Build unsigned `addSenders` / `removeSenders` calls.

POST 
/v1/senders/prepare

addSenders is never relayed free. It is billed to the account as a normal relay and carries the on-chain per-sender fee, which makes mass-creating senders expensive. removeSenders has no fee and is relayed free: it is how a payer cuts off a compromised sender key. The response members free, ru and feeMicroUsdc say which case applies; show them instead of working the rule out yourself.

addSenders(max_fee, senders...): the route fills the first argument max_fee with the quoted fee, so PreparedTransaction.feeMicroUsdc equals contractCall.args[0]. It is the ceiling the user signs. A higher on-chain fee at execution reverts with ERR_PRICE_ABOVE_MAX, reported as 409 PRICE_ABOVE_MAX. An increase of sender_fee_ru takes effect only 172 800 000 ms after it is set (SENDER_FEE_NOTICE_MS). GET /v1/pricing does not publish a pending sender_fee_ru: the fee this route quotes in feeMicroUsdc is the one in force when it answers, and it is the ceiling the user signs.

Request

Responses

200

Unsigned transaction + assignment + fee preview.

400

MALFORMED_REQUEST, VARIANTS_NOT_SUPPORTED, RELAYER_SIGNATURE_PRESENT, CHAIN_ID_MISMATCH, TX_VERSION_UNSUPPORTED, TX_OPTIONS_UNSUPPORTED, LEASE_MISSING, CURSOR_INVALID.

Response Headers

CoRelayer-Request-Id

Request id, also the instance of a problem document and the log correlation id.

422

REPLACEMENT_UNDERPRICED, RELAYER_UNKNOWN, RELAYER_SHARD_MISMATCH, GAS_PRICE_OUT_OF_RANGE, GAS_LIMIT_TOO_LOW, GAS_LIMIT_TOO_HIGH, GAS_OVERPROVISIONED, DATA_TOO_LARGE, SENDER_SIGNATURE_INVALID, GUARDIAN_*, INSUFFICIENT_SENDER_BALANCE, SIMULATION_FAILED, UNSUPPORTED_TX_FIELD, TIER_NOT_PURCHASABLE, DEPOSIT_BELOW_MIN, DEPOSIT_ABOVE_MAX, WEBHOOK_URL_NOT_ALLOWED, IDEMPOTENCY_KEY_REUSED.

429

RATE_LIMITED, GAS_BUDGET_EXCEEDED, HOURLY_BURN_EXCEEDED, TOO_MANY_IN_FLIGHT, QUOTA_EXHAUSTED (the latter without Retry-After; details.reason = CAP_REACHED_PAYG_OFF | PAYG_ESCROW_EMPTY).

Response Headers

Retry-After

Seconds (HTTP standard). Millisecond precision is in details.retryAfterMs of the problem body.

RateLimit-Limit

Requests (or RU on the relay path) allowed in the current window.

RateLimit-Remaining

Remaining units in the current window.

RateLimit-Reset

Seconds until the window resets (IETF RateLimit header fields).