Fixed parsing of buy and sell amounts in pricing (#326)

Author: naddison36

docs/ACTIONS.md

@@ -17,8 +17,9 @@ The mainnet `setPrices*` actions use `--amount` as the DEX swap amount when
 fetching the reference price quote. This is separate from `--buy-amount` and
 `--sell-amount`, which set the buy-side liquidity-asset and sell-side base-asset
 liquidity remaining on the Ethena, USDC, and WETH ARMs. If omitted, each limit is
-set to the maximum `uint128` value. Liquidity amounts are integer native token
-units (for example, `100000000` is 100 tokens for an asset with 6 decimals).
+set to the maximum `uint128` value. Liquidity amounts are token-denominated:
+`1` is one liquidity or base token, with the appropriate token decimals applied
+by the action.
 
 `--buy-price` and `--sell-price` bypass DEX-derived pricing and set an exact
 pair. Both must be supplied together; `--amount` is not used in this mode.

src/js/tasks/actions/setPricesEthena.ts

@@ -32,15 +32,15 @@ action({
       )
       .addOptionalParam(
         "buyAmount",
-        "Liquidity asset amount remaining at the buy price for multi-base ARMs, as an integer in native token units.",
+        "USDe remaining at the buy price, in token units (1 = 1 USDe).",
         undefined,
-        types.string,
+        types.float,
       )
       .addOptionalParam(
         "sellAmount",
-        "Base asset amount remaining at the sell price for multi-base ARMs, as an integer in native token units.",
+        "sUSDe remaining at the sell price, in token units (1 = 1 sUSDe).",
         undefined,
-        types.string,
+        types.float,
       )
       .addOptionalParam(
         "maxBuyPrice",

src/js/tasks/actions/setPricesUSDC.ts

@@ -36,15 +36,15 @@ action({
       )
       .addOptionalParam(
         "buyAmount",
-        "Liquidity asset amount remaining at the buy price for multi-base ARMs, as an integer in native token units.",
+        "USDC remaining at the buy price, in token units (1 = 1 USDC).",
         undefined,
-        types.string,
+        types.float,
       )
       .addOptionalParam(
         "sellAmount",
-        "Base asset amount remaining at the sell price for multi-base ARMs, as an integer in native token units.",
+        "Base asset remaining at the sell price, in token units (1 = 1 token).",
         undefined,
-        types.string,
+        types.float,
       )
       .addOptionalParam(
         "maxBuyPrice",

src/js/tasks/actions/setPricesWETH.ts

@@ -56,15 +56,15 @@ action({
       )
       .addOptionalParam(
         "buyAmount",
-        "WETH remaining at the buy price, as an integer in native token units.",
+        "WETH remaining at the buy price, in token units (1 = 1 WETH).",
         undefined,
-        types.string,
+        types.float,
       )
       .addOptionalParam(
         "sellAmount",
-        "Base asset remaining at the sell price, as an integer in native token units.",
+        "Base asset remaining at the sell price, in token units (1 = 1 token).",
         undefined,
-        types.string,
+        types.float,
       )
       .addOptionalParam(
         "maxBuyPrice",

src/js/tasks/armPrices.js

@@ -88,6 +88,13 @@ const setPrices = async (options) => {
   // Base asset decimals used to scale aggregator quote amounts. Legacy ARM
   // configs don't expose baseAssetDecimals as all their assets are 18 decimals.
   const baseDecimals = Number(config.baseAssetDecimals ?? 18);
+  const liquidityDecimals = Number(
+    await new Contract(
+      liquidityAddress,
+      ["function decimals() view returns (uint8)"],
+      signer,
+    ).decimals(),
+  );
 
   log(`Getting current ARM prices:`);
   log(`base asset         : ${baseSymbol}`);
@@ -111,17 +118,6 @@ const setPrices = async (options) => {
         ? 10n
         : 30n;
 
-    // The liquidity asset decimals are not in the base asset config so read
-    // them on-chain. Can differ from the base asset decimals, eg an 18
-    // decimals base asset over a 6 decimals USDC liquidity asset.
-    const liquidityDecimals = Number(
-      await new Contract(
-        liquidityAddress,
-        ["function decimals() view returns (uint8)"],
-        signer,
-      ).decimals(),
-    );
-
     // 2.1 Get reference prices
     let referencePrices;
     if (midPrice) {
@@ -361,8 +357,8 @@ const setPrices = async (options) => {
   const toleranceScaled = parseUnits(tolerance.toString(), 36 - 4);
   log(`tolerance          : ${formatUnits(toleranceScaled, 32)} basis points`);
 
-  const targetBuyAmount = parseSwapCap(buyAmount);
-  const targetSellAmount = parseSwapCap(sellAmount);
+  const targetBuyAmount = parseSwapCap(buyAmount, liquidityDecimals);
+  const targetSellAmount = parseSwapCap(sellAmount, baseDecimals);
   const swapCapsChanged = haveSwapCapsChanged(
     baseContext,
     targetBuyAmount,

src/js/utils/arm.js

@@ -136,12 +136,10 @@ const getArmBaseSymbols = async ({ arm, armName, base, blockTag }) => {
   return [defaultBaseSymbol(armName)];
 };
 
-const parseSwapCap = (amount) => {
+const parseSwapCap = (amount, decimals = 18) => {
   if (amount === undefined || amount === null) return MAX_SWAP_LIQUIDITY;
   if (typeof amount === "bigint") return amount;
-  if (typeof amount === "number") return parseUnits(amount.toString(), 18);
-  const value = amount.toString();
-  return value.includes(".") ? parseUnits(value, 18) : BigInt(value);
+  return parseUnits(amount.toString(), decimals);
 };
 
 const toConfigObject = (config) => ({

test/js/armPrices.test.js

@@ -1,6 +1,25 @@
 const assert = require("assert");
 
 const { haveSwapCapsChanged } = require("../../src/js/utils/priceUpdate");
+const { parseSwapCap } = require("../../src/js/utils/arm");
+
+assert.strictEqual(
+  parseSwapCap("1", 18),
+  10n ** 18n,
+  "one 18-decimal token should not be parsed as one wei",
+);
+
+assert.strictEqual(
+  parseSwapCap("1", 6),
+  10n ** 6n,
+  "one 6-decimal token should use the token's native decimals",
+);
+
+assert.strictEqual(
+  parseSwapCap("1.5", 6),
+  1_500_000n,
+  "fractional token amounts should be supported",
+);
 
 const multiBaseContext = (buyLiquidityRemaining, sellLiquidityRemaining) => ({
   version: "multiBase",