Wow, that was a great review, thanks! I agree with most points. There are definitely improvements to be made. This is the first version, I wanted to get it out

Wow, that was a great review, thanks! I agree with most points. There are definitely improvements to be made. This is the first version, I wanted to get it out and start getting feedback sooner. This is my take on each point: For some reason Dynamodb was not sorting the partition with KSUIDs string, so I added the LSI. This is probably something I did wrong and is just matter of fixing the query or the insert and move back to using the PK. Adding more than one balanced transaction per request is on the roadmap, but this will be limited to the DynamoDB transactions API limit of 25 items as you mentioned (25 / 2*2 WCU per tx = 6 transactions per request). Each entry only uses 4 items in the worst case (seeding a new currency in an account). In most cases (existing balances/currencies), there will be only 2 new items. I think even more improvements can be made. And the goal of open-sourcing is to get more heads thinking about how we can do it :)