diff --git a/src/webparts/stroyBot/services/http/IHttpClient.test.ts b/src/webparts/stroyBot/services/http/IHttpClient.test.ts
new file mode 100644
index 0000000..30a45c7
--- /dev/null
+++ b/src/webparts/stroyBot/services/http/IHttpClient.test.ts
@@ -0,0 +1,9 @@
+import { HttpError } from './IHttpClient';
+
+describe('HttpError', () => {
+  it('распознаётся через instanceof (сборка в ES5 ломала это без setPrototypeOf)', () => {
+    const error: unknown = new HttpError(403, 'Forbidden');
+    expect(error instanceof HttpError).toBe(true);
+    expect((error as HttpError).status).toEqual(403);
+  });
+});
diff --git a/src/webparts/stroyBot/services/http/IHttpClient.ts b/src/webparts/stroyBot/services/http/IHttpClient.ts
index bbf745e..25137db 100644
--- a/src/webparts/stroyBot/services/http/IHttpClient.ts
+++ b/src/webparts/stroyBot/services/http/IHttpClient.ts
@@ -31,6 +31,8 @@ export class HttpError extends Error {
 
   constructor(status: number, statusText: string, details?: string) {
     super(details ? `${status} ${statusText}: ${details}` : `${status} ${statusText}`);
+    // Сборка SPFx компилирует в ES5: без этого `error instanceof HttpError` всегда false.
+    Object.setPrototypeOf(this, HttpError.prototype);
     this.status = status;
     this.statusText = statusText;
   }