L2 Bridge & Vault Compose

Move stablecoins across chains and into a yield position in a single user operation. Built on LayerZero V2 OFT and VaultComposerSync.

The pattern

Source chain                          Destination chain
─────────────                          ─────────────
User OFT.send() ──► LZ V2 endpoint ──► OFT.receive() ──► VaultComposerSync.deposit()

The user signs once. The bridge transport and the destination vault deposit are composed — the recipient on the destination chain is the vault, with the user’s deposit credited atomically.

Use cases

• Settlement to a yield position. Customer pays on Base; funds land in an sUSDe vault on Ethereum.
• Treasury rebalancing. Move idle USDC from Arbitrum to Base and deposit into a yield strategy in one step.
• Cross-chain checkout. Accept payment on any supported chain, settle on the chain you operate from.

API

Quote a bridge

curl -X POST https://api.stablecoinx.com/v1/bridge/quote \
  -H "Authorization: Bearer $STABLECOINX_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "fromChain": "arbitrum",
    "toChain": "base",
    "asset": "USDC",
    "amount": "10000",
    "composeAction": {
      "type": "vault_deposit",
      "vault": "sUSDe"
    }
  }'

Response:

{
  "quoteId": "qte_01HX2K9...",
  "estimatedTime": "90s",
  "fees": {
    "bridge": "0.50",
    "gas": "0.15",
    "total": "0.65"
  },
  "minReceived": "9999.35",
  "expiresAt": "2026-05-26T17:05:00Z"
}

Execute

Submit the quote with a signature from the holding wallet:

curl -X POST https://api.stablecoinx.com/v1/bridge/execute \
  -H "Authorization: Bearer $STABLECOINX_KEY" \
  -d '{ "quoteId": "qte_01HX2K9...", "signature": "0x..." }'

You get back a transferId to poll or subscribe to via webhook.

Settlement stepper

Each transfer moves through observable legs:

Step	State	Typical duration
1	source_pending	< 12s
2	in_flight (LayerZero in transit)	30–90s
3	dest_received (compose pending)	< 6s
4	composed (terminal)	—

If a leg stalls, the transfer’s status payload includes a recoveryAction describing what’s required to unstick it.

Error paths

Error	Recovery
Destination compose reverts	OFT funds are credited to the recipient; retry the compose via POST /v1/bridge/{id}/retry-compose.
LZ message stalls	Manual retry via the LayerZero Scan dashboard, then re-poll status.
Insufficient gas on destination	Top up the relayer, or switch to a Paymaster-sponsored compose.

Gas model

• Source gas — paid by the wallet executing OFT.send(). Sponsorable via the Paymaster.
• Destination gas — covered by the LayerZero relayer fee, embedded in the quote.

Supported routes

From	To	Asset
Base	Arbitrum, Optimism, Ethereum	USDC, USDT, sUSDe
Arbitrum	Base, Optimism, Ethereum	USDC, USDT, sUSDe
Optimism	Base, Arbitrum, Ethereum	USDC, USDT, sUSDe
Ethereum	Base, Arbitrum, Optimism	USDC, USDT, sUSDe