What is here
Quickstart
An API key to a registered customer in two signed requests, with the signing string built line by line.
Concepts
The six pages that define the model: tenants, customers, XP and the ledger, tiers, rewards and redemptions, and on-chain XP.
API reference
Both API surfaces, each labelled with who calls it and what credential it takes, plus a signed sample on every gateway operation.
Request conventions
The error envelope and the codes to branch on, the idempotency header a write needs, and what a rate limit looks like.

