diff --git a/frontend/src/types/index.ts b/frontend/src/types/index.ts
new file mode 100644
index 0000000..57d50d2
--- /dev/null
+++ b/frontend/src/types/index.ts
@@ -0,0 +1,283 @@
+// ============ User & Auth ============
+
+export type UserRole = 'super_admin' | 'tenant_admin' | 'project_manager' | 'reviewer' | 'worker';
+
+export interface User {
+  id: number;
+  email: string;
+  username: string;
+  role: UserRole;
+  user_type: string;
+  tenant_id: number;
+  is_active: boolean;
+  avatar?: string;
+  phone?: string;
+  worker_id?: number;
+  created_at: string;
+}
+
+export interface AuthResponse {
+  access_token: string;
+  token_type?: string;
+  user: User;
+}
+
+export interface LoginPayload {
+  email: string;
+  password: string;
+}
+
+export interface RegisterPayload {
+  email: string;
+  username: string;
+  password: string;
+  role: string;
+  tenant_slug: string;
+  tenant_name: string;
+}
+
+// ============ Tenant ============
+
+export interface Tenant {
+  id: number;
+  name: string;
+  slug: string;
+  description?: string;
+  is_active: boolean;
+  created_at: string;
+}
+
+export interface TenantCreate {
+  name: string;
+  slug: string;
+  description?: string;
+}
+
+// ============ Project ============
+
+export type ProjectStatus = 'draft' | 'planning' | 'in_progress' | 'review' | 'accepted' | 'archived';
+
+export interface Project {
+  id: number;
+  name: string;
+  description: string;
+  status: string;
+  owner_id: number;
+  tenant_id: number;
+  start_date?: string;
+  end_date?: string;
+  budget_limit_cents?: number;
+  acceptance_criteria: string;
+  tags: string;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface ProjectCreate {
+  name: string;
+  description?: string;
+  start_date?: string;
+  end_date?: string;
+  budget_limit_cents?: number;
+  acceptance_criteria?: string;
+  tags?: string;
+}
+
+export interface ProjectStats {
+  total_tasks: number;
+  pending_tasks: number;
+  in_progress_tasks: number;
+  review_tasks: number;
+  done_tasks: number;
+  total_cost_cents: number;
+  total_artifacts: number;
+  pending_reviews: number;
+}
+
+// ============ Task ============
+
+export type TaskStatus =
+  | 'pending'
+  | 'assigned'
+  | 'in_progress'
+  | 'review'
+  | 'done'
+  | 'rejected'
+  | 'cancelled';
+
+export type TaskPriority = 'low' | 'medium' | 'high' | 'urgent';
+
+export interface Task {
+  id: number;
+  project_id: number;
+  title: string;
+  description: string;
+  status: TaskStatus;
+  priority: TaskPriority;
+  assignee_id?: number;
+  worker_id?: number;
+  task_type: string;
+  input_data: string;
+  output_data?: string;
+  requires_review: boolean;
+  review_status?: string;
+  due_date?: string;
+  started_at?: string;
+  completed_at?: string;
+  tenant_id: number;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface TaskCreate {
+  title: string;
+  description?: string;
+  priority?: TaskPriority;
+  task_type?: string;
+  input_data?: string;
+  requires_review?: boolean;
+  assignee_id?: number;
+  worker_id?: number;
+  due_date?: string;
+  depends_on?: string;
+}
+
+export interface TaskAssignPayload {
+  assignee_id?: number;
+  worker_id?: number;
+}
+
+export interface TaskExecutePayload {
+  override_input?: string;
+  max_retries?: number;
+}
+
+export interface ExecutionResult {
+  task_id: number;
+  status: string;
+  output: string;
+  token_usage: number;
+  cost_cents: number;
+  duration_ms: number;
+  error?: string;
+  artifact_id?: number;
+}
+
+// ============ Worker ============
+
+export interface Worker {
+  id: number;
+  name: string;
+  description: string;
+  provider: string;
+  model_name: string;
+  base_url?: string;
+  temperature: number;
+  system_prompt: string;
+  tools: string;
+  max_cost_per_task_cents?: number;
+  max_cost_per_month_cents?: number;
+  status: string;
+  is_active: boolean;
+  current_task_count: number;
+  max_concurrent_tasks: number;
+  tenant_id: number;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface WorkerCreate {
+  name: string;
+  description?: string;
+  provider: string;
+  model_name: string;
+  api_key?: string;
+  base_url?: string;
+  temperature?: number;
+  system_prompt?: string;
+  tools?: string;
+  max_cost_per_task_cents?: number;
+  max_cost_per_month_cents?: number;
+  available_hours?: string;
+  max_concurrent_tasks?: number;
+}
+
+export interface WorkerTestResult {
+  success: boolean;
+  response: string;
+  latency_ms: number;
+  error?: string;
+}
+
+// ============ Review ============
+
+export interface Review {
+  id: number;
+  task_id: number;
+  project_id: number;
+  review_type: string;
+  status: string;
+  reviewer_id?: number;
+  reviewer_role?: string;
+  review_content: string;
+  reviewer_comment: string;
+  auto_check_result: string;
+  submitted_at: string;
+  reviewed_at?: string;
+  tenant_id: number;
+  created_at: string;
+}
+
+export interface ReviewDecisionPayload {
+  comment: string;
+  status: 'approved' | 'rejected';
+}
+
+// ============ Artifact ============
+
+export interface Artifact {
+  id: number;
+  task_id: number;
+  project_id: number;
+  title: string;
+  content: string;
+  artifact_type: string;
+  version: number;
+  is_latest: string;
+  created_by_user_id?: number;
+  created_by_worker_id?: number;
+  sources: string;
+  tenant_id: number;
+  created_at: string;
+}
+
+// ============ Dashboard ============
+
+export interface DashboardStats {
+  projects: number;
+  tasks: number;
+  active_workers: number;
+  pending_reviews: number;
+  task_status: Record<string, number>;
+  cost: {
+    total_cost_cents: number;
+    total_calls: number;
+    by_model: Array<{
+      model: string;
+      cost_cents: number;
+      tokens: number;
+      calls: number;
+    }>;
+  };
+  user: {
+    id: number;
+    username: string;
+    role: string;
+  };
+}
+
+// ============ Generic ============
+
+export interface ApiError {
+  detail: string;
+}