feat: establish NekoNest Cloud control and relay

app/api/respond.ts

@@ -0,0 +1,72 @@
+import { DomainError } from "@/db/repository";
+
+function requireJsonMutation(request: Request): void {
+  const contentType = request.headers
+    .get("content-type")
+    ?.split(";", 1)[0]
+    .trim()
+    .toLowerCase();
+  if (contentType !== "application/json") {
+    throw new DomainError(
+      "json_required",
+      "写操作只接受 application/json",
+      415,
+    );
+  }
+
+  const contentLength = Number(request.headers.get("content-length") ?? "0");
+  if (Number.isFinite(contentLength) && contentLength > 32_768) {
+    throw new DomainError("request_too_large", "请求内容过大", 413);
+  }
+
+  const origin = request.headers.get("origin");
+  if (origin && origin !== new URL(request.url).origin) {
+    throw new DomainError("invalid_origin", "拒绝跨站写操作", 403);
+  }
+  const fetchSite = request.headers.get("sec-fetch-site");
+  if (fetchSite && fetchSite !== "same-origin") {
+    throw new DomainError("invalid_fetch_site", "拒绝跨站写操作", 403);
+  }
+}
+
+export async function readJsonMutation<T>(request: Request): Promise<T> {
+  requireJsonMutation(request);
+  const body = await request.text();
+  if (new TextEncoder().encode(body).byteLength > 32_768) {
+    throw new DomainError("request_too_large", "请求内容过大", 413);
+  }
+  try {
+    return JSON.parse(body) as T;
+  } catch {
+    throw new DomainError("invalid_json", "请求不是有效 JSON", 400);
+  }
+}
+
+export function apiError(error: unknown) {
+  if (error instanceof DomainError) {
+    const headers = new Headers({ "cache-control": "no-store" });
+    if (error.retryAfterSeconds !== undefined) {
+      headers.set("retry-after", String(error.retryAfterSeconds));
+    }
+    return Response.json({
+      error_code: error.code,
+      error: error.code,
+      message: error.message,
+      retryable: error.retryable,
+      ...(error.retryAfterSeconds === undefined
+        ? {}
+        : { retry_after_seconds: error.retryAfterSeconds }),
+      ...(error.actionUrl === undefined ? {} : { action_url: error.actionUrl }),
+    }, { status: error.status, headers });
+  }
+  console.error("Unhandled NekoNest Cloud API error", error);
+  return Response.json(
+    {
+      error_code: "internal_error",
+      error: "internal_error",
+      message: "服务暂时不可用，请稍后重试",
+      retryable: true,
+    },
+    { status: 500, headers: { "cache-control": "no-store" } },
+  );
+}