@anywalletkit/protocol-swap2-usdt0

USDT0 — Tether's USDT as a LayerZero OFT — as a swap2 provider: USDT / USDT0 between 16 EVM chains in one source transaction. send(SendParam, MessagingFee, refund) on the chain's OFT with the LayerZero messaging fee as msg.value; LayerZero's DVNs verify the packet and the executor delivers on the destination (USDT0 minted, or USDT released from the Ethereum adapter). No spread, no protocol fee today — the only cost is the LayerZero fee in the source chain's native coin (≈ 0.0000024 ETH for Arbitrum → HyperEVM on 2026-10-20). It is the only direct USDT path into HyperEVM.

Install

npm install @anywalletkit/protocol-swap2-usdt0 @anywalletkit/core
# or: pnpm add @anywalletkit/protocol-swap2-usdt0 @anywalletkit/core  ·  yarn add @anywalletkit/protocol-swap2-usdt0 @anywalletkit/core

On npm: @anywalletkit/protocol-swap2-usdt0, published from the release workflow with provenance.

import {usdt0Provider} from "@anywalletkit/protocol-swap2-usdt0/provider";
import {RouterSwap2Protocol} from "@anywalletkit/protocol-swap2-router/swap2/router";

const swap2 = new RouterSwap2Protocol(arbitrumAccount, {fromChain: "eip155:42161", providers: [usdt0Provider({rpcUrls})]});
const res = await swap2.swap2({fromToken: "USDT0", toToken: "USDT0", toChain: 999, fromTokenAmount: 10_000_000n, minAmountOut: 10_000_000n});
// … poll …
const status = await swap2.getSwap2Status(res.id);   // "pending" → "completed" with the HyperEVM delivery hash

rpcUrls (CAIP-2 → URL or URLs) is required for every chain the provider quotes from: the fee and the received amount come from the OFT itself, not from an API.

What the provider does

• Quote = two eth_calls on the source OFT. quoteOFT(SendParam) gives the limits, any OFT fee rows and amountReceivedLD — what really arrives after dust removal (shared decimals = 6 on every deployment, so nothing is removed today). That amount becomes minAmountLD, and quoteSend prices the message with it. The contract reverts rather than deliver less.
• Calldata is sealed in the quote: send(SendParam{dstEid, to, amountLD, minAmountLD, extraOptions: 0x, composeMsg: 0x, oftCmd: 0x}, {nativeFee, 0}, refundAddress), value = nativeFee = the quoted LayerZero fee + 25 % headroom — the fee is paid at send time and moves with gas (live: +1.7 % in a minute on Ethereum); OAppSender needs msg.value == nativeFee and the endpoint refunds the unused part to refundAddress in the same transaction (declared as txRequest.nativeFee so the engine caps it per chain and the router prices it). extraOptions stays empty: every deployment's enforcedOptions already carry the executor gas (type-3, lzReceive gas 80 000, read on-chain 2026-10-20).
• Approvals: Ethereum locks USDT in an OFT adapter (approvalRequired() = true) → approvalAddress is the adapter, exact amount. Every other chain's OFT burns the caller's USDT0 through the token's mint/burn role (approvalRequired() = false) → no approval at all.
• Bound on-chain: before the first quote on a chain the OFT's token() and approvalRequired() must match config.ts; per pair, peers(dstEid) must be the destination OFT. A mismatch refuses the route with its reason.
• Preflight (right before signing): target is the source OFT, peer still wired, and the current quoteSend fee still fits the sealed value — the endpoint reverts an underpaid send, so a fee past the headroom means re-quote.
• Tracking: LayerZero Scan GET /v1/messages/tx/{sourceTxHash}, matched to the route's eids and the source OFT. INFLIGHT / CONFIRMING / BLOCKED → pending; DELIVERED → completed with the destination hash; PAYLOAD_STORED → action-required; FAILED and the burned / skipped / malformed statuses → failed; a hash whose message belongs to another pathway → failed.
• Claim (buildClaim, through the engine's claimSwap2): a delivery that reverted on the destination is stored by the endpoint and can be retried by anyone — EndpointV2.lzReceive(origin, receiver, guid, message, 0x) with the exact packet Scan recorded, on the destination chain. Null otherwise.
• Deployments (docs.usdt0.to, every address re-read on-chain 2026-10-20): Ethereum (eid 30101, adapter), Arbitrum 30110, OP Mainnet 30111, Polygon 30109, HyperEVM 30367, Ink 30339, Berachain 30362, Unichain 30320, Sei 30280, Plasma 30383, Monad 30390, MegaETH 30398, X Layer 30274, Mantle 30181, Morph 30322, Flare 30295. USDT0 is also live on Conflux eSpace, Hedera, Rootstock, Stable, Tempo, HyperCore, IOTA and Stellar — not wallet chains here yet. OP's catalog USDT is the legacy bridged token (not the OFT); USDT0 is.

Tests

pnpm test — provider tests over a fake JSON-RPC + fake LayerZero Scan (route gating, quote maths incl. dust and OFT fee rows, calldata binding, every named refusal, on-chain binding failures, preflight, the whole pending → completed / action-required / failed lifecycle, the lzReceive claim, the router snapshot) and the conformance suite incl. the behaviour fixture (the engine executes exactly the reviewed plan, no approval). USDT0_LIVE=1 pnpm test adds a live read-only quote on Arbitrum. pnpm verify:live re-reads all 13 deployments on-chain and quotes 10 USDT0 Arbitrum → HyperEVM with the preflight.

Status

2026-10-20: built, tests green, all 13 deployments verified on-chain, live quote + preflight verified. No funded transfer yet (plan: 10 USDT Arbitrum → HyperEVM from the phone, then the status through LayerZero Scan).

Behind remoteProvider

When the provider runs on your server, spread its pins into the app's stub: remoteProvider({name: "usdt0", baseUrl, ...usdt0Pins}). The engine then lets the EVM route call and approve only the USDT0 OFT (and, on Ethereum, the adapter as spender), never an address the backend names, and usdt0VerifyQuote decodes the server's send on the device: the destination eid, the recipient, the input, a minAmountLD that keeps the quoted minimum, no options or compose message, the trader as refund and the declared native fee as value. Without the pins the stub gets no EVM calldata route (fail closed).

Activity

describeActivity: send on the OFT → "Bridged USDT0" ("Bridged USDT" on Ethereum); the executor's delivery (USDT0 minted to the owner, or USDT released by the adapter, in a transaction the owner did not send) → "Received USDT0 via LayerZero"; the owner's own lzReceive retry → the same. Fixtures are recorded mainnet transactions (fixtures/activity).