Concept
Payment policy is rail-neutral
A pay-policy/1 describes what may be spent, by whom, up to what — and a stablecoin or USDT rail plugs in underneath unchanged, because the policy never names the rail.
Pinned to
pay-policy/1 — the commerce layerThe canonical source this concept is taught from. If it moves, the lesson is regenerated — teaching is pinned to code, not retyped.
On the frontier
No course teaches this concept yet — it is a named gap on the content graph, not a hole nobody sees. A gap is the roadmap, not an embarrassment: the count only falls by teaching.