Wire AssignmentPicker into TaskDetailPanel for task assignment

TaskDetailPanel now shows an interactive AssignmentPicker (click to
open dropdown, select members, remove with X) when the user has
create_modify permission or is the owner. Read-only users see static
chips. Owner is included as a synthetic entry in the picker so they
can self-assign. Both assign and unassign mutations invalidate the
project query for immediate UI refresh.

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

frontend/src/components/projects/ProjectDetail.tsx

@@ -710,6 +710,10 @@ export default function ProjectDetail() {
                 <TaskDetailPanel
                   task={selectedTask}
                   projectId={parseInt(id!)}
+                  members={acceptedMembers}
+                  currentUserId={currentUserId}
+                  ownerId={project?.user_id ?? 0}
+                  canAssign={isOwner || acceptedMembers.some(m => m.user_id === currentUserId && m.permission === 'create_modify')}
                   onDelete={handleDeleteTask}
                   onAddSubtask={(parentId) => openTaskForm(null, parentId)}
                   onClose={() => setSelectedTaskId(null)}

frontend/src/components/projects/TaskDetailPanel.tsx

@@ -9,7 +9,8 @@ import {
 import axios from 'axios';
 import api, { getErrorMessage } from '@/lib/api';
 import { formatUpdatedAt } from '@/components/shared/utils';
-import type { ProjectTask, TaskComment } from '@/types';
+import type { ProjectTask, TaskComment, ProjectMember } from '@/types';
+import { AssignmentPicker } from './AssignmentPicker';
 import { Button } from '@/components/ui/button';
 import { Badge } from '@/components/ui/badge';
 import { Checkbox } from '@/components/ui/checkbox';
@@ -46,6 +47,10 @@ const priorityColors: Record<string, string> = {
 interface TaskDetailPanelProps {
   task: ProjectTask | null;
   projectId: number;
+  members?: ProjectMember[];
+  currentUserId?: number;
+  ownerId?: number;
+  canAssign?: boolean;
   onDelete: (taskId: number) => void;
   onAddSubtask: (parentId: number) => void;
   onClose?: () => void;
@@ -82,6 +87,10 @@ function buildEditState(task: ProjectTask): EditState {
 export default function TaskDetailPanel({
   task,
   projectId,
+  members = [],
+  currentUserId = 0,
+  ownerId = 0,
+  canAssign = false,
   onDelete,
   onAddSubtask,
   onClose,
@@ -94,6 +103,17 @@ export default function TaskDetailPanel({
     task ? buildEditState(task) : { title: '', status: 'pending', priority: 'none', due_date: todayLocal(), person_id: '', description: '' }
   );
 
+  // Build a combined members list that includes the owner for the AssignmentPicker
+  const allMembers: ProjectMember[] = [
+    // Synthetic owner entry so they appear in the picker
+    ...(ownerId ? [{
+      id: 0, project_id: projectId, user_id: ownerId, invited_by: ownerId,
+      permission: 'create_modify' as const, status: 'accepted' as const,
+      source: 'invited' as const, user_name: currentUserId === ownerId ? 'Me (Owner)' : 'Owner',
+      inviter_name: null, created_at: '', updated_at: '', accepted_at: null,
+    }] : []),
+    ...members.filter(m => m.status === 'accepted'),
+  ];
 
   // --- Mutations ---
 
@@ -168,6 +188,30 @@ export default function TaskDetailPanel({
     },
   });
 
+  const assignMutation = useMutation({
+    mutationFn: async (userIds: number[]) => {
+      await api.post(`/projects/${projectId}/tasks/${task!.id}/assignments`, { user_ids: userIds });
+    },
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['projects', projectId.toString()] });
+    },
+    onError: (error) => {
+      toast.error(getErrorMessage(error, 'Failed to assign'));
+    },
+  });
+
+  const unassignMutation = useMutation({
+    mutationFn: async (userId: number) => {
+      await api.delete(`/projects/${projectId}/tasks/${task!.id}/assignments/${userId}`);
+    },
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['projects', projectId.toString()] });
+    },
+    onError: (error) => {
+      toast.error(getErrorMessage(error, 'Failed to unassign'));
+    },
+  });
+
   // --- Handlers ---
 
   const handleAddComment = () => {
@@ -375,7 +419,17 @@ export default function TaskDetailPanel({
               <User className="h-3 w-3" />
               Assigned
             </div>
-            {task.assignments && task.assignments.length > 0 ? (
+            {canAssign ? (
+              <AssignmentPicker
+                currentAssignments={task.assignments ?? []}
+                members={allMembers}
+                currentUserId={currentUserId}
+                ownerId={ownerId}
+                onAssign={(userIds) => assignMutation.mutate(userIds)}
+                onUnassign={(userId) => unassignMutation.mutate(userId)}
+                disabled={assignMutation.isPending || unassignMutation.isPending}
+              />
+            ) : task.assignments && task.assignments.length > 0 ? (
               <div className="flex flex-wrap gap-1.5">
                 {task.assignments.map((a) => (
                   <span