@spec broadcast_async(String.t(), String.t(), keyword()) ::
  {:ok, String.t()} | {:error, String.t()}

Broadcast a signed transaction via async eth_sendRawTransaction.

Returns the transaction hash immediately without waiting for block inclusion.

@spec broadcast_sync(String.t(), String.t(), keyword()) ::
  {:ok, String.t(), map()} | {:error, String.t()}

Broadcast a signed transaction via Tempo's synchronous eth_sendRawTransactionSync.

Waits for block inclusion and returns the full receipt inline. Returns {:ok, tx_hash, receipt} on success.

@spec fetch_receipt(String.t(), String.t(), keyword()) ::
  {:ok, map()} | {:error, String.t()}

Fetch a transaction receipt via eth_getTransactionReceipt.

@spec parse_receipt(map()) :: map()

Parse a raw JSON-RPC receipt map into atom-keyed format.

The output is compatible with Onchain.Transfer.parse_logs/1 and Onchain.Tempo.Transfer.parse_transfer_with_memo_logs/1.

@spec simulate(String.t(), String.t(), keyword()) ::
  {:ok, :success}
  | {:ok, {:revert, String.t()}}
  | {:ok, :unsupported}
  | {:error, String.t()}

Simulate a co-signed Tempo 0x76 transaction via eth_simulateV1 before broadcasting, so a fee payer can confirm the transaction would SUCCEED before paying its gas.

Reconstructs a TempoTransactionRequest from the decoded envelope (recovering the sender for from and folding the tail call into to/input), runs the simulation against latest state with validation: false (no signature checks), and reports the execution outcome:

• {:ok, :success} — the transaction would succeed (call status 0x1)
• {:ok, {:revert, detail}} — the transaction would fail on-chain: either the call status is 0x0 (revert / out-of-gas, the gas-draining DoS this guards against) or the node rejected the transaction as invalid (an eth_simulateV1 execution error such as -38013 "intrinsic gas too low"). detail carries the node's error message / revert data. A fail-open caller MUST still reject on this result — it means the transaction is bad, not the node.
• {:ok, :unsupported} — the node does not implement eth_simulateV1 (JSON-RPC error -32601); the caller decides whether to fail open or closed
• {:error, reason} — the transaction could not be decoded, or the RPC failed for an operational reason (transport error, or a non-execution RPC error)

raw_hex is an already co-signed 0x76 transaction hex string.