refactor: centralize frontend auth query gating

src/shared/api/client.ts

@@ -12,9 +12,27 @@ type AuthHandlers = {
 };
 
 let auth: AuthHandlers | null = null;
+let hasAuthenticatedSession = false;
+const authSessionListeners = new Set<() => void>();
+
+function setAuthenticatedSession(next: boolean) {
+	if (next === hasAuthenticatedSession) return;
+	hasAuthenticatedSession = next;
+	for (const listener of authSessionListeners) listener();
+}
 
 export function configureAuthClient(handlers: AuthHandlers | null) {
 	auth = handlers;
+	setAuthenticatedSession(Boolean(auth?.accessToken()));
+}
+
+export function getAuthenticatedSessionSnapshot() {
+	return hasAuthenticatedSession;
+}
+
+export function subscribeAuthenticatedSession(listener: () => void) {
+	authSessionListeners.add(listener);
+	return () => authSessionListeners.delete(listener);
 }
 
 async function authenticatedFetch(request: Request): Promise<Response> {