feat(mcp): подготовить сервер и доступ к приёмке

lib/backend-url.ts

@@ -0,0 +1,51 @@
+export const LOCAL_DEFAULT_BACKEND_URL = "http://localhost:8000"
+
+export type ConfiguredBackendUrl =
+  | { kind: "local" }
+  | { kind: "fixed"; url: string }
+  | { kind: "same-origin" }
+
+export function configuredBackendUrl(): ConfiguredBackendUrl {
+  const raw = process.env.NEXT_PUBLIC_BACKEND_URL
+  if (raw === undefined || raw === "local") return { kind: "local" }
+  if (raw === "" || raw === "same-origin") return { kind: "same-origin" }
+  return { kind: "fixed", url: raw.replace(/\/$/, "") }
+}
+
+export function defaultDataSourceMode(): "mock" | "live" {
+  if (!isMockDataSourceAvailable()) return "live"
+  return process.env.NEXT_PUBLIC_DEFAULT_DATA_SOURCE === "live" ? "live" : "mock"
+}
+
+export function isMockDataSourceAvailable(): boolean {
+  return process.env.NEXT_PUBLIC_ALLOW_MOCK_DATA !== "false"
+}
+
+export function isBackendUrlLocked(): boolean {
+  const cfg = configuredBackendUrl()
+  return cfg.kind === "same-origin" || cfg.kind === "fixed"
+}
+
+function isLoopbackHost(hostname: string): boolean {
+  return hostname === "localhost" || hostname === "127.0.0.1"
+}
+
+/** Prefer same-origin when the UI is not on loopback — never point the browser at localhost. */
+export function resolveStoredBackendUrl(stored: string | null): string {
+  const cfg = configuredBackendUrl()
+  if (cfg.kind === "fixed") return cfg.url
+  if (cfg.kind === "same-origin") {
+    if (typeof window !== "undefined") return window.location.origin
+    return ""
+  }
+  if (typeof window !== "undefined" && !isLoopbackHost(window.location.hostname)) {
+    return window.location.origin
+  }
+  const trimmed = stored?.trim().replace(/\/$/, "")
+  if (trimmed && /^https?:\/\/(localhost|127\.0\.0\.1)(:\d+)?$/i.test(trimmed)) {
+    if (typeof window !== "undefined" && !isLoopbackHost(window.location.hostname)) {
+      return window.location.origin
+    }
+  }
+  return trimmed || LOCAL_DEFAULT_BACKEND_URL
+}