fix(wallets): subtract the estimated onchain fee from sendAll sweeps (#270)

src/app/wallets/get-send-all-onchain-amount.ts

@@ -0,0 +1,61 @@
+import { USDAmount } from "@domain/shared"
+
+import Ibex from "@services/ibex/client"
+import { IbexError } from "@services/ibex/errors"
+import { baseLogger } from "@services/logger"
+
+// #270: `onChainPaymentSendAll` handed IBEX the entire wallet balance, and IBEX
+// charges the on-chain fee on top of the amount it forwards. A full-balance
+// request therefore either fails at the rail or leaves dust behind instead of
+// sweeping the wallet. Estimate the fee for this payout and subtract it so the
+// sweep lands.
+//
+// A failed estimate is not a reason to refuse the send: every branch below
+// returns a usable amount, and the caller keeps the pre-existing behaviour
+// (whole balance) when the rail has nothing to say about the fee.
+export const getSendAllOnChainAmount = async ({
+  amount,
+  address,
+}: {
+  amount: USDAmount
+  address: OnChainAddress
+}): Promise<USDAmount> => {
+  const resp = await Ibex.estimateOnchainFee(amount, address)
+  if (resp instanceof IbexError) {
+    baseLogger.warn(
+      { address, message: resp.message },
+      "Onchain fee estimate unavailable for sendAll; sweeping the full balance",
+    )
+    return amount
+  }
+
+  const fee = resp.fee === undefined ? Number.NaN : Number(resp.fee)
+  if (!Number.isFinite(fee) || fee <= 0) {
+    baseLogger.warn(
+      { address, fee: resp.fee },
+      "Onchain fee estimate returned no fee for sendAll; sweeping the full balance",
+    )
+    return amount
+  }
+
+  const feeAmount = USDAmount.dollars(fee)
+  if (feeAmount instanceof Error) {
+    baseLogger.warn(
+      { address, fee, message: feeAmount.message },
+      "Could not parse the onchain fee estimate for sendAll; sweeping the full balance",
+    )
+    return amount
+  }
+
+  // A fee that eats the whole balance is not a sendable sweep: sending
+  // `amount - fee` would be zero or negative, which the rail refuses anyway.
+  if (!amount.isGreaterThan(feeAmount)) {
+    baseLogger.warn(
+      { address, fee },
+      "Onchain fee covers the whole balance for sendAll; nothing left to sweep",
+    )
+    return amount
+  }
+
+  return amount.subtract(feeAmount)
+}

src/app/wallets/index.ts

@@ -1,41 +1,42 @@
-export * from "./add-invoice-for-wallet"
-export * from "./add-pending-on-chain-transaction"
-export * from "./remove-pending-on-chain-transaction"
-export * from "./add-settled-on-chain-transaction"
-export * from "./create-on-chain-address"
-export * from "./get-balance-for-wallet"
-export * from "./get-last-on-chain-address"
-export * from "./get-on-chain-fee"
-export * from "./get-pending-onchain-balance-for-wallet"
-export * from "./get-transaction-by-id"
-export * from "./get-transactions-by-addresses"
-export * from "./get-transactions-by-hash"
-export * from "./get-transactions-for-wallet"
-export * from "./send-on-chain"
-export * from "./register-broadcasted-payout-txn"
-export * from "./settle-payout-txn"
-export * from "./update-legacy-on-chain-receipt"
-export * from "./update-pending-invoices"
-export * from "./validate"
-export * from "./usd-wallet-amount"
-
-import { WalletsRepository } from "@services/mongoose"
-
-export const getWallet = async (walletId: WalletId) => {
-  const wallets = WalletsRepository()
-  return wallets.findById(walletId)
-}
-
-export const listWalletsByAccountId = async (
-  accountId: AccountId,
-): Promise<Wallet[] | RepositoryError> => {
-  return WalletsRepository().listByAccountId(accountId)
-}
-
-export const listWalletIds = async (
-  walletCurrency: WalletCurrency,
-): Promise<WalletId[] | RepositoryError> => {
-  const wallets = await WalletsRepository().listByWalletCurrency(walletCurrency)
-  if (wallets instanceof Error) return wallets
-  return wallets.map((wallet) => wallet.id)
-}
+export * from "./add-invoice-for-wallet"
+export * from "./add-pending-on-chain-transaction"
+export * from "./remove-pending-on-chain-transaction"
+export * from "./add-settled-on-chain-transaction"
+export * from "./create-on-chain-address"
+export * from "./get-balance-for-wallet"
+export * from "./get-last-on-chain-address"
+export * from "./get-on-chain-fee"
+export * from "./get-pending-onchain-balance-for-wallet"
+export * from "./get-transaction-by-id"
+export * from "./get-transactions-by-addresses"
+export * from "./get-transactions-by-hash"
+export * from "./get-transactions-for-wallet"
+export * from "./get-send-all-onchain-amount"
+export * from "./send-on-chain"
+export * from "./register-broadcasted-payout-txn"
+export * from "./settle-payout-txn"
+export * from "./update-legacy-on-chain-receipt"
+export * from "./update-pending-invoices"
+export * from "./validate"
+export * from "./usd-wallet-amount"
+
+import { WalletsRepository } from "@services/mongoose"
+
+export const getWallet = async (walletId: WalletId) => {
+  const wallets = WalletsRepository()
+  return wallets.findById(walletId)
+}
+
+export const listWalletsByAccountId = async (
+  accountId: AccountId,
+): Promise<Wallet[] | RepositoryError> => {
+  return WalletsRepository().listByAccountId(accountId)
+}
+
+export const listWalletIds = async (
+  walletCurrency: WalletCurrency,
+): Promise<WalletId[] | RepositoryError> => {
+  const wallets = await WalletsRepository().listByWalletCurrency(walletCurrency)
+  if (wallets instanceof Error) return wallets
+  return wallets.map((wallet) => wallet.id)
+}