# TradingLimitsV2

In **Mento V3**, FPMM pools enforce **per-token net-flow limits** to bound adverse flow over time. The **TradingLimitsV2** library is used by the pool to apply these limits after each swap. (TradingLimits v1 applied to Mento V2; V3 uses TradingLimitsV2.)

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## Checking limits (code example)

You do not call TradingLimitsV2 directly; the [FPMM](https://docs.mento.org/mento-v3/build/smart-contracts/fpmm) applies it after every swap. To **inspect** the current config and state for a token (e.g. for a UI or to debug a reverted swap), use the pool’s view:

```solidity
IFPMM pool = IFPMM(poolAddress);
(address token0, address token1) = pool.tokens();

(
    ITradingLimitsV2.Config memory config,
    ITradingLimitsV2.State memory state
) = pool.getTradingLimits(token0);  // or token1

// config.limit0, config.limit1 => caps (e.g. 5-min and 1-day)
// state.netflow0, state.netflow1 => current net flow in the windows
// If a swap would push netflow over the limit, the swap reverts
```

***

## Behavior

* **L0** — Short-term limit over a **5-minute** rolling window: net flow of the token in that window must stay within the configured bounds (e.g. `-limit0 <= netflow0 <= limit0`).
* **L1** — Medium-term limit over a **1-day** rolling window: net flow over the day must stay within the configured bounds.

Each pool token can have its own config (limit0, limit1). If a swap would cause either limit to be exceeded, the swap reverts. Limits are applied after the swap amounts are determined; fee is deducted from inflow before updating net flow.

This protects the pool and the protocol from large one-sided flow in a short period (e.g. oracle lag or manipulation) while still allowing normal trading.

**Contract:** [mento-protocol/mento-core](https://github.com/mento-protocol/mento-core) — `contracts/libraries/TradingLimitsV2.sol`

For how TradingLimitsV2 is configured and used on a pool, see [TradingLimitsV2](https://docs.mento.org/mento-v3/dive-deeper/fpmm/trading-limits) in Dive Deeper.