Background revalidate provider models when model selector opens

On fresh startup the initial provider snapshot request can return
before providers finish loading, leaving the model picker empty.
The server broadcasts updates once providers are ready, but if the
user opens the picker in the interim they see "No models match".

Invalidate the React Query cache (background refetch, no loading
flash) every time the model selector popup opens so stale data is
silently refreshed.

packages/app/src/hooks/use-agent-form-state.ts

@@ -93,6 +93,7 @@ type UseAgentFormStateResult = {
   isModelLoading: boolean;
   modelError: string | null;
   refreshProviderModels: () => void;
+  invalidateProviderModels: () => void;
   setProviderAndModelFromUser: (provider: AgentProvider, modelId: string) => void;
   workingDirIsEmpty: boolean;
   persistFormPreferences: () => Promise<void>;
@@ -375,6 +376,7 @@ export function useAgentFormState(options: UseAgentFormStateOptions = {}): UseAg
     isFetching: snapshotIsFetching,
     error: snapshotError,
     refresh: refreshSnapshot,
+    invalidate: invalidateSnapshot,
   } = useProvidersSnapshot(formState.serverId);
 
   const allProviderEntries = useMemo(() => snapshotEntries ?? [], [snapshotEntries]);
@@ -648,6 +650,10 @@ export function useAgentFormState(options: UseAgentFormStateOptions = {}): UseAg
     refreshSnapshot();
   }, [refreshSnapshot]);
 
+  const invalidateProviderModels = useCallback(() => {
+    invalidateSnapshot();
+  }, [invalidateSnapshot]);
+
   const persistFormPreferences = useCallback(async () => {
     const resolvedModel = resolveEffectiveModel(availableModels, formState.model);
     const modelId = resolvedModel?.id ?? formState.model;
@@ -714,6 +720,7 @@ export function useAgentFormState(options: UseAgentFormStateOptions = {}): UseAg
       isModelLoading,
       modelError,
       refreshProviderModels,
+      invalidateProviderModels,
       setProviderAndModelFromUser,
       workingDirIsEmpty,
       persistFormPreferences,
@@ -745,6 +752,7 @@ export function useAgentFormState(options: UseAgentFormStateOptions = {}): UseAg
       isModelLoading,
       modelError,
       refreshProviderModels,
+      invalidateProviderModels,
       setProviderAndModelFromUser,
       workingDirIsEmpty,
       persistFormPreferences,

packages/app/src/hooks/use-providers-snapshot.ts

@@ -17,6 +17,7 @@ interface UseProvidersSnapshotResult {
   error: string | null;
   supportsSnapshot: boolean;
   refresh: () => void;
+  invalidate: () => void;
 }
 
 export function useProvidersSnapshot(serverId: string | null): UseProvidersSnapshotResult {
@@ -66,6 +67,10 @@ export function useProvidersSnapshot(serverId: string | null): UseProvidersSnaps
     void client.refreshProvidersSnapshot();
   }, [client]);
 
+  const invalidate = useCallback(() => {
+    void queryClient.invalidateQueries({ queryKey });
+  }, [queryClient, queryKey]);
+
   return {
     entries: snapshotQuery.data?.entries ?? undefined,
     isLoading: snapshotQuery.isLoading,
@@ -73,6 +78,7 @@ export function useProvidersSnapshot(serverId: string | null): UseProvidersSnaps
     error: snapshotQuery.error instanceof Error ? snapshotQuery.error.message : null,
     supportsSnapshot,
     refresh,
+    invalidate,
   };
 }