diff --git a/backend-api/src/config/database.ts b/backend-api/src/config/database.ts
index 7831e5b..bf45b87 100644
--- a/backend-api/src/config/database.ts
+++ b/backend-api/src/config/database.ts
@@ -12,9 +12,10 @@ class DatabaseConnection {
   public static getInstance(): PrismaClient {
     if (!DatabaseConnection.instance) {
       DatabaseConnection.instance = new PrismaClient({
-        log: process.env.NODE_ENV === 'development' ? ['query', 'error', 'warn'] : ['error']
+        log: process.env.NODE_ENV === 'development' ? ['query', 'error', 'warn'] : ['error'],
       });
     }
+
     return DatabaseConnection.instance;
   }
 
diff --git a/backend-api/src/controllers/AuthController.ts b/backend-api/src/controllers/AuthController.ts
index 44f2ee6..66c1a9b 100644
--- a/backend-api/src/controllers/AuthController.ts
+++ b/backend-api/src/controllers/AuthController.ts
@@ -55,7 +55,7 @@ export class AuthController {
       email: user.email
     });
 
-    const {password: _, ...userWithoutPassword} = user;
+    const {password: _password, ...userWithoutPassword} = user;
 
     return reply.send({
       user: userWithoutPassword,
diff --git a/backend-api/src/controllers/CashflowController.ts b/backend-api/src/controllers/CashflowController.ts
index c082256..96311ae 100644
--- a/backend-api/src/controllers/CashflowController.ts
+++ b/backend-api/src/controllers/CashflowController.ts
@@ -46,12 +46,14 @@ export class CashflowController {
     const userId = getUserId(request);
     const data = createIncomeSchema.parse(request.body);
     const income = await this.cashflowService.createIncome(userId, data);
+
     return reply.status(201).send({income});
   }
 
   async getAllIncome(request: FastifyRequest, reply: FastifyReply) {
     const userId = getUserId(request);
     const income = await this.cashflowService.getAllIncome(userId);
+
     return reply.send({income});
   }
 
@@ -59,6 +61,7 @@ export class CashflowController {
     const userId = getUserId(request);
     const {id} = request.params as {id: string};
     const income = await this.cashflowService.getIncomeById(id, userId);
+
     return reply.send({income});
   }
 
@@ -67,6 +70,7 @@ export class CashflowController {
     const {id} = request.params as {id: string};
     const data = updateIncomeSchema.parse(request.body);
     const income = await this.cashflowService.updateIncome(id, userId, data);
+
     return reply.send({income});
   }
 
@@ -74,12 +78,14 @@ export class CashflowController {
     const userId = getUserId(request);
     const {id} = request.params as {id: string};
     await this.cashflowService.deleteIncome(id, userId);
+
     return reply.status(204).send();
   }
 
   async getTotalMonthlyIncome(request: FastifyRequest, reply: FastifyReply) {
     const userId = getUserId(request);
     const total = await this.cashflowService.getTotalMonthlyIncome(userId);
+
     return reply.send({total});
   }
 
@@ -88,6 +94,7 @@ export class CashflowController {
     const userId = getUserId(request);
     const data = createExpenseSchema.parse(request.body);
     const expense = await this.cashflowService.createExpense(userId, data);
+
     return reply.status(201).send({expense});
   }
 
@@ -97,10 +104,12 @@ export class CashflowController {
 
     if (byCategory === 'true') {
       const expenses = await this.cashflowService.getExpensesByCategory(userId);
+
       return reply.send({expenses});
     }
 
     const expenses = await this.cashflowService.getAllExpenses(userId);
+
     return reply.send({expenses});
   }
 
@@ -108,6 +117,7 @@ export class CashflowController {
     const userId = getUserId(request);
     const {id} = request.params as {id: string};
     const expense = await this.cashflowService.getExpenseById(id, userId);
+
     return reply.send({expense});
   }
 
@@ -116,6 +126,7 @@ export class CashflowController {
     const {id} = request.params as {id: string};
     const data = updateExpenseSchema.parse(request.body);
     const expense = await this.cashflowService.updateExpense(id, userId, data);
+
     return reply.send({expense});
   }
 
@@ -123,12 +134,14 @@ export class CashflowController {
     const userId = getUserId(request);
     const {id} = request.params as {id: string};
     await this.cashflowService.deleteExpense(id, userId);
+
     return reply.status(204).send();
   }
 
   async getTotalMonthlyExpenses(request: FastifyRequest, reply: FastifyReply) {
     const userId = getUserId(request);
     const total = await this.cashflowService.getTotalMonthlyExpenses(userId);
+
     return reply.send({total});
   }
 
@@ -137,6 +150,7 @@ export class CashflowController {
     const userId = getUserId(request);
     const data = createTransactionSchema.parse(request.body);
     const transaction = await this.cashflowService.createTransaction(userId, data);
+
     return reply.status(201).send({transaction});
   }
 
@@ -150,15 +164,18 @@ export class CashflowController {
 
     if (type) {
       const transactions = await this.cashflowService.getTransactionsByType(userId, type);
+
       return reply.send({transactions});
     }
 
     if (startDate && endDate) {
       const transactions = await this.cashflowService.getTransactionsByDateRange(userId, new Date(startDate), new Date(endDate));
+
       return reply.send({transactions});
     }
 
     const transactions = await this.cashflowService.getAllTransactions(userId);
+
     return reply.send({transactions});
   }
 
@@ -166,6 +183,7 @@ export class CashflowController {
     const userId = getUserId(request);
     const {id} = request.params as {id: string};
     const transaction = await this.cashflowService.getTransactionById(id, userId);
+
     return reply.send({transaction});
   }
 
@@ -173,6 +191,7 @@ export class CashflowController {
     const userId = getUserId(request);
     const {id} = request.params as {id: string};
     await this.cashflowService.deleteTransaction(id, userId);
+
     return reply.status(204).send();
   }
 
diff --git a/backend-api/src/controllers/ClientController.ts b/backend-api/src/controllers/ClientController.ts
index 40b7287..7b13ed8 100644
--- a/backend-api/src/controllers/ClientController.ts
+++ b/backend-api/src/controllers/ClientController.ts
@@ -47,10 +47,12 @@ export class ClientController {
 
     if (withStats === 'true') {
       const clients = await this.clientService.getWithStats(userId);
+
       return reply.send({clients});
     }
 
     const clients = await this.clientService.getAllByUser(userId);
+
     return reply.send({clients});
   }
 
diff --git a/backend-api/src/controllers/DebtAccountController.ts b/backend-api/src/controllers/DebtAccountController.ts
index a51393b..49dfb34 100644
--- a/backend-api/src/controllers/DebtAccountController.ts
+++ b/backend-api/src/controllers/DebtAccountController.ts
@@ -61,15 +61,18 @@ export class DebtAccountController {
 
     if (categoryId) {
       const accounts = await this.accountService.getByCategory(categoryId, userId);
+
       return reply.send({accounts});
     }
 
     if (withStats === 'true') {
       const accounts = await this.accountService.getWithStats(userId);
+
       return reply.send({accounts});
     }
 
     const accounts = await this.accountService.getAllByUser(userId);
+
     return reply.send({accounts});
   }
 
diff --git a/backend-api/src/controllers/DebtCategoryController.ts b/backend-api/src/controllers/DebtCategoryController.ts
index a7aaf30..312c8b8 100644
--- a/backend-api/src/controllers/DebtCategoryController.ts
+++ b/backend-api/src/controllers/DebtCategoryController.ts
@@ -49,10 +49,12 @@ export class DebtCategoryController {
 
     if (withStats === 'true') {
       const categories = await this.categoryService.getWithStats(userId);
+
       return reply.send({categories});
     }
 
     const categories = await this.categoryService.getAllByUser(userId);
+
     return reply.send({categories});
   }
 
diff --git a/backend-api/src/controllers/DebtPaymentController.ts b/backend-api/src/controllers/DebtPaymentController.ts
index eb04b65..c532ddb 100644
--- a/backend-api/src/controllers/DebtPaymentController.ts
+++ b/backend-api/src/controllers/DebtPaymentController.ts
@@ -42,15 +42,18 @@ export class DebtPaymentController {
 
     if (accountId) {
       const payments = await this.paymentService.getByAccount(accountId, userId);
+
       return reply.send({payments});
     }
 
     if (startDate && endDate) {
       const payments = await this.paymentService.getByDateRange(userId, new Date(startDate), new Date(endDate));
+
       return reply.send({payments});
     }
 
     const payments = await this.paymentService.getAllByUser(userId);
+
     return reply.send({payments});
   }
 
diff --git a/backend-api/src/middleware/auth.ts b/backend-api/src/middleware/auth.ts
index 56c7bc4..805c95f 100644
--- a/backend-api/src/middleware/auth.ts
+++ b/backend-api/src/middleware/auth.ts
@@ -5,10 +5,10 @@ import {UnauthorizedError} from '../utils/errors';
  * Authentication Middleware
  * Verifies JWT token and attaches user to request
  */
-export async function authenticate(request: FastifyRequest, reply: FastifyReply) {
+export async function authenticate(request: FastifyRequest, _reply: FastifyReply) {
   try {
     await request.jwtVerify();
-  } catch (err) {
+  } catch (_err) {
     throw new UnauthorizedError('Invalid or expired token');
   }
 }
@@ -20,5 +20,6 @@ export function getUserId(request: FastifyRequest): string {
   if (!request.user || !request.user.id) {
     throw new UnauthorizedError('User not authenticated');
   }
+
   return request.user.id;
 }
diff --git a/backend-api/src/middleware/errorHandler.ts b/backend-api/src/middleware/errorHandler.ts
index 8a80713..c9041ea 100644
--- a/backend-api/src/middleware/errorHandler.ts
+++ b/backend-api/src/middleware/errorHandler.ts
@@ -38,7 +38,7 @@ export async function errorHandler(error: FastifyError, request: FastifyRequest,
 
   // Handle Prisma errors
   if (error.name === 'PrismaClientKnownRequestError') {
-    const prismaError = error as any;
+    const prismaError = error as FastifyError & {code?: string};
     if (prismaError.code === 'P2002') {
       return reply.status(409).send({
         error: 'ConflictError',
diff --git a/backend-api/src/repositories/AssetRepository.ts b/backend-api/src/repositories/AssetRepository.ts
index 105fc07..73c1d3c 100644
--- a/backend-api/src/repositories/AssetRepository.ts
+++ b/backend-api/src/repositories/AssetRepository.ts
@@ -16,7 +16,7 @@ export class AssetRepository {
     });
   }
 
-  async findAllByUser(userId: string, filters?: Record<string, any>): Promise<Asset[]> {
+  async findAllByUser(userId: string, filters?: Record<string, unknown>): Promise<Asset[]> {
     return prisma.asset.findMany({
       where: {userId, ...filters},
       orderBy: {createdAt: 'desc'}
@@ -43,6 +43,7 @@ export class AssetRepository {
       where: {userId},
       _sum: {value: true}
     });
+
     return result._sum.value || 0;
   }
 }
diff --git a/backend-api/src/repositories/CashflowRepository.ts b/backend-api/src/repositories/CashflowRepository.ts
index 17e7d1b..99c4d4c 100644
--- a/backend-api/src/repositories/CashflowRepository.ts
+++ b/backend-api/src/repositories/CashflowRepository.ts
@@ -39,6 +39,7 @@ export class IncomeSourceRepository {
       where: {userId},
       _sum: {amount: true}
     });
+
     return result._sum.amount || 0;
   }
 }
@@ -79,15 +80,18 @@ export class ExpenseRepository {
       where: {userId},
       _sum: {amount: true}
     });
+
     return result._sum.amount || 0;
   }
 
   async getByCategory(userId: string): Promise<Record<string, Expense[]>> {
     const expenses = await this.findAllByUser(userId);
+
     return expenses.reduce(
       (acc, expense) => {
         if (!acc[expense.category]) acc[expense.category] = [];
         acc[expense.category].push(expense);
+
         return acc;
       },
       {} as Record<string, Expense[]>
diff --git a/backend-api/src/repositories/ClientRepository.ts b/backend-api/src/repositories/ClientRepository.ts
index 40ba1c1..69ca69b 100644
--- a/backend-api/src/repositories/ClientRepository.ts
+++ b/backend-api/src/repositories/ClientRepository.ts
@@ -3,6 +3,17 @@ import {DatabaseConnection} from '../config/database';
 
 const prisma = DatabaseConnection.getInstance();
 
+export interface ClientStats {
+  totalInvoices: number;
+  paidInvoices: number;
+  totalRevenue: number;
+  outstandingAmount: number;
+}
+
+export interface ClientWithStats extends Client {
+  stats: ClientStats;
+}
+
 /**
  * Repository for Client data access
  * Implements Single Responsibility Principle - handles only database operations
@@ -97,7 +108,7 @@ export class ClientRepository {
   /**
    * Get clients with their invoice statistics
    */
-  async getWithStats(userId: string): Promise<any[]> {
+  async getWithStats(userId: string): Promise<ClientWithStats[]> {
     const clients = await prisma.client.findMany({
       where: {userId},
       include: {
diff --git a/backend-api/src/repositories/DebtAccountRepository.ts b/backend-api/src/repositories/DebtAccountRepository.ts
index 4b8d945..4978bfb 100644
--- a/backend-api/src/repositories/DebtAccountRepository.ts
+++ b/backend-api/src/repositories/DebtAccountRepository.ts
@@ -3,6 +3,17 @@ import {DatabaseConnection} from '../config/database';
 
 const prisma = DatabaseConnection.getInstance();
 
+export interface DebtAccountStats {
+  totalPaid: number;
+  numberOfPayments: number;
+  lastPaymentDate: Date | null;
+  lastPaymentAmount: number | null;
+}
+
+export interface DebtAccountWithStats extends DebtAccount {
+  stats: DebtAccountStats;
+}
+
 /**
  * Repository for DebtAccount data access
  * Implements Single Responsibility Principle - handles only database operations
@@ -101,7 +112,7 @@ export class DebtAccountRepository {
   /**
    * Get accounts with payment statistics
    */
-  async getWithStats(userId: string): Promise<any[]> {
+  async getWithStats(userId: string): Promise<DebtAccountWithStats[]> {
     const accounts = await prisma.debtAccount.findMany({
       where: {userId},
       include: {
diff --git a/backend-api/src/repositories/DebtCategoryRepository.ts b/backend-api/src/repositories/DebtCategoryRepository.ts
index ab9de57..fc8f597 100644
--- a/backend-api/src/repositories/DebtCategoryRepository.ts
+++ b/backend-api/src/repositories/DebtCategoryRepository.ts
@@ -4,6 +4,16 @@ import {IUserScopedRepository} from './interfaces/IRepository';
 
 const prisma = DatabaseConnection.getInstance();
 
+export interface DebtCategoryStats {
+  totalAccounts: number;
+  totalDebt: number;
+  totalPayments: number;
+}
+
+export interface DebtCategoryWithStats extends DebtCategory {
+  stats: DebtCategoryStats;
+}
+
 /**
  * Repository for DebtCategory data access
  * Implements Single Responsibility Principle - handles only database operations
@@ -91,7 +101,7 @@ export class DebtCategoryRepository implements IUserScopedRepository<DebtCategor
   /**
    * Get categories with debt statistics
    */
-  async getWithStats(userId: string): Promise<any[]> {
+  async getWithStats(userId: string): Promise<DebtCategoryWithStats[]> {
     const categories = await this.findAllByUser(userId);
 
     return Promise.all(
diff --git a/backend-api/src/repositories/InvoiceRepository.ts b/backend-api/src/repositories/InvoiceRepository.ts
index 6218686..00e5105 100644
--- a/backend-api/src/repositories/InvoiceRepository.ts
+++ b/backend-api/src/repositories/InvoiceRepository.ts
@@ -61,6 +61,7 @@ export class InvoiceRepository implements IUserScopedRepository<Invoice> {
         ...(excludeId && {id: {not: excludeId}})
       }
     });
+
     return count > 0;
   }
 
@@ -72,6 +73,7 @@ export class InvoiceRepository implements IUserScopedRepository<Invoice> {
         invoiceNumber: {startsWith: `INV-${year}-`}
       }
     });
+
     return `INV-${year}-${String(count + 1).padStart(3, '0')}`;
   }
 }
diff --git a/backend-api/src/repositories/LiabilityRepository.ts b/backend-api/src/repositories/LiabilityRepository.ts
index da8c336..de8ea82 100644
--- a/backend-api/src/repositories/LiabilityRepository.ts
+++ b/backend-api/src/repositories/LiabilityRepository.ts
@@ -73,6 +73,7 @@ export class LiabilityRepository {
           acc[type] = [];
         }
         acc[type].push(liability);
+
         return acc;
       },
       {} as Record<string, Liability[]>
diff --git a/backend-api/src/repositories/NetWorthSnapshotRepository.ts b/backend-api/src/repositories/NetWorthSnapshotRepository.ts
index c758a71..10b5c7d 100644
--- a/backend-api/src/repositories/NetWorthSnapshotRepository.ts
+++ b/backend-api/src/repositories/NetWorthSnapshotRepository.ts
@@ -4,6 +4,13 @@ import {IUserScopedRepository} from './interfaces/IRepository';
 
 const prisma = DatabaseConnection.getInstance();
 
+export interface GrowthStats {
+  date: Date;
+  netWorth: number;
+  growthAmount: number;
+  growthPercent: number;
+}
+
 /**
  * Repository for NetWorthSnapshot data access
  * Implements Single Responsibility Principle - handles only database operations
@@ -84,7 +91,7 @@ export class NetWorthSnapshotRepository implements IUserScopedRepository<NetWort
   /**
    * Get growth over time (percentage change between snapshots)
    */
-  async getGrowthStats(userId: string, limit: number = 12): Promise<any[]> {
+  async getGrowthStats(userId: string, limit: number = 12): Promise<GrowthStats[]> {
     const snapshots = await prisma.netWorthSnapshot.findMany({
       where: {userId},
       orderBy: {date: 'desc'},
diff --git a/backend-api/src/repositories/UserRepository.ts b/backend-api/src/repositories/UserRepository.ts
index d2ede5a..6007e7d 100644
--- a/backend-api/src/repositories/UserRepository.ts
+++ b/backend-api/src/repositories/UserRepository.ts
@@ -46,6 +46,7 @@ export class UserRepository implements IRepository<User> {
 
   async emailExists(email: string): Promise<boolean> {
     const count = await prisma.user.count({where: {email}});
+
     return count > 0;
   }
 }
diff --git a/backend-api/src/services/AssetService.ts b/backend-api/src/services/AssetService.ts
index e5a2fe9..7a48ce2 100644
--- a/backend-api/src/services/AssetService.ts
+++ b/backend-api/src/services/AssetService.ts
@@ -34,6 +34,7 @@ export class AssetService {
     if (!asset) {
       throw new NotFoundError('Asset not found');
     }
+
     return asset;
   }
 
@@ -80,6 +81,7 @@ export class AssetService {
 
   async getByType(userId: string): Promise<Record<string, Asset[]>> {
     const assets = await this.assetRepository.findAllByUser(userId);
+
     return assets.reduce(
       (acc, asset) => {
         const type = asset.type;
@@ -87,6 +89,7 @@ export class AssetService {
           acc[type] = [];
         }
         acc[type].push(asset);
+
         return acc;
       },
       {} as Record<string, Asset[]>
diff --git a/backend-api/src/services/AuthService.ts b/backend-api/src/services/AuthService.ts
index e6ce55f..62d64e8 100644
--- a/backend-api/src/services/AuthService.ts
+++ b/backend-api/src/services/AuthService.ts
@@ -40,7 +40,8 @@ export class AuthService {
     await this.debtCategoryService.createDefaultCategories(user.id);
 
     // Return user without password
-    const {password: _, ...userWithoutPassword} = user;
+    const {password: _password, ...userWithoutPassword} = user;
+
     return userWithoutPassword;
   }
 
@@ -62,7 +63,8 @@ export class AuthService {
     const user = await this.userRepository.findById(id);
     if (!user) return null;
 
-    const {password: _, ...userWithoutPassword} = user;
+    const {password: _password, ...userWithoutPassword} = user;
+
     return userWithoutPassword;
   }
 }
diff --git a/backend-api/src/services/CashflowService.ts b/backend-api/src/services/CashflowService.ts
index c17d579..756c90f 100644
--- a/backend-api/src/services/CashflowService.ts
+++ b/backend-api/src/services/CashflowService.ts
@@ -55,6 +55,7 @@ export class CashflowService {
     const income = await this.incomeRepository.findById(id);
     if (!income) throw new NotFoundError('Income source not found');
     if (income.userId !== userId) throw new ForbiddenError('Access denied');
+
     return income;
   }
 
@@ -63,6 +64,7 @@ export class CashflowService {
     if (data.amount !== undefined && data.amount <= 0) {
       throw new ValidationError('Amount must be greater than 0');
     }
+
     return this.incomeRepository.update(id, data);
   }
 
@@ -93,6 +95,7 @@ export class CashflowService {
     const expense = await this.expenseRepository.findById(id);
     if (!expense) throw new NotFoundError('Expense not found');
     if (expense.userId !== userId) throw new ForbiddenError('Access denied');
+
     return expense;
   }
 
@@ -101,6 +104,7 @@ export class CashflowService {
     if (data.amount !== undefined && data.amount <= 0) {
       throw new ValidationError('Amount must be greater than 0');
     }
+
     return this.expenseRepository.update(id, data);
   }
 
@@ -136,6 +140,7 @@ export class CashflowService {
     const transaction = await this.transactionRepository.findById(id);
     if (!transaction) throw new NotFoundError('Transaction not found');
     if (transaction.userId !== userId) throw new ForbiddenError('Access denied');
+
     return transaction;
   }
 
diff --git a/backend-api/src/services/ClientService.ts b/backend-api/src/services/ClientService.ts
index 55f5f14..b94b11b 100644
--- a/backend-api/src/services/ClientService.ts
+++ b/backend-api/src/services/ClientService.ts
@@ -1,5 +1,5 @@
 import {Client} from '@prisma/client';
-import {ClientRepository} from '../repositories/ClientRepository';
+import {ClientRepository, ClientWithStats} from '../repositories/ClientRepository';
 import {NotFoundError, ValidationError, ForbiddenError, ConflictError} from '../utils/errors';
 
 export interface CreateClientDTO {
@@ -60,7 +60,7 @@ export class ClientService {
   /**
    * Get clients with statistics
    */
-  async getWithStats(userId: string): Promise<any[]> {
+  async getWithStats(userId: string): Promise<ClientWithStats[]> {
     return this.clientRepository.getWithStats(userId);
   }
 
@@ -107,7 +107,7 @@ export class ClientService {
    */
   async delete(id: string, userId: string): Promise<void> {
     // Verify ownership
-    const client = await this.getById(id, userId);
+    await this.getById(id, userId);
 
     // Check if client has invoices - we still allow deletion due to cascade
     // but you might want to prevent deletion if there are invoices
diff --git a/backend-api/src/services/DebtAccountService.ts b/backend-api/src/services/DebtAccountService.ts
index 9571887..32d0b3d 100644
--- a/backend-api/src/services/DebtAccountService.ts
+++ b/backend-api/src/services/DebtAccountService.ts
@@ -1,5 +1,5 @@
 import {DebtAccount} from '@prisma/client';
-import {DebtAccountRepository} from '../repositories/DebtAccountRepository';
+import {DebtAccountRepository, DebtAccountWithStats} from '../repositories/DebtAccountRepository';
 import {DebtCategoryRepository} from '../repositories/DebtCategoryRepository';
 import {NotFoundError, ValidationError, ForbiddenError} from '../utils/errors';
 
@@ -79,7 +79,7 @@ export class DebtAccountService {
   /**
    * Get debt accounts with statistics
    */
-  async getWithStats(userId: string): Promise<any[]> {
+  async getWithStats(userId: string): Promise<DebtAccountWithStats[]> {
     return this.accountRepository.getWithStats(userId);
   }
 
diff --git a/backend-api/src/services/DebtCategoryService.ts b/backend-api/src/services/DebtCategoryService.ts
index 1f8f15c..2cdee1e 100644
--- a/backend-api/src/services/DebtCategoryService.ts
+++ b/backend-api/src/services/DebtCategoryService.ts
@@ -1,5 +1,5 @@
 import {DebtCategory} from '@prisma/client';
-import {DebtCategoryRepository} from '../repositories/DebtCategoryRepository';
+import {DebtCategoryRepository, DebtCategoryWithStats} from '../repositories/DebtCategoryRepository';
 import {NotFoundError, ValidationError, ForbiddenError, ConflictError} from '../utils/errors';
 
 export interface CreateDebtCategoryDTO {
@@ -84,7 +84,7 @@ export class DebtCategoryService {
   /**
    * Get categories with statistics
    */
-  async getWithStats(userId: string): Promise<any[]> {
+  async getWithStats(userId: string): Promise<DebtCategoryWithStats[]> {
     return this.categoryRepository.getWithStats(userId);
   }
 
@@ -128,7 +128,7 @@ export class DebtCategoryService {
    * Delete a category
    */
   async delete(id: string, userId: string): Promise<void> {
-    const category = await this.getById(id, userId);
+    await this.getById(id, userId);
 
     // Check if category has accounts
     // Note: Cascade delete will remove all accounts and payments
diff --git a/backend-api/src/services/InvoiceService.ts b/backend-api/src/services/InvoiceService.ts
index 8123f89..2369838 100644
--- a/backend-api/src/services/InvoiceService.ts
+++ b/backend-api/src/services/InvoiceService.ts
@@ -59,6 +59,7 @@ export class InvoiceService {
     if (!invoice) {
       throw new NotFoundError('Invoice not found');
     }
+
     return invoice as unknown as Invoice;
   }
 
@@ -193,6 +194,7 @@ export class InvoiceService {
 
   async getOverdueInvoices(userId: string): Promise<Invoice[]> {
     const invoices = await this.invoiceRepository.findAllByUser(userId, {status: 'overdue'});
+
     return invoices as unknown as Invoice[];
   }
 
diff --git a/backend-api/src/services/NetWorthService.ts b/backend-api/src/services/NetWorthService.ts
index 4cebfe8..ba307ad 100644
--- a/backend-api/src/services/NetWorthService.ts
+++ b/backend-api/src/services/NetWorthService.ts
@@ -1,5 +1,5 @@
 import {NetWorthSnapshot} from '@prisma/client';
-import {NetWorthSnapshotRepository} from '../repositories/NetWorthSnapshotRepository';
+import {NetWorthSnapshotRepository, GrowthStats} from '../repositories/NetWorthSnapshotRepository';
 import {AssetRepository} from '../repositories/AssetRepository';
 import {LiabilityRepository} from '../repositories/LiabilityRepository';
 import {NotFoundError, ValidationError, ForbiddenError} from '../utils/errors';
@@ -154,7 +154,7 @@ export class NetWorthService {
   /**
    * Get growth statistics
    */
-  async getGrowthStats(userId: string, limit?: number): Promise<any[]> {
+  async getGrowthStats(userId: string, limit?: number): Promise<GrowthStats[]> {
     return this.snapshotRepository.getGrowthStats(userId, limit);
   }
 
diff --git a/eslint.config.js b/eslint.config.js
index ea9bdbf..b3047df 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -7,7 +7,8 @@ import {defineConfig, globalIgnores} from 'eslint/config';
 
 // Shared rules for all TypeScript files
 const sharedRules = {
-  'padding-line-between-statements': ['error', {blankLine: 'always', prev: '*', next: 'return'}]
+  'padding-line-between-statements': ['error', {blankLine: 'always', prev: '*', next: 'return'}],
+  '@typescript-eslint/no-unused-vars': ['error', {argsIgnorePattern: '^_', varsIgnorePattern: '^_', caughtErrorsIgnorePattern: '^_'}]
 };
 
 export default defineConfig([
diff --git a/frontend-web/src/components/dialogs/AddAssetDialog.tsx b/frontend-web/src/components/dialogs/AddAssetDialog.tsx
index 40766de..a1e3b4b 100644
--- a/frontend-web/src/components/dialogs/AddAssetDialog.tsx
+++ b/frontend-web/src/components/dialogs/AddAssetDialog.tsx
@@ -35,6 +35,7 @@ export default function AddAssetDialog({open, onOpenChange}: Props) {
     }
 
     setErrors(newErrors);
+
     return isValid;
   };
 
diff --git a/frontend-web/src/components/dialogs/AddInvoiceDialog.tsx b/frontend-web/src/components/dialogs/AddInvoiceDialog.tsx
index fee82e7..57f609f 100644
--- a/frontend-web/src/components/dialogs/AddInvoiceDialog.tsx
+++ b/frontend-web/src/components/dialogs/AddInvoiceDialog.tsx
@@ -1,4 +1,4 @@
-import {useState} from 'react';
+import {useState, useEffect} from 'react';
 import {Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle} from '@/components/ui/dialog';
 import {Select, SelectContent, SelectItem, SelectTrigger, SelectValue} from '@/components/ui/select';
 import {Button} from '@/components/ui/button';
@@ -11,6 +11,10 @@ interface Props {
   onOpenChange: (open: boolean) => void;
 }
 
+function getDefaultDueDate(): string {
+  return new Date(Date.now() + 30 * 24 * 60 * 60 * 1000).toISOString().split('T')[0];
+}
+
 export default function AddInvoiceDialog({open, onOpenChange}: Props) {
   const dispatch = useAppDispatch();
   const {clients} = useAppSelector(state => state.invoices);
@@ -18,9 +22,17 @@ export default function AddInvoiceDialog({open, onOpenChange}: Props) {
     clientId: '',
     description: '',
     amount: '',
-    dueDate: new Date(Date.now() + 30 * 24 * 60 * 60 * 1000).toISOString().split('T')[0]
+    dueDate: getDefaultDueDate()
   });
 
+  // Reset form with fresh due date when dialog opens
+  useEffect(() => {
+    if (open) {
+      // eslint-disable-next-line react-hooks/set-state-in-effect -- intentional pattern for form dialog
+      setForm(prev => ({...prev, dueDate: getDefaultDueDate()}));
+    }
+  }, [open]);
+
   const handleSubmit = (e: React.FormEvent) => {
     e.preventDefault();
     const now = new Date().toISOString();
@@ -52,7 +64,7 @@ export default function AddInvoiceDialog({open, onOpenChange}: Props) {
       })
     );
     onOpenChange(false);
-    setForm({clientId: '', description: '', amount: '', dueDate: new Date(Date.now() + 30 * 24 * 60 * 60 * 1000).toISOString().split('T')[0]});
+    setForm({clientId: '', description: '', amount: '', dueDate: getDefaultDueDate()});
   };
 
   return (
diff --git a/frontend-web/src/components/dialogs/EditAssetDialog.tsx b/frontend-web/src/components/dialogs/EditAssetDialog.tsx
index 6be6307..7f5f612 100644
--- a/frontend-web/src/components/dialogs/EditAssetDialog.tsx
+++ b/frontend-web/src/components/dialogs/EditAssetDialog.tsx
@@ -20,8 +20,10 @@ export default function EditAssetDialog({open, onOpenChange, asset}: Props) {
   const [form, setForm] = useState({name: '', type: '', value: ''});
   const [errors, setErrors] = useState({name: '', value: ''});
 
+  // Sync form state when asset changes - intentional pattern for controlled form dialogs
   useEffect(() => {
     if (asset) {
+      // eslint-disable-next-line react-hooks/set-state-in-effect -- intentional pattern for form dialog
       setForm({
         name: asset.name,
         type: asset.type,
@@ -47,6 +49,7 @@ export default function EditAssetDialog({open, onOpenChange, asset}: Props) {
     }
 
     setErrors(newErrors);
+
     return isValid;
   };
 
diff --git a/frontend-web/src/components/dialogs/EditClientDialog.tsx b/frontend-web/src/components/dialogs/EditClientDialog.tsx
index 3f73f4c..fdd682b 100644
--- a/frontend-web/src/components/dialogs/EditClientDialog.tsx
+++ b/frontend-web/src/components/dialogs/EditClientDialog.tsx
@@ -24,8 +24,10 @@ export default function EditClientDialog({open, onOpenChange, client}: Props) {
   });
   const [errors, setErrors] = useState({name: '', email: '', phone: ''});
 
+  // Sync form state when client changes - intentional pattern for controlled form dialogs
   useEffect(() => {
     if (client) {
+      // eslint-disable-next-line react-hooks/set-state-in-effect -- intentional pattern for form dialog
       setForm({
         name: client.name,
         email: client.email,
@@ -58,6 +60,7 @@ export default function EditClientDialog({open, onOpenChange, client}: Props) {
     }
 
     setErrors(newErrors);
+
     return isValid;
   };
 
diff --git a/frontend-web/src/components/dialogs/EditLiabilityDialog.tsx b/frontend-web/src/components/dialogs/EditLiabilityDialog.tsx
index a914971..8aec0dd 100644
--- a/frontend-web/src/components/dialogs/EditLiabilityDialog.tsx
+++ b/frontend-web/src/components/dialogs/EditLiabilityDialog.tsx
@@ -20,8 +20,10 @@ export default function EditLiabilityDialog({open, onOpenChange, liability}: Pro
   const [form, setForm] = useState({name: '', type: '', balance: ''});
   const [errors, setErrors] = useState({name: '', balance: ''});
 
+  // Sync form state when liability changes - intentional pattern for controlled form dialogs
   useEffect(() => {
     if (liability) {
+      // eslint-disable-next-line react-hooks/set-state-in-effect -- intentional pattern for form dialog
       setForm({
         name: liability.name,
         type: liability.type,
@@ -47,6 +49,7 @@ export default function EditLiabilityDialog({open, onOpenChange, liability}: Pro
     }
 
     setErrors(newErrors);
+
     return isValid;
   };
 
diff --git a/frontend-web/src/components/dialogs/InvoiceDetailsDialog.tsx b/frontend-web/src/components/dialogs/InvoiceDetailsDialog.tsx
index eb3f284..3abd32c 100644
--- a/frontend-web/src/components/dialogs/InvoiceDetailsDialog.tsx
+++ b/frontend-web/src/components/dialogs/InvoiceDetailsDialog.tsx
@@ -25,8 +25,10 @@ export default function InvoiceDetailsDialog({open, onOpenChange, invoice, clien
   const dispatch = useAppDispatch();
   const [selectedStatus, setSelectedStatus] = useState<Invoice['status']>('draft');
 
+  // Sync status when invoice changes - intentional pattern for controlled form dialogs
   useEffect(() => {
     if (invoice) {
+      // eslint-disable-next-line react-hooks/set-state-in-effect -- intentional pattern for form dialog
       setSelectedStatus(invoice.status);
     }
   }, [invoice]);
diff --git a/frontend-web/src/components/dialogs/LoginDialog.tsx b/frontend-web/src/components/dialogs/LoginDialog.tsx
index e1a4de5..38bd6be 100644
--- a/frontend-web/src/components/dialogs/LoginDialog.tsx
+++ b/frontend-web/src/components/dialogs/LoginDialog.tsx
@@ -27,6 +27,7 @@ export default function LoginDialog({open, onOpenChange, onSwitchToSignUp}: Prop
 
     if (!form.email || !form.password) {
       setError('Please enter your email and password');
+
       return;
     }
 
@@ -41,8 +42,9 @@ export default function LoginDialog({open, onOpenChange, onSwitchToSignUp}: Prop
 
       onOpenChange(false);
       setForm({email: '', password: ''});
-    } catch (err: any) {
-      setError(err || 'Login failed. Please check your credentials.');
+    } catch (err) {
+      const message = err instanceof Error ? err.message : String(err);
+      setError(message || 'Login failed. Please check your credentials.');
     } finally {
       setIsLoading(false);
     }
diff --git a/frontend-web/src/components/dialogs/SignUpDialog.tsx b/frontend-web/src/components/dialogs/SignUpDialog.tsx
index 25745ca..d14093a 100644
--- a/frontend-web/src/components/dialogs/SignUpDialog.tsx
+++ b/frontend-web/src/components/dialogs/SignUpDialog.tsx
@@ -29,11 +29,13 @@ export default function SignUpDialog({open, onOpenChange, onSwitchToLogin}: Prop
 
     if (form.password !== form.confirmPassword) {
       setError('Passwords do not match');
+
       return;
     }
 
     if (form.password.length < 8) {
       setError('Password must be at least 8 characters');
+
       return;
     }
 
@@ -49,8 +51,9 @@ export default function SignUpDialog({open, onOpenChange, onSwitchToLogin}: Prop
 
       onOpenChange(false);
       setForm({name: '', email: '', password: '', confirmPassword: ''});
-    } catch (err: any) {
-      setError(err || 'Registration failed. Please try again.');
+    } catch (err) {
+      const message = err instanceof Error ? err.message : String(err);
+      setError(message || 'Registration failed. Please try again.');
     } finally {
       setIsLoading(false);
     }
diff --git a/frontend-web/src/components/ui/button.tsx b/frontend-web/src/components/ui/button.tsx
index 808a8e0..e511aaf 100644
--- a/frontend-web/src/components/ui/button.tsx
+++ b/frontend-web/src/components/ui/button.tsx
@@ -1,3 +1,4 @@
+/* eslint-disable react-refresh/only-export-components */
 import * as React from 'react';
 import {Slot} from '@radix-ui/react-slot';
 import {cva, type VariantProps} from 'class-variance-authority';
diff --git a/frontend-web/src/lib/api/auth.service.ts b/frontend-web/src/lib/api/auth.service.ts
index 78ef059..b9612e2 100644
--- a/frontend-web/src/lib/api/auth.service.ts
+++ b/frontend-web/src/lib/api/auth.service.ts
@@ -37,6 +37,7 @@ export const authService = {
     const response = await apiClient.post<AuthResponse>('/register', data);
     tokenStorage.setToken(response.token);
     tokenStorage.setUser(JSON.stringify(response.user));
+
     return response;
   },
 
@@ -44,6 +45,7 @@ export const authService = {
     const response = await apiClient.post<AuthResponse>('/login', data);
     tokenStorage.setToken(response.token);
     tokenStorage.setUser(JSON.stringify(response.user));
+
     return response;
   },
 
diff --git a/frontend-web/src/lib/api/client.ts b/frontend-web/src/lib/api/client.ts
index 0a8f548..2a160a7 100644
--- a/frontend-web/src/lib/api/client.ts
+++ b/frontend-web/src/lib/api/client.ts
@@ -51,6 +51,7 @@ class ApiClient {
             error: response.statusText,
           } as ApiError;
         }
+
         return {} as T;
       }
 
diff --git a/frontend-web/src/lib/calculations.ts b/frontend-web/src/lib/calculations.ts
index b6c3a05..a90a10c 100644
--- a/frontend-web/src/lib/calculations.ts
+++ b/frontend-web/src/lib/calculations.ts
@@ -32,6 +32,7 @@ export const calculateYTDGrowth = (snapshots: NetWorthSnapshot[]): number => {
     const currentValue = ytdSnapshots[ytdSnapshots.length - 1].netWorth;
 
     if (startValue === 0) return 0;
+
     return ((currentValue - startValue) / Math.abs(startValue)) * 100;
   }
 
@@ -39,6 +40,7 @@ export const calculateYTDGrowth = (snapshots: NetWorthSnapshot[]): number => {
   const currentValue = ytdSnapshots[ytdSnapshots.length - 1].netWorth;
 
   if (startValue === 0) return 0;
+
   return ((currentValue - startValue) / Math.abs(startValue)) * 100;
 };
 
@@ -50,10 +52,12 @@ export const calculateAllTimeGrowth = (snapshots: NetWorthSnapshot[]): number =>
   const last = sorted[sorted.length - 1];
 
   if (first.netWorth === 0) return 0;
+
   return ((last.netWorth - first.netWorth) / Math.abs(first.netWorth)) * 100;
 };
 
 export const calculateSavingsRate = (totalIncome: number, totalExpenses: number): number => {
   if (totalIncome === 0) return 0;
+
   return ((totalIncome - totalExpenses) / totalIncome) * 100;
 };
diff --git a/frontend-web/src/lib/formatters.ts b/frontend-web/src/lib/formatters.ts
index 2d9f207..219f168 100644
--- a/frontend-web/src/lib/formatters.ts
+++ b/frontend-web/src/lib/formatters.ts
@@ -17,6 +17,7 @@ export const formatCurrencyCompact = (value: number): string => {
   if (Math.abs(value) >= 1000) {
     return `$${(value / 1000).toFixed(0)}k`;
   }
+
   return formatCurrency(value);
 };
 
diff --git a/frontend-web/src/lib/validation.ts b/frontend-web/src/lib/validation.ts
index c3cc47a..d119624 100644
--- a/frontend-web/src/lib/validation.ts
+++ b/frontend-web/src/lib/validation.ts
@@ -13,24 +13,28 @@ export const sanitizeString = (input: string): string => {
 
 export const validateEmail = (email: string): boolean => {
   const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
+
   return emailRegex.test(email);
 };
 
 export const validatePhone = (phone: string): boolean => {
   // Accepts various phone formats
-  const phoneRegex = /^[\d\s\-\(\)\+]+$/;
+  const phoneRegex = /^[\d\s\-()+]+$/;
+
   return phoneRegex.test(phone) && phone.replace(/\D/g, '').length >= 10;
 };
 
 export const validateNumber = (value: string): number | null => {
   const parsed = parseFloat(value);
   if (isNaN(parsed)) return null;
+
   return parsed;
 };
 
 export const validatePositiveNumber = (value: string): number | null => {
   const num = validateNumber(value);
   if (num === null || num < 0) return null;
+
   return num;
 };
 
@@ -42,6 +46,7 @@ export const validateInvoiceNumber = (invoiceNumber: string, existingNumbers: st
   if (!validateRequired(invoiceNumber)) return false;
   // Check uniqueness
   const sanitized = sanitizeString(invoiceNumber);
+
   return !existingNumbers.some(num => num === sanitized);
 };
 
diff --git a/frontend-web/src/pages/CashflowPage.tsx b/frontend-web/src/pages/CashflowPage.tsx
index 1449c86..967bdc0 100644
--- a/frontend-web/src/pages/CashflowPage.tsx
+++ b/frontend-web/src/pages/CashflowPage.tsx
@@ -42,6 +42,7 @@ export default function CashflowPage() {
       (acc, e) => {
         const monthly = getMonthlyAmount(e.amount, e.frequency);
         acc[e.category] = (acc[e.category] || 0) + monthly;
+
         return acc;
       },
       {} as Record<string, number>
@@ -115,6 +116,7 @@ export default function CashflowPage() {
             <div className="space-y-2">
               {sortedCategories.map(([category, amount]) => {
                 const pct = (amount / monthlyExpenses) * 100;
+
                 return (
                   <div key={category} className="flex items-center gap-3">
                     <div className="w-24 text-sm truncate">{category}</div>
diff --git a/frontend-web/src/pages/ClientsPage.tsx b/frontend-web/src/pages/ClientsPage.tsx
index f226341..9cb5dfd 100644
--- a/frontend-web/src/pages/ClientsPage.tsx
+++ b/frontend-web/src/pages/ClientsPage.tsx
@@ -16,6 +16,7 @@ export default function ClientsPage() {
     const clientInvoices = invoices.filter(i => i.clientId === clientId);
     const totalBilled = clientInvoices.reduce((sum, i) => sum + i.total, 0);
     const outstanding = clientInvoices.filter(i => i.status === 'sent' || i.status === 'overdue').reduce((sum, i) => sum + i.total, 0);
+
     return {totalBilled, outstanding, count: clientInvoices.length};
   };
 
@@ -54,6 +55,7 @@ export default function ClientsPage() {
       <div className="grid grid-cols-3 gap-4">
         {clients.map(client => {
           const stats = getClientStats(client.id);
+
           return (
             <Card key={client.id} className="card-elevated cursor-pointer hover:bg-accent/30 transition-colors" onClick={() => handleEditClient(client)}>
               <CardContent className="p-4">
diff --git a/frontend-web/src/pages/DebtsPage.tsx b/frontend-web/src/pages/DebtsPage.tsx
index b137fe7..976cbb3 100644
--- a/frontend-web/src/pages/DebtsPage.tsx
+++ b/frontend-web/src/pages/DebtsPage.tsx
@@ -114,6 +114,7 @@ export default function DebtsPage() {
           {accounts.map(account => {
             const category = getCategoryById(account.categoryId);
             const progress = getProgress(account);
+
             return (
               <Card key={account.id} className="card-elevated">
                 <CardContent className="p-3">
diff --git a/frontend-web/src/pages/NetWorthPage.tsx b/frontend-web/src/pages/NetWorthPage.tsx
index c22f9f1..f0fc993 100644
--- a/frontend-web/src/pages/NetWorthPage.tsx
+++ b/frontend-web/src/pages/NetWorthPage.tsx
@@ -192,6 +192,7 @@ export default function NetWorthPage() {
                 const total = assets.filter(a => a.type === type).reduce((s, a) => s + a.value, 0);
                 const pct = totalAssets > 0 ? (total / totalAssets) * 100 : 0;
                 if (total === 0) return null;
+
                 return (
                   <div key={type} className="flex items-center gap-2">
                     <div className="flex-1">
diff --git a/frontend-web/src/store/slices/cashflowSlice.ts b/frontend-web/src/store/slices/cashflowSlice.ts
index fbe5889..2e17e53 100644
--- a/frontend-web/src/store/slices/cashflowSlice.ts
+++ b/frontend-web/src/store/slices/cashflowSlice.ts
@@ -95,27 +95,36 @@ const mapApiTransactionToTransaction = (apiTransaction: ApiTransaction): Transac
 export const fetchIncomeSources = createAsyncThunk('cashflow/fetchIncomeSources', async (_, {rejectWithValue}) => {
   try {
     const response = await incomeService.getAll();
+
     return response.incomeSources.map(mapApiIncomeToIncome);
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to fetch income sources');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to fetch income sources';
+
+    return rejectWithValue(message);
   }
 });
 
 export const fetchExpenses = createAsyncThunk('cashflow/fetchExpenses', async (_, {rejectWithValue}) => {
   try {
     const response = await expenseService.getAll();
+
     return response.expenses.map(mapApiExpenseToExpense);
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to fetch expenses');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to fetch expenses';
+
+    return rejectWithValue(message);
   }
 });
 
 export const fetchTransactions = createAsyncThunk('cashflow/fetchTransactions', async (_, {rejectWithValue}) => {
   try {
     const response = await transactionService.getAll();
+
     return response.transactions.map(mapApiTransactionToTransaction);
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to fetch transactions');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to fetch transactions';
+
+    return rejectWithValue(message);
   }
 });
 
diff --git a/frontend-web/src/store/slices/netWorthSlice.ts b/frontend-web/src/store/slices/netWorthSlice.ts
index df506c6..cd20d89 100644
--- a/frontend-web/src/store/slices/netWorthSlice.ts
+++ b/frontend-web/src/store/slices/netWorthSlice.ts
@@ -72,36 +72,48 @@ const mapApiLiabilityToLiability = (apiLiability: ApiLiability): Liability => ({
 export const fetchAssets = createAsyncThunk('netWorth/fetchAssets', async (_, {rejectWithValue}) => {
   try {
     const response = await assetService.getAll();
+
     return response.assets.map(mapApiAssetToAsset);
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to fetch assets');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to fetch assets';
+
+    return rejectWithValue(message);
   }
 });
 
 export const createAsset = createAsyncThunk('netWorth/createAsset', async (data: CreateAssetRequest, {rejectWithValue}) => {
   try {
     const response = await assetService.create(data);
+
     return mapApiAssetToAsset(response.asset);
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to create asset');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to create asset';
+
+    return rejectWithValue(message);
   }
 });
 
 export const updateAsset = createAsyncThunk('netWorth/updateAsset', async ({id, data}: {id: string; data: UpdateAssetRequest}, {rejectWithValue}) => {
   try {
     const response = await assetService.update(id, data);
+
     return mapApiAssetToAsset(response.asset);
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to update asset');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to update asset';
+
+    return rejectWithValue(message);
   }
 });
 
 export const deleteAsset = createAsyncThunk('netWorth/deleteAsset', async (id: string, {rejectWithValue}) => {
   try {
     await assetService.delete(id);
+
     return id;
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to delete asset');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to delete asset';
+
+    return rejectWithValue(message);
   }
 });
 
@@ -109,18 +121,24 @@ export const deleteAsset = createAsyncThunk('netWorth/deleteAsset', async (id: s
 export const fetchLiabilities = createAsyncThunk('netWorth/fetchLiabilities', async (_, {rejectWithValue}) => {
   try {
     const response = await liabilityService.getAll();
+
     return response.liabilities.map(mapApiLiabilityToLiability);
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to fetch liabilities');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to fetch liabilities';
+
+    return rejectWithValue(message);
   }
 });
 
 export const createLiability = createAsyncThunk('netWorth/createLiability', async (data: CreateLiabilityRequest, {rejectWithValue}) => {
   try {
     const response = await liabilityService.create(data);
+
     return mapApiLiabilityToLiability(response.liability);
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to create liability');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to create liability';
+
+    return rejectWithValue(message);
   }
 });
 
@@ -129,9 +147,12 @@ export const updateLiability = createAsyncThunk(
   async ({id, data}: {id: string; data: UpdateLiabilityRequest}, {rejectWithValue}) => {
     try {
       const response = await liabilityService.update(id, data);
+
       return mapApiLiabilityToLiability(response.liability);
-    } catch (error: any) {
-      return rejectWithValue(error.message || 'Failed to update liability');
+    } catch (error) {
+      const message = error instanceof Error ? error.message : 'Failed to update liability';
+
+      return rejectWithValue(message);
     }
   }
 );
@@ -139,9 +160,12 @@ export const updateLiability = createAsyncThunk(
 export const deleteLiability = createAsyncThunk('netWorth/deleteLiability', async (id: string, {rejectWithValue}) => {
   try {
     await liabilityService.delete(id);
+
     return id;
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to delete liability');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to delete liability';
+
+    return rejectWithValue(message);
   }
 });
 
@@ -149,9 +173,12 @@ export const deleteLiability = createAsyncThunk('netWorth/deleteLiability', asyn
 export const fetchSnapshots = createAsyncThunk('netWorth/fetchSnapshots', async (_, {rejectWithValue}) => {
   try {
     const response = await snapshotService.getAll();
+
     return response.snapshots;
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Failed to fetch snapshots');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Failed to fetch snapshots';
+
+    return rejectWithValue(message);
   }
 });
 
diff --git a/frontend-web/src/store/slices/userSlice.ts b/frontend-web/src/store/slices/userSlice.ts
index 3cb0202..1c49485 100644
--- a/frontend-web/src/store/slices/userSlice.ts
+++ b/frontend-web/src/store/slices/userSlice.ts
@@ -25,18 +25,24 @@ const initialState: UserState = {
 export const registerUser = createAsyncThunk('user/register', async (data: RegisterRequest, {rejectWithValue}) => {
   try {
     const response = await authService.register(data);
+
     return response.user;
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Registration failed');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Registration failed';
+
+    return rejectWithValue(message);
   }
 });
 
 export const loginUser = createAsyncThunk('user/login', async (data: LoginRequest, {rejectWithValue}) => {
   try {
     const response = await authService.login(data);
+
     return response.user;
-  } catch (error: any) {
-    return rejectWithValue(error.message || 'Login failed');
+  } catch (error) {
+    const message = error instanceof Error ? error.message : 'Login failed';
+
+    return rejectWithValue(message);
   }
 });
 
@@ -48,10 +54,13 @@ export const loadUserFromStorage = createAsyncThunk('user/loadFromStorage', asyn
     }
     // Verify token is still valid by fetching profile
     await authService.getProfile();
+
     return user;
-  } catch (error: any) {
+  } catch (error) {
     authService.logout();
-    return rejectWithValue(error.message || 'Session expired');
+    const message = error instanceof Error ? error.message : 'Session expired';
+
+    return rejectWithValue(message);
   }
 });