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Smart Contract Call Flow

Call an EVM smart contract from a Tezos X EVM dApp via the NAC gateway. A transaction with non-empty calldata is routed through the gateway's call_evm entrypoint.

Example: Counter contract​

// increment()
await window.ethereum.request({
  method: 'eth_sendTransaction',
  params: [{
    to: '0x525982C267F4B93cCB075B9323B069A993a9DEd7',
    data: '0xd09de08a', // increment() selector
  }]
});
Gas fields are ignored

gas, gasPrice, maxFeePerGas and maxPriorityFeePerGas are silently ignored on this path — the relayer reads only to, value and data. The transaction executes as a Michelson operation whose fee is denominated in mutez and computed when the wallet signs; there is no EVM gas market to bid into. Correspondingly, eth_estimateGas answers a constant headroom figure and eth_gasPrice answers 0x0. See Gotchas.

Function selectors (Counter)​

FunctionSelectorNotes
increment()0xd09de08a
decrement()0x2baeceb7
setNumber(uint256)0x3fb5c1cb
retrieve()0x2e64cec1Read — goes through eth_call, not the gateway

Only selectors on the relayer's curated allow-list can be sent via eth_sendTransaction; an unknown selector is rejected with UnknownSelectorError (JSON-RPC -32602) before any signing popup opens. Extending the list is a code change in the relayer, not configuration — each entry's text signature is embedded verbatim in the signed Micheline payload and is reviewed before being added. See Selector resolution.

Sequence​

The hash returned to the dApp is a synthetic hash — the real kernel-synthesized EVM hash is resolved lazily. See EIP-1193 → synthetic hash.

ABI encoding​

// setNumber(42)
function encodeSetNumber(num: bigint): string {
  return '0x3fb5c1cb' + num.toString(16).padStart(64, '0');
}

await window.ethereum.request({
  method: 'eth_sendTransaction',
  params: [{
    to: '0x525982C267F4B93cCB075B9323B069A993a9DEd7',
    data: encodeSetNumber(42n),
  }]
});

Attaching value​

A payable contract call may carry a value, and the same mutez-alignment rule as transfers applies: the wei → mutez conversion runs on the call_evm path too, and a value not divisible by 10¹² wei is rejected with SubMutezPrecisionError (-32602) before signing. Compute values as mutez × 10¹² with BigInt. The destination check also runs first on this path: a non-canonical to is rejected with InvalidDestinationError (-32602).

See also​