🎯 refactor: Centralize Agent Model Handling Across Conversation Lifecycle (#10956)

* refactor: Implement clearModelForNonEphemeralAgent utility for improved agent handling

- Introduced clearModelForNonEphemeralAgent function to manage model state for non-ephemeral agents across various components.
- Updated ModelSelectorContext to initialize model based on agent type.
- Enhanced useNavigateToConvo, useQueryParams, and useSelectMention hooks to clear model for non-ephemeral agents.
- Refactored buildDefaultConvo and endpoints utility to ensure proper handling of agent_id and model state.
- Improved overall conversation logic and state management for better performance and reliability.

* refactor: Enhance useNewConvo hook to improve agent conversation handling

- Added logic to skip access checks for existing agent conversations, utilizing localStorage to restore conversations after refresh.
- Improved handling of default endpoints for agents based on user access and existing conversation state, ensuring more reliable conversation initialization.

* refactor: Update ChatRoute and useAuthRedirect to include user roles

- Enhanced ChatRoute to utilize user roles for improved conversation state management.
- Modified useAuthRedirect to return user roles alongside authentication status, ensuring roles are available for conditional logic in ChatRoute.
- Adjusted conversation initialization logic to depend on the loaded roles, enhancing the reliability of the conversation setup.

* refactor: Update BaseClient to handle non-ephemeral agents in conversation logic

- Added a check for non-ephemeral agents in BaseClient, modifying the exceptions set to include 'model' when applicable.
- Enhanced conversation handling to improve flexibility based on agent type.

* test: Add mock for clearModelForNonEphemeralAgent in useQueryParams tests

- Introduced a mock for clearModelForNonEphemeralAgent to enhance testing of query parameters related to non-ephemeral agents.
- This addition supports improved test coverage and ensures proper handling of model state in relevant scenarios.

* refactor: Simplify mocks in useQueryParams tests for improved clarity

- Updated the mocking strategy for utilities in useQueryParams tests to use actual implementations where possible, while still suppressing test output for the logger.
- Enhanced the mock for tQueryParamsSchema to minimize complexity and avoid unnecessary validation during tests, improving test reliability and maintainability.

* refactor: Enhance agent identification logic in BaseClient for improved clarity

* chore: Import Constants in families.ts for enhanced functionality

client/src/hooks/useNewConvo.ts

@@ -24,6 +24,7 @@ import type {
 import type { AssistantListItem } from '~/common';
 import {
   updateLastSelectedModel,
+  getLocalStorageItems,
   getDefaultModelSpec,
   getDefaultEndpoint,
   getModelSpecPreset,
@@ -112,7 +113,21 @@ const useNewConvo = (index = 0) => {
           });
 
           // If the selected endpoint is agents but user doesn't have access, find an alternative
-          if (defaultEndpoint && isAgentsEndpoint(defaultEndpoint) && !hasAgentAccess) {
+          // Skip this check for existing agent conversations (they have agent_id set)
+          // Also check localStorage for new conversations restored after refresh
+          const { lastConversationSetup } = getLocalStorageItems();
+          const storedAgentId =
+            isAgentsEndpoint(lastConversationSetup?.endpoint) && lastConversationSetup?.agent_id;
+          const isExistingAgentConvo =
+            isAgentsEndpoint(defaultEndpoint) &&
+            ((conversation.agent_id && conversation.agent_id !== Constants.EPHEMERAL_AGENT_ID) ||
+              (storedAgentId && storedAgentId !== Constants.EPHEMERAL_AGENT_ID));
+          if (
+            defaultEndpoint &&
+            isAgentsEndpoint(defaultEndpoint) &&
+            !hasAgentAccess &&
+            !isExistingAgentConvo
+          ) {
             defaultEndpoint = Object.keys(endpointsConfig ?? {}).find(
               (ep) => !isAgentsEndpoint(ep as EModelEndpoint) && endpointsConfig?.[ep],
             ) as EModelEndpoint | undefined;
@@ -121,7 +136,11 @@ const useNewConvo = (index = 0) => {
           if (!defaultEndpoint) {
             // Find first available endpoint that's not agents (if no access) or any endpoint
             defaultEndpoint = Object.keys(endpointsConfig ?? {}).find((ep) => {
-              if (isAgentsEndpoint(ep as EModelEndpoint) && !hasAgentAccess) {
+              if (
+                isAgentsEndpoint(ep as EModelEndpoint) &&
+                !hasAgentAccess &&
+                !isExistingAgentConvo
+              ) {
                 return false;
               }
               return !!endpointsConfig?.[ep];