We model the interaction between three services a platform provides: matching in the goods market, token money creation, and credit extension. The platform designs interoperability to restrict competition with the public marketplace and possible platform entrants. We identify three forms of relevant interoperability: exchangeability, acceptability, and ledger portability.
Limiting exchangeability of tokens ``locks-in'' customers and discourages platform entry.
Limiting which currency sellers can accept improves the platform's ability to enforce ``smart'' credit contracts. Improving ledger portability makes entrant threats less credible. A legal tender CBDC does not necessarily give policy makers the optimal trade-off between regulating the different forms of interoperability.