Deposit

A deposit moves public ERC-20 tokens into the pool and mints a private note. The pool pulls tokens with transfer_from while the proof executes, so the ERC-20 approve must already be visible on-chain - it is a separate transaction, submitted and waited on first.

Snippets assume transfers, account and provider from Getting Started.

const poolAddress = process.env.POOL_ADDRESS!
const tokenAddress = "0x049d..." // any ERC-20
const amount = 100n

// Transaction 1 - approve the pool to pull tokens.
const approveTx = await account.execute(
  {
    contractAddress: tokenAddress,
    entrypoint: "approve",
    calldata: [poolAddress, amount.toString(), "0"],
  },
  { tip: 0n },
)
await provider.waitForTransaction(approveTx.transaction_hash)

// Transaction 2 - the private deposit.
// Re-fetch provingBlockId AFTER the approve lands, so the proof base
// is not older than the approval.
const provingBlockId = (await provider.getBlockNumber()) - 10

const { callAndProof } = await transfers
  .build({ autoSetup: true })
  .with(tokenAddress, (t) => t.deposit({ amount }))
  .surplusTo(account.address) // the deposited amount becomes my note
  .execute({ provingBlockId })

const proofDetails = callAndProof.proof.proofFacts?.length
  ? { proofFacts: callAndProof.proof.proofFacts, proof: callAndProof.proof.data }
  : {}
const tx = await account.execute(callAndProof.call, { tip: 0n, ...proofDetails })
await provider.waitForTransaction(tx.transaction_hash)

Things to notice

• Two transactions, never one. The pool's apply_actions entrypoint is reentrancy-guarded against sharing a transaction with other calls, so you cannot batch approve and the deposit into a single account.execute.
• The deposit omits recipient; surplusTo(account.address) directs the unassigned amount into a note owned by you. This is the shape that scales to deposit-and-transfer on the next page.
• Amounts are bigint literals (100n) in the token's smallest unit.
• autoSetup: true opens your self-channel and the token subchannel if they do not exist yet - a first deposit needs both.
• The new note matures 10 blocks after creation. Spending it earlier produces a proof the contract rejects with Note not mature.
• Every deposit is screened. FPI (the screening provider) screens the depositing address and signs each deposit, and the pool verifies that signature onchain - enforcement is part of the protocol since the v0.14.3 upgrade. Wallet and hosted-proving flows handle this step for you; if a structurally valid deposit reverts, screening is the first thing to check. See Compliance & Auditing.

Next: Transfer a note privately to another account.