Police and prisons are institutions of state power and thus must be kept in the transition towards communism.

Not necessarily, especially not at their current scale.

Police have no reason to be involved in most small-scale situations and could be largely replaced by “neighbourhood watch” groups – whether they’re called “police” or something else, the main point is that they’d live in the area and would actually have to be accountable to the people there (which would also mean that the people would be able to collectively remove them from their position).

Prisons should be “abolished” in the sense that the goal of imprisonment should be rehabilitation rather than punishment (and slave labour, in Amerika’s case).

This can all happen during socialism, although the implementations obviously wouldn’t be ideal as long as a foreign imperialist threat remains