feat: add task management features to calendar

app/[locale]/calendar/page.tsx

@@ -23,6 +23,9 @@ import { CalendarMonthView } from "@/components/calendar/calendar-month-view";
 import { CalendarWeekView } from "@/components/calendar/calendar-week-view";
 import { CalendarDayView } from "@/components/calendar/calendar-day-view";
 import { CalendarAgendaView } from "@/components/calendar/calendar-agenda-view";
+import { TaskListView } from "@/components/calendar/task-list-view";
+import { TaskToolbar } from "@/components/calendar/task-toolbar";
+import { TaskModal } from "@/components/calendar/task-modal";
 import { MiniCalendar } from "@/components/calendar/mini-calendar";
 import { CalendarSidebarPanel } from "@/components/calendar/calendar-sidebar-panel";
 import { EventModal, type PendingEventPreview } from "@/components/calendar/event-modal";
@@ -35,6 +38,7 @@ import { SidebarAppsModal } from "@/components/layout/sidebar-apps-modal";
 import { InlineAppView } from "@/components/layout/inline-app-view";
 import { useSidebarApps } from "@/hooks/use-sidebar-apps";
 import { ResizeHandle } from "@/components/layout/resize-handle";
+import { useTaskStore } from "@/stores/task-store";
 import { cn } from "@/lib/utils";
 import type { CalendarEvent, CalendarParticipant } from "@/lib/jmap/types";
 import { getUserParticipantId } from "@/lib/calendar-participants";
@@ -63,7 +67,8 @@ export default function CalendarPage() {
     setSelectedDate, setViewMode, toggleCalendarVisibility, updateCalendar,
     refreshAllSubscriptions,
   } = useCalendarStore();
-  const { firstDayOfWeek, timeFormat, showWeekNumbers } = useSettingsStore();
+  const { firstDayOfWeek, timeFormat, showWeekNumbers, enableCalendarTasks, showTasksOnCalendar } = useSettingsStore();
+  const taskStore = useTaskStore();
   const { identities } = useIdentityStore();
   const normalizedViewMode = isCalendarViewMode(viewMode) ? viewMode : "month";
 
@@ -83,6 +88,8 @@ export default function CalendarPage() {
   const [detailEvent, setDetailEvent] = useState<CalendarEvent | null>(null);
   const [detailAnchorRect, setDetailAnchorRect] = useState<DOMRect | null>(null);
   const [pendingPreview, setPendingPreview] = useState<PendingEventPreview | null>(null);
+  const [showTaskModal, setShowTaskModal] = useState(false);
+  const [editTask, setEditTask] = useState<import("@/lib/jmap/types").CalendarTask | null>(null);
   const hasFetched = useRef(false);
 
   // Sidebar resize state
@@ -166,9 +173,18 @@ export default function CalendarPage() {
           end: format(addDays(agendaStart, 30), "yyyy-MM-dd'T'23:59:59"),
         };
       }
+      case "tasks":
+        return null;
     }
   }, [selectedDate, normalizedViewMode, firstDayOfWeek]);
 
+  // Fetch tasks when tasks view is active or when tasks are shown on calendar grid
+  useEffect(() => {
+    if (client && enableCalendarTasks && (normalizedViewMode === "tasks" || showTasksOnCalendar)) {
+      taskStore.fetchTasks(client);
+    }
+  }, [client, enableCalendarTasks, normalizedViewMode, showTasksOnCalendar]);
+
   useEffect(() => {
     if (client && calendars.length > 0 && dateRange) {
       fetchEvents(client, dateRange.start, dateRange.end);
@@ -182,6 +198,7 @@ export default function CalendarPage() {
       case "week": next = subWeeks(selectedDate, 1); break;
       case "day": next = subDays(selectedDate, 1); break;
       case "agenda": next = subMonths(selectedDate, 1); break;
+      case "tasks": return;
     }
     setSelectedDate(next);
     setMiniMonth(next);
@@ -194,6 +211,7 @@ export default function CalendarPage() {
       case "week": next = addWeeks(selectedDate, 1); break;
       case "day": next = addDays(selectedDate, 1); break;
       case "agenda": next = addMonths(selectedDate, 1); break;
+      case "tasks": return;
     }
     setSelectedDate(next);
     setMiniMonth(next);
@@ -254,6 +272,34 @@ export default function CalendarPage() {
     setShowEventModal(true);
   }, []);
 
+  const openCreateTaskModal = useCallback(() => {
+    setEditTask(null);
+    setShowTaskModal(true);
+  }, []);
+
+  const openEditTaskModal = useCallback((task: import("@/lib/jmap/types").CalendarTask) => {
+    setEditTask(task);
+    setShowTaskModal(true);
+  }, []);
+
+  const handleSaveTask = useCallback(async (data: Partial<import("@/lib/jmap/types").CalendarTask>) => {
+    if (!client) return;
+    if (editTask) {
+      await taskStore.updateTask(client, editTask.id, data);
+    } else {
+      await taskStore.createTask(client, data);
+    }
+    setShowTaskModal(false);
+    setEditTask(null);
+  }, [client, editTask, taskStore]);
+
+  const handleDeleteTask = useCallback(async (id: string) => {
+    if (!client) return;
+    await taskStore.deleteTask(client, id);
+    setShowTaskModal(false);
+    setEditTask(null);
+  }, [client, taskStore]);
+
   const hoverTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
 
   const closeDetail = useCallback(() => {
@@ -608,6 +654,7 @@ export default function CalendarPage() {
         case "w": setViewMode("week"); break;
         case "d": setViewMode("day"); break;
         case "a": setViewMode("agenda"); break;
+        case "k": if (enableCalendarTasks) setViewMode("tasks"); break;
         case "n": openCreateModal(); break;
       }
     };
@@ -668,6 +715,8 @@ export default function CalendarPage() {
               timeFormat={timeFormat}
               isMobile={isMobile}
               pendingPreview={pendingPreview}
+              tasks={enableCalendarTasks && showTasksOnCalendar ? taskStore.tasks : undefined}
+              onToggleTaskComplete={(task) => { if (client) taskStore.toggleTaskComplete(client, task); }}
             />
           );
         case "day":
@@ -683,6 +732,8 @@ export default function CalendarPage() {
               timeFormat={timeFormat}
               isMobile={isMobile}
               pendingPreview={pendingPreview}
+              tasks={enableCalendarTasks && showTasksOnCalendar ? taskStore.tasks : undefined}
+              onToggleTaskComplete={(task) => { if (client) taskStore.toggleTaskComplete(client, task); }}
             />
           );
         case "agenda":
@@ -697,6 +748,33 @@ export default function CalendarPage() {
               timeFormat={timeFormat}
             />
           );
+        case "tasks":
+          return (
+            <div className="flex flex-col h-full">
+              <TaskToolbar
+                filter={taskStore.filter}
+                showCompleted={taskStore.showCompleted}
+                onFilterChange={taskStore.setFilter}
+                onShowCompletedChange={taskStore.setShowCompleted}
+                onCreateTask={openCreateTaskModal}
+              />
+              <TaskListView
+                tasks={taskStore.tasks}
+                calendars={calendars}
+                selectedCalendarIds={selectedCalendarIds}
+                filter={taskStore.filter}
+                showCompleted={taskStore.showCompleted}
+                onSelectTask={openEditTaskModal}
+                onToggleComplete={(task) => { if (client) taskStore.toggleTaskComplete(client, task); }}
+                selectedTaskId={taskStore.selectedTaskId}
+                onQuickCreate={(title) => {
+                  if (client) {
+                    taskStore.createTask(client, { "@type": "Task", title, progress: "needs-action", calendarIds: { [calendars[0]?.id ?? ""]: true } });
+                  }
+                }}
+              />
+            </div>
+          );
       }
     })();
 
@@ -792,6 +870,7 @@ export default function CalendarPage() {
           calendars={calendars}
           selectedCalendarIds={selectedCalendarIds}
           onToggleVisibility={toggleCalendarVisibility}
+          enableCalendarTasks={enableCalendarTasks}
         />
 
         <div
@@ -823,6 +902,21 @@ export default function CalendarPage() {
             </div>
           )}
 
+          {/* Desktop task panel */}
+          {!isMobile && showTaskModal && (
+            <div className="w-[400px] border-l border-border flex-shrink-0 overflow-hidden">
+              <TaskModal
+                key={editTask?.id ?? 'new-task'}
+                task={editTask}
+                calendars={calendars}
+                onSave={handleSaveTask}
+                onDelete={handleDeleteTask}
+                onClose={() => { setShowTaskModal(false); setEditTask(null); }}
+                isMobile={false}
+              />
+            </div>
+          )}
+
           {/* Floating Create Event Button (mobile) */}
           {isMobile && (
             <Button

components/calendar/calendar-day-view.tsx

@@ -4,10 +4,11 @@ import { useMemo, useEffect, useRef, useState } from "react";
 import { useTranslations, useFormatter } from "next-intl";
 import { format, isSameDay, isToday, parseISO } from "date-fns";
 import { cn } from "@/lib/utils";
+import { Check } from "lucide-react";
 import { EventCard, parseDuration } from "./event-card";
 import { QuickEventInput } from "./quick-event-input";
 import { formatSnapTime, getEventDayBounds, getPrimaryCalendarId, layoutOverlappingEvents } from "@/lib/calendar-utils";
-import type { CalendarEvent, Calendar } from "@/lib/jmap/types";
+import type { CalendarEvent, Calendar, CalendarTask } from "@/lib/jmap/types";
 import { useTimeGridInteractions } from "@/hooks/use-time-grid-interactions";
 import type { PendingEventPreview } from "./event-modal";
 
@@ -22,6 +23,8 @@ interface CalendarDayViewProps {
   timeFormat?: "12h" | "24h";
   isMobile?: boolean;
   pendingPreview?: PendingEventPreview | null;
+  tasks?: CalendarTask[];
+  onToggleTaskComplete?: (task: CalendarTask) => void;
 }
 
 const HOUR_HEIGHT = 64;
@@ -38,6 +41,8 @@ export function CalendarDayView({
   timeFormat = "24h",
   isMobile,
   pendingPreview,
+  tasks,
+  onToggleTaskComplete,
 }: CalendarDayViewProps) {
   const t = useTranslations("calendar");
   const intlFormatter = useFormatter();
@@ -68,6 +73,16 @@ export function CalendarDayView({
     return { timedEvents: timed, allDayEvents: allDay };
   }, [events, selectedDate]);
 
+  const dayTasks = useMemo(() => {
+    if (!tasks?.length) return [];
+    return tasks.filter(task => {
+      if (!task.due) return false;
+      try {
+        return isSameDay(parseISO(task.due), selectedDate);
+      } catch { return false; }
+    });
+  }, [tasks, selectedDate]);
+
   useEffect(() => {
     if (scrollRef.current) {
       const now = new Date();
@@ -125,25 +140,63 @@ export function CalendarDayView({
         </h3>
       </div>
 
-      {allDayEvents.length > 0 && (
+      {(allDayEvents.length > 0 || dayTasks.length > 0) && (
         <div className="px-4 py-2 border-b border-border">
-          <div className="text-[10px] text-muted-foreground mb-1">{t("events.all_day")}</div>
-          <div className="space-y-1">
-            {allDayEvents.map((ev) => {
-              const calId = getPrimaryCalendarId(ev);
-              return (
-                <EventCard
-                  key={ev.id}
-                  event={ev}
-                  calendar={calId ? calendarMap.get(calId) : undefined}
-                  variant="chip"
-                  onClick={(rect) => onSelectEvent(ev, rect)}
-                  onMouseEnter={(rect) => onHoverEvent?.(ev, rect)}
-                  onMouseLeave={onHoverLeave}
-                />
-              );
-            })}
-          </div>
+          {allDayEvents.length > 0 && (
+            <>
+              <div className="text-[10px] text-muted-foreground mb-1">{t("events.all_day")}</div>
+              <div className="space-y-1">
+                {allDayEvents.map((ev) => {
+                  const calId = getPrimaryCalendarId(ev);
+                  return (
+                    <EventCard
+                      key={ev.id}
+                      event={ev}
+                      calendar={calId ? calendarMap.get(calId) : undefined}
+                      variant="chip"
+                      onClick={(rect) => onSelectEvent(ev, rect)}
+                      onMouseEnter={(rect) => onHoverEvent?.(ev, rect)}
+                      onMouseLeave={onHoverLeave}
+                    />
+                  );
+                })}
+              </div>
+            </>
+          )}
+          {dayTasks.length > 0 && (
+            <>
+              <div className={cn("text-[10px] text-muted-foreground mb-1", allDayEvents.length > 0 && "mt-2")}>{t("tasks.label")}</div>
+              <div className="space-y-0.5">
+                {dayTasks.map((task) => {
+                  const isCompleted = task.progress === "completed";
+                  const cal = calendars.find(c => task.calendarIds[c.id]);
+                  const color = cal?.color || "#3b82f6";
+                  return (
+                    <div
+                      key={task.id}
+                      className="flex items-center gap-1.5 px-1.5 py-0.5 rounded text-xs cursor-pointer hover:bg-muted/50 transition-colors"
+                      style={{ borderLeft: `3px solid ${color}` }}
+                    >
+                      <button
+                        onClick={(e) => { e.stopPropagation(); onToggleTaskComplete?.(task); }}
+                        className={cn(
+                          "flex-shrink-0 w-3.5 h-3.5 rounded-full border flex items-center justify-center",
+                          isCompleted
+                            ? "bg-green-500 border-green-500 text-white"
+                            : "border-muted-foreground/40 hover:border-primary"
+                        )}
+                      >
+                        {isCompleted && <Check className="h-2.5 w-2.5" />}
+                      </button>
+                      <span className={cn("truncate", isCompleted && "line-through text-muted-foreground")}>
+                        {task.title || t("tasks.no_title")}
+                      </span>
+                    </div>
+                  );
+                })}
+              </div>
+            </>
+          )}
         </div>
       )}
 

components/calendar/calendar-sidebar-panel.tsx

@@ -2,12 +2,13 @@
 
 import { useState, useRef, useEffect, useMemo } from "react";
 import { useTranslations } from "next-intl";
-import { Globe, Plus, RefreshCw, Share2, Trash2 } from "lucide-react";
+import { Globe, ListTodo, Plus, RefreshCw, Share2, Trash2 } from "lucide-react";
 import { cn, formatDateTime } from "@/lib/utils";
 import type { Calendar } from "@/lib/jmap/types";
 import { CalendarColorPicker } from "@/components/settings/calendar-management-settings";
 import { useCalendarStore } from "@/stores/calendar-store";
 import { useSettingsStore } from "@/stores/settings-store";
+import { useTaskStore } from "@/stores/task-store";
 import { toast } from "@/stores/toast-store";
 import type { IJMAPClient } from '@/lib/jmap/client-interface';
 
@@ -35,6 +36,15 @@ export function CalendarSidebarPanel({
   const refreshICalSubscription = useCalendarStore((s) => s.refreshICalSubscription);
   const removeICalSubscription = useCalendarStore((s) => s.removeICalSubscription);
   const timeFormat = useSettingsStore((s) => s.timeFormat);
+  const enableCalendarTasks = useSettingsStore((s) => s.enableCalendarTasks);
+  const tasks = useTaskStore((s) => s.tasks);
+  const setViewMode = useCalendarStore((s) => s.setViewMode);
+
+  const pendingTaskCount = useMemo(() => tasks.filter(t => t.progress !== 'completed' && t.progress !== 'cancelled').length, [tasks]);
+  const overdueTaskCount = useMemo(() => {
+    const now = new Date();
+    return tasks.filter(t => t.progress !== 'completed' && t.progress !== 'cancelled' && t.due && new Date(t.due) < now).length;
+  }, [tasks]);
 
   const [colorPickerId, setColorPickerId] = useState<string | null>(null);
   const [contextMenuCalId, setContextMenuCalId] = useState<string | null>(null);
@@ -209,6 +219,21 @@ export function CalendarSidebarPanel({
 
   return (
     <div className="mt-4">
+      {enableCalendarTasks && (
+        <button
+          onClick={() => setViewMode('tasks')}
+          className="flex items-center gap-2 w-full px-1.5 py-1.5 mb-3 rounded-md text-sm hover:bg-muted transition-colors"
+        >
+          <ListTodo className="w-4 h-4 text-muted-foreground" />
+          <span>{t('tasks.label')}</span>
+          {pendingTaskCount > 0 && (
+            <span className="ml-auto text-xs text-muted-foreground">{pendingTaskCount}</span>
+          )}
+          {overdueTaskCount > 0 && (
+            <span className="text-xs text-destructive font-medium">{overdueTaskCount} {t('tasks.filter_overdue').toLowerCase()}</span>
+          )}
+        </button>
+      )}
       <h3 className="text-xs font-medium text-muted-foreground uppercase tracking-wider mb-2 px-1">
         {t("my_calendars")}
       </h3>

components/calendar/calendar-toolbar.tsx

@@ -3,7 +3,7 @@
 import { useState, useRef, useEffect } from "react";
 import { useTranslations, useFormatter } from "next-intl";
 import { Button } from "@/components/ui/button";
-import { ChevronLeft, ChevronRight, Plus, Upload, CalendarDays, Globe, ChevronDown } from "lucide-react";
+import { ChevronLeft, ChevronRight, Plus, Upload, CalendarDays, Globe, ChevronDown, ListTodo } from "lucide-react";
 import { addDays, startOfWeek } from "date-fns";
 import { cn } from "@/lib/utils";
 import type { CalendarViewMode } from "@/stores/calendar-store";
@@ -25,6 +25,7 @@ interface CalendarToolbarProps {
   calendars?: Calendar[];
   selectedCalendarIds?: string[];
   onToggleVisibility?: (id: string) => void;
+  enableCalendarTasks?: boolean;
 }
 
 export function CalendarToolbar({
@@ -42,10 +43,13 @@ export function CalendarToolbar({
   calendars,
   selectedCalendarIds,
   onToggleVisibility,
+  enableCalendarTasks,
 }: CalendarToolbarProps) {
   const t = useTranslations("calendar");
   const formatter = useFormatter();
-  const views: CalendarViewMode[] = ["month", "week", "day", "agenda"];
+  const views: CalendarViewMode[] = enableCalendarTasks
+    ? ["month", "week", "day", "agenda", "tasks"]
+    : ["month", "week", "day", "agenda"];
   const [showCalendarDropdown, setShowCalendarDropdown] = useState(false);
   const dropdownRef = useRef<HTMLDivElement>(null);
 
@@ -86,6 +90,8 @@ export function CalendarToolbar({
         return isMobile
           ? formatter.dateTime(selectedDate, { month: "short", year: "numeric" })
           : formatter.dateTime(selectedDate, { month: "long", year: "numeric" });
+      case "tasks":
+        return t("views.tasks");
     }
   };
 

components/calendar/calendar-week-view.tsx

@@ -6,10 +6,11 @@ import {
   startOfWeek, addDays, format, isSameDay, isToday, parseISO,
 } from "date-fns";
 import { cn } from "@/lib/utils";
+import { Check } from "lucide-react";
 import { EventCard, parseDuration } from "./event-card";
 import { QuickEventInput } from "./quick-event-input";
 import { buildWeekSegments, formatSnapTime, getEventDayBounds, getPrimaryCalendarId, layoutOverlappingEvents } from "@/lib/calendar-utils";
-import type { CalendarEvent, Calendar } from "@/lib/jmap/types";
+import type { CalendarEvent, Calendar, CalendarTask } from "@/lib/jmap/types";
 import { useTimeGridInteractions } from "@/hooks/use-time-grid-interactions";
 import type { PendingEventPreview } from "./event-modal";
 
@@ -26,6 +27,8 @@ interface CalendarWeekViewProps {
   timeFormat?: "12h" | "24h";
   isMobile?: boolean;
   pendingPreview?: PendingEventPreview | null;
+  tasks?: CalendarTask[];
+  onToggleTaskComplete?: (task: CalendarTask) => void;
 }
 
 const HOUR_HEIGHT = 60;
@@ -44,6 +47,8 @@ export function CalendarWeekView({
   timeFormat = "24h",
   isMobile,
   pendingPreview,
+  tasks,
+  onToggleTaskComplete,
 }: CalendarWeekViewProps) {
   const t = useTranslations("calendar");
   const intlFormatter = useFormatter();
@@ -96,9 +101,36 @@ export function CalendarWeekView({
     return allDaySegments.reduce((maxRows, segment) => Math.max(maxRows, segment.row + 1), 0);
   }, [allDaySegments]);
 
+  // Tasks grouped by day for the week
+  const tasksByDay = useMemo(() => {
+    if (!tasks?.length) return new Map<string, CalendarTask[]>();
+    const map = new Map<string, CalendarTask[]>();
+    for (const task of tasks) {
+      if (!task.due) continue;
+      try {
+        const key = format(parseISO(task.due), "yyyy-MM-dd");
+        const existing = map.get(key) || [];
+        existing.push(task);
+        map.set(key, existing);
+      } catch { /* skip */ }
+    }
+    return map;
+  }, [tasks]);
+
+  // Max tasks on any single day in this week
+  const taskRowCount = useMemo(() => {
+    let max = 0;
+    for (const day of weekDays) {
+      const key = format(day, "yyyy-MM-dd");
+      const count = tasksByDay.get(key)?.length ?? 0;
+      if (count > max) max = count;
+    }
+    return max;
+  }, [tasksByDay, weekDays]);
+
   const hasAllDay = useMemo(() => {
-    return allDaySegments.length > 0;
-  }, [allDaySegments]);
+    return allDaySegments.length > 0 || taskRowCount > 0;
+  }, [allDaySegments, taskRowCount]);
 
   useEffect(() => {
     if (scrollRef.current) {
@@ -151,13 +183,13 @@ export function CalendarWeekView({
         <div className="flex border-b border-border">
           <div
             className={cn("flex-shrink-0 text-[10px] text-muted-foreground p-1 text-right", isMobile ? "w-10" : "w-14")}
-            style={{ minHeight: Math.max(28, allDayRowCount * 24 + 4) }}
+            style={{ minHeight: Math.max(28, (allDayRowCount + taskRowCount) * 24 + 4) }}
           >
             {t("events.all_day")}
           </div>
           <div
             className={cn("flex-1 relative grid gap-px bg-border", isMobile ? "grid-cols-3" : "grid-cols-7")}
-            style={{ minHeight: Math.max(28, allDayRowCount * 24 + 4) }}
+            style={{ minHeight: Math.max(28, (allDayRowCount + taskRowCount) * 24 + 4) }}
           >
             {weekDays.map((day) => (
               <div key={format(day, "yyyy-MM-dd")} className="bg-background min-h-[28px]" />
@@ -191,6 +223,49 @@ export function CalendarWeekView({
                 );
               })}
             </div>
+
+            {/* Task chips in all-day area */}
+            {taskRowCount > 0 && (
+              <div className="absolute inset-x-0 pointer-events-none" style={{ top: allDayRowCount * 24 + 2 }}>
+                {weekDays.map((day, dayIndex) => {
+                  const key = format(day, "yyyy-MM-dd");
+                  const dayTasks = tasksByDay.get(key) || [];
+                  return dayTasks.map((task, taskIndex) => {
+                    const isCompleted = task.progress === "completed";
+                    const cal = calendars.find(c => task.calendarIds[c.id]);
+                    const color = cal?.color || "#3b82f6";
+                    return (
+                      <div
+                        key={`task-${task.id}`}
+                        className="absolute px-0.5 pointer-events-auto"
+                        style={{
+                          left: `calc(${(dayIndex / colCount) * 100}% + 1px)`,
+                          width: `calc(${(1 / colCount) * 100}% - 2px)`,
+                          top: taskIndex * 24,
+                          height: 20,
+                        }}
+                      >
+                        <div
+                          className="h-full rounded text-[10px] leading-[20px] font-medium px-1.5 truncate flex items-center gap-1 cursor-pointer hover:opacity-80"
+                          style={{ backgroundColor: `${color}20`, borderLeft: `3px solid ${color}` }}
+                          onClick={() => onToggleTaskComplete?.(task)}
+                        >
+                          <span className={cn(
+                            "w-2.5 h-2.5 rounded-full border flex-shrink-0 flex items-center justify-center",
+                            isCompleted ? "bg-green-500 border-green-500" : "border-current"
+                          )}>
+                            {isCompleted && <Check className="h-2 w-2 text-white" />}
+                          </span>
+                          <span className={cn("truncate", isCompleted && "line-through text-muted-foreground")}>
+                            {task.title}
+                          </span>
+                        </div>
+                      </div>
+                    );
+                  });
+                })}
+              </div>
+            )}
           </div>
         </div>
       )}

components/calendar/task-list-view.tsx

@@ -1,9 +1,9 @@
 "use client";
 
-import { useMemo, useCallback } from "react";
+import { useMemo, useCallback, useState } from "react";
 import { useTranslations } from "next-intl";
 import { format, parseISO, isPast, isToday, isTomorrow } from "date-fns";
-import { Check, Circle, Flag, CalendarDays, ListTodo } from "lucide-react";
+import { Check, Circle, Flag, CalendarDays, ListTodo, Plus } from "lucide-react";
 import { cn } from "@/lib/utils";
 import type { CalendarTask, Calendar } from "@/lib/jmap/types";
 import type { TaskViewFilter } from "@/stores/task-store";
@@ -18,6 +18,7 @@ interface TaskListViewProps {
   onSelectTask: (task: CalendarTask) => void;
   onToggleComplete: (task: CalendarTask) => void;
   selectedTaskId?: string | null;
+  onQuickCreate?: (title: string) => void;
 }
 
 function getTaskPriorityIcon(priority: number) {
@@ -69,9 +70,11 @@ export function TaskListView({
   onSelectTask,
   onToggleComplete,
   selectedTaskId,
+  onQuickCreate,
 }: TaskListViewProps) {
   const t = useTranslations("calendar");
   const timeFormat = useSettingsStore((s) => s.timeFormat);
+  const [quickAddTitle, setQuickAddTitle] = useState("");
 
   const filteredTasks = useMemo(() => {
     let result = tasks.filter(task => {
@@ -128,15 +131,57 @@ export function TaskListView({
 
   if (filteredTasks.length === 0) {
     return (
-      <div className="flex flex-col items-center justify-center flex-1 text-muted-foreground py-12">
-        <ListTodo className="h-12 w-12 mb-3 opacity-30" />
-        <p className="text-sm">{t("tasks.no_tasks")}</p>
+      <div className="flex flex-col flex-1">
+        {onQuickCreate && (
+          <div className="px-4 py-2 border-b border-border">
+            <div className="flex items-center gap-2">
+              <Plus className="h-4 w-4 text-muted-foreground flex-shrink-0" />
+              <input
+                type="text"
+                value={quickAddTitle}
+                onChange={(e) => setQuickAddTitle(e.target.value)}
+                onKeyDown={(e) => {
+                  if (e.key === "Enter" && quickAddTitle.trim()) {
+                    onQuickCreate(quickAddTitle.trim());
+                    setQuickAddTitle("");
+                  }
+                }}
+                placeholder={t("tasks.quick_add_placeholder")}
+                className="flex-1 bg-transparent text-sm outline-none placeholder:text-muted-foreground"
+              />
+            </div>
+          </div>
+        )}
+        <div className="flex flex-col items-center justify-center flex-1 text-muted-foreground py-12">
+          <ListTodo className="h-12 w-12 mb-3 opacity-30" />
+          <p className="text-sm">{t("tasks.no_tasks")}</p>
+        </div>
       </div>
     );
   }
 
   return (
     <div className="flex-1 overflow-y-auto">
+      {onQuickCreate && (
+        <div className="px-4 py-2 border-b border-border">
+          <div className="flex items-center gap-2">
+            <Plus className="h-4 w-4 text-muted-foreground flex-shrink-0" />
+            <input
+              type="text"
+              value={quickAddTitle}
+              onChange={(e) => setQuickAddTitle(e.target.value)}
+              onKeyDown={(e) => {
+                if (e.key === "Enter" && quickAddTitle.trim()) {
+                  onQuickCreate(quickAddTitle.trim());
+                  setQuickAddTitle("");
+                }
+              }}
+              placeholder={t("tasks.quick_add_placeholder")}
+              className="flex-1 bg-transparent text-sm outline-none placeholder:text-muted-foreground"
+            />
+          </div>
+        </div>
+      )}
       <div className="divide-y divide-border">
         {filteredTasks.map(task => {
           const cal = calendars.find(c => task.calendarIds[c.id]);

components/calendar/task-modal.tsx

@@ -0,0 +1,321 @@
+"use client";
+
+import { useState, useEffect, useCallback, useRef } from "react";
+import { useTranslations } from "next-intl";
+import { Button } from "@/components/ui/button";
+import { Input } from "@/components/ui/input";
+import { X, Trash2, CalendarDays, Bell, Flag } from "lucide-react";
+import { format, parseISO } from "date-fns";
+import { cn } from "@/lib/utils";
+import type { CalendarTask, Calendar, CalendarEventAlert } from "@/lib/jmap/types";
+
+interface TaskModalProps {
+  task?: CalendarTask | null;
+  calendars: Calendar[];
+  onSave: (data: Partial<CalendarTask>) => void | Promise<void>;
+  onDelete?: (id: string) => void;
+  onClose: () => void;
+  isMobile?: boolean;
+}
+
+type PriorityLevel = "none" | "high" | "medium" | "low";
+type AlertOption = "none" | "at_time" | "5" | "15" | "30" | "60" | "1440";
+
+function priorityToLevel(p: number): PriorityLevel {
+  if (p >= 1 && p <= 4) return "high";
+  if (p === 5) return "medium";
+  if (p >= 6 && p <= 9) return "low";
+  return "none";
+}
+
+function levelToPriority(l: PriorityLevel): number {
+  switch (l) {
+    case "high": return 1;
+    case "medium": return 5;
+    case "low": return 9;
+    default: return 0;
+  }
+}
+
+export function TaskModal({
+  task,
+  calendars,
+  onSave,
+  onDelete,
+  onClose,
+  isMobile,
+}: TaskModalProps) {
+  const t = useTranslations("calendar");
+  const isEdit = !!task;
+  const titleRef = useRef<HTMLInputElement>(null);
+
+  const writableCalendars = calendars.filter(c => !c.isShared || c.myRights?.mayWriteAll || c.myRights?.mayWriteOwn);
+  const defaultCalendarId = writableCalendars[0]?.id ?? calendars[0]?.id ?? "";
+
+  const [title, setTitle] = useState(task?.title ?? "");
+  const [description, setDescription] = useState(task?.description ?? "");
+  const [dueDate, setDueDate] = useState(task?.due ? format(parseISO(task.due), "yyyy-MM-dd") : "");
+  const [dueTime, setDueTime] = useState(task?.due && !task.showWithoutTime ? format(parseISO(task.due), "HH:mm") : "");
+  const [showTime, setShowTime] = useState(task?.due ? !task.showWithoutTime : false);
+  const [priority, setPriority] = useState<PriorityLevel>(priorityToLevel(task?.priority ?? 0));
+  const [progress, setProgress] = useState<CalendarTask["progress"]>(task?.progress ?? "needs-action");
+  const [calendarId, setCalendarId] = useState(() => {
+    if (task) {
+      const ids = Object.keys(task.calendarIds);
+      return ids[0] ?? defaultCalendarId;
+    }
+    return defaultCalendarId;
+  });
+  const [alertOption, setAlertOption] = useState<AlertOption>(() => {
+    if (!task?.alerts) return "none";
+    const first = Object.values(task.alerts)[0];
+    if (!first || first.trigger["@type"] !== "OffsetTrigger") return "none";
+    const offset = first.trigger.offset;
+    if (offset === "PT0S") return "at_time";
+    const m = offset.match(/-?PT?(\d+)M$/);
+    if (m) return m[1] as AlertOption;
+    const h = offset.match(/-?PT?(\d+)H$/);
+    if (h) return String(parseInt(h[1]) * 60) as AlertOption;
+    const d = offset.match(/-?P(\d+)D/);
+    if (d) return String(parseInt(d[1]) * 1440) as AlertOption;
+    return "none";
+  });
+  const [saving, setSaving] = useState(false);
+
+  useEffect(() => {
+    titleRef.current?.focus();
+  }, []);
+
+  const handleSave = useCallback(async () => {
+    if (!title.trim()) return;
+    setSaving(true);
+    try {
+      let due: string | null = null;
+      let showWithoutTime = true;
+      if (dueDate) {
+        if (showTime && dueTime) {
+          due = `${dueDate}T${dueTime}:00`;
+          showWithoutTime = false;
+        } else {
+          due = `${dueDate}T00:00:00`;
+          showWithoutTime = true;
+        }
+      }
+
+      let alerts: Record<string, CalendarEventAlert> | null = null;
+      if (alertOption !== "none") {
+        const offset = alertOption === "at_time" ? "PT0S" : `-PT${alertOption}M`;
+        alerts = {
+          "default-alert": {
+            "@type": "Alert",
+            trigger: { "@type": "OffsetTrigger", offset, relativeTo: "start" },
+            action: "display",
+            acknowledged: null,
+            relatedTo: null,
+          },
+        };
+      }
+
+      const data: Partial<CalendarTask> = {
+        "@type": "Task",
+        title: title.trim(),
+        description: description.trim() || "",
+        due,
+        showWithoutTime,
+        priority: levelToPriority(priority),
+        progress,
+        calendarIds: { [calendarId]: true },
+        alerts,
+      };
+
+      if (isEdit && task) {
+        data.id = task.id;
+      }
+
+      await onSave(data);
+      onClose();
+    } finally {
+      setSaving(false);
+    }
+  }, [title, description, dueDate, dueTime, showTime, priority, progress, calendarId, alertOption, isEdit, task, onSave, onClose]);
+
+  const handleKeyDown = useCallback((e: React.KeyboardEvent) => {
+    if (e.key === "Escape") {
+      e.preventDefault();
+      onClose();
+    }
+    if ((e.ctrlKey || e.metaKey) && e.key === "Enter") {
+      e.preventDefault();
+      handleSave();
+    }
+  }, [onClose, handleSave]);
+
+  return (
+    <div className="flex flex-col h-full bg-background" onKeyDown={handleKeyDown}>
+      {/* Header */}
+      <div className="flex items-center justify-between px-4 py-3 border-b border-border">
+        <h2 className="text-sm font-semibold">
+          {isEdit ? t("tasks.edit") : t("tasks.create")}
+        </h2>
+        <Button variant="ghost" size="icon" className="h-7 w-7" onClick={onClose}>
+          <X className="h-4 w-4" />
+        </Button>
+      </div>
+
+      {/* Body */}
+      <div className="flex-1 overflow-y-auto p-4 space-y-4">
+        {/* Title */}
+        <Input
+          ref={titleRef}
+          value={title}
+          onChange={(e) => setTitle(e.target.value)}
+          placeholder={t("tasks.title_placeholder")}
+          className="text-base font-medium"
+        />
+
+        {/* Description */}
+        <textarea
+          value={description}
+          onChange={(e) => setDescription(e.target.value)}
+          placeholder={t("tasks.description_placeholder")}
+          rows={3}
+          className="w-full rounded-md border border-input bg-background px-3 py-2 text-sm ring-offset-background placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring resize-none"
+        />
+
+        {/* Due Date */}
+        <div className="space-y-2">
+          <label className="text-xs font-medium text-muted-foreground flex items-center gap-1.5">
+            <CalendarDays className="h-3.5 w-3.5" />
+            {t("tasks.due_date")}
+          </label>
+          <div className="flex items-center gap-2">
+            <input
+              type="date"
+              value={dueDate}
+              onChange={(e) => setDueDate(e.target.value)}
+              className="rounded-md border border-input bg-background px-3 py-1.5 text-sm"
+            />
+            {dueDate && (
+              <label className="flex items-center gap-1.5 text-xs text-muted-foreground cursor-pointer">
+                <input
+                  type="checkbox"
+                  checked={showTime}
+                  onChange={(e) => setShowTime(e.target.checked)}
+                  className="rounded"
+                />
+                {t("tasks.include_time")}
+              </label>
+            )}
+            {showTime && (
+              <input
+                type="time"
+                value={dueTime}
+                onChange={(e) => setDueTime(e.target.value)}
+                className="rounded-md border border-input bg-background px-3 py-1.5 text-sm"
+              />
+            )}
+          </div>
+        </div>
+
+        {/* Priority */}
+        <div className="space-y-2">
+          <label className="text-xs font-medium text-muted-foreground flex items-center gap-1.5">
+            <Flag className="h-3.5 w-3.5" />
+            {t("tasks.priority")}
+          </label>
+          <select
+            value={priority}
+            onChange={(e) => setPriority(e.target.value as PriorityLevel)}
+            className="rounded-md border border-input bg-background px-3 py-1.5 text-sm w-full"
+          >
+            <option value="none">{t("tasks.priority_none")}</option>
+            <option value="high">{t("tasks.priority_high")}</option>
+            <option value="medium">{t("tasks.priority_medium")}</option>
+            <option value="low">{t("tasks.priority_low")}</option>
+          </select>
+        </div>
+
+        {/* Progress */}
+        <div className="space-y-2">
+          <label className="text-xs font-medium text-muted-foreground">
+            {t("tasks.progress")}
+          </label>
+          <select
+            value={progress}
+            onChange={(e) => setProgress(e.target.value as CalendarTask["progress"])}
+            className="rounded-md border border-input bg-background px-3 py-1.5 text-sm w-full"
+          >
+            <option value="needs-action">{t("tasks.progress_needs_action")}</option>
+            <option value="in-process">{t("tasks.progress_in_process")}</option>
+            <option value="completed">{t("tasks.progress_completed")}</option>
+            <option value="cancelled">{t("tasks.progress_cancelled")}</option>
+          </select>
+        </div>
+
+        {/* Calendar */}
+        {writableCalendars.length > 1 && (
+          <div className="space-y-2">
+            <label className="text-xs font-medium text-muted-foreground">
+              {t("tasks.calendar")}
+            </label>
+            <select
+              value={calendarId}
+              onChange={(e) => setCalendarId(e.target.value)}
+              className="rounded-md border border-input bg-background px-3 py-1.5 text-sm w-full"
+            >
+              {writableCalendars.map((cal) => (
+                <option key={cal.id} value={cal.id}>{cal.name}</option>
+              ))}
+            </select>
+          </div>
+        )}
+
+        {/* Alert */}
+        <div className="space-y-2">
+          <label className="text-xs font-medium text-muted-foreground flex items-center gap-1.5">
+            <Bell className="h-3.5 w-3.5" />
+            {t("tasks.alert")}
+          </label>
+          <select
+            value={alertOption}
+            onChange={(e) => setAlertOption(e.target.value as AlertOption)}
+            className="rounded-md border border-input bg-background px-3 py-1.5 text-sm w-full"
+          >
+            <option value="none">{t("tasks.alert_none")}</option>
+            <option value="at_time">{t("tasks.alert_at_time")}</option>
+            <option value="5">{t("tasks.alert_5min")}</option>
+            <option value="15">{t("tasks.alert_15min")}</option>
+            <option value="30">{t("tasks.alert_30min")}</option>
+            <option value="60">{t("tasks.alert_1hr")}</option>
+            <option value="1440">{t("tasks.alert_1day")}</option>
+          </select>
+        </div>
+      </div>
+
+      {/* Footer */}
+      <div className="flex items-center justify-between px-4 py-3 border-t border-border">
+        <div>
+          {isEdit && onDelete && task && (
+            <Button
+              variant="ghost"
+              size="sm"
+              className="text-destructive hover:text-destructive"
+              onClick={() => onDelete(task.id)}
+            >
+              <Trash2 className="h-4 w-4 mr-1" />
+              {t("tasks.delete")}
+            </Button>
+          )}
+        </div>
+        <div className="flex items-center gap-2">
+          <Button variant="outline" size="sm" onClick={onClose}>
+            {t("tasks.cancel")}
+          </Button>
+          <Button size="sm" onClick={handleSave} disabled={!title.trim() || saving}>
+            {t("tasks.save")}
+          </Button>
+        </div>
+      </div>
+    </div>
+  );
+}

components/calendar/task-toolbar.tsx

@@ -0,0 +1,65 @@
+"use client";
+
+import { useTranslations } from "next-intl";
+import { Plus } from "lucide-react";
+import { Button } from "@/components/ui/button";
+import { cn } from "@/lib/utils";
+import type { TaskViewFilter } from "@/stores/task-store";
+
+interface TaskToolbarProps {
+  filter: TaskViewFilter;
+  showCompleted: boolean;
+  onFilterChange: (filter: TaskViewFilter) => void;
+  onShowCompletedChange: (show: boolean) => void;
+  onCreateTask: () => void;
+}
+
+const FILTERS: TaskViewFilter[] = ["all", "pending", "completed", "overdue"];
+
+export function TaskToolbar({
+  filter,
+  showCompleted,
+  onFilterChange,
+  onShowCompletedChange,
+  onCreateTask,
+}: TaskToolbarProps) {
+  const t = useTranslations("calendar");
+
+  return (
+    <div className="flex items-center gap-2 px-4 py-2 border-b border-border flex-wrap">
+      <div className="flex border border-border rounded-md overflow-hidden">
+        {FILTERS.map((f) => (
+          <button
+            key={f}
+            onClick={() => onFilterChange(f)}
+            className={cn(
+              "px-3 py-1.5 text-xs font-medium transition-colors",
+              f === filter
+                ? "bg-primary text-primary-foreground"
+                : "hover:bg-muted text-muted-foreground"
+            )}
+          >
+            {t(`tasks.filter_${f}`)}
+          </button>
+        ))}
+      </div>
+
+      <label className="flex items-center gap-1.5 text-xs text-muted-foreground cursor-pointer select-none ml-2">
+        <input
+          type="checkbox"
+          checked={showCompleted}
+          onChange={(e) => onShowCompletedChange(e.target.checked)}
+          className="rounded border-border"
+        />
+        {t("tasks.show_completed")}
+      </label>
+
+      <div className="flex-1" />
+
+      <Button size="sm" onClick={onCreateTask}>
+        <Plus className="w-4 h-4 mr-1" />
+        {t("tasks.create")}
+      </Button>
+    </div>
+  );
+}

components/settings/calendar-settings.tsx

@@ -19,6 +19,8 @@ export function CalendarSettings() {
     calendarNotificationsEnabled,
     calendarNotificationSound,
     calendarInvitationParsingEnabled,
+    enableCalendarTasks,
+    showTasksOnCalendar,
     updateSetting,
   } = useSettingsStore();
 
@@ -79,6 +81,28 @@ export function CalendarSettings() {
         />
       </SettingItem>
 
+      <SettingItem
+        label={t('enable_tasks')}
+        description={t('enable_tasks_desc')}
+      >
+        <ToggleSwitch
+          checked={enableCalendarTasks}
+          onChange={(checked) => updateSetting('enableCalendarTasks', checked)}
+        />
+      </SettingItem>
+
+      {enableCalendarTasks && (
+        <SettingItem
+          label={t('show_tasks_on_calendar')}
+          description={t('show_tasks_on_calendar_desc')}
+        >
+          <ToggleSwitch
+            checked={showTasksOnCalendar}
+            onChange={(checked) => updateSetting('showTasksOnCalendar', checked)}
+          />
+        </SettingItem>
+      )}
+
       <SettingItem
         label={t('notifications_enabled')}
         description={t('notifications_enabled_desc')}

hooks/use-calendar-alerts.ts

@@ -5,9 +5,10 @@ import { useTranslations, useLocale } from 'next-intl';
 import { useAuthStore } from '@/stores/auth-store';
 import { useCalendarStore } from '@/stores/calendar-store';
 import { useSettingsStore } from '@/stores/settings-store';
+import { useTaskStore } from '@/stores/task-store';
 import { useCalendarNotificationStore } from '@/stores/calendar-notification-store';
 import { useToastStore } from '@/stores/toast-store';
-import { getPendingAlerts, buildAlertKey } from '@/lib/calendar-alerts';
+import { getPendingAlerts, getPendingTaskAlerts, buildAlertKey } from '@/lib/calendar-alerts';
 import { playNotificationSound } from '@/lib/notification-sound';
 import type { CalendarEvent } from '@/lib/jmap/types';
 
@@ -18,7 +19,8 @@ const PROACTIVE_THROTTLE_MS = CHECK_INTERVAL_MS * 5;
 export function useCalendarAlerts() {
   const { isAuthenticated, client } = useAuthStore();
   const { events, calendars, supportsCalendar } = useCalendarStore();
-  const { calendarNotificationsEnabled, calendarNotificationSound } = useSettingsStore();
+  const { calendarNotificationsEnabled, calendarNotificationSound, enableCalendarTasks } = useSettingsStore();
+  const { tasks: storeTasks } = useTaskStore();
   const { acknowledgedAlerts, acknowledgeAlert, cleanupStaleAlerts } = useCalendarNotificationStore();
   const addToast = useToastStore((s) => s.addToast);
   const t = useTranslations('calendar.notifications');
@@ -69,6 +71,36 @@ export function useCalendarAlerts() {
           },
         });
       }
+
+      // Task alerts
+      if (enableCalendarTasks && storeTasks.length > 0) {
+        const pendingTaskAlerts = getPendingTaskAlerts(storeTasks, calendars, acknowledgedKeys, now);
+        for (const taskAlert of pendingTaskAlerts) {
+          const key = buildAlertKey(taskAlert.taskId, taskAlert.alertId, taskAlert.fireTimeMs);
+          if (shownKeysRef.current.has(key)) continue;
+
+          shownKeysRef.current.add(key);
+          acknowledgeAlert(key, taskAlert.fireTimeMs);
+
+          if (calendarNotificationSound) {
+            playNotificationSound();
+          }
+
+          const taskMsg = taskAlert.calendarName
+            ? `${t('task_due')} · ${taskAlert.calendarName}`
+            : t('task_due');
+
+          addToast({
+            type: 'info',
+            title: taskAlert.task.title || t('alert_title'),
+            message: taskMsg,
+            duration: 15000,
+            onClick: () => {
+              window.location.href = `/${locale}/calendar`;
+            },
+          });
+        }
+      }
     } catch {
       // Silently ignore alert evaluation errors
     }

lib/calendar-alerts.ts

@@ -4,6 +4,7 @@ import type {
   CalendarOffsetTrigger,
   CalendarAbsoluteTrigger,
   Calendar,
+  CalendarTask,
 } from '@/lib/jmap/types';
 
 export interface PendingAlert {
@@ -121,3 +122,68 @@ export function getPendingAlerts(
 
   return pending;
 }
+
+export interface PendingTaskAlert {
+  taskId: string;
+  alertId: string;
+  fireTimeMs: number;
+  task: CalendarTask;
+  calendarName: string | null;
+}
+
+export function computeTaskFireTime(
+  task: CalendarTask,
+  trigger: CalendarOffsetTrigger | CalendarAbsoluteTrigger
+): number | null {
+  if (trigger['@type'] === 'AbsoluteTrigger') {
+    const t = new Date(trigger.when).getTime();
+    return Number.isNaN(t) ? null : t;
+  }
+
+  const offsetMs = parseAlertOffset(trigger.offset);
+  if (offsetMs === null) return null;
+
+  if (!task.due) return null;
+  const baseTime = new Date(task.due).getTime();
+  if (Number.isNaN(baseTime)) return null;
+  return baseTime + offsetMs;
+}
+
+export function getPendingTaskAlerts(
+  tasks: CalendarTask[],
+  calendars: Calendar[],
+  acknowledgedKeys: Set<string>,
+  now: number
+): PendingTaskAlert[] {
+  const pending: PendingTaskAlert[] = [];
+
+  for (const task of tasks) {
+    if (!task.alerts) continue;
+    if (task.progress === 'completed' || task.progress === 'cancelled') continue;
+
+    const calendar = calendars.find(c => c.id === Object.keys(task.calendarIds)[0]) ?? null;
+
+    for (const [alertId, alert] of Object.entries(task.alerts)) {
+      if (alert.action !== 'display') continue;
+      if (alert.acknowledged) continue;
+
+      const fireTimeMs = computeTaskFireTime(task, alert.trigger);
+      if (fireTimeMs === null) continue;
+      if (fireTimeMs > now) continue;
+      if (fireTimeMs <= now - STALE_THRESHOLD_MS) continue;
+
+      const key = buildAlertKey(task.id, alertId, fireTimeMs);
+      if (acknowledgedKeys.has(key)) continue;
+
+      pending.push({
+        taskId: task.id,
+        alertId,
+        fireTimeMs,
+        task,
+        calendarName: calendar?.name ?? null,
+      });
+    }
+  }
+
+  return pending;
+}

lib/demo/demo-client.ts

@@ -1,5 +1,5 @@
 import type { IJMAPClient } from '@/lib/jmap/client-interface';
-import type { Email, Mailbox, StateChange, AccountStates, Thread, Identity, EmailAddress, ContactCard, AddressBook, VacationResponse, Calendar, CalendarEvent, CalendarEventFilter, FileNode } from '@/lib/jmap/types';
+import type { Email, Mailbox, StateChange, AccountStates, Thread, Identity, EmailAddress, ContactCard, AddressBook, VacationResponse, Calendar, CalendarEvent, CalendarEventFilter, CalendarTask, FileNode } from '@/lib/jmap/types';
 import type { SieveScript, SieveCapabilities } from '@/lib/jmap/sieve-types';
 import { getDemoData, type DemoData } from './demo-data';
 import { generateDemoId } from './demo-utils';
@@ -621,6 +621,55 @@ export class DemoJMAPClient implements IJMAPClient {
     return []; // no-op in demo
   }
 
+  // ── Calendar Tasks ────────────────────────────────────────────
+
+  async getCalendarTasks(calendarIds?: string[]): Promise<CalendarTask[]> {
+    let tasks = this.data.calendarTasks || [];
+    if (calendarIds) {
+      tasks = tasks.filter(t => Object.keys(t.calendarIds).some(id => calendarIds.includes(id)));
+    }
+    return [...tasks];
+  }
+
+  async createCalendarTask(task: Partial<CalendarTask>): Promise<CalendarTask> {
+    const full: CalendarTask = {
+      id: generateDemoId('task'),
+      uid: generateDemoId('task-uid'),
+      '@type': 'Task',
+      calendarIds: task.calendarIds || { [this.data.calendars[0]?.id || 'cal-1']: true },
+      title: task.title || '',
+      description: task.description || '',
+      due: task.due || null,
+      start: task.start || null,
+      duration: task.duration || null,
+      timeZone: task.timeZone || null,
+      showWithoutTime: task.showWithoutTime ?? true,
+      progress: task.progress || 'needs-action',
+      progressUpdated: null,
+      priority: task.priority || 0,
+      privacy: task.privacy || 'public',
+      keywords: task.keywords || null,
+      categories: task.categories || null,
+      color: task.color || null,
+      created: new Date().toISOString(),
+      updated: new Date().toISOString(),
+      recurrenceRules: task.recurrenceRules || null,
+      alerts: task.alerts || null,
+      relatedTo: task.relatedTo || null,
+    };
+    this.data.calendarTasks.push(full);
+    return full;
+  }
+
+  async updateCalendarTask(taskId: string, updates: Partial<CalendarTask>): Promise<void> {
+    const task = this.data.calendarTasks.find(t => t.id === taskId);
+    if (task) Object.assign(task, updates, { updated: new Date().toISOString() });
+  }
+
+  async deleteCalendarTask(taskId: string): Promise<void> {
+    this.data.calendarTasks = this.data.calendarTasks.filter(t => t.id !== taskId);
+  }
+
   // ── Sieve / Filters ──────────────────────────────────────────
 
   getSieveAccountId(): string { return 'demo-account'; }

lib/demo/demo-data.ts

@@ -3,12 +3,13 @@ import { createDemoMailboxes } from './fixtures/mailboxes';
 import { createDemoEmails } from './fixtures/emails';
 import { createDemoContacts, createDemoAddressBooks } from './fixtures/contacts';
 import { createDemoCalendars, createDemoCalendarEvents } from './fixtures/calendars';
+import { createDemoCalendarTasks } from './fixtures/tasks';
 import { createDemoIdentities } from './fixtures/identities';
 import { createDemoSieveScripts, createDemoSieveCapabilities, createDemoSieveContent } from './fixtures/filters';
 import { createDemoFileNodes } from './fixtures/files';
 import { createDemoVacationResponse } from './fixtures/vacation';
 
-import type { Email, Mailbox, ContactCard, AddressBook, Calendar, CalendarEvent, Identity, VacationResponse, FileNode } from '@/lib/jmap/types';
+import type { Email, Mailbox, ContactCard, AddressBook, Calendar, CalendarEvent, CalendarTask, Identity, VacationResponse, FileNode } from '@/lib/jmap/types';
 import type { SieveScript, SieveCapabilities } from '@/lib/jmap/sieve-types';
 
 export interface DemoData {
@@ -18,6 +19,7 @@ export interface DemoData {
   addressBooks: AddressBook[];
   calendars: Calendar[];
   calendarEvents: CalendarEvent[];
+  calendarTasks: CalendarTask[];
   identities: Identity[];
   sieveScripts: SieveScript[];
   sieveCapabilities: SieveCapabilities;
@@ -35,6 +37,7 @@ export function getDemoData(): DemoData {
     addressBooks: createDemoAddressBooks(),
     calendars: createDemoCalendars(),
     calendarEvents: createDemoCalendarEvents(),
+    calendarTasks: createDemoCalendarTasks(),
     identities: createDemoIdentities(),
     sieveScripts: createDemoSieveScripts(),
     sieveCapabilities: createDemoSieveCapabilities(),

lib/demo/fixtures/tasks.ts

@@ -0,0 +1,140 @@
+import type { CalendarTask } from '@/lib/jmap/types';
+import { demoDate } from '../demo-utils';
+
+export function createDemoCalendarTasks(): CalendarTask[] {
+  return [
+    {
+      id: 'demo-task-1',
+      calendarIds: { 'demo-calendar-personal': true },
+      '@type': 'Task',
+      uid: 'demo-task-uid-1',
+      title: 'Buy groceries',
+      description: 'Milk, bread, eggs, and vegetables',
+      due: demoDate(0, 2),
+      start: null,
+      duration: null,
+      timeZone: null,
+      showWithoutTime: false,
+      progress: 'needs-action',
+      progressUpdated: null,
+      priority: 0,
+      privacy: 'public',
+      keywords: null,
+      categories: null,
+      color: null,
+      created: demoDate(-3),
+      updated: demoDate(-1),
+      recurrenceRules: null,
+      alerts: null,
+      relatedTo: null,
+    },
+    {
+      id: 'demo-task-2',
+      calendarIds: { 'demo-calendar-work': true },
+      '@type': 'Task',
+      uid: 'demo-task-uid-2',
+      title: 'Prepare quarterly report',
+      description: 'Compile Q4 metrics and send to team',
+      due: demoDate(1, 4),
+      start: null,
+      duration: null,
+      timeZone: null,
+      showWithoutTime: false,
+      progress: 'in-process',
+      progressUpdated: demoDate(-1),
+      priority: 1,
+      privacy: 'public',
+      keywords: null,
+      categories: null,
+      color: null,
+      created: demoDate(-5),
+      updated: demoDate(0),
+      recurrenceRules: null,
+      alerts: {
+        'demo-alert-1': {
+          '@type': 'Alert',
+          trigger: { '@type': 'OffsetTrigger', offset: '-PT15M', relativeTo: 'start' },
+          action: 'display',
+          acknowledged: null,
+          relatedTo: null,
+        },
+      },
+      relatedTo: null,
+    },
+    {
+      id: 'demo-task-3',
+      calendarIds: { 'demo-calendar-personal': true },
+      '@type': 'Task',
+      uid: 'demo-task-uid-3',
+      title: 'Schedule dentist appointment',
+      description: '',
+      due: demoDate(3),
+      start: null,
+      duration: null,
+      timeZone: null,
+      showWithoutTime: true,
+      progress: 'needs-action',
+      progressUpdated: null,
+      priority: 5,
+      privacy: 'public',
+      keywords: null,
+      categories: null,
+      color: null,
+      created: demoDate(-2),
+      updated: demoDate(-2),
+      recurrenceRules: null,
+      alerts: null,
+      relatedTo: null,
+    },
+    {
+      id: 'demo-task-4',
+      calendarIds: { 'demo-calendar-work': true },
+      '@type': 'Task',
+      uid: 'demo-task-uid-4',
+      title: 'Review pull requests',
+      description: 'Review open PRs from the team',
+      due: demoDate(-1),
+      start: null,
+      duration: null,
+      timeZone: null,
+      showWithoutTime: true,
+      progress: 'completed',
+      progressUpdated: demoDate(0),
+      priority: 0,
+      privacy: 'public',
+      keywords: null,
+      categories: null,
+      color: null,
+      created: demoDate(-4),
+      updated: demoDate(0),
+      recurrenceRules: null,
+      alerts: null,
+      relatedTo: null,
+    },
+    {
+      id: 'demo-task-5',
+      calendarIds: { 'demo-calendar-personal': true },
+      '@type': 'Task',
+      uid: 'demo-task-uid-5',
+      title: 'Pay electricity bill',
+      description: '',
+      due: demoDate(-2),
+      start: null,
+      duration: null,
+      timeZone: null,
+      showWithoutTime: true,
+      progress: 'needs-action',
+      progressUpdated: null,
+      priority: 1,
+      privacy: 'public',
+      keywords: null,
+      categories: null,
+      color: null,
+      created: demoDate(-7),
+      updated: demoDate(-7),
+      recurrenceRules: null,
+      alerts: null,
+      relatedTo: null,
+    },
+  ];
+}

lib/jmap/client-interface.ts

@@ -1,4 +1,4 @@
-import type { Email, Mailbox, StateChange, AccountStates, Thread, Identity, EmailAddress, ContactCard, AddressBook, VacationResponse, Calendar, CalendarEvent, CalendarEventFilter, FileNode } from "./types";
+import type { Email, Mailbox, StateChange, AccountStates, Thread, Identity, EmailAddress, ContactCard, AddressBook, VacationResponse, Calendar, CalendarEvent, CalendarEventFilter, CalendarTask, FileNode } from "./types";
 import type { SieveScript, SieveCapabilities } from "./sieve-types";
 
 /**
@@ -201,6 +201,12 @@ export interface IJMAPClient {
   queryAllCalendarEvents(filter: CalendarEventFilter, sort?: Array<{ property: string; isAscending: boolean }>, limit?: number): Promise<CalendarEvent[]>;
   parseCalendarEvents(accountId: string, blobId: string): Promise<Partial<CalendarEvent>[]>;
 
+  // ── Calendar Tasks ────────────────────────────────────────────
+  getCalendarTasks(calendarIds?: string[], targetAccountId?: string): Promise<CalendarTask[]>;
+  createCalendarTask(task: Partial<CalendarTask>, targetAccountId?: string): Promise<CalendarTask>;
+  updateCalendarTask(taskId: string, updates: Partial<CalendarTask>, targetAccountId?: string): Promise<void>;
+  deleteCalendarTask(taskId: string, targetAccountId?: string): Promise<void>;
+
   // ── Sieve / Filters ──────────────────────────────────────────
   getSieveAccountId(): string;
   getSieveCapabilities(): SieveCapabilities | null;

lib/jmap/client.ts

@@ -1,4 +1,4 @@
-import type { Email, Mailbox, StateChange, AccountStates, Thread, Identity, EmailAddress, ContactCard, AddressBook, VacationResponse, Calendar, CalendarEvent, CalendarEventFilter, FileNode, FileNodeFilter } from "./types";
+import type { Email, Mailbox, StateChange, AccountStates, Thread, Identity, EmailAddress, ContactCard, AddressBook, VacationResponse, Calendar, CalendarEvent, CalendarEventFilter, CalendarTask, FileNode, FileNodeFilter } from "./types";
 import type { SieveScript, SieveCapabilities } from "./sieve-types";
 import type { IJMAPClient } from "./client-interface";
 import { toWildcardQuery } from "./search-utils";
@@ -3173,6 +3173,34 @@ export class JMAPClient implements IJMAPClient {
     return { destroyed, notDestroyed };
   }
 
+  // ─── Calendar Tasks (JSCalendar Task objects via CalendarEvent endpoints) ───
+
+  async getCalendarTasks(calendarIds?: string[], targetAccountId?: string): Promise<CalendarTask[]> {
+    try {
+      const events = await this.getCalendarEvents(calendarIds, targetAccountId);
+      return events.filter((e): e is CalendarTask & CalendarEvent =>
+        (e as unknown as CalendarTask)['@type'] === 'Task'
+      ) as unknown as CalendarTask[];
+    } catch (error) {
+      console.error('Failed to get calendar tasks:', error);
+      return [];
+    }
+  }
+
+  async createCalendarTask(task: Partial<CalendarTask>, targetAccountId?: string): Promise<CalendarTask> {
+    const event = { ...task, '@type': 'Task' } as unknown as Partial<CalendarEvent>;
+    const created = await this.createCalendarEvent(event, false, targetAccountId);
+    return created as unknown as CalendarTask;
+  }
+
+  async updateCalendarTask(taskId: string, updates: Partial<CalendarTask>, targetAccountId?: string): Promise<void> {
+    await this.updateCalendarEvent(taskId, updates as unknown as Partial<CalendarEvent>, false, targetAccountId);
+  }
+
+  async deleteCalendarTask(taskId: string, targetAccountId?: string): Promise<void> {
+    await this.deleteCalendarEvent(taskId, false, targetAccountId);
+  }
+
   // ─── JMAP FileNode methods (draft-ietf-jmap-filenode) ───
 
   supportsFiles(): boolean {

locales/en/common.json

@@ -1753,7 +1753,9 @@
       "month_hint": "Month (m)",
       "week_hint": "Week (w)",
       "day_hint": "Day (d)",
-      "agenda_hint": "Agenda (a)"
+      "agenda_hint": "Agenda (a)",
+      "tasks": "Tasks",
+      "tasks_hint": "Tasks (k)"
     },
     "events": {
       "create": "Create event",
@@ -1866,7 +1868,11 @@
       "show_time_in_month_view": "Show time in month view",
       "show_time_in_month_view_desc": "Display event times in the month calendar view",
       "show_week_numbers": "Show week numbers",
-      "show_week_numbers_desc": "Display week numbers in the mini-calendar"
+      "show_week_numbers_desc": "Display week numbers in the mini-calendar",
+      "enable_tasks": "Enable tasks",
+      "enable_tasks_desc": "Show a tasks view in the calendar for managing to-dos",
+      "show_tasks_on_calendar": "Show tasks on calendar",
+      "show_tasks_on_calendar_desc": "Display task chips on the day and week calendar views"
     },
     "days": {
       "monday": "Monday",
@@ -1899,7 +1905,8 @@
       "rsvp_updated": "Response updated",
       "rsvp_error": "Failed to update response",
       "event_duplicated": "Event duplicated",
-      "event_error": "Failed to save event"
+      "event_error": "Failed to save event",
+      "task_due": "Task due"
     },
     "status": {
       "loading_calendars": "Loading calendars...",
@@ -1997,10 +2004,48 @@
       "last_refreshed": "Last updated: {time}"
     },
     "tasks": {
+      "label": "Tasks",
       "no_tasks": "No tasks",
       "no_title": "(No title)",
       "mark_complete": "Mark as complete",
-      "mark_incomplete": "Mark as incomplete"
+      "mark_incomplete": "Mark as incomplete",
+      "filter_all": "All",
+      "filter_pending": "Pending",
+      "filter_completed": "Completed",
+      "filter_overdue": "Overdue",
+      "show_completed": "Show completed",
+      "create": "New Task",
+      "edit": "Edit Task",
+      "title_placeholder": "Task title",
+      "description_placeholder": "Add a description...",
+      "due_date": "Due date",
+      "include_time": "Include time",
+      "priority": "Priority",
+      "priority_none": "None",
+      "priority_high": "High",
+      "priority_medium": "Medium",
+      "priority_low": "Low",
+      "progress": "Status",
+      "progress_needs_action": "Needs action",
+      "progress_in_process": "In process",
+      "progress_completed": "Completed",
+      "progress_cancelled": "Cancelled",
+      "calendar": "Calendar",
+      "alert": "Reminder",
+      "alert_none": "None",
+      "alert_at_time": "At time of due date",
+      "alert_5min": "5 minutes before",
+      "alert_15min": "15 minutes before",
+      "alert_30min": "30 minutes before",
+      "alert_1hr": "1 hour before",
+      "alert_1day": "1 day before",
+      "delete": "Delete",
+      "cancel": "Cancel",
+      "save": "Save",
+      "quick_add_placeholder": "Add a task...",
+      "due_today": "Today",
+      "due_tomorrow": "Tomorrow",
+      "overdue": "Overdue"
     }
   },
   "advanced_search": {

stores/calendar-store.ts

@@ -5,9 +5,9 @@ import type { Calendar, CalendarEvent, CalendarParticipant } from '@/lib/jmap/ty
 import { debug } from '@/lib/debug';
 import { normalizeAllDayDuration } from '@/lib/calendar-utils';
 
-export type CalendarViewMode = 'month' | 'week' | 'day' | 'agenda';
+export type CalendarViewMode = 'month' | 'week' | 'day' | 'agenda' | 'tasks';
 
-const CALENDAR_VIEW_MODES: CalendarViewMode[] = ['month', 'week', 'day', 'agenda'];
+const CALENDAR_VIEW_MODES: CalendarViewMode[] = ['month', 'week', 'day', 'agenda', 'tasks'];
 
 export function isCalendarViewMode(value: unknown): value is CalendarViewMode {
   return typeof value === 'string' && CALENDAR_VIEW_MODES.includes(value as CalendarViewMode);

stores/settings-store.ts

@@ -126,6 +126,10 @@ interface SettingsState {
   showTimeInMonthView: boolean;
   showWeekNumbers: boolean;
 
+  // Calendar Tasks
+  enableCalendarTasks: boolean;
+  showTasksOnCalendar: boolean;
+
   // Calendar Notifications
   calendarNotificationsEnabled: boolean;
   calendarNotificationSound: boolean;
@@ -230,6 +234,10 @@ const DEFAULT_SETTINGS = {
   showTimeInMonthView: false,
   showWeekNumbers: false,
 
+  // Calendar Tasks
+  enableCalendarTasks: false,
+  showTasksOnCalendar: true,
+
   // Calendar Notifications
   calendarNotificationsEnabled: true,
   calendarNotificationSound: true,
@@ -314,6 +322,8 @@ export const useSettingsStore = create<SettingsState>()(
           calendarNotificationsEnabled: state.calendarNotificationsEnabled,
           calendarNotificationSound: state.calendarNotificationSound,
           calendarInvitationParsingEnabled: state.calendarInvitationParsingEnabled,
+          enableCalendarTasks: state.enableCalendarTasks,
+          showTasksOnCalendar: state.showTasksOnCalendar,
           expandedFilterView: state.expandedFilterView,
           showTimeInMonthView: state.showTimeInMonthView,
           showWeekNumbers: state.showWeekNumbers,

stores/task-store.ts

@@ -1,5 +1,6 @@
 import { create } from 'zustand';
 import type { CalendarTask } from '@/lib/jmap/types';
+import type { IJMAPClient } from '@/lib/jmap/client-interface';
 
 export type TaskViewFilter = 'all' | 'pending' | 'completed' | 'overdue';
 
@@ -8,19 +9,75 @@ interface TaskStore {
   selectedTaskId: string | null;
   filter: TaskViewFilter;
   showCompleted: boolean;
+  isLoading: boolean;
+  error: string | null;
   setTasks: (tasks: CalendarTask[]) => void;
   setSelectedTaskId: (id: string | null) => void;
   setFilter: (filter: TaskViewFilter) => void;
   setShowCompleted: (show: boolean) => void;
+  fetchTasks: (client: IJMAPClient, calendarIds?: string[]) => Promise<void>;
+  createTask: (client: IJMAPClient, task: Partial<CalendarTask>) => Promise<CalendarTask>;
+  updateTask: (client: IJMAPClient, id: string, updates: Partial<CalendarTask>) => Promise<void>;
+  deleteTask: (client: IJMAPClient, id: string) => Promise<void>;
+  toggleTaskComplete: (client: IJMAPClient, task: CalendarTask) => Promise<void>;
+  clearTasks: () => void;
 }
 
-export const useTaskStore = create<TaskStore>((set) => ({
+export const useTaskStore = create<TaskStore>((set, get) => ({
   tasks: [],
   selectedTaskId: null,
   filter: 'all',
   showCompleted: false,
+  isLoading: false,
+  error: null,
   setTasks: (tasks) => set({ tasks }),
   setSelectedTaskId: (id) => set({ selectedTaskId: id }),
   setFilter: (filter) => set({ filter }),
   setShowCompleted: (show) => set({ showCompleted: show }),
+
+  fetchTasks: async (client, calendarIds) => {
+    set({ isLoading: true, error: null });
+    try {
+      const tasks = await client.getCalendarTasks(calendarIds);
+      set({ tasks, isLoading: false });
+    } catch (error) {
+      console.error('Failed to fetch tasks:', error);
+      set({ isLoading: false, error: 'Failed to fetch tasks' });
+    }
+  },
+
+  createTask: async (client, task) => {
+    const created = await client.createCalendarTask(task);
+    set({ tasks: [...get().tasks, created] });
+    return created;
+  },
+
+  updateTask: async (client, id, updates) => {
+    await client.updateCalendarTask(id, updates);
+    set({
+      tasks: get().tasks.map(t => t.id === id ? { ...t, ...updates, updated: new Date().toISOString() } : t),
+    });
+  },
+
+  deleteTask: async (client, id) => {
+    await client.deleteCalendarTask(id);
+    set({
+      tasks: get().tasks.filter(t => t.id !== id),
+      selectedTaskId: get().selectedTaskId === id ? null : get().selectedTaskId,
+    });
+  },
+
+  toggleTaskComplete: async (client, task) => {
+    const newProgress = task.progress === 'completed' ? 'needs-action' : 'completed';
+    const updates: Partial<CalendarTask> = {
+      progress: newProgress,
+      progressUpdated: new Date().toISOString(),
+    };
+    await client.updateCalendarTask(task.id, updates);
+    set({
+      tasks: get().tasks.map(t => t.id === task.id ? { ...t, ...updates, updated: new Date().toISOString() } : t),
+    });
+  },
+
+  clearTasks: () => set({ tasks: [], selectedTaskId: null, error: null }),
 }));