fix(sdk): use six decimals for Arc and Stable Chain offers

src/sdk.ts

@@ -12,6 +12,7 @@ import {
   getDefaultConduit,
   getListingPaymentToken,
   getOfferPaymentToken,
+  getOfferPaymentTokenDecimals,
   getSeaportAddress,
 } from "./utils/utils"
 
@@ -62,7 +63,8 @@ export class OpenSeaSDK extends BaseOpenSeaSDK {
     })
 
     const cachedPaymentTokenDecimals: { [address: string]: number } = {}
-    cachedPaymentTokenDecimals[getOfferPaymentToken(chain).toLowerCase()] = 18
+    cachedPaymentTokenDecimals[getOfferPaymentToken(chain).toLowerCase()] =
+      getOfferPaymentTokenDecimals(chain)
     cachedPaymentTokenDecimals[getListingPaymentToken(chain).toLowerCase()] = 18
 
     super({

src/utils/chain.ts

@@ -118,6 +118,17 @@ export const getOfferPaymentToken = (chain: Chain) => {
   }
 }
 
+/** Returns the decimals for the chain's default offer currency. */
+export const getOfferPaymentTokenDecimals = (chain: Chain): number => {
+  switch (chain) {
+    case Chain.Arc:
+    case Chain.StableChain:
+      return 6
+    default:
+      return 18
+  }
+}
+
 /**
  * Returns the default currency for listings on the given chain.
  * @param chain The chain to get the listing payment token for

src/viem.ts

@@ -34,6 +34,7 @@ import {
   getDefaultConduit,
   getListingPaymentToken,
   getOfferPaymentToken,
+  getOfferPaymentTokenDecimals,
   getSeaportAddress,
 } from "./utils/utils"
 
@@ -101,7 +102,8 @@ export class OpenSeaSDK extends BaseOpenSeaSDK {
     })
 
     const cachedPaymentTokenDecimals: { [address: string]: number } = {}
-    cachedPaymentTokenDecimals[getOfferPaymentToken(chain).toLowerCase()] = 18
+    cachedPaymentTokenDecimals[getOfferPaymentToken(chain).toLowerCase()] =
+      getOfferPaymentTokenDecimals(chain)
     cachedPaymentTokenDecimals[getListingPaymentToken(chain).toLowerCase()] = 18
 
     super({

test/sdk/getPriceParameters.spec.ts

@@ -1,6 +1,11 @@
+import { ethers } from "ethers"
+import { createPublicClient, defineChain, http } from "viem"
 import { describe, expect, test, vi } from "vitest"
+import { OpenSeaSDK } from "../../src"
 import { ZERO_ADDRESS } from "../../src/constants"
-import { OrderSide } from "../../src/types"
+import { Chain, OrderSide } from "../../src/types"
+import { getChainId, getOfferPaymentToken } from "../../src/utils"
+import { OpenSeaSDK as ViemSDK } from "../../src/viem"
 import { sdk } from "../utils/sdk"
 
 describe("SDK: _getPriceParameters", () => {
@@ -27,4 +32,58 @@ describe("SDK: _getPriceParameters", () => {
       ),
     ).rejects.toThrow("Too many decimal places")
   })
+
+  describe.each([
+    ["Arc", Chain.Arc],
+    ["Stable Chain", Chain.StableChain],
+  ])("%s default offer currency", (_name, chain) => {
+    const chainId = Number(getChainId(chain))
+    const rpcUrl = "http://127.0.0.1:1"
+
+    test.each([
+      [
+        "ethers",
+        () =>
+          new OpenSeaSDK(
+            new ethers.JsonRpcProvider(rpcUrl, chainId, {
+              staticNetwork: true,
+            }),
+            { chain },
+          ),
+      ],
+      [
+        "viem",
+        () => {
+          const viemChain = defineChain({
+            id: chainId,
+            name: chain,
+            nativeCurrency: { name: "Native", symbol: "NATIVE", decimals: 18 },
+            rpcUrls: { default: { http: [rpcUrl] } },
+          })
+          return new ViemSDK(
+            {
+              publicClient: createPublicClient({
+                chain: viemChain,
+                transport: http(rpcUrl),
+              }),
+              rpcUrl,
+            },
+            { chain },
+          )
+        },
+      ],
+    ])("uses six decimals with the %s entrypoint", async (_entrypoint, createSDK) => {
+      const chainSDK = createSDK()
+      const getPaymentToken = vi.spyOn(chainSDK.api, "getPaymentToken")
+
+      await expect(
+        (chainSDK as any)._getPriceParameters(
+          OrderSide.OFFER,
+          getOfferPaymentToken(chain),
+          "1.5",
+        ),
+      ).resolves.toEqual({ basePrice: 1500000n })
+      expect(getPaymentToken).not.toHaveBeenCalled()
+    })
+  })
 })

test/utils/chain.spec.ts

@@ -25,6 +25,7 @@ import {
   getListingPaymentToken,
   getNativeWrapTokenAddress,
   getOfferPaymentToken,
+  getOfferPaymentTokenDecimals,
   getSeaportAddress,
   getSignedZone,
   usesAlternateProtocol,
@@ -269,6 +270,18 @@ describe("Utils: chain", () => {
     })
   })
 
+  describe("getOfferPaymentTokenDecimals", () => {
+    test("returns six for the Arc and Stable Chain offer mirrors", () => {
+      expect(getOfferPaymentTokenDecimals(Chain.Arc)).toBe(6)
+      expect(getOfferPaymentTokenDecimals(Chain.StableChain)).toBe(6)
+    })
+
+    test("returns 18 for existing wrapped-native offer currencies", () => {
+      expect(getOfferPaymentTokenDecimals(Chain.Mainnet)).toBe(18)
+      expect(getOfferPaymentTokenDecimals(Chain.Base)).toBe(18)
+    })
+  })
+
   describe("getListingPaymentToken", () => {
     test("returns ETH (0x0) for Mainnet", () => {
       expect(getListingPaymentToken(Chain.Mainnet)).toBe(ZERO_ADDRESS)