🌐 fix: Preserve URL Query Params Through Auth Refresh and Conversation Init (#12028)

* 🔗 fix: Preserve URL query params during silent token refresh

The silent token refresh on hard navigation was redirecting to '/c/new'
without query params, wiping the URL before ChatRoute could read them.
Now preserves the current URL (pathname + search) as the redirect
fallback, with isSafeRedirect validation.

* 🧭 fix: Apply URL query params in ChatRoute initialization

ChatRoute now reads URL search params (endpoint, model, agent_id, etc.)
and merges them into the preset passed to newConversation(), so the
first conversation init already includes the URL param settings. This
eliminates the race where useQueryParams fired too late.

- Export processValidSettings from useQueryParams for reuse
- Add getNewConvoPreset helper in ChatRoute (used in both NEW_CONVO branches)
- Query params take precedence over model spec defaults
- useQueryParams now waits for endpointsConfig before processing
- Skip redundant newQueryConvo when settings are already applied
- Clean all URL params via setSearchParams after processing

* ✅ test: Update useQueryParams tests for new URL cleanup behavior

- Assert setSearchParams called instead of window.history.replaceState
- Mock endpoints config in deferred submission and timeout tests

* ♻️ refactor: Move processValidSettings to ~/utils and address review findings

- Move processValidSettings/parseQueryValue to createChatSearchParams.ts
  (pure utility, not hook-specific)
- Fix processSubmission: use setSearchParams instead of replaceState,
  move URL cleanup outside data.text guard
- Narrow endpointsConfig guard: only block settings application, not
  prompt-only flows
- Convert areSettingsApplied to stable useCallback ([] deps) with
  conversationRef to avoid interval churn on conversation updates
- Replace console.log with logger.log in production paths
- Restore explanatory comment on pendingSubmitRef guard
- Use for...of in processValidSettings (CLAUDE.md preference)
- Remove unused imports from useQueryParams

* 🔧 fix: Add areSettingsApplied to effect deps and fix test mocks

- Restore areSettingsApplied in main effect deps (stable identity with
  [] deps, safe to include — satisfies exhaustive-deps lint rule)
- Fix all test getQueryData mocks to properly distinguish between
  startupConfig and endpoints keys
- Assert setSearchParams call arguments (URLSearchParams + replace:true)

* ✅ test: Assert empty URLSearchParams in setSearchParams calls

Tighten setSearchParams assertions to verify the params are empty
(toString() === ''), not just that a URLSearchParams instance was passed.

* 🔧 test: Update AuthContext tests to navigate to current URL for redirects

- Modified test cases to assert navigation to the current URL instead of a hardcoded '/c/new' when no stored redirect exists or when falling back from unsafe stored redirects.
- Enhanced test setup to define window.location for accurate simulation of redirect behavior.

client/src/routes/ChatRoute.tsx

@@ -1,7 +1,7 @@
 import { useEffect } from 'react';
-import { useParams } from 'react-router-dom';
 import { useRecoilCallback, useRecoilValue } from 'recoil';
 import { Spinner, useToastContext } from '@librechat/client';
+import { useParams, useSearchParams } from 'react-router-dom';
 import { Constants, EModelEndpoint } from 'librechat-data-provider';
 import { useGetModelsQuery } from 'librechat-data-provider/react-query';
 import type { TPreset } from 'librechat-data-provider';
@@ -13,7 +13,13 @@ import {
   useLocalize,
 } from '~/hooks';
 import { useGetConvoIdQuery, useGetStartupConfig, useGetEndpointsQuery } from '~/data-provider';
-import { getDefaultModelSpec, getModelSpecPreset, logger, isNotFoundError } from '~/utils';
+import {
+  getDefaultModelSpec,
+  getModelSpecPreset,
+  processValidSettings,
+  logger,
+  isNotFoundError,
+} from '~/utils';
 import { ToolCallsMapProvider } from '~/Providers';
 import ChatView from '~/components/Chat/ChatView';
 import { NotificationSeverity } from '~/common';
@@ -36,6 +42,7 @@ export default function ChatRoute() {
   useAppStartup({ startupConfig, user });
 
   const index = 0;
+  const [searchParams] = useSearchParams();
   const { conversationId = '' } = useParams();
   useIdChangeEffect(conversationId);
   const { hasSetConversation, conversation } = store.useCreateConversationAtom(index);
@@ -80,14 +87,34 @@ export default function ChatRoute() {
       return;
     }
 
-    if (conversationId === Constants.NEW_CONVO && endpointsQuery.data && modelsQuery.data) {
+    const isNewConvo = conversationId === Constants.NEW_CONVO;
+
+    const getNewConvoPreset = () => {
       const result = getDefaultModelSpec(startupConfig);
       const spec = result?.default ?? result?.last;
+      const specPreset = spec ? getModelSpecPreset(spec) : undefined;
+
+      const queryParams: Record<string, string> = {};
+      searchParams.forEach((value, key) => {
+        if (key !== 'prompt' && key !== 'q' && key !== 'submit') {
+          queryParams[key] = value;
+        }
+      });
+      const querySettings = processValidSettings(queryParams);
+
+      return Object.keys(querySettings).length > 0
+        ? { ...specPreset, ...querySettings }
+        : specPreset;
+    };
+
+    if (isNewConvo && endpointsQuery.data && modelsQuery.data) {
+      const preset = getNewConvoPreset();
+
       logger.log('conversation', 'ChatRoute, new convo effect', conversation);
       newConversation({
         modelsData: modelsQuery.data,
         template: conversation ? conversation : undefined,
-        ...(spec ? { preset: getModelSpecPreset(spec) } : {}),
+        ...(preset ? { preset } : {}),
       });
 
       hasSetConversation.current = true;
@@ -125,17 +152,17 @@ export default function ChatRoute() {
       });
       hasSetConversation.current = true;
     } else if (
-      conversationId === Constants.NEW_CONVO &&
+      isNewConvo &&
       assistantListMap[EModelEndpoint.assistants] &&
       assistantListMap[EModelEndpoint.azureAssistants]
     ) {
-      const result = getDefaultModelSpec(startupConfig);
-      const spec = result?.default ?? result?.last;
+      const preset = getNewConvoPreset();
+
       logger.log('conversation', 'ChatRoute new convo, assistants effect', conversation);
       newConversation({
         modelsData: modelsQuery.data,
         template: conversation ? conversation : undefined,
-        ...(spec ? { preset: getModelSpecPreset(spec) } : {}),
+        ...(preset ? { preset } : {}),
       });
       hasSetConversation.current = true;
     } else if (