fix: resolve 404 balances endpoint and currency formatting errors

- Add missing /api/v1/balances endpoint to backend
- Update frontend Account type to match backend AccountDetails model
- Add currency validation with EUR fallback in formatCurrency function
- Update AccountsOverview, TransactionsList, and Dashboard components
- Fix balance calculations to use balances array structure
- All pre-commit checks pass

frontend/src/components/AccountsOverview.tsx

@@ -61,9 +61,13 @@ export default function AccountsOverview() {
     );
   }
 
-  const totalBalance = accounts?.reduce((sum, account) => sum + (account.balance || 0), 0) || 0;
+  const totalBalance = accounts?.reduce((sum, account) => {
+    // Get the first available balance from the balances array
+    const primaryBalance = account.balances?.[0]?.amount || 0;
+    return sum + primaryBalance;
+  }, 0) || 0;
   const totalAccounts = accounts?.length || 0;
-  const uniqueBanks = new Set(accounts?.map(acc => acc.bank_name) || []).size;
+  const uniqueBanks = new Set(accounts?.map(acc => acc.institution_id) || []).size;
 
   return (
     <div className="space-y-6">
@@ -125,54 +129,57 @@ export default function AccountsOverview() {
           </div>
         ) : (
           <div className="divide-y divide-gray-200">
-            {accounts.map((account) => {
-              const accountBalance = balances?.find(b => b.account_id === account.id);
-              const balance = account.balance || accountBalance?.balance_amount || 0;
-              const isPositive = balance >= 0;
+             {accounts.map((account) => {
+               // Get balance from account's balances array or fallback to balances query
+               const accountBalance = account.balances?.[0];
+               const fallbackBalance = balances?.find(b => b.account_id === account.id);
+               const balance = accountBalance?.amount || fallbackBalance?.balance_amount || 0;
+               const currency = accountBalance?.currency || fallbackBalance?.currency || account.currency || 'EUR';
+               const isPositive = balance >= 0;
 
-              return (
-                <div key={account.id} className="p-6 hover:bg-gray-50 transition-colors">
-                  <div className="flex items-center justify-between">
-                    <div className="flex items-center space-x-4">
-                      <div className="p-3 bg-gray-100 rounded-full">
-                        <Building2 className="h-6 w-6 text-gray-600" />
-                      </div>
-                      <div>
-                        <h4 className="text-lg font-medium text-gray-900">
-                          {account.name}
-                        </h4>
-                        <p className="text-sm text-gray-600">
-                          {account.bank_name} • {account.account_type}
-                        </p>
-                        {account.iban && (
-                          <p className="text-xs text-gray-500 mt-1">
-                            IBAN: {account.iban}
-                          </p>
-                        )}
-                      </div>
-                    </div>
+               return (
+                 <div key={account.id} className="p-6 hover:bg-gray-50 transition-colors">
+                   <div className="flex items-center justify-between">
+                     <div className="flex items-center space-x-4">
+                       <div className="p-3 bg-gray-100 rounded-full">
+                         <Building2 className="h-6 w-6 text-gray-600" />
+                       </div>
+                       <div>
+                         <h4 className="text-lg font-medium text-gray-900">
+                           {account.name || 'Unnamed Account'}
+                         </h4>
+                         <p className="text-sm text-gray-600">
+                           {account.institution_id} • {account.status}
+                         </p>
+                         {account.iban && (
+                           <p className="text-xs text-gray-500 mt-1">
+                             IBAN: {account.iban}
+                           </p>
+                         )}
+                       </div>
+                     </div>
 
-                    <div className="text-right">
-                      <div className="flex items-center space-x-2">
-                        {isPositive ? (
-                          <TrendingUp className="h-4 w-4 text-green-500" />
-                        ) : (
-                          <TrendingDown className="h-4 w-4 text-red-500" />
-                        )}
-                        <p className={`text-lg font-semibold ${
-                          isPositive ? 'text-green-600' : 'text-red-600'
-                        }`}>
-                          {formatCurrency(balance, account.currency)}
-                        </p>
-                      </div>
-                      <p className="text-sm text-gray-500">
-                        Updated {formatDate(account.updated_at)}
-                      </p>
-                    </div>
-                  </div>
-                </div>
-              );
-            })}
+                     <div className="text-right">
+                       <div className="flex items-center space-x-2">
+                         {isPositive ? (
+                           <TrendingUp className="h-4 w-4 text-green-500" />
+                         ) : (
+                           <TrendingDown className="h-4 w-4 text-red-500" />
+                         )}
+                         <p className={`text-lg font-semibold ${
+                           isPositive ? 'text-green-600' : 'text-red-600'
+                         }`}>
+                           {formatCurrency(balance, currency)}
+                         </p>
+                       </div>
+                       <p className="text-sm text-gray-500">
+                         Updated {formatDate(account.last_accessed || account.created)}
+                       </p>
+                     </div>
+                   </div>
+                 </div>
+               );
+             })}
           </div>
         )}
       </div>

frontend/src/components/Dashboard.tsx

@@ -34,7 +34,11 @@ export default function Dashboard() {
     { name: 'Analytics', icon: BarChart3, id: 'analytics' as TabType },
   ];
 
-  const totalBalance = accounts?.reduce((sum, account) => sum + (account.balance || 0), 0) || 0;
+  const totalBalance = accounts?.reduce((sum, account) => {
+    // Get the first available balance from the balances array
+    const primaryBalance = account.balances?.[0]?.amount || 0;
+    return sum + primaryBalance;
+  }, 0) || 0;
 
   return (
     <div className="flex h-screen bg-gray-100">

frontend/src/components/TransactionsList.tsx

@@ -163,11 +163,11 @@ export default function TransactionsList() {
                   className="w-full border border-gray-300 rounded-md px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:border-blue-500"
                 >
                   <option value="">All accounts</option>
-                  {accounts?.map((account) => (
-                    <option key={account.id} value={account.id}>
-                      {account.name} ({account.bank_name})
-                    </option>
-                  ))}
+                   {accounts?.map((account) => (
+                     <option key={account.id} value={account.id}>
+                       {account.name || 'Unnamed Account'} ({account.institution_id})
+                     </option>
+                   ))}
                 </select>
               </div>
 
@@ -259,10 +259,10 @@ export default function TransactionsList() {
                           {transaction.description}
                         </h4>
 
-                        <div className="text-xs text-gray-500 space-y-1">
-                          {account && (
-                            <p>{account.name} • {account.bank_name}</p>
-                          )}
+                         <div className="text-xs text-gray-500 space-y-1">
+                           {account && (
+                             <p>{account.name || 'Unnamed Account'} • {account.institution_id}</p>
+                           )}
 
                           {(transaction.creditor_name || transaction.debtor_name) && (
                             <p>

frontend/src/lib/utils.ts

@@ -5,10 +5,22 @@ export function cn(...inputs: ClassValue[]) {
 }
 
 export function formatCurrency(amount: number, currency: string = 'EUR'): string {
-  return new Intl.NumberFormat('en-US', {
-    style: 'currency',
-    currency: currency,
-  }).format(amount);
+  // Validate currency code - must be 3 letters and a valid ISO 4217 code
+  const validCurrency = currency && /^[A-Z]{3}$/.test(currency) ? currency : 'EUR';
+
+  try {
+    return new Intl.NumberFormat('en-US', {
+      style: 'currency',
+      currency: validCurrency,
+    }).format(amount);
+  } catch (error) {
+    // Fallback if currency is still invalid
+    console.warn(`Invalid currency code: ${currency}, falling back to EUR`);
+    return new Intl.NumberFormat('en-US', {
+      style: 'currency',
+      currency: 'EUR',
+    }).format(amount);
+  }
 }
 
 export function formatDate(date: string): string {

frontend/src/types/api.ts

@@ -1,13 +1,20 @@
+export interface AccountBalance {
+  amount: number;
+  currency: string;
+  balance_type: string;
+  last_change_date?: string;
+}
+
 export interface Account {
   id: string;
-  name: string;
-  bank_name: string;
-  account_type: string;
-  currency: string;
-  balance?: number;
+  institution_id: string;
+  status: string;
   iban?: string;
-  created_at: string;
-  updated_at: string;
+  name?: string;
+  currency?: string;
+  created: string;
+  last_accessed?: string;
+  balances: AccountBalance[];
 }
 
 export interface Transaction {

leggend/api/routes/accounts.py

@@ -164,6 +164,56 @@ async def get_account_balances(account_id: str) -> APIResponse:
         ) from e
 
 
+@router.get("/balances", response_model=APIResponse)
+async def get_all_balances() -> APIResponse:
+    """Get all balances from all accounts in database"""
+    try:
+        # Get all accounts first to iterate through them
+        db_accounts = await database_service.get_accounts_from_db()
+
+        all_balances = []
+        for db_account in db_accounts:
+            try:
+                # Get balances for this account
+                db_balances = await database_service.get_balances_from_db(
+                    account_id=db_account["id"]
+                )
+
+                # Process balances and add account info
+                for balance in db_balances:
+                    balance_data = {
+                        "id": f"{db_account['id']}_{balance['type']}",  # Create unique ID
+                        "account_id": db_account["id"],
+                        "balance_amount": balance["amount"],
+                        "balance_type": balance["type"],
+                        "currency": balance["currency"],
+                        "reference_date": balance.get(
+                            "timestamp", db_account.get("last_accessed")
+                        ),
+                        "created_at": db_account.get("created"),
+                        "updated_at": db_account.get("last_accessed"),
+                    }
+                    all_balances.append(balance_data)
+
+            except Exception as e:
+                logger.error(
+                    f"Failed to get balances for account {db_account['id']}: {e}"
+                )
+                continue
+
+        return APIResponse(
+            success=True,
+            data=all_balances,
+            message=f"Retrieved {len(all_balances)} balances from {len(db_accounts)} accounts",
+        )
+
+    except Exception as e:
+        logger.error(f"Failed to get all balances: {e}")
+        raise HTTPException(
+            status_code=500, detail=f"Failed to get balances: {str(e)}"
+        ) from e
+
+
 @router.get("/accounts/{account_id}/transactions", response_model=APIResponse)
 async def get_account_transactions(
     account_id: str,