feat: implement Kanban board with drag-and-drop task management

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

TaskTracker.Web/src/components/KanbanBoard.tsx

@@ -0,0 +1,153 @@
+import { useMemo, useCallback } from 'react'
+import {
+  DndContext,
+  DragOverlay,
+  PointerSensor,
+  useSensor,
+  useSensors,
+  closestCorners,
+} from '@dnd-kit/core'
+import type { DragEndEvent, DragStartEvent } from '@dnd-kit/core'
+import { useState } from 'react'
+import { Loader2 } from 'lucide-react'
+import {
+  useTasks,
+  useStartTask,
+  usePauseTask,
+  useResumeTask,
+  useCompleteTask,
+} from '../api/tasks.ts'
+import { WorkTaskStatus } from '../types/index.ts'
+import type { WorkTask } from '../types/index.ts'
+import { COLUMN_CONFIG } from '../lib/constants.ts'
+import KanbanColumn from './KanbanColumn.tsx'
+import TaskCard from './TaskCard.tsx'
+
+interface KanbanBoardProps {
+  onTaskClick: (id: number) => void
+}
+
+export default function KanbanBoard({ onTaskClick }: KanbanBoardProps) {
+  const { data: tasks, isLoading } = useTasks()
+  const startTask = useStartTask()
+  const pauseTask = usePauseTask()
+  const resumeTask = useResumeTask()
+  const completeTask = useCompleteTask()
+
+  const [activeTask, setActiveTask] = useState<WorkTask | null>(null)
+
+  const sensors = useSensors(
+    useSensor(PointerSensor, { activationConstraint: { distance: 8 } })
+  )
+
+  // Filter to top-level tasks only and group by status
+  const columns = useMemo(() => {
+    const topLevel = (tasks ?? []).filter((t) => t.parentTaskId === null)
+    return COLUMN_CONFIG.map((col) => ({
+      ...col,
+      tasks: topLevel.filter((t) => t.status === col.status),
+    }))
+  }, [tasks])
+
+  const handleDragStart = useCallback(
+    (event: DragStartEvent) => {
+      const draggedId = Number(event.active.id)
+      const task = (tasks ?? []).find((t) => t.id === draggedId) ?? null
+      setActiveTask(task)
+    },
+    [tasks]
+  )
+
+  const handleDragEnd = useCallback(
+    (event: DragEndEvent) => {
+      setActiveTask(null)
+
+      const { active, over } = event
+      if (!over) return
+
+      const taskId = Number(active.id)
+      const task = (tasks ?? []).find((t) => t.id === taskId)
+      if (!task) return
+
+      // Determine target status from the droppable column ID
+      let targetStatus: number | null = null
+      const overId = String(over.id)
+
+      if (overId.startsWith('column-')) {
+        targetStatus = Number(overId.replace('column-', ''))
+      } else {
+        // Dropped over another card - find which column it belongs to
+        const overTaskId = Number(over.id)
+        const overTask = (tasks ?? []).find((t) => t.id === overTaskId)
+        if (overTask) {
+          targetStatus = overTask.status
+        }
+      }
+
+      if (targetStatus === null || targetStatus === task.status) return
+
+      // Map transitions to API calls
+      switch (targetStatus) {
+        case WorkTaskStatus.Active:
+          // Works for both Pending->Active and Paused->Active
+          if (task.status === WorkTaskStatus.Paused) {
+            resumeTask.mutate({ id: taskId })
+          } else {
+            startTask.mutate(taskId)
+          }
+          break
+        case WorkTaskStatus.Paused:
+          if (task.status === WorkTaskStatus.Active) {
+            pauseTask.mutate({ id: taskId })
+          }
+          break
+        case WorkTaskStatus.Completed:
+          completeTask.mutate(taskId)
+          break
+        case WorkTaskStatus.Pending:
+          // Transition back to Pending is not supported
+          break
+      }
+    },
+    [tasks, startTask, pauseTask, resumeTask, completeTask]
+  )
+
+  if (isLoading) {
+    return (
+      <div className="flex items-center justify-center h-64">
+        <Loader2 className="animate-spin text-[#64748b]" size={32} />
+      </div>
+    )
+  }
+
+  return (
+    <DndContext
+      sensors={sensors}
+      collisionDetection={closestCorners}
+      onDragStart={handleDragStart}
+      onDragEnd={handleDragEnd}
+    >
+      <div className="grid grid-cols-4 gap-4 h-full">
+        {columns.map((col) => (
+          <KanbanColumn
+            key={col.status}
+            status={col.status}
+            label={col.label}
+            color={col.color}
+            tasks={col.tasks}
+            onTaskClick={onTaskClick}
+            onAddTask={col.status === 0 ? () => {} : undefined}
+          />
+        ))}
+      </div>
+
+      <DragOverlay>
+        {activeTask ? (
+          <div className="rotate-2 scale-105">
+            <TaskCard task={activeTask} onClick={() => {}} />
+          </div>
+        ) : null}
+      </DragOverlay>
+    </DndContext>
+  )
+}

TaskTracker.Web/src/components/KanbanColumn.tsx

@@ -0,0 +1,79 @@
+import { useDroppable } from '@dnd-kit/core'
+import { SortableContext, verticalListSortingStrategy } from '@dnd-kit/sortable'
+import { Plus } from 'lucide-react'
+import type { WorkTask } from '../types/index.ts'
+import TaskCard from './TaskCard.tsx'
+
+interface KanbanColumnProps {
+  status: number
+  label: string
+  color: string
+  tasks: WorkTask[]
+  onTaskClick: (id: number) => void
+  onAddTask?: () => void
+}
+
+export default function KanbanColumn({
+  status,
+  label,
+  color,
+  tasks,
+  onTaskClick,
+  onAddTask,
+}: KanbanColumnProps) {
+  const { setNodeRef, isOver } = useDroppable({ id: `column-${status}` })
+
+  const taskIds = tasks.map((t) => t.id)
+
+  return (
+    <div
+      className={`
+        flex flex-col min-h-[400px] rounded-xl
+        bg-white/[0.02] border transition-colors duration-150
+        ${isOver ? 'border-white/20 bg-white/[0.04]' : 'border-white/5'}
+      `}
+    >
+      {/* Column header */}
+      <div className="px-4 pt-4 pb-3">
+        <div className="flex items-center justify-between mb-2">
+          <h2 className="text-sm font-semibold text-white">{label}</h2>
+          <span
+            className="text-[11px] font-medium px-2 py-0.5 rounded-full"
+            style={{
+              backgroundColor: color + '20',
+              color,
+            }}
+          >
+            {tasks.length}
+          </span>
+        </div>
+        <div className="h-0.5 rounded-full" style={{ backgroundColor: color }} />
+      </div>
+
+      {/* Cards area */}
+      <div
+        ref={setNodeRef}
+        className="flex-1 flex flex-col gap-2 px-3 pb-3 overflow-y-auto"
+      >
+        <SortableContext items={taskIds} strategy={verticalListSortingStrategy}>
+          {tasks.map((task) => (
+            <TaskCard key={task.id} task={task} onClick={onTaskClick} />
+          ))}
+        </SortableContext>
+      </div>
+
+      {/* Add task button (Pending column only) */}
+      {status === 0 && onAddTask && (
+        <button
+          onClick={onAddTask}
+          className="flex items-center justify-center gap-1.5 mx-3 mb-3 py-2 rounded-lg
+            text-xs text-[#64748b] border border-dashed border-white/10
+            hover:text-white hover:border-white/20 transition-colors duration-150"
+        >
+          <Plus size={14} />
+          Add Task
+        </button>
+      )}
+    </div>
+  )
+}

TaskTracker.Web/src/components/TaskCard.tsx

@@ -0,0 +1,129 @@
+import { useSortable } from '@dnd-kit/sortable'
+import { CSS } from '@dnd-kit/utilities'
+import { CheckSquare, Clock } from 'lucide-react'
+import { WorkTaskStatus } from '../types/index.ts'
+import type { WorkTask } from '../types/index.ts'
+import { CATEGORY_COLORS } from '../lib/constants.ts'
+
+function formatElapsed(task: WorkTask): string | null {
+  if (!task.startedAt) return null
+  const start = new Date(task.startedAt).getTime()
+  const end = task.completedAt ? new Date(task.completedAt).getTime() : Date.now()
+  const mins = Math.floor((end - start) / 60_000)
+  if (mins < 60) return `${mins}m`
+  const hours = Math.floor(mins / 60)
+  const remainder = mins % 60
+  if (hours < 24) return `${hours}h ${remainder}m`
+  const days = Math.floor(hours / 24)
+  return `${days}d ${hours % 24}h`
+}
+
+interface TaskCardProps {
+  task: WorkTask
+  onClick: (id: number) => void
+}
+
+export default function TaskCard({ task, onClick }: TaskCardProps) {
+  const {
+    attributes,
+    listeners,
+    setNodeRef,
+    transform,
+    transition,
+    isDragging,
+  } = useSortable({ id: task.id })
+
+  const style = {
+    transform: CSS.Transform.toString(transform),
+    transition,
+    opacity: isDragging ? 0.5 : 1,
+  }
+
+  const categoryColor = CATEGORY_COLORS[task.category ?? 'Unknown'] ?? CATEGORY_COLORS['Unknown']
+  const isActive = task.status === WorkTaskStatus.Active
+  const elapsed = formatElapsed(task)
+
+  const completedSubTasks = task.subTasks?.filter(
+    (s) => s.status === WorkTaskStatus.Completed
+  ).length ?? 0
+  const totalSubTasks = task.subTasks?.length ?? 0
+
+  let progressPercent: number | null = null
+  if (task.estimatedMinutes && task.startedAt) {
+    const start = new Date(task.startedAt).getTime()
+    const end = task.completedAt ? new Date(task.completedAt).getTime() : Date.now()
+    const elapsedMins = (end - start) / 60_000
+    progressPercent = Math.min(100, (elapsedMins / task.estimatedMinutes) * 100)
+  }
+
+  return (
+    <div
+      ref={setNodeRef}
+      style={style}
+      {...attributes}
+      {...listeners}
+      onClick={() => onClick(task.id)}
+      className={`
+        relative rounded-lg cursor-grab active:cursor-grabbing
+        bg-[#1a1d27] hover:-translate-y-0.5 hover:shadow-lg
+        transition-all duration-150
+        ${isActive ? 'ring-1 ring-cyan-400/60 shadow-[0_0_12px_rgba(6,182,212,0.25)] animate-pulse-glow' : ''}
+      `}
+    >
+      {/* Category left border */}
+      <div
+        className="absolute left-0 top-0 bottom-0 w-1 rounded-l-lg"
+        style={{ backgroundColor: categoryColor }}
+      />
+
+      <div className="pl-4 pr-3 py-3">
+        {/* Title */}
+        <p className="text-sm font-medium text-white leading-snug mb-2 truncate">
+          {task.title}
+        </p>
+
+        {/* Category badge */}
+        {task.category && (
+          <span
+            className="inline-block text-[11px] font-medium px-2 py-0.5 rounded-full mb-2"
+            style={{
+              backgroundColor: categoryColor + '20',
+              color: categoryColor,
+            }}
+          >
+            {task.category}
+          </span>
+        )}
+
+        {/* Progress bar */}
+        {progressPercent !== null && (
+          <div className="h-1 w-full bg-white/5 rounded-full mb-2 overflow-hidden">
+            <div
+              className="h-full rounded-full bg-indigo-500 transition-all duration-300"
+              style={{ width: `${progressPercent}%` }}
+            />
+          </div>
+        )}
+
+        {/* Footer row */}
+        <div className="flex items-center justify-between text-[11px] text-[#64748b]">
+          <div className="flex items-center gap-2">
+            {elapsed && (
+              <span className="flex items-center gap-1">
+                <Clock size={12} />
+                {elapsed}
+              </span>
+            )}
+          </div>
+
+          {totalSubTasks > 0 && (
+            <span className="flex items-center gap-1">
+              <CheckSquare size={12} />
+              {completedSubTasks}/{totalSubTasks}
+            </span>
+          )}
+        </div>
+      </div>
+    </div>
+  )
+}

TaskTracker.Web/src/index.css

@@ -1 +1,14 @@
 @import "tailwindcss";
+
+@keyframes pulse-glow {
+  0%, 100% {
+    box-shadow: 0 0 8px rgba(6, 182, 212, 0.2);
+  }
+  50% {
+    box-shadow: 0 0 16px rgba(6, 182, 212, 0.4);
+  }
+}
+
+.animate-pulse-glow {
+  animation: pulse-glow 2s ease-in-out infinite;
+}

TaskTracker.Web/src/lib/constants.ts

@@ -0,0 +1,16 @@
+export const COLUMN_CONFIG = [
+  { status: 0, label: 'Pending', color: '#94a3b8' },
+  { status: 1, label: 'Active', color: '#06b6d4' },
+  { status: 2, label: 'Paused', color: '#f59e0b' },
+  { status: 3, label: 'Completed', color: '#10b981' },
+] as const
+
+export const CATEGORY_COLORS: Record<string, string> = {
+  Development: '#6366f1',
+  Research: '#06b6d4',
+  Communication: '#8b5cf6',
+  DevOps: '#f97316',
+  Documentation: '#14b8a6',
+  Design: '#ec4899',
+  Unknown: '#64748b',
+}

TaskTracker.Web/src/pages/Board.tsx

@@ -1,7 +1,16 @@
+import { useState } from 'react'
+import KanbanBoard from '../components/KanbanBoard.tsx'
+
 export default function Board() {
+  const [selectedTaskId, setSelectedTaskId] = useState<number | null>(null)
+
+  // selectedTaskId will be used by TaskDetailPanel in Task 6
+  void selectedTaskId
+
   return (
-    <div>
-      <h1 className="text-xl font-semibold text-white">Board</h1>
+    <div className="h-full">
+      <KanbanBoard onTaskClick={(id) => setSelectedTaskId(id)} />
+      {/* TaskDetailPanel will be added in Task 6 */}
     </div>
   )
 }