🌐 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/utils/createChatSearchParams.ts

@@ -1,11 +1,65 @@
 import {
+  EModelEndpoint,
   isAgentsEndpoint,
   tQueryParamsSchema,
   isAssistantsEndpoint,
 } from 'librechat-data-provider';
-import type { TConversation, TPreset } from 'librechat-data-provider';
+import type { TPreset, TConversation } from 'librechat-data-provider';
+import type { ZodAny } from 'zod';
 import { isEphemeralAgent } from '~/common';
 
+const parseQueryValue = (value: string) => {
+  if (value === 'true') {
+    return true;
+  }
+  if (value === 'false') {
+    return false;
+  }
+  if (!isNaN(Number(value))) {
+    return Number(value);
+  }
+  return value;
+};
+
+/**
+ * Processes and validates URL query parameters using schema definitions.
+ * Extracts valid settings based on tQueryParamsSchema and handles special endpoint cases
+ * for assistants and agents.
+ */
+export function processValidSettings(queryParams: Record<string, string>) {
+  const validSettings = {} as TPreset;
+
+  for (const [key, value] of Object.entries(queryParams)) {
+    try {
+      const schema = tQueryParamsSchema.shape[key] as ZodAny | undefined;
+      if (schema) {
+        const parsedValue = parseQueryValue(value);
+        const validValue = schema.parse(parsedValue);
+        validSettings[key] = validValue;
+      }
+    } catch (error) {
+      console.warn(`Invalid value for setting ${key}:`, error);
+    }
+  }
+
+  if (
+    validSettings.assistant_id != null &&
+    validSettings.assistant_id &&
+    !isAssistantsEndpoint(validSettings.endpoint)
+  ) {
+    validSettings.endpoint = EModelEndpoint.assistants;
+  }
+  if (
+    validSettings.agent_id != null &&
+    validSettings.agent_id &&
+    !isAgentsEndpoint(validSettings.endpoint)
+  ) {
+    validSettings.endpoint = EModelEndpoint.agents;
+  }
+
+  return validSettings;
+}
+
 const allowedParams = Object.keys(tQueryParamsSchema.shape);
 export default function createChatSearchParams(
   input: TConversation | TPreset | Record<string, string> | null,

client/src/utils/index.ts

@@ -34,7 +34,7 @@ export { default as getLoginError } from './getLoginError';
 export { default as cleanupPreset } from './cleanupPreset';
 export { default as buildDefaultConvo } from './buildDefaultConvo';
 export { default as getDefaultEndpoint } from './getDefaultEndpoint';
-export { default as createChatSearchParams } from './createChatSearchParams';
+export { default as createChatSearchParams, processValidSettings } from './createChatSearchParams';
 export { getThemeFromEnv } from './getThemeFromEnv';
 
 export const languages = [