getMaxCollateral - Ostium

getMaxCollateral(params) returns what a Max button should fill in, and which limit stopped it there — so a UI can explain why, rather than showing a number that refuses to grow.

const { max, bound, limits } = await client.getMaxCollateral({
  pairId: 0,
  isLong: true,
  leverage: 10,
});

console.log(max);     // "13204.51" — fill this into the collateral field
console.log(bound);   // "openInterest" — why it stopped here
console.log(limits);  // every ceiling considered

The connected trader’s wallet balance and USDC allowance are included automatically. Call it on OstiumSubgraphClient for the protocol-side limits only.

Parameters

Parameter	Type	Default	Description
`pairId`	`string \| number`	—	Pair the trade would open on.
`isLong`	`boolean`	—	Direction — each side has its own open-interest headroom.
`leverage`	`number`	—	Leverage the trade would use. Open-interest headroom depends on it.
`user`	`Address`	connected wallet	Trader whose balance and allowance to fold in.

Response schema

interface MaxCollateralResult {
  max: string;    // the binding value — what a Max button fills in
  bound: 'openInterest' | 'groupCollateral' | 'perTradeMax' | 'balance' | 'allowance' | 'none';
  limits: {
    openInterest: string;     // headroom under this side's OI cap, at this leverage
    groupCollateral: string;  // headroom under the group's share of vault liquidity
    perTradeMax: string;      // MAX_COLLATERAL_USD
    balance?: string;         // trader's USDC balance — only when a trader was resolved
    allowance?: string;       // USDC allowance to TradingStorage — same
  };
}

groupCollateral can come back as "unknown" when the vault balance could not be read. max then reflects only the limits that were checked.

max is point-in-time. The open-interest cap is denominated in USD, so it moves with the price — a value sitting exactly on the boundary can be rejected moments later. Re-run previewOpenTrade() before enabling submit, or apply your own margin.