fix: stabilize model selection across session boundaries

src/components/chat/ChatView.tsx

@@ -122,6 +122,9 @@ export function ChatView({ sessionId, initialMessages = [], initialHasMore = fal
   const handleProviderModelChange = useCallback((newProviderId: string, model: string) => {
     setCurrentProviderId(newProviderId);
     setCurrentModel(model);
+    // Persist to localStorage so new chats inherit the latest selection
+    localStorage.setItem('codepilot:last-model', model);
+    localStorage.setItem('codepilot:last-provider-id', newProviderId);
     fetch(`/api/chat/sessions/${sessionId}`, {
       method: 'PATCH',
       headers: { 'Content-Type': 'application/json' },

src/components/chat/MessageInput.tsx

@@ -81,17 +81,19 @@ export function MessageInput({
 
   // --- Extracted hooks ---
   const popover = usePopoverState(modelName);
-  const { providerGroups, currentProviderIdValue, modelOptions, currentModelOption } = useProviderModels(providerId, modelName);
+  const { providerGroups, currentProviderIdValue, modelOptions, currentModelOption, loaded: modelsLoaded } = useProviderModels(providerId, modelName);
 
   // Auto-correct model when it doesn't exist in the current provider's model list.
   // This prevents sending an unsupported model name (e.g. 'opus' to MiniMax which only has 'sonnet').
+  // Gate on `modelsLoaded` to avoid premature correction before the provider models API responds.
   useEffect(() => {
+    if (!modelsLoaded) return;
     if (modelName && modelOptions.length > 0 && !modelOptions.some(m => m.value === modelName)) {
       const fallback = modelOptions[0].value;
       onModelChange?.(fallback);
       onProviderModelChange?.(currentProviderIdValue, fallback);
     }
-  }, [modelName, modelOptions, currentProviderIdValue, onModelChange, onProviderModelChange]);
+  }, [modelsLoaded, modelName, modelOptions, currentProviderIdValue, onModelChange, onProviderModelChange]);
 
   const { badge, setBadge, cliBadge, setCliBadge, removeBadge, removeCliBadge, hasBadge } = useCommandBadge(textareaRef);
 

src/hooks/useProviderModels.ts

@@ -13,6 +13,8 @@ export interface UseProviderModelsReturn {
   currentProviderIdValue: string;
   modelOptions: typeof DEFAULT_MODEL_OPTIONS;
   currentModelOption: (typeof DEFAULT_MODEL_OPTIONS)[number];
+  /** True once the initial fetch has completed (success or error). */
+  loaded: boolean;
 }
 
 export function useProviderModels(
@@ -21,6 +23,7 @@ export function useProviderModels(
 ): UseProviderModelsReturn {
   const [providerGroups, setProviderGroups] = useState<ProviderModelGroup[]>([]);
   const [defaultProviderId, setDefaultProviderId] = useState<string>('');
+  const [loaded, setLoaded] = useState(false);
 
   const fetchProviderModels = useCallback(() => {
     fetch('/api/providers/models')
@@ -46,6 +49,9 @@ export function useProviderModels(
           models: DEFAULT_MODEL_OPTIONS,
         }]);
         setDefaultProviderId('');
+      })
+      .finally(() => {
+        setLoaded(true);
       });
   }, []);
 
@@ -75,5 +81,6 @@ export function useProviderModels(
     currentProviderIdValue,
     modelOptions,
     currentModelOption,
+    loaded,
   };
 }