I did, it is the essence of my question. A tokenizer from the tokenizer repo will generate tokenizer.json and merges.txt while a tokenizer from the transformers repo will require different files. In particular, the decode function is roughly implemented in the following way in transformers.BertTokenizer:
def decode(self, ids):
    return " ".join([self.vocab[token_id] for token_id in ids]).replace("##", "")

In tokenizer’s repo, the process is entirely different, using merges.txt to decide what should be merged and vocab as a lookup table.
My question being: How can I convert one to the other?