# Creating a Stable Pool

Stable pools are created through the `StableSwapFactory`, which deploys the
swap contract and its LP token in one transaction and registers the pair for
the [Smart Router](/smart-router).

:::note[Permissioned creation]
`createSwapPair` is `onlyOwner` — new stable pools are curated by the
protocol team. This is deliberate: a stable pool with a badly chosen `A` or a
non-pegged pair gives LPs a false sense of safety. Want a pair listed? Reach
out on [Telegram](https://t.me/+3gVQE9ZzFecwYzY0).
:::

## Factory flow

```
createSwapPair(tokenA, tokenB, A, fee, admin_fee)
        │
        ├── sorts tokens (t0 < t1), rejects existing pairs
        ├── StableSwapLPFactory.createSwapLP()     → LP token (ERC-20)
        ├── StableSwapPoolDeployer.createSwapPair() → StableSwapPool
        └── registers pairInfo[t0][t1] = { swapContract, token0, token1, LP }
```

## Parameters

| Parameter | Deployed value (USDC/EURC) | Constraint |
| --- | --- | --- |
| `_A` — amplification | `200` | `< 1,000,000` |
| `_fee` — swap fee | `4000000` (0.04%) | `≤ 5e9` (0.5%), denominator `1e10` |
| `_admin_fee` — protocol share of the fee | `5000000000` (50%) | `≤ 1e10` (100%) |

## Create a pool (owner)

```bash
cast send $STABLE_SWAP_FACTORY \
  "createSwapPair(address,address,uint256,uint256,uint256)" \
  $TOKEN_A $TOKEN_B 200 4000000 5000000000 \
  --rpc-url $RPC_URL --private-key $PRIVATE_KEY
```

## Look up a deployed pool

```bash
cast call $STABLE_SWAP_FACTORY \
  "getPairInfo(address,address)(address,address,address,address)" \
  $TOKEN_A $TOKEN_B \
  --rpc-url $RPC_URL
```

Returns `(swapContract, token0, token1, lpToken)` regardless of the argument
order you pass.

## After creation

:::steps
### Seed liquidity

The first `add_liquidity` must deposit **both** coins to establish the
balance.

### Register a farm (optional)

Add the LP token to [MasterChefERC20](/farms/classic-farms) so LPs earn BSCT:

```bash
cast send $MASTERCHEF_ERC20 "add(uint256,address,bool)" \
  100 $LP_TOKEN true \
  --rpc-url $RPC_URL --private-key $PRIVATE_KEY
```

### Router picks it up automatically

The Smart Router resolves stable pools from the factory on-chain — no router
change is needed for a new pair.
:::