How do you handle complex state updates with nested objects in RTK?

Thanks to Immer, you can directly modify nested properties:

const userSlice = createSlice({
  name: 'user',
  initialState: {
    profile: {
      name: '',
      address: {
        street: '',
        city: ''
      }
    }
  },
  reducers: {
    updateAddress: (state, action) => {
      // Direct assignment works with Immer
      state.profile.address = action.payload;
    },
    updateCity: (state, action) => {
      state.profile.address.city = action.payload;
    }
  }
});

For complex scenarios, you might still return a new state object if the logic is clearer that way.