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Lighter is a ZK-rollup whose bridge contract lives on Ethereum mainnet (chain ID 1). The DEPOSIT action is therefore an EVM transaction signed by the user’s L1 wallet — not a WASM-signed Lighter transaction.

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deposit

SignersUSER (L1 wallet, EVM transaction)
ParamsDepositParams — { chainId, tokenAddress, amount }
Stepsapprove then deposit (two EVM_TX action steps)
ConstraintchainId must be 1 (Ethereum mainnet)

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Flow

A DEPOSIT request returns two EVM_TX action steps in order:
  1. approve(spender, amount) on the source USDC token contract, where spender is the Lighter bridge contract address.
  2. deposit(_to, _assetIndex, _routeType, _amount) on the Lighter bridge contract, with _assetIndex and _routeType set to USDC and the perpetuals route respectively.
Both transactions are signed by the user’s L1 wallet via EVM_TX (no WASM blob involved).
SignerUSER (L1 wallet, EVM transaction)
ChainEthereum mainnet (chainId: 1) only
Stepsapprove then deposit
Quote assetUSDC

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Source chains other than Ethereum

If the user holds USDC on a chain other than Ethereum mainnet, the backend rejects the DEPOSIT request. Bridge USDC to Ethereum first via the LI.FI SDK or API, then submit the Lighter DEPOSIT action.

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Account creation

Lighter requires a deposit to create an account before an API key can be registered. On a fresh L1 address:
  1. Submit a DEPOSIT action — this creates the on-chain Lighter account and assigns it an account_index.
  2. Wait for the deposit to be indexed (the L1 transaction confirms, then Lighter’s relayer mints the L2 account).
  3. Submit REGISTER_API_KEY (see Setup) — this requires an existing account_index, so it will fail with AccountNotFound if the deposit has not yet been indexed.
The SDK’s checkSetup() will surface a “deposit first” condition for fresh addresses rather than silently reporting that setup is complete.