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Alternative Mempools

Submit a Frame Transaction

Disclaimer: Content created from source code using generative AI. Contact us for clarifications or if you find mistakes in this document.

Send

Section titled “Send”

Submit the JSON form of the transaction to the sidecar with eth_sendFrameTransaction.

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "eth_sendFrameTransaction",
  "params": [
    {
      "chainId": "0x539",
      "nonce": "0x6",
      "sender": "0x5544596212F91984C986A919C8026DF0576816f9",
      "frames": [
        { "mode": 1, "flags": 3, "target": null,
          "limits": { "execution": "0x7530", "state": "0x0" }, "value": "0x0", "data": "0x" },
        { "mode": 2, "flags": 0, "target": "0x5544596212F91984C986A919C8026DF0576816f9",
          "limits": { "execution": "0xc350", "state": "0x0" }, "value": "0x1", "data": "0x" }
      ],
      "signatures": [
        { "scheme": 1, "signer": "0x", "msg": "0x",
          "signature": "0x00<r: 32 bytes><s: 32 bytes>" }
      ],
      "fees": {
        "maxPriorityFeePerGas": "0x3b9aca00",
        "maxFeePerGas": "0x77359400",
        "maxFeePerBlobGas": "0x0"
      },
      "blobVersionedHashes": []
    }
  ]
}

This is a self relay. Frame 0 is a VERIFY frame that approves both execution and payment (flags: 3, so the sender pays its own gas). Frame 1 is a SENDER frame that moves 1 wei. The signature is over the canonical signature hash, packed as <1 byte y-parity (0/1)><r><s>. signer: "0x" means tx.sender, and msg: "0x" means the canonical signature hash.

The response is the transaction hash, keccak256(encodeRawFrameTx(tx)). A rejected transaction returns no hash. Compute keccak256(0x06 || rlp(tx)) yourself if you want to look the rejection up.

The helpers that build and sign this shape are buildUnsignedFrameTx, signFrameTx and toWire in the sidecar repository’s test/e2e/helpers.ts, backed by computeSigHash in packages/executor/src/services/FrameTxService/codec.ts.

Frame limits

Section titled “Frame limits”

Execution and state gas are limited separately, per frame. A frame that creates a new account needs a non-zero state limit. With state: 0 it silently fails and drags the transaction’s top-level result to failure. Sending value to an existing account needs no state gas.

Follow it

Section titled “Follow it”
Terminal window
# The sidecar's view: Submitted -> OnChain
curl -s -X POST https://altmempool.forshtat.com/rpc -H 'content-type: application/json' \
  --data '{"jsonrpc":"2.0","id":1,"method":"skandha_frameTransactionStatus","params":["0x<hash>"]}'


# Per-frame receipt
curl -s -X POST https://altmempool.forshtat.com/rpc -H 'content-type: application/json' \
  --data '{"jsonrpc":"2.0","id":1,"method":"eth_getFrameTransactionReceipt","params":["0x<hash>"]}'

skandha_frameTransactionStatus returns one of New, Pending, Submitted, OnChain, Finalized, Cancelled or Reverted. For an unknown hash it returns the error “Frame transaction not found”.

Dry run

Section titled “Dry run”
  • eth_estimateFrameTransactionGas on /rpc returns per-frame gas limits with markup applied.
  • ethrex_simulateFrameTransaction on the ethrex URL runs ethrex’s admission check plus full execution, optionally with a validation trace. It takes the RLP-encoded raw transaction (0x06 || rlp(...)), not the JSON form.

Common gotchas

Section titled “Common gotchas”
  • Fund a paymaster through the value of its CREATE, never by a later plain transfer. Any external call runs the contract’s runtime code, which calls APPROVE outside a frame and halts.
  • A freshly created contract account starts at nonce 1. Use nonce: "0x1" for the first Frame Transaction from such a wallet.
  • Give a wallet contract a non-zero balance if a SENDER frame transfers value from it.
  • More nonce keys cost more validation gas.