroupPropertyId!,
			pathToProps
		);
		this.setSortScopeCandidatePaths(buildTaskListSubPropertyScopePaths(allGroupedTasks));
		this.applyGroupingSnapshot(this.createSubPropertyHierarchySnapshot(groupedTasks));

		// Build flat items array (treat sub-groups as primary groups)
		const items = buildTaskListSubPropertyRenderItems(groupedTasks, this.collapsedGroups);

		// Decide whether to use virtual scrolling
		const shouldUseVirtualScrolling = items.length >= this.VIRTUAL_SCROLL_THRESHOLD;

		// Switch rendering mode if needed
		if (this.useVirtualScrolling && shouldUseVirtualScrolling && this.virtualScroller) {
			await this.renderGroupedVirtual(items, visibleProperties, cardOptions);
			this.lastFlatPaths = taskNotes.map((task) => task.path);
			return;
		}

		// Full render needed
		this.itemsContainer!.empty();
		this.currentTaskElements.clear();
		this.clearClickTimeouts();
		this.taskInfoCache.clear();