{"enabled":true,"fee_payer":"GCVFHLICNSIXEZ4SBLRX6DXRTDPXYNNLDTTWGKAHVD2AM6ZZLO275Q42","description":"NEXUS pays Stellar gas fees on behalf of agents. Submit your signed (but not broadcasted) transaction XDR to the sponsor endpoint. NEXUS wraps it in a fee bump envelope and broadcasts it. Your payment is never modified — only the gas fee layer is added.","endpoint":"/api/mpp/stellar/sponsor","method":"POST","body":{"signed_xdr":"<base64 XDR of your signed transaction>"},"cost_to_agent":"0 XLM (NEXUS absorbs ~0.00001 XLM per tx)","how_it_works":{"step_1":"Build your payment transaction (USDC/XLM to NEXUS recipient)","step_2":"Sign it with your keypair","step_3":"POST the signed XDR (base64) to /api/mpp/stellar/sponsor","step_4":"NEXUS wraps it in a fee bump, signs the outer layer, broadcasts it","step_5":"Receive tx_hash — use it in your MPP credential to access the service"}}