fix: apply same decimals + Math.round fixes to Privy example

Mirror of the wallet-adapter fixes:
- useUnifiedBalance: fetch actual mint decimals via getMint()
- useTransfer, useWrap, useUnwrap: Math.floor → Math.round

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: klausundklaus

toolkits/sign-with-privy/react/src/hooks/useTransfer.ts

@@ -39,7 +39,7 @@ export function useTransfer() {
       const owner = new PublicKey(ownerPublicKey);
       const mintPubkey = new PublicKey(mint);
       const recipient = new PublicKey(toAddress);
-      const tokenAmount = Math.floor(amount * Math.pow(10, decimals));
+      const tokenAmount = Math.round(amount * Math.pow(10, decimals));
 
       // Returns TransactionInstruction[][].
       // Each inner array is one transaction.

toolkits/sign-with-privy/react/src/hooks/useUnifiedBalance.ts

@@ -1,6 +1,6 @@
 import { useState, useCallback } from 'react';
 import { PublicKey, LAMPORTS_PER_SOL } from '@solana/web3.js';
-import { TOKEN_PROGRAM_ID, TOKEN_2022_PROGRAM_ID } from '@solana/spl-token';
+import { TOKEN_PROGRAM_ID, TOKEN_2022_PROGRAM_ID, getMint } from '@solana/spl-token';
 import { createRpc } from '@lightprotocol/stateless.js';
 import {
   getAssociatedTokenAddressInterface,
@@ -84,8 +84,21 @@ export function useUnifiedBalance() {
         // No Token 2022 accounts
       }
 
-      // 4. Hot balance from Light Token associated token account
+      // 4. Fetch actual decimals for each mint
       const mintKeys = [...mintMap.keys()];
+      await Promise.allSettled(
+        mintKeys.map(async (mintStr) => {
+          try {
+            const mint = new PublicKey(mintStr);
+            const mintInfo = await getMint(rpc, mint);
+            getOrCreate(mintStr).decimals = mintInfo.decimals;
+          } catch {
+            // Keep default decimals if mint fetch fails
+          }
+        }),
+      );
+
+      // 5. Hot balance from Light Token associated token account
       await Promise.allSettled(
         mintKeys.map(async (mintStr) => {
           try {
@@ -100,7 +113,7 @@ export function useUnifiedBalance() {
         }),
       );
 
-      // 5. Cold balance from compressed token accounts
+      // 6. Cold balance from compressed token accounts
       try {
         const compressed = await rpc.getCompressedTokenBalancesByOwnerV2(owner);
         for (const item of compressed.value.items) {
@@ -111,7 +124,7 @@ export function useUnifiedBalance() {
         // No compressed accounts
       }
 
-      // 6. Assemble TokenBalance[]
+      // 7. Assemble TokenBalance[]
       const result: TokenBalance[] = [];
 
       // SOL entry

toolkits/sign-with-privy/react/src/hooks/useUnwrap.ts

@@ -38,7 +38,7 @@ export function useUnwrap() {
 
       const owner = new PublicKey(ownerPublicKey);
       const mintPubkey = new PublicKey(mint);
-      const tokenAmount = BigInt(Math.floor(amount * Math.pow(10, decimals)));
+      const tokenAmount = BigInt(Math.round(amount * Math.pow(10, decimals)));
 
       // Auto-detect token program (SPL vs T22) from mint account owner
       const mintAccountInfo = await rpc.getAccountInfo(mintPubkey);

toolkits/sign-with-privy/react/src/hooks/useWrap.ts

@@ -40,7 +40,7 @@ export function useWrap() {
 
       const owner = new PublicKey(ownerPublicKey);
       const mintPubkey = new PublicKey(mint);
-      const tokenAmount = BigInt(Math.floor(amount * Math.pow(10, decimals)));
+      const tokenAmount = BigInt(Math.round(amount * Math.pow(10, decimals)));
 
       // Get SPL interface info — determines whether mint uses SPL or T22
       const splInterfaceInfos = await getSplInterfaceInfos(rpc, mintPubkey);