What problem does this feature solve?

We can control which dependencies will track.

Consider this situation, we have filter options like

let filter = reactive({
 foo: 'a',
 bar:'b'
})

when filter change we will pull server data and update the list state. code like this

let filter = reactive({
 foo: 'a',
 bar:'b'
})
let list = ref([]);

watchEffect(async () => {
   let res = await  getDate(filter);

  // this will make watchEffect to track list change, so watchEffect  callback will infinite run.
  list = res;
})

I konw, we can use watch to make it work, but I think use watchEffect may more clear. so we can config which dependency wants track, like react useEffect.

watchEffect(async () => {
   let res = await  getDate(filter);

  // only track filter, so list update will not make wachtEffect loop run .
  list = res;
}, {
deps: [filter]
})

What does the proposed API look like?

watchEffect(cb, {
// which state you want track
deps: [ state1,state2, ... ]

})

Use a watch to explicitly define its dependencies, it's even clearer and shorter than the change you proposed with watchEffect