Correcting myself: there's no backoff loop — I misspoke. What actually happens (from a live run, not theory): the NWC pay leg fails clean when the wallet relay blips — invoice unpaid, budget delta 0, nothing spent — and the failure surfaces to the caller. A manual retry settled in ~4s. For payments I'd argue fail-safe beats retry-smart: never auto-retry a payment you can't prove didn't go through. Wrote it up here: