fix: restore gateway spend script test coverage

lib/earn/format.ts

@@ -25,6 +25,7 @@ export function formatApy(decimal: number, fractionDigits = 2): string {
 export function formatCompactUsd(value: string | number): string {
   const n = typeof value === "string" ? Number(value) : value
   if (!Number.isFinite(n)) return "$0"
+  if (n === 0) return "$0"
   return new Intl.NumberFormat("en-US", {
     style: "currency",
     currency: "USD",

package.json

@@ -7,6 +7,7 @@
     "lint": "eslint .",
     "test": "vitest run",
     "test:watch": "vitest",
+    "spend:gateway:arc": "node scripts/spend-arc-gateway-usdc.mjs",
     "webhooks:register": "node scripts/register-gateway-webhooks.mjs",
     "db:start": "supabase start",
     "db:stop": "supabase stop",

scripts/spend-arc-gateway-usdc.mjs

@@ -0,0 +1,67 @@
+/**
+ * Copyright 2026 Circle Internet Group, Inc.  All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { AppKit } from "@circle-fin/app-kit"
+import { createCircleWalletsAdapter } from "@circle-fin/adapter-circle-wallets"
+
+export const CIRCLE_API_KEY = process.env.CIRCLE_API_KEY ?? ""
+export const CIRCLE_ENTITY_SECRET = process.env.CIRCLE_ENTITY_SECRET ?? ""
+export const ARC_SOURCE_ADDRESS =
+  process.env.ARC_SOURCE_ADDRESS ?? "0x1111111111111111111111111111111111111111"
+export const ARC_DELEGATE_ADDRESS =
+  process.env.ARC_DELEGATE_ADDRESS ?? "0x2222222222222222222222222222222222222222"
+export const ARC_RECIPIENT_ADDRESS =
+  process.env.ARC_RECIPIENT_ADDRESS ?? "0x3333333333333333333333333333333333333333"
+export const ARC_SPEND_AMOUNT = process.env.ARC_SPEND_AMOUNT ?? "0.002"
+
+const ARC_CHAIN = "Arc_Testnet"
+const TOKEN = "USDC"
+
+const kit = new AppKit()
+const adapter = createCircleWalletsAdapter({
+  apiKey: CIRCLE_API_KEY,
+  entitySecret: CIRCLE_ENTITY_SECRET,
+})
+
+const addDelegateResult = await kit.unifiedBalance.addDelegate({
+  from: {
+    adapter,
+    address: ARC_SOURCE_ADDRESS,
+    chain: ARC_CHAIN,
+  },
+  delegateAddress: ARC_DELEGATE_ADDRESS,
+})
+console.log(addDelegateResult)
+
+const balancesResult = await kit.unifiedBalance.getBalances({
+  token: TOKEN,
+  sources: { address: ARC_SOURCE_ADDRESS },
+  networkType: "testnet",
+})
+console.log(JSON.stringify(balancesResult, null, 2))
+
+const spendResult = await kit.unifiedBalance.spend({
+  from: {
+    adapter,
+    address: ARC_DELEGATE_ADDRESS,
+    sourceAccount: ARC_SOURCE_ADDRESS,
+    allocations: [{ amount: ARC_SPEND_AMOUNT, chain: ARC_CHAIN }],
+  },
+  to: {
+    chain: ARC_CHAIN,
+    recipientAddress: ARC_RECIPIENT_ADDRESS,
+    useForwarder: true,
+  },
+  token: TOKEN,
+  amount: ARC_SPEND_AMOUNT,
+})
+console.log(spendResult)