feat(x402): support USDT payments on BNB Smart Chain#455
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The Nansen API now advertises USDT on BNB Smart Chain (eip155:56) as an x402 payment option. Payment signing already handles any EVM network generically (chain id, token contract, and EIP-712 domain all come from the 402 accepts entry), so this wires up the remaining network-specific piece: the post-payment balance check. - Add eip155:56 to the EVM payment-token registry (now exported as EVM_X402_TOKENS) with the BSC USDT contract and 18-decimal precision — the existing tokens (Base USDC, X Layer USDT0) use 6 decimals, so the divisor is now per-token instead of a hardcoded 1e6. - Add bsc to CHAIN_RPCS with a NANSEN_BSC_RPC override, matching the existing per-chain env-var pattern. - Tests for the registry (networks, decimals, token contracts, RPCs). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
kome12
approved these changes
Jun 11, 2026
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What
The Nansen API now advertises USDT on BNB Smart Chain (
eip155:56) as an x402 payment option. This PR adds BSC support to the CLI's x402 auto-payment flow.Why almost everything already worked
Payment signing is network-generic: the chain id, token contract, recipient, amount, and EIP-712 domain (
extra.name/extra.version) are all taken from the 402acceptsentry, and the fallback loop inapi.jsalready tries each advertised network in order. So a wallet holding BSC USDT could already pay — but the post-payment balance check was wrong for BSC.Changes
src/x402.js— the per-network EVM token map (now exported asEVM_X402_TOKENS) gainseip155:56(BSC USDT0x55d398…7955) and a per-tokendecimalsfield. BSC USDT uses 18 decimals, unlike the 6-decimal Base USDC / X Layer USDT0, so the previous hardcoded1e6divisor would have reported balances off by 10¹².src/rpc-urls.js— addbsctoCHAIN_RPCS(defaulthttps://bsc-dataseed.binance.org, override withNANSEN_BSC_RPC), matching the existing per-chain pattern.src/__tests__/x402-balance.test.js— registry tests: covered networks, decimals, pinned token contracts, RPC resolution.Testing
vitest run— x402 suites green (11/11 in the touched areas); full suite 1490 passed with one unrelated flake inupdate-check.test.js(passes in isolation, before and after this change).🤖 Generated with Claude Code