TronClientSigner.ensure_allowance fails: tronpy build() missing raw_data_hex

[Tristenyang]

Description

TronClientSigner.ensure_allowance() in bankofai/x402/signers/client/tron_signer.py fails when trying to approve token allowance on TRON networks.

Error

bankofai.x402.exceptions.InsufficientAllowanceError: Approval transaction failed: Tron sign_transaction failed: Payload must be an unsigned transaction with {raw_data_hex}. Use TronGrid API to build the transaction first.

Root Cause

In tron_signer.py line 249-251, the approve transaction is built locally via tronpy's AsyncTron:

txn = await txn_builder.build()
txn_dict = txn.to_json()
raw_result = await self._wallet.sign_transaction(txn_dict)

txn.to_json() returns a dict with keys {txID, raw_data, signature, permission} — no raw_data_hex field.

However, bankofai-agent-wallet's TronSigner.sign_transaction() (agent_wallet/core/adapters/tron.py:50) requires raw_data_hex in the payload:

if "raw_data_hex" not in payload:
    raise ValueError(
        "Payload must be an unsigned transaction with {raw_data_hex}. "
        "Use TronGrid API to build the transaction first."
    )

This is an interface mismatch between bankofai-x402 (v0.5.8) and bankofai-agent-wallet (v2.4.0).

Expected Behavior

The approve transaction should be built in a format compatible with agent_wallet's sign_transaction, which requires raw_data_hex.

Suggested Fix

Use the TronGrid HTTP API (wallet/triggersmartcontract) to build the transaction instead of tronpy's local build(). The TronGrid API response includes raw_data_hex in the transaction object.

Environment

• bankofai-x402: 0.5.8
• bankofai-agent-wallet: 2.4.0
• Python: 3.12
• Network: tron:nile (testnet)

[boboliu-1010]

Fixed in #66.

Root cause: the Python TronClientSigner.ensure_allowance() path was passing txn.to_json() directly into sign_transaction(), but transactions built via tronpy may not include raw_data_hex at that stage. agent-wallet requires raw_data_hex, so the approval flow failed.

The fix preserves the existing tronpy build / broadcast / receipt flow and only patches the unsigned payload passed to the wallet signer so raw_data_hex is included when available.

Validation:

• reproduced the failure on main
• confirmed the fix resolves the same repro case
• ran targeted TRON signer / permit / exact client tests successfully