# modifyTokenSupply

The `modifyTokenSupply()` operation allows you to **mint** (increase) or **burn** (decrease) the total supply of a token on KeetaNet. This is a low-level supply management tool that modifies the global token supply stored in a given token account.

This operation is part of the transaction builder and must be **published** to take effect.

## When to Use

* Minting new tokens to increase supply (e.g. when issuing rewards or enabling inflation).
* Burning tokens to reduce supply (e.g. for deflationary models or manual corrections).
* Dynamically adjusting circulating supply in response to governance or economic rules.

## How It Works

{% stepper %}
{% step %}

### Get a Token Account

You need the token account you want to modify. This is usually derived from a known public key.

```typescript
const tokenAccount = Client.lib.Account.fromPublicKeyString(tokenPublicKey)
```

{% endstep %}

{% step %}

### Initialize a Builder

Start a transaction builder using `userClient.initBuilder()`.

```typescript
const builder = userClient.initBuilder()
```

{% endstep %}

{% step %}

### Call `modifyTokenSupply()`

Provide an amount and a token account:

* Positive values **mint** tokens.
* Negative values **burn** tokens.\
  The amount must be an integer or a BigNumber.

```typescript
const builder = userClient.initBuilder()
builder.modifyTokenSupply(1000n, { account: tokenAccount }) // Mint 1000 tokens
await userClient.publishBuilder(builder)

const builder = userClient.initBuilder()
builder.modifyTokenSupply(-500n, { account: tokenAccount }) // Burn 500 tokens
await userClient.publishBuilder(builder)
```

{% endstep %}

{% step %}

### Publish the Builder

Send the transaction to the network using `userClient.publishBuilder()`

```typescript
await userClient.publishBuilder(builder)
```

{% endstep %}
{% endstepper %}

## Full Example

```typescript
// Step 1: Load token account
const tokenAccount = Client.lib.Account.fromPublicKeyString(tokenPublicKey)
if (!tokenAccount.isToken()) {
  throw new Error("Invalid token public key")
}

// Step 2: Start builder
const builder = userClient.initBuilder()

// Step 3a: Burn 100 tokens
builder.modifyTokenSupply(-100n, { account: tokenAccount })
// Step 3b: Or mint 100 tokens
builder.modifyTokenSupply(100n, { account: tokenAccount })

// Step 4: Publish the transaction
await userClient.publishBuilder(builder)

```

## Method

```typescript
modifyTokenSupply(
  amount: BigNumber | number,
  options: {
    account: Account; // The token account whose supply you're modifying
  }
): void
```


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