Top-level /generative/** endpoints. Authorize with your
project's identity-token of the central
incore store (Settings › Plan › Credits) — the
store header and a store access-token are
not used here. Every call is metered and logged against
incore: credits debit
promo/incore/credits/{customer}, the identity's customer.
Only a master access-token works without an identity (and
bypasses metering).