How do you build your service layer first but your APIs last? Aren't APIs part of the service layer? The interesting thing about DynamoDB single-table design th

How do you build your service layer first but your APIs last? Aren't APIs part of the service layer? The interesting thing about DynamoDB single-table design that I'm really starting to like is it forces you to start with API calls. I literally start with an excel spreadsheet of API declarations and corresponding HASH/SORT keys.