I've been using jotai to manage the global state for my recent (and ongoing) refactor of Offworld. I kind of love jotai's simple and composable building blocks. I haven't used svelte yet, but if I recall from reading the docs correctly, it is somewhat similar to the svelte/store.

Here is a little example for creating a getter and setter (which is an async function using another function to find a user). The setter takes up to 3 arguments: a get function (for reading atoms within your setter callback), a set function (for actually changing state), and a value which is passed when the setter is called. In this example, the setter is called without any arguments so we leave out the value argument.

const userAtomPrimitive = atom(undefined);
export const userAtom = atom(
  (get) => get(userAtomPrimitive),
  async (_, set) => {
    const user = await findUser();
  
    set(userAtomPrimitive, user);
  } 
);