create-python-x402-facilitator

Install x402-avm with the avm and fastapi extras, implement the FacilitatorAvmSigner protocol using py-algorand-sdk, register it via register_exact_avm_facilitator, and expose /verify, /settle, and /supported endpoints through FastAPI.

Implement six methods: get_addresses, sign_transaction, sign_group, simulate_group, send_group, and confirm_transaction. The protocol uses structural typing, so any class implementing all methods satisfies it without inheritance.

Python algosdk's msgpack_decode expects a base64 string, not raw bytes. Convert with base64.b64encode(raw_bytes).decode() before decoding, and use base64.b64decode on msgpack_encode output when returning bytes.

Yes, a single x402Facilitator instance supports multiple networks by calling register_exact_evm_facilitator, register_exact_svm_facilitator, and register_exact_avm_facilitator with their respective signer implementations.

AVM_PRIVATE_KEY is required as a base64-encoded 64-byte key. ALGOD_SERVER and ALGOD_TOKEN are optional for custom nodes; otherwise public AlgoNode endpoints for testnet and mainnet are used by default.

Simulation fails when the transaction group would fail on-chain, typically due to insufficient balances, missing asset opt-ins, or incorrect fee amounts. Check the failure-message field in the simulation result for the specific cause.