redirect to last known replica

typescript/packages/jumble/src/contexts/CharmManagerContext.tsx

@@ -17,28 +17,20 @@ export const CharmsManagerProvider: React.FC<{ children: React.ReactNode }> = (
   { children },
 ) => {
   const { replicaName } = useParams<{ replicaName: string }>();
-  const [effectiveReplica, setEffectiveReplica] = React.useState<string>(
-    () => localStorage.getItem("lastReplica") || "common-knowledge",
-  );
   const { user } = useAuthentication();
 
-  React.useEffect(() => {
+  const charmManager = useMemo(() => {
     console.log("CharmManagerProvider", replicaName);
 
     if (replicaName) {
-      // When a replica is provided in the URL, use it and save it as the last visited
-      setEffectiveReplica(replicaName);
       localStorage.setItem("lastReplica", replicaName);
     }
-  }, [replicaName]);
-
-  const charmManager = useMemo(() => {
-    return user ? new CharmManager(effectiveReplica, user) : null;
-  }, [effectiveReplica, user]);
+    return user && replicaName ? new CharmManager(replicaName, user) : null;
+  }, [replicaName, user]);
 
   return (
     <CharmManagerContext.Provider
-      value={{ charmManager, currentReplica: effectiveReplica }}
+      value={{ charmManager, currentReplica: replicaName || "" }}
     >
       {children}
     </CharmManagerContext.Provider>

typescript/packages/jumble/src/main.tsx

@@ -26,6 +26,11 @@ import SpellbookLaunchView from "./views/spellbook/SpellbookLaunchView.tsx";
 import { ActionManagerProvider } from "./contexts/ActionManagerContext.tsx";
 import { ROUTES } from "./routes.ts";
 
+const ReplicaRedirect = () => {
+  const savedReplica = localStorage.getItem("replica");
+  return <Navigate to={savedReplica || ROUTES.defaultReplica} replace />;
+};
+
 setupIframe();
 
 createRoot(document.getElementById("root")!).render(
@@ -37,10 +42,10 @@ createRoot(document.getElementById("root")!).render(
             <LanguageModelProvider>
               <Router>
                 <Routes>
-                  {/* Redirect root to common-knowledge */}
+                  {/* Redirect root to saved replica or default */}
                   <Route
                     path={ROUTES.root}
-                    element={<Navigate to={ROUTES.defaultReplica} replace />}
+                    element={<ReplicaRedirect />}
                   />
 
                   <Route