feat(cast): add --sponsor-url for remote Tempo fee payer sponsorship#14790
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decofe wants to merge 9 commits into
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feat(cast): add --sponsor-url for remote Tempo fee payer sponsorship#14790decofe wants to merge 9 commits into
decofe wants to merge 9 commits into
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Adds --sponsor-url (alias --tempo.sponsor-url) to cast send. When set, the transaction is signed locally and forwarded to the remote sponsor service via eth_sendRawTransaction. The service adds its fee payer signature and broadcasts the sponsored transaction. Usage: cast send 0x... --sponsor-url https://sponsor.tempo.xyz/tp_abc123 This works with the existing fee-payer service in tempo-apps without any changes — no new RPC methods required. The sponsor URL can also be set via TEMPO_SPONSOR_URL env var. Amp-Thread-ID: https://ampcode.com/threads/T-019e2d8c-7750-71a5-924c-2394c0c4e070
…nsor_url - Use eth_signRawTransaction to get the sponsored tx from the service, then submit via the regular RPC's send_raw_transaction. This matches the viem withFeePayer sign-only protocol. - Clone sponsor_url instead of take() so it's still present when TempoOpts::apply() runs, ensuring nonce_key=0 is set and the tx builds as a Tempo AA (0x76) type instead of EIP-1559 (0x02). - Handle sponsor service error responses that have name/code but no message field. Amp-Thread-ID: https://ampcode.com/threads/T-019e2d8c-7750-71a5-924c-2394c0c4e070
- Sign sponsored Tempo payload by setting a placeholder fee_payer_signature before local signing, so the sender commits to the sponsored variant - Bail out when --sponsor-url is combined with --unlocked, --browser, or a Tempo access key instead of silently ignoring it - Validate sponsor URL scheme (require https://, allow http only for localhost/127.0.0.1) - Tighten JSON-RPC response parsing: accept arbitrary result types, drop non-standard 'name' error field Co-authored-by: Amp <amp@ampcode.com>
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Summary
Adds
--sponsor-url(alias--tempo.sponsor-url) tocast send. When set, the transaction is signed locally, then the raw signed bytes are forwarded to the remote sponsor service viaeth_sendRawTransaction. The service adds its fee payer signature and broadcasts the fully-sponsored transaction.Usage
Or via env var:
How it works
TxEnvelopeto raw RLP byteseth_sendRawTransactionto the sponsor URLNo new RPC methods required — works with the existing fee-payer service as-is.
Changes
crates/cli/src/opts/tempo.rs: New--sponsor-url/--tempo.sponsor-urlarg onTempoOpts, conflicts with--tempo.sponsor/--tempo.sponsor-signer/--tempo.sponsor-sig. Forces AA tx type (sets nonce_key=0) like the existing sponsor flow.crates/cast/src/cmd/send.rs: New case inrun_genericthat signs locally, encodes, and sends to the sponsor URL. Addedsend_via_sponsor_urlhelper.crates/cast/Cargo.toml: Addedreqwestdirect dependency for the HTTP call.