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A deposit moves USDC from your associated EOA into your on-chain vault, where it becomes spendable as available balance and is required collateral for placing BUY orders. It is always a user-initiated on-chain transaction — neither the platform nor a partner API key can pull funds out of an EOA without the owner’s authorisation.

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Prerequisites

RequirementHow to satisfy
Vault deployed for your EOAAuto-deployed by the platform — see Backend auto-deploy. Verify with GET /api/me/vault (deployed: true).
USDC in the EOABuy / bridge on mainnet; on testnet call MockCollateral.mint(eoa, amount) (public).
ERC-20 allowanceYour EOA must have called USDC.approve(vault, X) for at least X = depositAmount. MaxUint256 is the standard one-time pattern.
Within deposit limitsThe platform pre-initialises per-EOA daily / weekly / monthly caps — see Deposit limits.

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End-to-end flow

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Step 1 — approve (once per vault)

import { Contract, MaxUint256 } from 'ethers';

const usdc = new Contract(
  '0x9bC8244c0F531F27fe3636FFdAf2C586d11241e1',
  ['function approve(address,uint256) returns (bool)'],
  eoa,
);

await (await usdc.approve(vault, MaxUint256, { gasLimit: 100_000n })).wait();
MaxUint256 saves gas on every future deposit. Tighten to a per-deposit allowance if your security model requires it — the trade-off is one extra approve per deposit.

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Step 2 — depositERC20

import { Contract, parseUnits } from 'ethers';

const v = new Contract(
  vault,
  ['function depositERC20(address token, uint256 amount)'],
  eoa,
);

await (await v.depositERC20(
  '0x9bC8244c0F531F27fe3636FFdAf2C586d11241e1',
  parseUnits('500', 6),                          // 500 USDC (6 decimals)
  { gasLimit: 600_000n },
)).wait();
Inside the tx the vault calls transferFrom(eoa → vault), increments its internal collateral ledger by amount, and checks the deposit-cap windows in DepositLimitRegistry before settling. If the cap would be exceeded, the tx reverts with DepositCapExceeded() — see Deposit limits.

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Step 3 — wait for the platform to credit

After the deposit tx mines, the platform indexes the on-chain event and credits exchange.balances.available for your associated EOA. End-to-end latency from mined tx to credited balance is typically under 5 seconds on testnet and similar on mainnet. Two ways to observe it: 
async function waitForDeposit(amountUsdc: string, timeoutMs = 30_000) {
  const start = Date.now();
  while (Date.now() - start < timeoutMs) {
    const r = await fetch(`${BASE}/api/me/balances`, {
      headers: { 'X-Api-Key': process.env.PS_API_KEY! },
    });
    const balances = await r.json();
    const usdc = balances.find((b: any) => b.token === 'USDC');
    if (usdc && Number(usdc.available) >= Number(amountUsdc)) return usdc;
    await new Promise(r => setTimeout(r, 1000));
  }
  throw new Error('deposit not credited within timeout');
}

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Idempotency and replays

Deposits are uniquely keyed by their on-chain (txHash, logIndex). If you receive the same vault.deposit_confirmed event twice (network retry, WS reconnect with replay), the platform credits the deposit exactly once — replays are cheap no-ops. Safe to handle naively.

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Withdrawing later

Funds in the vault stay liquid — withdraw any time via the dual-signed flow documented in Withdrawals overview. The vault also exposes a 7-day-timelocked emergency withdraw for recovery if the platform is unavailable; see Vault contract reference.

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Common failures

SymptomCauseFix
ERC20InsufficientAllowanceStep 1 skipped or insufficient capRun usdc.approve(vault, MaxUint256) first
Revert with selector 0x87138d5cNotInitialized() — your code raced ahead of auto-deploy (the VaultCreated and cap-init txs land in adjacent blocks)Wait one block and retry; or gate the deposit on GET /api/me/vault returning deployed: true
Revert with DepositCapExceededThe deposit would exceed your daily / weekly / monthly capSee Deposit limits — wait for the rolling window or request a higher tier
Tx mined but available still 0 in /api/me/balances after >1 minuteIndexer lag or transient incidentCheck status page; if persistent, contact support with txHash

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Next

Deposit limits

Daily / weekly / monthly caps and how rolling windows are applied.

Withdrawals overview

Dual-signature flow, AML review, state machine.

Place your first order

Sign + POST a vault-backed order against any open market.

Vault contract reference

Full ABI for the vault, including the deposit entry point.