🧭 fix: Subdirectory Deployment Auth Redirect Path Doubling (#12077)

* fix: subdirectory redirects

* fix: use path-segment boundary check when stripping BASE_URL prefix

A bare `startsWith(BASE_URL)` matches on character prefix, not path
segments. With BASE_URL="/chat", a path like "/chatroom/c/abc" would
incorrectly strip to "room/c/abc" (no leading slash). Guard with an
exact-match-or-slash check: `p === BASE_URL || p.startsWith(BASE_URL + '/')`.

Also removes the dead `BASE_URL !== '/'` guard — module init already
converts '/' to ''.

* test: add path-segment boundary tests and clarify subdirectory coverage

- Add /chatroom, /chatbot, /app/chatroom regression tests to verify
  BASE_URL stripping only matches on segment boundaries
- Clarify useAuthRedirect subdirectory test documents React Router
  basename behavior (BASE_URL stripping tested in api-endpoints-subdir)
- Use `delete proc.browser` instead of undefined assignment for cleanup
- Add rationale to eslint-disable comment for isolateModules require

* fix: use relative path and correct instructions in subdirectory test script

- Replace hardcoded /home/danny/LibreChat/.env with repo-root-relative
  path so the script works from any checkout location
- Update instructions to use production build (npm run build && npm run
  backend) since nginx proxies to :3080 which only serves the SPA after
  a full build, not during frontend:dev on :3090

* fix: skip pointless redirect_to=/ for root path and fix jsdom 26+ compat

buildLoginRedirectUrl now returns plain /login when the resolved path
is root — redirect_to=/ adds no value since / immediately redirects
to /c/new after login anyway.

Also rewrites api-endpoints.spec.ts to use window.history.replaceState
instead of Object.defineProperty(window, 'location', ...) which jsdom
26+ no longer allows.

* test: fix request-interceptor.spec.ts for jsdom 26+ compatibility

Switch from jsdom to happy-dom environment which allows
Object.defineProperty on window.location. jsdom 26+ made
location non-configurable, breaking all 8 tests in this file.

* chore: update browser property handling in api-endpoints-subdir test

Changed the handling of the `proc.browser` property from deletion to setting it to false, ensuring compatibility with the current testing environment.

* chore: update backend restart instructions in test subdirectory setup script

Changed the instruction for restarting the backend from "npm run backend:dev" to "npm run backend" to reflect the correct command for the current setup.

* refactor: ensure proper cleanup in loadModuleWithBase function

Wrapped the module loading logic in a try-finally block to guarantee that the `proc.browser` property is reset to false and the base element is removed, improving reliability in the testing environment.

* refactor: improve browser property handling in loadModuleWithBase function

Revised the management of the `proc.browser` property to store the original value before modification, ensuring it is restored correctly after module loading. This enhances the reliability of the testing environment.

packages/data-provider/src/api-endpoints.ts

@@ -174,13 +174,20 @@ const LOGIN_PATH_RE = /(?:^|\/)login(?:\/|$)/;
 export function buildLoginRedirectUrl(pathname?: string, search?: string, hash?: string): string {
   const p = pathname ?? window.location.pathname;
   if (LOGIN_PATH_RE.test(p)) {
-    return `${BASE_URL}/login`;
+    return '/login';
   }
   const s = search ?? window.location.search;
   const h = hash ?? window.location.hash;
-  const currentPath = `${p}${s}${h}`;
-  const encoded = encodeURIComponent(currentPath || '/');
-  return `${BASE_URL}/login?${REDIRECT_PARAM}=${encoded}`;
+
+  const stripped =
+    BASE_URL && (p === BASE_URL || p.startsWith(BASE_URL + '/'))
+      ? p.slice(BASE_URL.length) || '/'
+      : p;
+  const currentPath = `${stripped}${s}${h}`;
+  if (!currentPath || currentPath === '/') {
+    return '/login';
+  }
+  return `/login?${REDIRECT_PARAM}=${encodeURIComponent(currentPath)}`;
 }
 
 export const resendVerificationEmail = () => `${BASE_URL}/api/user/verify/resend`;

packages/data-provider/src/request.ts

@@ -141,7 +141,7 @@ if (typeof window !== 'undefined') {
             return await axios(originalRequest);
           } else {
             processQueue(error, null);
-            window.location.href = endpoints.buildLoginRedirectUrl();
+            window.location.href = endpoints.apiBaseUrl() + endpoints.buildLoginRedirectUrl();
           }
         } catch (err) {
           processQueue(err as AxiosError, null);