phase 2 and 3

lib/client-api.ts

@@ -0,0 +1,29 @@
+export interface ApiFailure {
+  error: string;
+  code?: string;
+  issues?: Array<{ path: unknown; message: string }>;
+}
+
+export class ApiClientError extends Error {
+  constructor(public status: number, public code: string | undefined, message: string) {
+    super(message);
+  }
+}
+
+export async function apiFetch<T>(
+  input: string,
+  init: RequestInit = {},
+): Promise<T> {
+  const headers = new Headers(init.headers);
+  if (init.body && !headers.has("content-type") && !(init.body instanceof FormData)) {
+    headers.set("content-type", "application/json");
+  }
+  const res = await fetch(input, { ...init, headers });
+  const text = await res.text();
+  const data = text ? (JSON.parse(text) as unknown) : undefined;
+  if (!res.ok) {
+    const fail = (data ?? { error: res.statusText }) as ApiFailure;
+    throw new ApiClientError(res.status, fail.code, fail.error);
+  }
+  return data as T;
+}