How it works
In the made-up town of Pennywell, Tess's card came with a limit of twenty coins. A limit is the most the bank lets her owe at one time. It is a ceiling, a top, not a goal.
Owing is not owning. When the bank pays the shop, Tess owes the bank, and every coin used is paid back.
Room is what is left under the limit. Room works like a cushion that catches surprises, like a flat tire.
The bank sets the top, but how far to go is the borrower's own choice, every time.