swap: handle native balance drift and low bridge amounts

src/swap/routing/exact-in.ts

@@ -1,6 +1,7 @@
 import Decimal from 'decimal.js';
 import { formatUnits, type Hex } from 'viem';
 import { Errors } from '../../domain/errors';
+import { formatTokenBalance } from '../../domain/utils/format';
 import { logger } from '../../domain/utils/logger';
 import { divDecimals, mulDecimals } from '../../services/math';
 import { MAYAN_MIN_USD_PER_LEG, selectMayanQuoteOutput } from '../../services/mayan';
@@ -221,7 +222,7 @@ const buildExactInBridge = async (input: {
       } = feeSummary;
       if (effectiveBridgedToDestination.lte(0)) {
         throw Errors.insufficientBalance(
-          `Bridge fees (${totalFeeAmount.toString()}) exceed bridged COT (${bridgedCOT.toString()})`
+          `Bridge fees (${formatTokenBalance(totalFeeAmount.toFixed())}) exceed bridged amount (${formatTokenBalance(bridgedCOT.toFixed())})`
         );
       }
 

src/swap/routing/fast-paths.ts

@@ -3,6 +3,7 @@ import { formatUnits, type Hex } from 'viem';
 import type { ChainListType } from '../../domain';
 import { ZERO_ADDRESS } from '../../domain/constants/addresses';
 import { Errors } from '../../domain/errors';
+import { formatTokenBalance } from '../../domain/utils/format';
 import { logger } from '../../domain/utils/logger';
 import { isNativeAddress } from '../../services/addresses';
 import { divDecimals, mulDecimals } from '../../services/math';
@@ -612,7 +613,7 @@ export async function buildSameTokenBridgeRoute(
     deliveredFromBridge = deliveredAmount;
     if (deliveredFromBridge.lte(0)) {
       throw Errors.insufficientBalance(
-        `Bridge fees (${totalFee.toString()}) exceed bridged amount (${bridgedToken.toString()})`
+        `Bridge fees (${formatTokenBalance(totalFee.toFixed())}) exceed bridged amount (${formatTokenBalance(bridgedToken.toFixed())})`
       );
     }
     // The fast path participates in provider selection too, querying the server with the actual

src/swap/routing/holdings.ts

@@ -2,7 +2,9 @@ import Decimal from 'decimal.js';
 import { type Hex, parseUnits } from 'viem';
 import type { ChainListType } from '../../domain';
 import { Errors } from '../../domain/errors';
+import { formatTokenBalance } from '../../domain/utils/format';
 import { logger } from '../../domain/utils/logger';
+import { isNativeAddress } from '../../services/addresses';
 import { divDecimals } from '../../services/math';
 import { equalFold } from '../../services/strings';
 import { filterMayanSourcesByChain } from '../algorithms/mayan-floor';
@@ -269,14 +271,18 @@ export function resolveExactInHoldings(
         entry.chainID === source.chainId && equalFold(entry.tokenAddress, source.tokenAddress)
     );
     if (!balance || new Decimal(balance.amount).lte(0)) {
-      throw Errors.insufficientBalance('Requested source has no usable balance');
+      throw Errors.insufficientBalance(
+        `Requested source ${source.tokenAddress} on chain ${source.chainId} has no usable balance`
+      );
     }
 
     const availableRaw = parseUnits(balance.amount, balance.decimals);
     const amountRaw = source.amountRaw ?? availableRaw;
 
-    if (amountRaw > availableRaw) {
-      throw Errors.insufficientBalance('Requested source amount exceeds available balance');
+    if (!isNativeAddress(source.tokenAddress) && amountRaw > availableRaw) {
+      throw Errors.insufficientBalance(
+        `Requested source (${balance.symbol}, ${source.chainId}) amount (${formatTokenBalance(divDecimals(amountRaw, balance.decimals).toFixed())}) exceeds available balance (${formatTokenBalance(divDecimals(availableRaw, balance.decimals).toFixed())})`
+      );
     }
 
     return amountRaw > 0n