[Python] Buy Operation for Jettons Results in Normal TON Transfer Instead of Token Purchase

I'm working on a script to purchase Blum tokens using the TEP-74 Jettons standard, but instead of triggering the buy operation, the transaction is being processed as a normal TON transfer. Below is the relevant excerpt from my code:


# Constants - Operation codes from TEP-74
BUY_OP = 0xaf750d34 # Convert from string as defined in contract

def create_buy_payload():
"""Creates payload for buying Blum tokens"""
try:
# Create the builder for the main message
body = begin_cell()
body.store_uint(BUY_OP, 32) # buy operation
body.store_uint(0, 64) # query id
body.store_coins(0) # min_receive_amount
body.store_uint(0, 1) # no referral
# Additional fields required by the contract may be added here
return body.end_cell()
except Exception as e:
print(f"❌ Error creating payload: {str(e)}")
raise

async def buy_blum():
"""Purchases Blum tokens"""
client = await get_client()
wallet = import_wallet(my_mnemonics)

# Get wallet address and sequence number
wallet_address = wallet.address.to_string()
state = await client.generic_get_account_state(wallet_address)
seqno = state.get('account_state', {}).get('seqno', 0)

# Create the buy payload
payload = create_buy_payload()

# Create the transfer message with the payload attached
query = wallet.create_transfer_message(
to_addr=JETTON_MASTER,
amount=to_nano(AMOUNT + MIN_GAS, 'ton'),
seqno=seqno,
payload=payload,
send_mode=3
)

message_boc = query['message'].to_boc(False)
await client.raw_send_message(message_boc)


Despite using the BUY_OP and constructing the payload accordingly, the operation doesn’t trigger token purchase logic on the contract side—it only executes as a regular TON transfer.

Questions:

Is the payload format incomplete or missing additional fields required by the TEP-74 specification for buying jettons?
What additional parameters or data should be included in the payload for the contract to recognize and execute a buy operation?
Any guidance or suggestions would be appreciated. Thank you!

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