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## Missing events arithmetic

**Severity**: `Low`
**ID**: `missing-events-arithmetic`

Flags protected entry-point functions that update tainted integer state used in arithmetic by an
unprotected function without emitting an event.

### What it does

This lint looks for scalar `int`/`uint` state variables that are:

* written by a public or external state-mutating function with access control,
* assigned from function input, directly or through local aliases/internal helpers, or changed with
  an arithmetic assignment or increment/decrement,
* used in arithmetic by an unprotected public or external function, and
* changed along a path that does not emit an event.

State variables and entry points are collected across the whole inheritance chain, with
overridden base functions resolved to the most derived implementation.

It intentionally skips fixed-value writes, constructors, unprotected setters, mappings/arrays, and
update paths that emit an event directly or through an internal helper. Those limits keep the rule
focused on Slither's low-severity `events-maths` case while avoiding common false positives.

### Why is this bad?

Off-chain monitors, users, and auditors often rely on events to track changes to critical contract
parameters such as prices, fees, caps, and rates. If a protected function silently changes a
parameter used in calculations, downstream behavior can change without an easy audit trail.

### Example

#### Bad

```solidity
function setBuyPrice(uint256 newBuyPrice) external onlyOwner {
    buyPrice = newBuyPrice;
}
```

#### Good

```solidity
event BuyPriceUpdated(uint256 newBuyPrice);

function setBuyPrice(uint256 newBuyPrice) external onlyOwner {
    buyPrice = newBuyPrice;
    emit BuyPriceUpdated(newBuyPrice);
}
```