Pillar 3, reframed around the operator's BTCPay infra. The game no longer
implements per-chain wallet/daemon code directly; it talks to pluggable
payment providers behind one contract (createInvoice/getInvoiceStatus/
startWatch/sendPayout/validateAddress/supportsChain).
- paymentProvider.js: PaymentProvider base + PaymentProviderRegistry with
operator-configurable chain->provider routing and support-based fallback.
- btcpayProvider.js: first plugin. BTCPay Greenfield API client covering all
five Smirk chains (BTC/LTC native, XMR via xmrcheckout, WOW via wowcheckout,
GRIN via the in-house plugin). Invoice priced in the chain's own crypto;
address read from the invoice payment-methods. Injectable fetch for tests.
- nativeMoneroProvider.js: second plugin. Wraps the existing walletRPCService
(subaddress invoicing + transfer_split payouts) so our own XMR/WOW stack is
just another routable option. Behavior-preserving delegation.
- paymentProviders_ultra.test.js: registry routing/fallback, BTCPay invoice+
status mapping with mock fetch, native provider delegation. 6 tests.
Not yet wired into the live payment flow (env config + registry bootstrap is
the next step). Suite 51 suites / 356 tests green.