Python

Use full service RPC for fetching latest blockhash.

import aiohttp
import asyncio
import base64

from typing import List

from solders.pubkey import Pubkey
from solders.keypair import Keypair
from solders.instruction import Instruction
from solders.transaction import Transaction
from solders.system_program import transfer, TransferParams
from solders.hash import Hash

from solana.rpc.async_api import AsyncClient

NOZOMI_ENDPOINT = "https://nozomi.temporal.xyz/api/sendTransaction2?c=<YOUR_API_KEY>"
NOZOMI_TIP = Pubkey.from_string("TEMPaMeCRFAS9EKF53Jd6KpHxgL47uWLcpFArU1Fanq")
MIN_TIP_AMOUNT = 1_000_000

SOLANA_RPC_ENDPOINT = "https://api.mainnet-beta.solana.com"

async def send_nozomi_txn(
    ixns: List[Instruction],
    signer: Keypair,
    nozomi_endpoint: str,
    solana_rpc_client: AsyncClient
) -> None:
    tip_ixn = transfer(TransferParams(
        from_pubkey=signer.pubkey(),
        to_pubkey=NOZOMI_TIP,
        lamports=MIN_TIP_AMOUNT
    ))
    ixns.append(tip_ixn)

    blockhash_resp = await solana_rpc_client.get_latest_blockhash()
    blockhash = blockhash_resp.value.blockhash

    txn = Transaction.new_signed_with_payer(
        ixns,
        signer.pubkey(),
        [signer],
        blockhash
    )

    txn_bytes = bytes(txn)
    txn_base64 = base64.b64encode(txn_bytes).decode('utf-8')

    async with aiohttp.ClientSession() as session:
        async with session.post(
            nozomi_endpoint,
            headers={"Content-Type": "text/plain"},
            data=txn_base64
        ) as response:
            # api v2 does not return a signature, just check for success
            if response.status >= 200 and response.status < 300:
                print("Transaction sent successfully")
            else:
                error_text = await response.text()
                raise Exception(f"Transaction failed with status {response.status}: {error_text}")

def build_ixns() -> List[Instruction]:
    # your instruction building logic here..
    return []

async def main():
    solana_rpc_client = AsyncClient(SOLANA_RPC_ENDPOINT)

    # replace with actual keypair loading logic
    signer = Keypair()

    ixns = build_ixns()

    await send_nozomi_txn(ixns, signer, NOZOMI_ENDPOINT, solana_rpc_client)

if __name__ == "__main__":
    asyncio.run(main())