Stableswap API

Protocol-specific classes for Curve-style Stableswap — the amplification-coefficient AMM optimized for stablecoin pairs. These live in stableswappy and are imported into DeFiPy’s namespace at install time.

When working through DeFiPy’s Core API, you typically don’t touch these classes directly — Join, Swap, AddLiquidity, RemoveLiquidity dispatch to them. You’ll reach for them when constructing a custom-A pool, evaluating depeg risk, or extending the library.

Public classes

Factory and exchange

Class	Module	Purpose
`StableswapFactory`	`stableswappy.cpt.factory`	Deploys stableswap pools.
`StableswapExchange`	`stableswappy.cpt.exchg`	The pool — token reserves, amplification coefficient `A`, fee config, pool-share supply.
`StableswapExchangeData`	`stableswappy.cpt.exchg`	Configuration: token list, A, fee, address.
`StableswapVault`	`stableswappy.cpt.vault`	Vault holding pool’s underlying tokens. Exchange tokens via `vault.get_token(name)`.

Math

Module / class	Purpose
`StableswapPoolMath`	The integer-math state solvers — `get_y`, `get_D`, `_dydx`. Newton iterations; can fail to converge at extreme balance ratios (no iteration cap in the current release).
`stableswappy.analytics.risk.StableswapImpLoss`	2-asset stableswap IL math with `DepegUnreachableError` semantics. Used by `AnalyzeStableswapPosition`, `SimulateStableswapPriceMove`, and `AssessDepegRisk`.

Conventions

Decimal-units for balances. math_pool.balances[i] is in each token’s native decimal units (USDC at 10⁶, DAI at 10¹⁸). Convert to human via dec2amt(balance, token_decimals).
The rates table is internal. Used to build xp (all tokens at 10¹⁸ scale for invariant math). Don’t pass through it twice when converting balance → human; that’s a known footgun.
dydx(0, 1, use_fee=False) returns 1.0 exactly at peg. Algebraically, when xi == xj the formula collapses to 1.0 — safe abs(dydx - 1.0) < 1e-12 short-circuit for at-peg detection.
Depeg unreachability is real. At high A, many depeg targets require |ε| > 1 and have no physical solution. Primitives raise DepegUnreachableError and analytics dataclasses surface Optional[float] fields that are None for unreachable scenarios.
2-asset only in v1. N-asset baskets work in Stableswap the protocol but DeFiPy’s analytics math is 2-asset for now.

Construction example

from defipy import *

usdc = ERC20("USDC", "0xa0b8")
dai = ERC20("DAI", "0x6b17")

# 2-asset USDC/DAI stableswap at A=10
factory = StableswapFactory("USDC-DAI factory", "0x2")
# ...exchange data construction with A, fee, decimals...
# lp = factory.deploy(exchg_data)

For a complete construction walkthrough see the Stableswap abstract-interface tutorial.