diff --git a/src/api/contracts/common.ts b/src/api/contracts/common.ts
new file mode 100644
index 0000000..c85c7c4
--- /dev/null
+++ b/src/api/contracts/common.ts
@@ -0,0 +1,98 @@
+export type ApiErrorCode =
+  | "VALIDATION_ERROR"
+  | "PERMISSION_DENIED"
+  | "NETWORK_ERROR"
+  | "MAINTENANCE"
+  | "NOT_FOUND"
+  | "PARTIAL_FAILURE";
+
+export type ApiError = {
+  code: ApiErrorCode;
+  message: string;
+  fields?: Record<string, string>;
+};
+
+export type ApiMeta = {
+  requestId: string;
+  latencyMs?: number;
+  pagination?: PaginationMeta;
+  permissions?: PermissionCheck[];
+};
+
+export type ApiResponse<T> =
+  | {
+      data: T;
+      meta: ApiMeta;
+      error: null;
+    }
+  | {
+      data: null;
+      meta: ApiMeta;
+      error: ApiError;
+    };
+
+export type Pagination = {
+  page: number;
+  pageSize: number;
+};
+
+export type PaginationMeta = Pagination & {
+  total: number;
+  pageCount: number;
+};
+
+export type Sort = {
+  field: string;
+  direction: "asc" | "desc";
+};
+
+export type Filter = {
+  field: string;
+  operator: "equals" | "contains" | "startsWith" | "gt" | "lt";
+  value: string | number | boolean;
+};
+
+export type QueryParams = {
+  search?: string;
+  pagination?: Pagination;
+  sort?: Sort;
+  filters?: Filter[];
+};
+
+export type BulkOperation<TPayload = unknown> = {
+  ids: string[];
+  operation: string;
+  payload?: TPayload;
+};
+
+export type JobProgress = {
+  id: string;
+  label: string;
+  status: "queued" | "running" | "succeeded" | "failed" | "cancelled";
+  progress: number;
+  startedAt: string;
+  finishedAt?: string;
+  message?: string;
+};
+
+export type AuditMetadata = {
+  actorId: string;
+  actorName: string;
+  requestId: string;
+  ipAddress: string;
+  userAgent: string;
+};
+
+export type PermissionCheck = {
+  permission: string;
+  allowed: boolean;
+  reason?: string;
+};
+
+export type WebSocketEvent<T = unknown> = {
+  id: string;
+  type: string;
+  channel: string;
+  payload: T;
+  createdAt: string;
+};