Hello,
What is the officially supported method to delay capture a transaction that uses the Square Reader for payment? I have seen some discussion about deprecated Transaction APIs, and want to make sure as we start to implement that we use an approach that will not be deprecated soon.
Thank you
Currently, with Reader SDK the only way to enable delay capture is to use the deprecated Transactions API. This API will eventually be retired but not until a replacement is made available and ample time has passed for migration. 
if i delay capture with reader sdk, what’s the state of created order?
could i update order with items by response transaction id , and then catpure the transaction?
Updating Reader SDK orders isn’t currently available. Once an order is paid for additional items can’t be added or removed from the order. Even if that order is in an AUTHORIZED state. 