feat(US-702): Restore from archive

- Added restoreTask() to TaskService
- Added POST /api/tasks/:id/restore endpoint
- Added useRestoreTask() hook
- Added restore button (hover) to ArchiveSidebar items
- Tasks restore to Done column with all data preserved

docs/sprint-7.md

@@ -12,7 +12,7 @@
 | ID | Title | Status | Dependencies | Notes |
 |----|-------|--------|--------------|-------|
 | US-701 | Archive sidebar | ✅ Done | None | Slide-out viewer with search/filter for archived tasks |
-| US-702 | Restore from archive | ⏳ Todo | US-701 | Unarchive tasks back to board |
+| US-702 | Restore from archive | ✅ Done | US-701 | Unarchive tasks back to board |
 | US-703 | Subtasks | ⏳ Todo | None | Nested tasks with parent completion logic |
 | US-704 | Task dependencies | ⏳ Todo | US-703 | Block tasks until dependencies complete |
 | US-705 | Multiple task attempts | ⏳ Todo | None | Retry with different agent, preserve history |

server/.veritas-kanban/activity.json

@@ -1,4 +1,45 @@
 [
+  {
+    "id": "activity_1769427982787_zlmx7wl1j",
+    "type": "status_changed",
+    "taskId": "task_20260126_UBz41o",
+    "taskTitle": "US-702: Restore from archive",
+    "details": {
+      "from": "in-progress",
+      "status": "done"
+    },
+    "timestamp": "2026-01-26T11:46:22.788Z"
+  },
+  {
+    "id": "activity_1769427885455_irs3lpfay",
+    "type": "status_changed",
+    "taskId": "task_20260126_UBz41o",
+    "taskTitle": "US-702: Restore from archive",
+    "details": {
+      "from": "todo",
+      "status": "in-progress"
+    },
+    "timestamp": "2026-01-26T11:44:45.455Z"
+  },
+  {
+    "id": "activity_1769427882031_qsa7fjdlb",
+    "type": "task_created",
+    "taskId": "task_20260126_UBz41o",
+    "taskTitle": "US-702: Restore from archive",
+    "details": {
+      "type": "code",
+      "priority": "medium",
+      "project": "veritas-kanban"
+    },
+    "timestamp": "2026-01-26T11:44:42.031Z"
+  },
+  {
+    "id": "activity_1769427809793_r57vixvwa",
+    "type": "task_updated",
+    "taskId": "task_20260126_wzj1d0",
+    "taskTitle": "US-701: Archive sidebar",
+    "timestamp": "2026-01-26T11:43:29.793Z"
+  },
   {
     "id": "activity_1769427062484_c9s4q6kiq",
     "type": "task_created",

server/src/routes/tasks.ts

@@ -201,6 +201,27 @@ router.post('/:id/archive', async (req, res) => {
   }
 });
 
+// POST /api/tasks/:id/restore - Restore task from archive
+router.post('/:id/restore', async (req, res) => {
+  try {
+    const task = await taskService.restoreTask(req.params.id);
+    if (!task) {
+      return res.status(404).json({ error: 'Archived task not found' });
+    }
+    
+    // Log activity
+    await activityService.logActivity('status_changed', task.id, task.title, {
+      from: 'archived',
+      status: 'done',
+    });
+    
+    res.json(task);
+  } catch (error) {
+    console.error('Error restoring task:', error);
+    res.status(500).json({ error: 'Failed to restore task' });
+  }
+});
+
 // === Worktree Routes ===
 
 // POST /api/tasks/:id/worktree - Create worktree

server/src/services/task-service.ts

@@ -228,4 +228,28 @@ export class TaskService {
     const tasks = await this.listArchivedTasks();
     return tasks.find(t => t.id === id) || null;
   }
+
+  async restoreTask(id: string): Promise<Task | null> {
+    const task = await this.getArchivedTask(id);
+    if (!task) return null;
+
+    const filename = this.taskToFilename(task);
+    const sourcePath = path.join(this.archiveDir, filename);
+    const destPath = path.join(this.tasksDir, filename);
+    
+    // Move back to active and set status to done
+    await fs.rename(sourcePath, destPath);
+    
+    // Update status to done
+    const restoredTask: Task = {
+      ...task,
+      status: 'done',
+      updated: new Date().toISOString(),
+    };
+    
+    const content = this.taskToMarkdown(restoredTask);
+    await fs.writeFile(destPath, content, 'utf-8');
+    
+    return restoredTask;
+  }
 }

web/src/components/layout/ArchiveSidebar.tsx

@@ -1,5 +1,5 @@
 import { useState, useMemo } from 'react';
-import { Archive, RefreshCw, Search, Calendar, FolderOpen } from 'lucide-react';
+import { Archive, RefreshCw, Search, Calendar, FolderOpen, RotateCcw } from 'lucide-react';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { ScrollArea } from '@/components/ui/scroll-area';
@@ -17,7 +17,7 @@ import {
   SelectTrigger,
   SelectValue,
 } from '@/components/ui/select';
-import { useArchivedTasks } from '@/hooks/useTasks';
+import { useArchivedTasks, useRestoreTask } from '@/hooks/useTasks';
 import { cn } from '@/lib/utils';
 import type { Task, TaskType } from '@veritas-kanban/shared';
 
@@ -50,11 +50,21 @@ function formatDate(dateString: string): string {
   });
 }
 
-function ArchivedTaskItem({ task, onClick }: { task: Task; onClick?: () => void }) {
+function ArchivedTaskItem({ 
+  task, 
+  onClick,
+  onRestore,
+  isRestoring,
+}: { 
+  task: Task; 
+  onClick?: () => void;
+  onRestore?: () => void;
+  isRestoring?: boolean;
+}) {
   return (
     <div 
       className={cn(
-        "flex items-start gap-3 py-3 px-2 rounded-md transition-colors",
+        "flex items-start gap-3 py-3 px-2 rounded-md transition-colors group",
         onClick ? "hover:bg-muted/50 cursor-pointer" : ""
       )}
       onClick={onClick}
@@ -93,6 +103,21 @@ function ArchivedTaskItem({ task, onClick }: { task: Task; onClick?: () => void
           </div>
         )}
       </div>
+      {onRestore && (
+        <Button
+          variant="ghost"
+          size="icon"
+          className="h-8 w-8 opacity-0 group-hover:opacity-100 transition-opacity flex-shrink-0"
+          onClick={(e) => {
+            e.stopPropagation();
+            onRestore();
+          }}
+          disabled={isRestoring}
+          title="Restore to board"
+        >
+          <RotateCcw className={cn("h-4 w-4", isRestoring && "animate-spin")} />
+        </Button>
+      )}
     </div>
   );
 }
@@ -101,8 +126,21 @@ export function ArchiveSidebar({ open, onOpenChange, onTaskClick }: ArchiveSideb
   const [search, setSearch] = useState('');
   const [typeFilter, setTypeFilter] = useState<string>('all');
   const [projectFilter, setProjectFilter] = useState<string>('all');
+  const [restoringId, setRestoringId] = useState<string | null>(null);
   
   const { data: archivedTasks, isLoading, refetch, isRefetching } = useArchivedTasks();
+  const restoreTask = useRestoreTask();
+
+  const handleRestore = async (task: Task) => {
+    setRestoringId(task.id);
+    try {
+      await restoreTask.mutateAsync(task.id);
+    } catch (error) {
+      console.error('Failed to restore task:', error);
+    } finally {
+      setRestoringId(null);
+    }
+  };
 
   // Get unique projects for filter dropdown
   const projects = useMemo(() => {
@@ -224,6 +262,8 @@ export function ArchiveSidebar({ open, onOpenChange, onTaskClick }: ArchiveSideb
                     key={task.id} 
                     task={task}
                     onClick={onTaskClick ? () => onTaskClick(task) : undefined}
+                    onRestore={() => handleRestore(task)}
+                    isRestoring={restoringId === task.id}
                   />
                 ))}
               </div>

web/src/hooks/useTasks.ts

@@ -66,6 +66,19 @@ export function useArchiveTask() {
     mutationFn: (id: string) => api.tasks.archive(id),
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['tasks'] });
+      queryClient.invalidateQueries({ queryKey: ['tasks', 'archived'] });
+    },
+  });
+}
+
+export function useRestoreTask() {
+  const queryClient = useQueryClient();
+  
+  return useMutation({
+    mutationFn: (id: string) => api.tasks.restore(id),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['tasks'] });
+      queryClient.invalidateQueries({ queryKey: ['tasks', 'archived'] });
     },
   });
 }

web/src/lib/api.ts

@@ -98,6 +98,13 @@ export const api = {
       });
       return handleResponse<void>(response);
     },
+
+    restore: async (id: string): Promise<Task> => {
+      const response = await fetch(`${API_BASE}/tasks/${id}/restore`, {
+        method: 'POST',
+      });
+      return handleResponse<Task>(response);
+    },
   },
 
   config: {