What Infra is
The short version.
Infra is the part of QUAD that remembers things — a place to store files and data and get back proof it actually happened. You pay for the work with a token called BIGHT, and every job leaves a receipt you can check later.
The loop is simple: buy BIGHT, upload your work, pay the quoted price, keep the receipt. When you want the file back you retrieve it; when you need to prove it was stored, you verify the receipt.