📌 feat: memorize agent/model selection and use from last choice

client/src/hooks/useNewConvo.ts

@@ -297,8 +297,42 @@ const useNewConvo = (index = 0) => {
 
       let preset = _preset;
       const result = getDefaultModelSpec(startupConfig);
-      const defaultModelSpec = result?.default ?? result?.last;
-      if (
+
+      // Prefer last used spec over default spec for better user experience
+      const defaultModelSpec = result?.last ?? result?.default;
+
+      // Check for last used agent_id that might be outside of modelSpecs
+      const lastAgentId = localStorage.getItem(`${LocalStorageKeys.AGENT_ID_PREFIX}${index}`);
+
+      // Get the last conversation setup to determine what was most recently selected
+      // This is the most reliable way to know if a custom agent was selected after a modelSpec
+      const lastConvoSetup = JSON.parse(
+        localStorage.getItem(`${LocalStorageKeys.LAST_CONVO_SETUP}_${index}`) ?? '{}',
+      );
+      const lastConvoAgentId = lastConvoSetup?.agent_id;
+      const lastConvoSpec = lastConvoSetup?.spec;
+
+      // Use lastAgentId if:
+      // 1. No preset passed AND no template AND lastAgentId exists
+      // 2. AND the last conversation had this agent_id without a spec (custom agent selection)
+      //    OR there's no defaultModelSpec at all
+      // This ensures:
+      // - Custom agent selection (no spec) is remembered
+      // - ModelSpec selections (has spec) take priority when they were the last action
+      const shouldUseLastAgent =
+        !_preset &&
+        lastAgentId &&
+        Object.keys(_template).length === 0 &&
+        ((!lastConvoSpec && lastConvoAgentId === lastAgentId) || !defaultModelSpec);
+
+      if (shouldUseLastAgent) {
+        // Create a preset for the last used agent outside of modelSpecs
+        preset = {
+          endpoint: EModelEndpoint.agents,
+          agent_id: lastAgentId,
+        };
+        logger.log('conversation', 'Using last used agent_id outside modelSpecs', lastAgentId);
+      } else if (
         !preset &&
         startupConfig &&
         (startupConfig.modelSpecs?.prioritize === true ||
@@ -352,6 +386,7 @@ const useNewConvo = (index = 0) => {
       );
     },
     [
+      index,
       files,
       setFiles,
       saveDrafts,

client/src/routes/ChatRoute.tsx

@@ -7,7 +7,7 @@ import { useGetModelsQuery } from 'librechat-data-provider/react-query';
 import type { TPreset } from 'librechat-data-provider';
 import { useGetConvoIdQuery, useGetStartupConfig, useGetEndpointsQuery } from '~/data-provider';
 import { useNewConvo, useAppStartup, useAssistantListMap, useIdChangeEffect } from '~/hooks';
-import { getDefaultModelSpec, getModelSpecPreset, logger } from '~/utils';
+import { logger } from '~/utils';
 import { ToolCallsMapProvider } from '~/Providers';
 import ChatView from '~/components/Chat/ChatView';
 import useAuthRedirect from './useAuthRedirect';
@@ -72,13 +72,12 @@ export default function ChatRoute() {
     }
 
     if (conversationId === Constants.NEW_CONVO && endpointsQuery.data && modelsQuery.data) {
-      const result = getDefaultModelSpec(startupConfig);
-      const spec = result?.default ?? result?.last;
+      // Let useNewConvo handle the full logic for determining the preset
+      // (including last used agent_id that might be outside of modelSpecs)
       logger.log('conversation', 'ChatRoute, new convo effect', conversation);
       newConversation({
         modelsData: modelsQuery.data,
         template: conversation ? conversation : undefined,
-        ...(spec ? { preset: getModelSpecPreset(spec) } : {}),
       });
 
       hasSetConversation.current = true;
@@ -97,13 +96,12 @@ export default function ChatRoute() {
       assistantListMap[EModelEndpoint.assistants] &&
       assistantListMap[EModelEndpoint.azureAssistants]
     ) {
-      const result = getDefaultModelSpec(startupConfig);
-      const spec = result?.default ?? result?.last;
+      // Let useNewConvo handle the full logic for determining the preset
+      // (including last used agent_id that might be outside of modelSpecs)
       logger.log('conversation', 'ChatRoute new convo, assistants effect', conversation);
       newConversation({
         modelsData: modelsQuery.data,
         template: conversation ? conversation : undefined,
-        ...(spec ? { preset: getModelSpecPreset(spec) } : {}),
       });
       hasSetConversation.current = true;
     } else if (

client/src/utils/endpoints.ts

@@ -229,8 +229,8 @@ export function applyModelSpecEphemeralAgent({
 
 /**
  * Gets default model spec from config and user preferences.
- * Priority: admin default → last selected → first spec (when prioritize=true or modelSelect disabled).
- * Otherwise: admin default or last conversation spec.
+ * Returns both admin default and last selected spec when available.
+ * Priority for usage: last selected → admin default → first spec (when prioritize=true or modelSelect disabled).
  */
 export function getDefaultModelSpec(startupConfig?: t.TStartupConfig):
   | {
@@ -244,20 +244,30 @@ export function getDefaultModelSpec(startupConfig?: t.TStartupConfig):
     return;
   }
   const defaultSpec = list?.find((spec) => spec.default);
-  if (prioritize === true || !interfaceConfig?.modelSelect) {
-    const lastSelectedSpecName = localStorage.getItem(LocalStorageKeys.LAST_SPEC);
-    const lastSelectedSpec = list?.find((spec) => spec.name === lastSelectedSpecName);
-    return { default: defaultSpec || lastSelectedSpec || list?.[0] };
-  } else if (defaultSpec) {
-    return { default: defaultSpec };
+
+  // Try to get last selected spec from localStorage
+  const lastSelectedSpecName = localStorage.getItem(LocalStorageKeys.LAST_SPEC);
+  let lastSelectedSpec = lastSelectedSpecName
+    ? list?.find((spec) => spec.name === lastSelectedSpecName)
+    : undefined;
+
+  // Fallback: try to get spec from last conversation setup
+  if (!lastSelectedSpec) {
+    const lastConversationSetup = JSON.parse(
+      localStorage.getItem(LocalStorageKeys.LAST_CONVO_SETUP + '_0') ?? '{}',
+    );
+    if (lastConversationSetup.spec) {
+      lastSelectedSpec = list?.find((spec) => spec.name === lastConversationSetup.spec);
+    }
   }
-  const lastConversationSetup = JSON.parse(
-    localStorage.getItem(LocalStorageKeys.LAST_CONVO_SETUP + '_0') ?? '{}',
-  );
-  if (!lastConversationSetup.spec) {
-    return;
+
+  if (prioritize === true || !interfaceConfig?.modelSelect) {
+    // When prioritize is true or modelSelect is disabled, return the effective spec as default
+    return { default: lastSelectedSpec || defaultSpec || list?.[0], last: lastSelectedSpec };
   }
-  return { last: list?.find((spec) => spec.name === lastConversationSetup.spec) };
+
+  // Return both default and last, allowing consumer to choose priority
+  return { default: defaultSpec, last: lastSelectedSpec };
 }
 
 export function getModelSpecPreset(modelSpec?: t.TModelSpec) {