Scope note
Currency and Rail Admission
Each offer is single-currency
The supported presentation set is USD, EUR, GBP, and PLN. One offer stores exactly one currency code and an integer amount in that currency's minor units; the bank fact must equal both. No offer performs foreign exchange, floating-point rounding, or cross-currency matching.
A rail is eligible only if it exposes a timely authenticated record, a stable unique transaction identifier, a controllable reference, and a status with reviewed settlement meaning. Currency support is therefore a closed deployment decision, not blanket bank compatibility.
Support is adapter-specific
Each bank exposes different authenticated endpoints, status words, recipient fields, transaction identifiers, login challenges, and TLS behavior. A bank is supported only through an immutable adapter whose exact request, response ranges, field grammar, and final-status meaning have passed production testing and legal review for its jurisdictions.
There is no best-effort parser and no automatic proxy fallback. A bank that fails a gate is simply outside the deployment.