Adding the sandbox hooks to BTC

 All we need for short chain cash is hold until timeout protocol for new transactions.  Embedded in short chain cash is revert within timeout. And that is compatible with ledger swaps. 

There is no effect on old, nor any risk of lost coins that remain on main chain accounts.  This is a neutral functions added. The double spending risk is relative to short chain size., we should add less risk of that then we earn in miner fees by a long shot.

Short chain shards operate the same block chain protocol, they just collapse and revert the top account back to main chain, and pay off loose cash on the main chain. The main chain may itself be a shard, one account buying off a bunch of lower shards.

The real main chain, the single shard built from the top, is still there. The same miners run that and the short chain shards, the fees still  competitive. It is just that BTC becomes more widely used than any other payment system. It has managed to arrange the transaction queue to structured maximum entropy, earnings are as smooth as the liquidity miners make by sharding.   This is the most efficient and flexible form and naturally tends to a hedgeless trading pit between miners now invested in future service sales. A very wide market where the sharded block chain competes effectively against the automated S/L; and they intermingle.

Making block chain shards make for low risk S/L. Known time and space limits. The created shards offered up for loans.  Short term payday loans from familiar Swift accounts.  Do it as a cub, all the guys in the union join the shard account.  They are risk adjusted, the one an take a vacation and run up the loans, return to work. He is going to be here next year. This group i already risk adjusted, they just need to down load the contract to their  smart phone. No need for secure id, hey already have  union proven id cards.

Any local union has a local bank account. They can individually pay in and take out, wait, they already do that! The union can just create a Swift chard off a union funded account. Now the steps are: Down load app. Use union member id as account ID.  Put some portion of union account account reserve balance with an internal time and space agreement.  Not only are union members free to use automated short term credit but they are free to deposit in the shard Swift account. 

But the interface needs access via current terminal technology, so it needs to mimic the MasterCharge format, or shards need to market stable coins to vendors for a set up expense. Any other solution requires too many trips to Swift.