refactor(todo,calendar): extract duplicated constants and utilities

Todo:
- Extract priority colors to lib/constants/priority.ts (was in TaskItem + KanbanTaskCard)
- Extract formatDueDate to lib/utils/date-display.ts (was in TaskItem + KanbanTaskCard + task-parser)
- Extract withErrorHandling to lib/stores/store-helpers.ts (was in 3 stores)

Calendar:
- Extract formatTime, snapToGrid, getDayFromX, getMinutesFromY to lib/utils/drag-helpers.ts
  (was duplicated across 4 drag/drop composables)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/todo/apps/web/src/lib/components/TaskItem.svelte

@@ -9,8 +9,8 @@
 	} from '@todo/shared';
 	import type { ContactReference, ContactOrManual } from '@manacore/shared-types';
 	import { STATUS_OPTIONS, RECURRENCE_OPTIONS } from '@todo/shared';
-	import { format, isToday, isPast, isTomorrow } from 'date-fns';
-	import { de } from 'date-fns/locale';
+	import { isToday, isPast } from 'date-fns';
+	import { formatDueDate } from '$lib/utils/date-display';
 	import { getContext } from 'svelte';
 	import type { Project } from '@todo/shared';
 	import { getActiveProjects, getProjectColor } from '$lib/data/task-queries';
@@ -27,6 +27,7 @@
 		FunRatingPicker,
 		TagSelector,
 	} from './form';
+	import { PRIORITY_COLORS } from '$lib/constants/priority';
 
 	interface Props {
 		task: Task;
@@ -291,21 +292,12 @@
 		subtasks = newSubtasks;
 	}
 
-	// Priority colors
-	const priorityColors: Record<string, string> = {
-		low: '#22c55e',
-		medium: '#eab308',
-		high: '#f97316',
-		urgent: '#ef4444',
-	};
+	const priorityColors = PRIORITY_COLORS;
 
 	// Format due date
 	let dueDateText = $derived(() => {
 		if (!task.dueDate) return null;
-		const date = new Date(task.dueDate);
-		if (isToday(date)) return 'Heute';
-		if (isTomorrow(date)) return 'Morgen';
-		return format(date, 'dd. MMM', { locale: de });
+		return formatDueDate(new Date(task.dueDate));
 	});
 
 	// Check if overdue

apps/todo/apps/web/src/lib/components/kanban/KanbanTaskCard.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
 	import type { Task } from '@todo/shared';
-	import { format, isToday, isPast, isTomorrow } from 'date-fns';
-	import { de } from 'date-fns/locale';
+	import { isToday, isPast } from 'date-fns';
+	import { formatDueDate } from '$lib/utils/date-display';
 	import { ConfirmationModal, ContactAvatar } from '@manacore/shared-ui';
 	import TaskEditModal from '../TaskEditModal.svelte';
 	import {
@@ -12,6 +12,7 @@
 		Note,
 		Trash,
 	} from '@manacore/shared-icons';
+	import { PRIORITY_BG_CLASSES } from '$lib/constants/priority';
 
 	interface Props {
 		task: Task;
@@ -36,21 +37,12 @@
 	let contextMenuX = $state(0);
 	let contextMenuY = $state(0);
 
-	// Priority colors (consistent with KanbanFilters)
-	const priorityColors: Record<string, string> = {
-		low: 'bg-blue-500',
-		medium: 'bg-yellow-500',
-		high: 'bg-orange-500',
-		urgent: 'bg-red-500',
-	};
+	const priorityColors = PRIORITY_BG_CLASSES;
 
 	// Format due date
 	let dueDateText = $derived(() => {
 		if (!task.dueDate) return null;
-		const date = new Date(task.dueDate);
-		if (isToday(date)) return 'Heute';
-		if (isTomorrow(date)) return 'Morgen';
-		return format(date, 'dd. MMM', { locale: de });
+		return formatDueDate(new Date(task.dueDate));
 	});
 
 	// Check if overdue

apps/todo/apps/web/src/lib/constants/priority.ts

@@ -0,0 +1,37 @@
+import type { TaskPriority } from '@todo/shared';
+
+/**
+ * Hex color for each priority level, used for inline styles (e.g. checkbox tint).
+ */
+export const PRIORITY_COLORS: Record<TaskPriority, string> = {
+	low: '#22c55e',
+	medium: '#eab308',
+	high: '#f97316',
+	urgent: '#ef4444',
+};
+
+/**
+ * Tailwind background-color class for each priority level,
+ * used for dot indicators and filter pill backgrounds.
+ */
+export const PRIORITY_BG_CLASSES: Record<TaskPriority, string> = {
+	low: 'bg-blue-500',
+	medium: 'bg-yellow-500',
+	high: 'bg-orange-500',
+	urgent: 'bg-red-500',
+};
+
+/**
+ * Full priority option descriptors for filter UIs.
+ */
+export const PRIORITY_OPTIONS: {
+	value: TaskPriority;
+	label: string;
+	color: string;
+	bgColor: string;
+}[] = [
+	{ value: 'urgent', label: 'Dringend', color: '#ef4444', bgColor: 'bg-red-500' },
+	{ value: 'high', label: 'Hoch', color: '#f97316', bgColor: 'bg-orange-500' },
+	{ value: 'medium', label: 'Normal', color: '#eab308', bgColor: 'bg-yellow-500' },
+	{ value: 'low', label: 'Niedrig', color: '#3b82f6', bgColor: 'bg-blue-500' },
+];

apps/todo/apps/web/src/lib/stores/board-views.svelte.ts

@@ -6,8 +6,10 @@
  */
 
 import { boardViewCollection, type LocalBoardView, type ViewColumn } from '$lib/data/local-store';
+import { withErrorHandling } from './store-helpers';
 
 let error = $state<string | null>(null);
+const setError = (e: string | null) => (error = e);
 
 export const boardViewsStore = {
 	get error() {
@@ -15,70 +17,74 @@ export const boardViewsStore = {
 	},
 
 	async createView(data: Omit<LocalBoardView, 'id'>) {
-		error = null;
-		try {
-			const count = await boardViewCollection.count();
-			const newView: LocalBoardView = {
-				...data,
-				id: crypto.randomUUID(),
-				order: data.order ?? count,
-			};
-			return await boardViewCollection.insert(newView);
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to create view';
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				const count = await boardViewCollection.count();
+				const newView: LocalBoardView = {
+					...data,
+					id: crypto.randomUUID(),
+					order: data.order ?? count,
+				};
+				return await boardViewCollection.insert(newView);
+			},
+			'Failed to create view',
+			{ log: false }
+		);
 	},
 
 	async updateView(id: string, data: Partial<LocalBoardView>) {
-		error = null;
-		try {
-			return await boardViewCollection.update(id, data as Partial<LocalBoardView>);
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to update view';
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				return await boardViewCollection.update(id, data as Partial<LocalBoardView>);
+			},
+			'Failed to update view',
+			{ log: false }
+		);
 	},
 
 	async deleteView(id: string) {
-		error = null;
-		try {
-			await boardViewCollection.delete(id);
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to delete view';
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				await boardViewCollection.delete(id);
+			},
+			'Failed to delete view',
+			{ log: false }
+		);
 	},
 
 	async reorderViews(viewIds: string[]) {
-		error = null;
-		try {
-			for (let i = 0; i < viewIds.length; i++) {
-				await boardViewCollection.update(viewIds[i], { order: i } as Partial<LocalBoardView>);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to reorder views';
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				for (let i = 0; i < viewIds.length; i++) {
+					await boardViewCollection.update(viewIds[i], { order: i } as Partial<LocalBoardView>);
+				}
+			},
+			'Failed to reorder views',
+			{ rethrow: false, log: false }
+		);
 	},
 
 	/** Update a column's taskIds (for custom groupBy with manual task assignment) */
 	async updateColumnTaskIds(viewId: string, columnId: string, taskIds: string[]) {
-		error = null;
-		try {
-			const view = await boardViewCollection.get(viewId);
-			if (!view) return;
+		return withErrorHandling(
+			setError,
+			async () => {
+				const view = await boardViewCollection.get(viewId);
+				if (!view) return;
 
-			const updatedColumns = view.columns.map((col: ViewColumn) =>
-				col.id === columnId
-					? { ...col, match: { ...col.match, taskIds } }
-					: col
-			);
-			await boardViewCollection.update(viewId, {
-				columns: updatedColumns,
-			} as Partial<LocalBoardView>);
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to update column';
-			throw e;
-		}
+				const updatedColumns = view.columns.map((col: ViewColumn) =>
+					col.id === columnId ? { ...col, match: { ...col.match, taskIds } } : col
+				);
+				await boardViewCollection.update(viewId, {
+					columns: updatedColumns,
+				} as Partial<LocalBoardView>);
+			},
+			'Failed to update column',
+			{ log: false }
+		);
 	},
 };

apps/todo/apps/web/src/lib/stores/projects.svelte.ts

@@ -10,8 +10,10 @@ import type { Project } from '@todo/shared';
 import { projectCollection, type LocalProject } from '$lib/data/local-store';
 import { toProject } from '$lib/data/task-queries';
 import { TodoEvents } from '@manacore/shared-utils/analytics';
+import { withErrorHandling } from './store-helpers';
 
 let error = $state<string | null>(null);
+const setError = (e: string | null) => (error = e);
 
 export const projectsStore = {
 	get error() {
@@ -19,85 +21,80 @@ export const projectsStore = {
 	},
 
 	async createProject(data: { name: string; description?: string; color?: string; icon?: string }) {
-		error = null;
-		try {
-			const count = await projectCollection.count();
-			const newLocal: LocalProject = {
-				id: crypto.randomUUID(),
-				name: data.name,
-				color: data.color ?? '#6b7280',
-				icon: data.icon ?? null,
-				order: count,
-				isArchived: false,
-				isDefault: false,
-			};
+		return withErrorHandling(
+			setError,
+			async () => {
+				const count = await projectCollection.count();
+				const newLocal: LocalProject = {
+					id: crypto.randomUUID(),
+					name: data.name,
+					color: data.color ?? '#6b7280',
+					icon: data.icon ?? null,
+					order: count,
+					isArchived: false,
+					isDefault: false,
+				};
 
-			const inserted = await projectCollection.insert(newLocal);
-			TodoEvents.projectCreated();
-			return toProject(inserted);
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to create project';
-			console.error('Failed to create project:', e);
-			throw e;
-		}
+				const inserted = await projectCollection.insert(newLocal);
+				TodoEvents.projectCreated();
+				return toProject(inserted);
+			},
+			'Failed to create project'
+		);
 	},
 
 	async updateProject(
 		id: string,
 		data: { name?: string; description?: string; color?: string; icon?: string }
 	) {
-		error = null;
-		try {
-			const updated = await projectCollection.update(id, data as Partial<LocalProject>);
-			if (updated) {
-				return toProject(updated);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to update project';
-			console.error('Failed to update project:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				const updated = await projectCollection.update(id, data as Partial<LocalProject>);
+				if (updated) {
+					return toProject(updated);
+				}
+			},
+			'Failed to update project'
+		);
 	},
 
 	async deleteProject(id: string) {
-		error = null;
-		try {
-			await projectCollection.delete(id);
-			TodoEvents.projectDeleted();
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to delete project';
-			console.error('Failed to delete project:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				await projectCollection.delete(id);
+				TodoEvents.projectDeleted();
+			},
+			'Failed to delete project'
+		);
 	},
 
 	async archiveProject(id: string) {
-		error = null;
-		try {
-			const updated = await projectCollection.update(id, {
-				isArchived: true,
-			} as Partial<LocalProject>);
-			if (updated) {
-				return toProject(updated);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to archive project';
-			console.error('Failed to archive project:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				const updated = await projectCollection.update(id, {
+					isArchived: true,
+				} as Partial<LocalProject>);
+				if (updated) {
+					return toProject(updated);
+				}
+			},
+			'Failed to archive project'
+		);
 	},
 
 	async reorderProjects(projectIds: string[]) {
-		error = null;
-		try {
-			for (let i = 0; i < projectIds.length; i++) {
-				await projectCollection.update(projectIds[i], { order: i } as Partial<LocalProject>);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to reorder projects';
-			console.error('Failed to reorder projects:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				for (let i = 0; i < projectIds.length; i++) {
+					await projectCollection.update(projectIds[i], { order: i } as Partial<LocalProject>);
+				}
+			},
+			'Failed to reorder projects'
+		);
 	},
 
 	get guestInboxId() {

apps/todo/apps/web/src/lib/stores/store-helpers.ts

@@ -0,0 +1,30 @@
+/**
+ * Shared error-handling helper for mutation stores.
+ *
+ * Wraps an async operation with consistent error state management:
+ * clears the error before the operation, captures it on failure,
+ * and optionally logs / re-throws.
+ */
+
+export async function withErrorHandling<T>(
+	setError: (e: string | null) => void,
+	operation: () => Promise<T>,
+	errorMessage: string,
+	options?: { rethrow?: boolean; log?: boolean }
+): Promise<T | undefined> {
+	const { rethrow = true, log = true } = options ?? {};
+	setError(null);
+	try {
+		return await operation();
+	} catch (e) {
+		const msg = e instanceof Error ? e.message : errorMessage;
+		setError(msg);
+		if (log) {
+			console.error(errorMessage + ':', e);
+		}
+		if (rethrow) {
+			throw e;
+		}
+		return undefined;
+	}
+}

apps/todo/apps/web/src/lib/stores/tasks.svelte.ts

@@ -10,8 +10,10 @@ import type { Task, TaskPriority, TaskStatus, Subtask } from '@todo/shared';
 import { taskCollection, type LocalTask } from '$lib/data/local-store';
 import { toTask } from '$lib/data/task-queries';
 import { TodoEvents } from '@manacore/shared-utils/analytics';
+import { withErrorHandling } from './store-helpers';
 
 let error = $state<string | null>(null);
+const setError = (e: string | null) => (error = e);
 
 export const tasksStore = {
 	get error() {
@@ -29,31 +31,30 @@ export const tasksStore = {
 		recurrenceRule?: string;
 		estimatedDuration?: number;
 	}) {
-		error = null;
-		try {
-			const count = await taskCollection.count();
-			const newLocal: LocalTask = {
-				id: crypto.randomUUID(),
-				title: data.title,
-				description: data.description,
-				projectId: data.projectId ?? null,
-				priority: data.priority ?? 'medium',
-				isCompleted: false,
-				dueDate: data.dueDate ?? null,
-				estimatedDuration: data.estimatedDuration ?? null,
-				order: count,
-				recurrenceRule: data.recurrenceRule ?? null,
-				subtasks: data.subtasks,
-			};
+		return withErrorHandling(
+			setError,
+			async () => {
+				const count = await taskCollection.count();
+				const newLocal: LocalTask = {
+					id: crypto.randomUUID(),
+					title: data.title,
+					description: data.description,
+					projectId: data.projectId ?? null,
+					priority: data.priority ?? 'medium',
+					isCompleted: false,
+					dueDate: data.dueDate ?? null,
+					estimatedDuration: data.estimatedDuration ?? null,
+					order: count,
+					recurrenceRule: data.recurrenceRule ?? null,
+					subtasks: data.subtasks,
+				};
 
-			const inserted = await taskCollection.insert(newLocal);
-			TodoEvents.taskCreated(!!data.dueDate);
-			return toTask(inserted);
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to create task';
-			console.error('Failed to create task:', e);
-			throw e;
-		}
+				const inserted = await taskCollection.insert(newLocal);
+				TodoEvents.taskCreated(!!data.dueDate);
+				return toTask(inserted);
+			},
+			'Failed to create task'
+		);
 	},
 
 	async updateTask(
@@ -77,17 +78,16 @@ export const tasksStore = {
 			labelIds?: string[];
 		}
 	) {
-		error = null;
-		try {
-			const updated = await taskCollection.update(id, data as Partial<LocalTask>);
-			if (updated) {
-				return toTask(updated);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to update task';
-			console.error('Failed to update task:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				const updated = await taskCollection.update(id, data as Partial<LocalTask>);
+				if (updated) {
+					return toTask(updated);
+				}
+			},
+			'Failed to update task'
+		);
 	},
 
 	async updateTaskOptimistic(
@@ -108,107 +108,102 @@ export const tasksStore = {
 	},
 
 	async deleteTask(id: string) {
-		error = null;
-		try {
-			await taskCollection.delete(id);
-			TodoEvents.taskDeleted();
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to delete task';
-			console.error('Failed to delete task:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				await taskCollection.delete(id);
+				TodoEvents.taskDeleted();
+			},
+			'Failed to delete task'
+		);
 	},
 
 	async completeTask(id: string) {
-		error = null;
-		try {
-			const updated = await taskCollection.update(id, {
-				isCompleted: true,
-				completedAt: new Date().toISOString(),
-			} as Partial<LocalTask>);
-			if (updated) {
-				TodoEvents.taskCompleted();
-				return toTask(updated);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to complete task';
-			console.error('Failed to complete task:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				const updated = await taskCollection.update(id, {
+					isCompleted: true,
+					completedAt: new Date().toISOString(),
+				} as Partial<LocalTask>);
+				if (updated) {
+					TodoEvents.taskCompleted();
+					return toTask(updated);
+				}
+			},
+			'Failed to complete task'
+		);
 	},
 
 	async uncompleteTask(id: string) {
-		error = null;
-		try {
-			const updated = await taskCollection.update(id, {
-				isCompleted: false,
-				completedAt: null,
-			} as Partial<LocalTask>);
-			if (updated) {
-				TodoEvents.taskUncompleted();
-				return toTask(updated);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to uncomplete task';
-			console.error('Failed to uncomplete task:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				const updated = await taskCollection.update(id, {
+					isCompleted: false,
+					completedAt: null,
+				} as Partial<LocalTask>);
+				if (updated) {
+					TodoEvents.taskUncompleted();
+					return toTask(updated);
+				}
+			},
+			'Failed to uncomplete task'
+		);
 	},
 
 	async moveTask(id: string, projectId: string | null) {
-		error = null;
-		try {
-			const updated = await taskCollection.update(id, { projectId } as Partial<LocalTask>);
-			if (updated) {
-				return toTask(updated);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to move task';
-			console.error('Failed to move task:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				const updated = await taskCollection.update(id, { projectId } as Partial<LocalTask>);
+				if (updated) {
+					return toTask(updated);
+				}
+			},
+			'Failed to move task'
+		);
 	},
 
 	async updateLabels(id: string, labelIds: string[]) {
-		error = null;
-		try {
-			const updated = await taskCollection.update(id, {
-				metadata: { labelIds },
-			} as Partial<LocalTask>);
-			if (updated) {
-				return toTask(updated);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to update labels';
-			console.error('Failed to update labels:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				const updated = await taskCollection.update(id, {
+					metadata: { labelIds },
+				} as Partial<LocalTask>);
+				if (updated) {
+					return toTask(updated);
+				}
+			},
+			'Failed to update labels'
+		);
 	},
 
 	async updateSubtasks(id: string, subtasks: Subtask[]) {
-		error = null;
-		try {
-			const updated = await taskCollection.update(id, { subtasks } as Partial<LocalTask>);
-			if (updated) {
-				return toTask(updated);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to update subtasks';
-			console.error('Failed to update subtasks:', e);
-			throw e;
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				const updated = await taskCollection.update(id, { subtasks } as Partial<LocalTask>);
+				if (updated) {
+					return toTask(updated);
+				}
+			},
+			'Failed to update subtasks'
+		);
 	},
 
 	async reorderTasks(taskIds: string[]) {
-		error = null;
-		try {
-			for (let i = 0; i < taskIds.length; i++) {
-				await taskCollection.update(taskIds[i], { order: i } as Partial<LocalTask>);
-			}
-		} catch (e) {
-			error = e instanceof Error ? e.message : 'Failed to reorder tasks';
-			console.error('Failed to reorder tasks:', e);
-		}
+		return withErrorHandling(
+			setError,
+			async () => {
+				for (let i = 0; i < taskIds.length; i++) {
+					await taskCollection.update(taskIds[i], { order: i } as Partial<LocalTask>);
+				}
+			},
+			'Failed to reorder tasks',
+			{ rethrow: false }
+		);
 	},
 
 	isDemoTask(_taskId: string) {

apps/todo/apps/web/src/lib/utils/date-display.ts

@@ -0,0 +1,12 @@
+import { format, isToday, isTomorrow } from 'date-fns';
+import { de } from 'date-fns/locale';
+
+/**
+ * Format a due date for display.
+ * Returns 'Heute' for today, 'Morgen' for tomorrow, or 'dd. MMM' (German locale) otherwise.
+ */
+export function formatDueDate(date: Date): string {
+	if (isToday(date)) return 'Heute';
+	if (isTomorrow(date)) return 'Morgen';
+	return format(date, 'dd. MMM', { locale: de });
+}