r402-hedera

Hedera chain support for the x402 payment protocol, part of the r402 workspace.

Highlights

• Exact scheme — a payer-signed TransferTransaction (HBAR or HTS FT) with the facilitator as feePayer. The facilitator adds its signature and submits; success requires a SUCCESS receipt.
• CAIP-2 networks — hedera:mainnet and hedera:testnet.
• extra.feePayer only — copied onto PriceTag from /supported. aliasPolicy is facilitator config (default reject), not wire extra.
• In-process facilitator — Mirror Node REST preflight (balance and token association) plus Hiero SDK execute. Duplicate settle is blocked by SettlementCache keyed by the base64 transaction.

Host tools

client, facilitator, and full depend on the Hiero SDK (hedera 0.43), which compiles hedera-proto with protoc and links OpenSSL. These are required host tools, same class as a C compiler — hedera-proto 0.20 has no vendored-protoc feature.

# macOS
brew install protobuf openssl

# Debian / Ubuntu
sudo apt-get install protobuf-compiler libssl-dev pkg-config

protoc must be on PATH. Workspace --all-features builds (including just test) need the same toolchain.

Cargo Features

Quick Start (server price tag)

use r402_hedera::{HederaExact, USDC};

let tag = HederaExact::price_tag(pay_to, USDC::hedera_testnet().amount(1_000_000u64));

Documentation

• Crate docs: https://docs.rs/r402-hedera
• Project README: ../../README.md

License

Dual-licensed under MIT and Apache-2.0.