Deployer API
Choosing the correct parameter value is trivial for the performance of the liquidity pool.
Name and Symbol¶
The input values of _name or _symbol are obviously non-trivial for the performance of the pool. These parameters should visualize, what kind of tokens are included in the pool.
Coins¶
_coins includes all tokens included in the pool as a DynArray.
_coins = ["0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2", "0xae78736Cd615f374D3085123A210448E74Fc6393"]
A, Fee, Off-Peg Fee Multiplier, and MA-Exp-Time¶
_Arepresents the amplification coefficient of the pool, signifying its density._feeis referred to as the "base fee."- The 
offpeg_fee_multiplierparameter enables the system to dynamically adjust fees according to the pool's state. ma_exp_timedenotes the time window for the moving average oracle.
Recommended Parameters:
| Parameter | Fiat-Redeemable Stablecoin | Crypto-Collateralized Stablecoin | 
|---|---|---|
A |  200 | 100 | 
fee |  0.04% | 0.04% | 
offpeg_fee_multiplier |  2 | 2 | 
ma_exp_time |  866 | 866 | 
_A = 200
_fee = 4000000                                          # 0.0001 or 0.01%
_offpeg_fee_multiplier = 20000000000                    # 5 or 500%
_ma_exp_time = 866                                      # ~600 seconds
Parameter Precision
The precision of _fee and _offpeg_fee_multiplier is 1e10.
 The time window of the moving average exponential oracle is calculated using time_in_seconds / ln(2).
Implemention ID¶
Pools are created from implementation contracts (blueprints). These contracts are added to the Factory and must be choosen when deploying a pool.
Warning
The Factory can have multiple plain- and meta-pool implementations. If there are multiple implementations for a plain or meta-pool, it's important to understand the differences and determine which one is suitable.
 Additionally, implementation contracts are upgradable. They can either be replaced or have additional implementation contracts set. Please always make sure to check the most recent ones.
To query the factory-specific implementations:
Assets Types¶
Stableswap-NG infrastructure supports pools with the following asset types:
| Asset Type | Description | 
|---|---|
0 |  Standard ERC-20 token with no additional features | 
1 |  Oracle - token with rate oracle (e.g. wstETH) | 
2 |  Rebasing - token with rebase (e.g. stETH) | 
3 |  ERC4626 - token with convertToAssets method (e.g. sDAI) |  
Consequently, supported tokens include:
- ERC-20 support for return 
True/revert,True/FalseorNone - ERC-20 tokens can have arbitrary decimals (≤18)
 - ERC-20 tokens that rebase (either positive or fee on transfer)
 - ERC-20 tokens that have a rate oracle (e.g. wstETH, cbETH) Oracle precision must be \(10^{18}\)
 - ERC-4626 tokens with arbitrary percision (≤18) of Vault token and underlying asset
 
Warning
ERC20:Users are advised to do careful due-diligence on ERC20 tokens that they interact with, as this contract cannot differentiate between harmless and malicious ERC20 tokens.Oracle:When using tokens with oracles, its important to know that they may be controlled externally by an EOA.Rebasing:Users and Integrators are advised to understand how the AMM contract works with rebasing balances.ERC4626:Some ERC4626 implementations may be susceptible to Donation/Inflation attacks. Users are advised to proceed with caution.
Choosing asset types can sometimes be quite tricky. Asset types should be seen more as information for the AMM on how to treat the assets under the hood.
Example
Let's consider the example of rmETH/mETH. - mETH is a token with a rate oracle (the underlying asset is ETH). The rate can be fetched by reading the mETHToETH method within the staking contract. - rmETH is a rebasing token.
Because the deployer wants rmETH and mETH to trade as close to 1:1 as possible, they need to treat mETH like a regular ERC-20 token (asset type 0), instead of a rate oraclized token (asset type 1).
Method IDs and Rate Oracles¶
method_ids and _oracles are required for rate oracles to function. ERC-4626 does not need either of these. The sole requirement for those is to have a convertToAssets method.
Info
When deploying pools that include coins not requiring a rate oracle, b"" or 0x00000000 should be included in the _methods_id array and the ZERO_ADDRESS should be used in the _oracles array as placeholders for each coin.
-  
_method_idsis the first four bytes of the Keccak-256 hash of the function signatures of the oracle addresses that give rate oracles.As an example, lets look at the rETH token. The relevant function which returns the rate is
getExchangeRate, the according first four bytes of the Keccak-256 hash of the functions signature is therefore0xe6aa216c. When calculating, its always important to include"()", as they will change the bytes. -  
_oraclesis simply the contract address which provides the rate oracle function. 
The input values are DynArrays with the length of tokens in the pool. Therefore, a rETH/wETH pool would have the following input values:
_method_id = [b"", "0xe6aa216c"]
_oracles = ["0x0000000000000000000000000000000000000000", "0xae78736cd615f374d3085123a210448e74fc6393"]
Examples¶
| Pool | Asset Types | Method ID's | Rate Oracle | 
|---|---|---|---|
| mkUSD/USDC | [0, 0] |  ['0x00000000', '0x00000000'] |  ['0x0000000000000000000000000000000000000000', '0x0000000000000000000000000000000000000000'] |  
| FRAX/sDAI | [0, 3] |  ['0x00000000', '0x00000000'] |  ['0x0000000000000000000000000000000000000000', '0x0000000000000000000000000000000000000000'] |  
| wETH/rETH | [0 , 1] |  ['0x00000000', '0xe6aa216c'] |  ['0x0000000000000000000000000000000000000000', '0xae78736Cd615f374D3085123A210448E74Fc6393'] |  
| rmETH/mETH | [2 , 0] |  ['0x00000000', '0x00000000'] |  ['0x0000000000000000000000000000000000000000', '0x0000000000000000000000000000000000000000'] |  
Deploying Liquidity Pools¶
deploy_plain_pool¶
 The pool deployment is permissionless, but it must adhere to certain parameter limitations:
- Minimum of 2 and maximum of 8 coins.
 - All coin arrays should be the same length.
 _fee≤ 100000000 (1%)._offpeg_fee_multiplier*_fee≤MAX_FEE*FEE_DENOMINATOR.- Maximum of 18 decimals for a coin.
 - No duplicate coins.
 - Valid implementation index.
 
Factory.deploy_plain_pool(_name: String[32], _symbol: String[10], _coins: DynArray[address, MAX_COINS], _A: uint256, _fee: uint256, _offpeg_fee_multiplier: uint256, _ma_exp_time: uint256, _implementation_idx: uint256, _asset_types: DynArray[uint8, MAX_COINS], _method_ids: DynArray[bytes4, MAX_COINS], _oracles: DynArray[address, MAX_COINS], ) -> address:
Function to deploy a stableswap-ng plain pool. The pool is created from a blueprint contract.
Returns: Deployed pool (address).
Emits: PlainPoolDeployed
| Input | Type | Description | 
|---|---|---|
_name |  String[32] |  Name of the new plain pool | 
_symbol |  String[10] |  Symbol for the new pool's LP token; this value will be concatenated with the factory symbol | 
_coins |  DynArray[address, MAX_COINS] |  Array of addresses of the coins being used in the pool | 
_A |  uint256 |  Amplification coefficient | 
_fee |  uint256 |  Trade fee, given as an integer with 1e10 precision |  
_offpeg_fee_multiplier |  uint256 |  Off-peg fee multiplier | 
_ma_exp_time |  uint256 |  MA time; set as time_in_seconds / ln(2) | 
_implementation_idx |  uint256 |  Index of the implementation to use | 
_asset_types |  DynArray[uint8, MAX_COINS] |  Asset type of the pool as an integer; more here | 
_method_ids |  DynArray[bytes4, MAX_COINS] |  Array of first four bytes of the Keccak-256 hash of the function signatures of the oracle addresses that give rate oracles | 
_oracles |  DynArray[address, MAX_COINS] |  Array of rate oracle addresses | 
Implementation ID
There might be multiple pool implementations. To query all available ones, see here. As of the current date (31.10.2023), there is only one pool implementation available. Since the _implementation_idx starts at 0, users need to input "0" when deploying a pool.
Source code
event PlainPoolDeployed:
    coins: DynArray[address, MAX_COINS]
    A: uint256
    fee: uint256
    deployer: address
MAX_COINS: constant(uint256) = 8
MAX_FEE: constant(uint256) = 5 * 10 ** 9
FEE_DENOMINATOR: constant(uint256) = 10 ** 10
@external
def deploy_plain_pool(
    _name: String[32],
    _symbol: String[10],
    _coins: DynArray[address, MAX_COINS],
    _A: uint256,
    _fee: uint256,
    _offpeg_fee_multiplier: uint256,
    _ma_exp_time: uint256,
    _implementation_idx: uint256,
    _asset_types: DynArray[uint8, MAX_COINS],
    _method_ids: DynArray[bytes4, MAX_COINS],
    _oracles: DynArray[address, MAX_COINS],
) -> address:
    """
    @notice Deploy a new plain pool
    @param _name Name of the new plain pool
    @param _symbol Symbol for the new plain pool - will be
                concatenated with factory symbol
    @param _coins List of addresses of the coins being used in the pool.
    @param _A Amplification co-efficient - a lower value here means
            less tolerance for imbalance within the pool's assets.
            Suggested values include:
            * Uncollateralized algorithmic stablecoins: 5-10
            * Non-redeemable, collateralized assets: 100
            * Redeemable assets: 200-400
    @param _fee Trade fee, given as an integer with 1e10 precision. The
                maximum is 1% (100000000). 50% of the fee is distributed to veCRV holders.
    @param _ma_exp_time Averaging window of oracle. Set as time_in_seconds / ln(2)
                        Example: for 10 minute EMA, _ma_exp_time is 600 / ln(2) ~= 866
    @param _implementation_idx Index of the implementation to use
    @param _asset_types Asset types for pool, as an integer
    @param _method_ids Array of first four bytes of the Keccak-256 hash of the function signatures
                    of the oracle addresses that gives rate oracles.
                    Calculated as: keccak(text=event_signature.replace(" ", ""))[:4]
    @param _oracles Array of rate oracle addresses.
    @return Address of the deployed pool
    """
    assert len(_coins) >= 2  # dev: pool needs to have at least two coins!
    assert len(_coins) == len(_method_ids)  # dev: All coin arrays should be same length
    assert len(_coins) ==  len(_oracles)  # dev: All coin arrays should be same length
    assert len(_coins) ==  len(_asset_types)  # dev: All coin arrays should be same length
    assert _fee <= 100000000, "Invalid fee"
    assert _offpeg_fee_multiplier * _fee <= MAX_FEE * FEE_DENOMINATOR
    n_coins: uint256 = len(_coins)
    _rate_multipliers: DynArray[uint256, MAX_COINS] = empty(DynArray[uint256, MAX_COINS])
    decimals: DynArray[uint256, MAX_COINS] = empty(DynArray[uint256, MAX_COINS])
    for i in range(MAX_COINS):
        if i == n_coins:
            break
        coin: address = _coins[i]
        decimals.append(ERC20(coin).decimals())
        assert decimals[i] < 19, "Max 18 decimals for coins"
        _rate_multipliers.append(10 ** (36 - decimals[i]))
        for j in range(i, i + MAX_COINS):
            if (j + 1) == n_coins:
                break
            assert coin != _coins[j+1], "Duplicate coins"
    implementation: address = self.pool_implementations[_implementation_idx]
    assert implementation != empty(address), "Invalid implementation index"
    pool: address = create_from_blueprint(
        implementation,
        _name,                                          # _name: String[32]
        _symbol,                                        # _symbol: String[10]
        _A,                                             # _A: uint256
        _fee,                                           # _fee: uint256
        _offpeg_fee_multiplier,                         # _offpeg_fee_multiplier: uint256
        _ma_exp_time,                                   # _ma_exp_time: uint256
        _coins,                                         # _coins: DynArray[address, MAX_COINS]
        _rate_multipliers,                              # _rate_multipliers: DynArray[uint256, MAX_COINS]
        _asset_types,                                   # _asset_types: DynArray[uint8, MAX_COINS]
        _method_ids,                                    # _method_ids: DynArray[bytes4, MAX_COINS]
        _oracles,                                       # _oracles: DynArray[address, MAX_COINS]
        code_offset=3
    )
    length: uint256 = self.pool_count
    self.pool_list[length] = pool
    self.pool_count = length + 1
    self.pool_data[pool].decimals = decimals
    self.pool_data[pool].n_coins = n_coins
    self.pool_data[pool].base_pool = empty(address)
    self.pool_data[pool].implementation = implementation
    self.pool_data[pool].asset_types = _asset_types
    for i in range(MAX_COINS):
        if i == n_coins:
            break
        coin: address = _coins[i]
        self.pool_data[pool].coins.append(coin)
        for j in range(i, i + MAX_COINS):
            if (j + 1) == n_coins:
                break
            swappable_coin: address = _coins[j + 1]
            key: uint256 = (convert(coin, uint256) ^ convert(swappable_coin, uint256))
            length = self.market_counts[key]
            self.markets[key][length] = pool
            self.market_counts[key] = length + 1
    log PlainPoolDeployed(_coins, _A, _fee, msg.sender)
    return pool
>>> Factory.deploy_plain_pool(
    "crvUSD/USDT",  # _name
    "crvusd-usdt",  # _symbol
    [ # coins:
        "0xf939E0A03FB07F59A73314E73794Be0E57ac1b4E", # crvusd 
        "0xdAC17F958D2ee523a2206206994597C13D831ec7" # usdt
    ],
    1500 # _A
    1000000, # _fee
    20000000000, # _offpeg_fee_multiplier
    865, # _ma_exp_time
    0, # _implementation_idx
    [0, 0], # _asset_types
    [b"", b""], # _method_ids
    ["0x0000000000000000000000000000000000000000", "0x0000000000000000000000000000000000000000"] # _oracles
)
'returns address of the deployed plain pool'  
deploy_metapool¶
 Limitations when deploying meta pools:
- Cannot pair against a token that is included in the base pool.
 _fee≤ 100000000 (1%)._offpeg_fee_multiplier*_fee≤MAX_FEE*FEE_DENOMINATOR.- Valid implementation index.
 - Maximum of 18 decimals for a coin.
 
Factory.deploy_metapool(_base_pool: address, _name: String[32], _symbol: String[10], _coin: address, _A: uint256, _fee: uint256, _offpeg_fee_multiplier: uint256, _ma_exp_time: uint256, _implementation_idx: uint256, _asset_type: uint8, _method_id: bytes4, _oracle: address) -> address:
Function to deploy a stableswap-ng metapool.
Returns: Deployed metapool (address).
Emits: MetaPoolDeployed
| Input | Type | Description | 
|---|---|---|
_base_pool |  address |  Address of the base pool to pair the token with | 
_name |  String[32] |  Name of the new metapool | 
_symbol |  String[10] |  Symbol for the new metapool’s LP token - will be concatenated with the base pool symbol | 
_coin |  address |  Address of the coin being used in the metapool | 
_A |  uint256 |  Amplification coefficient | 
_fee |  uint256 |  Trade fee, given as an integer with 1e10 precision |  
_offpeg_fee_multiplier |  uint256 |  Off-peg multiplier | 
_ma_exp_time |  uint256 |  MA time; set as time_in_seconds / ln(2) | 
_implementation_idx |  uint256 |  Index of the implementation to use | 
_asset_type |  uint8 |  Asset type of the pool as an integer; more here | 
_method_id |  bytes4 |  First four bytes of the Keccak-256 hash of the function signatures of the oracle addresses that give rate oracles | 
_oracle |  address |  Rate oracle address | 
Implementation ID
There might be multiple metapool implementations. To query all available ones, see here. As of the current date (31.10.2023), there is only one metapool implementation available. Since the _implementation_idx starts at 0, users need to input "0" when deploying a pool.
Source code
event MetaPoolDeployed:
    coin: address
    base_pool: address
    A: uint256
    fee: uint256
    deployer: address
MAX_COINS: constant(uint256) = 8
MAX_FEE: constant(uint256) = 5 * 10 ** 9
FEE_DENOMINATOR: constant(uint256) = 10 ** 10
@external
def deploy_metapool(
    _base_pool: address,
    _name: String[32],
    _symbol: String[10],
    _coin: address,
    _A: uint256,
    _fee: uint256,
    _offpeg_fee_multiplier: uint256,
    _ma_exp_time: uint256,
    _implementation_idx: uint256,
    _asset_type: uint8,
    _method_id: bytes4,
    _oracle: address,
) -> address:
    """
    @notice Deploy a new metapool
    @param _base_pool Address of the base pool to use
                    within the metapool
    @param _name Name of the new metapool
    @param _symbol Symbol for the new metapool - will be
                concatenated with the base pool symbol
    @param _coin Address of the coin being used in the metapool
    @param _A Amplification co-efficient - a higher value here means
            less tolerance for imbalance within the pool's assets.
            Suggested values include:
            * Uncollateralized algorithmic stablecoins: 5-10
            * Non-redeemable, collateralized assets: 100
            * Redeemable assets: 200-400
    @param _fee Trade fee, given as an integer with 1e10 precision. The
                the maximum is 1% (100000000).
                50% of the fee is distributed to veCRV holders.
    @param _ma_exp_time Averaging window of oracle. Set as time_in_seconds / ln(2)
                        Example: for 10 minute EMA, _ma_exp_time is 600 / ln(2) ~= 866
    @param _implementation_idx Index of the implementation to use
    @param _asset_type Asset type for token, as an integer
    @param _method_id  First four bytes of the Keccak-256 hash of the function signatures
                    of the oracle addresses that gives rate oracles.
                    Calculated as: keccak(text=event_signature.replace(" ", ""))[:4]
    @param _oracle Rate oracle address.
    @return Address of the deployed pool
    """
    assert not self.base_pool_assets[_coin], "Invalid asset: Cannot pair base pool asset with base pool's LP token"
    assert _fee <= 100000000, "Invalid fee"
    assert _offpeg_fee_multiplier * _fee <= MAX_FEE * FEE_DENOMINATOR
    base_pool_n_coins: uint256 = len(self.base_pool_data[_base_pool].coins)
    assert base_pool_n_coins != 0, "Base pool is not added"
    implementation: address = self.metapool_implementations[_implementation_idx]
    assert implementation != empty(address), "Invalid implementation index"
    # things break if a token has >18 decimals
    decimals: uint256 = ERC20(_coin).decimals()
    assert decimals < 19, "Max 18 decimals for coins"
    # combine _coins's _asset_type and basepool coins _asset_types:
    base_pool_asset_types: DynArray[uint8, MAX_COINS] = self.base_pool_data[_base_pool].asset_types
    asset_types: DynArray[uint8, MAX_COINS]  = [_asset_type, 0]
    for i in range(0, MAX_COINS):
        if i == base_pool_n_coins:
            break
        asset_types.append(base_pool_asset_types[i])
    _coins: DynArray[address, MAX_COINS] = [_coin, self.base_pool_data[_base_pool].lp_token]
    _rate_multipliers: DynArray[uint256, MAX_COINS] = [10 ** (36 - decimals), 10 ** 18]
    _method_ids: DynArray[bytes4, MAX_COINS] = [_method_id, empty(bytes4)]
    _oracles: DynArray[address, MAX_COINS] = [_oracle, empty(address)]
    pool: address = create_from_blueprint(
        implementation,
        _name,                                          # _name: String[32]
        _symbol,                                        # _symbol: String[10]
        _A,                                             # _A: uint256
        _fee,                                           # _fee: uint256
        _offpeg_fee_multiplier,                         # _offpeg_fee_multiplier: uint256
        _ma_exp_time,                                   # _ma_exp_time: uint256
        self.math_implementation,                       # _math_implementation: address
        _base_pool,                                     # _base_pool: address
        _coins,                                         # _coins: DynArray[address, MAX_COINS]
        self.base_pool_data[_base_pool].coins,          # base_coins: DynArray[address, MAX_COINS]
        _rate_multipliers,                              # _rate_multipliers: DynArray[uint256, MAX_COINS]
        asset_types,                                    # asset_types: DynArray[uint8, MAX_COINS]
        _method_ids,                                    # _method_ids: DynArray[bytes4, MAX_COINS]
        _oracles,                                       # _oracles: DynArray[address, MAX_COINS]
        code_offset=3
    )
    # add pool to pool_list
    length: uint256 = self.pool_count
    self.pool_list[length] = pool
    self.pool_count = length + 1
    base_lp_token: address = self.base_pool_data[_base_pool].lp_token
    self.pool_data[pool].decimals = [decimals, 18, 0, 0, 0, 0, 0, 0]
    self.pool_data[pool].n_coins = 2
    self.pool_data[pool].base_pool = _base_pool
    self.pool_data[pool].coins = [_coin, self.base_pool_data[_base_pool].lp_token]
    self.pool_data[pool].implementation = implementation
    is_finished: bool = False
    swappable_coin: address = empty(address)
    for i in range(MAX_COINS):
        if i < len(self.base_pool_data[_base_pool].coins):
            swappable_coin = self.base_pool_data[_base_pool].coins[i]
        else:
            is_finished = True
            swappable_coin = base_lp_token
        key: uint256 = (convert(_coin, uint256) ^ convert(swappable_coin, uint256))
        length = self.market_counts[key]
        self.markets[key][length] = pool
        self.market_counts[key] = length + 1
        if is_finished:
            break
    log MetaPoolDeployed(_coin, _base_pool, _A, _fee, msg.sender)
    return pool
>>> Factory.deploy_metapool(
    "0xbebc44782c7db0a1a60cb6fe97d0b483032ff1c7", # _base_pool
    "crvUSD/3CRV", # _name
    "crvusd-3crv" # _symbol
    "0xf939E0A03FB07F59A73314E73794Be0E57ac1b4E", # _coin
    1500 # _A
    1000000, # _fee
    20000000000, # _offpeg_fee_multiplier
    865, # _ma_exp_time
    0, # _implementation_idx
    0, # _asset_type
    "b""", # _method_id
    "0x0000000000000000000000000000000000000000" # _oracle
)
'returns address of the deployed metapool'   
Deploying Liquidity Gauges¶
Info
Liquidity gauges can only be successfully deployed from the same contract from which the pool was deployed!
deploy_gauge¶
 Factory.deploy_gauge(_pool: address) -> address:
Function to deploy a gauge. The Factory utilizes the gauge_implementation to create the contract from a blueprint.
Returns: Deployed gauge (address).
Emits: LiquidityGaugeDeployed
| Input | Type | Description | 
|---|---|---|
_pool |  address |  Pool address to deploy the gauge for | 
Source code
event LiquidityGaugeDeployed:
    pool: address
    gauge: address
@external
def deploy_gauge(_pool: address) -> address:
    """
    @notice Deploy a liquidity gauge for a factory pool
    @param _pool Factory pool address to deploy a gauge for
    @return Address of the deployed gauge
    """
    assert self.pool_data[_pool].coins[0] != empty(address), "Unknown pool"
    assert self.pool_data[_pool].liquidity_gauge == empty(address), "Gauge already deployed"
    implementation: address = self.gauge_implementation
    assert implementation != empty(address), "Gauge implementation not set"
    gauge: address = create_from_blueprint(self.gauge_implementation, _pool, code_offset=3)
    self.pool_data[_pool].liquidity_gauge = gauge
    log LiquidityGaugeDeployed(_pool, gauge)
    return gauge