Download the transaction receipt PDF

Streams the receipt document for a transaction — the "Download PDF" action on the receipt tab. For wire transfers this is the uploaded SWIFT/EFT receipt file (e.g. swift-receipt-9f31ad.pdf); for card/credit/refund entries it is the system-generated receipt for the ledger entry ({reference}.pdf). The response is the binary file itself, not JSON; no resource state changes. Validation: scope and transaction must exist and be visible to the caller (else NOT_FOUND); a receipt document must exist for the entry — entries without any generated or uploaded receipt map to NOT_FOUND; caller needs reader-or-higher or billing role, otherwise FORBIDDEN. Async & state: Synchronous read; no state change. The stream returns Content-Disposition: attachment with the receipt file name. Errors: 401 unauthenticated; 403 caller lacks billing read permission in the scope; 404 unknown scope/transaction or no receipt available for this entry; 429 bulk download bursts rate-limited; 500 object-store read failure. Idempotency/Concurrency: Safe, cacheable; no idempotency key required. Repeated downloads return the identical artifact for an unchanged receipt (strong ETag on the file content).