User A send a transaction to user B. Those transactions are bundled together into a merkle tree. User A and B can both use the transaction plus the merkle root, plus the merkle path to prove the merkle root in the block header is correct.
I understand all that.. what I don’t understand is how do A and B know the correct merkle path without needing the entire block?
Do they need a centralized provider that processes the blocks to calculate these for them? Is it possible to do in a decentralized way?