diff --git a/packages/shared/package-lock.json b/packages/shared/package-lock.json
new file mode 100644
index 0000000..0626cd9
--- /dev/null
+++ b/packages/shared/package-lock.json
@@ -0,0 +1,41 @@
+{
+  "name": "@padel-pro/shared",
+  "version": "0.1.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "@padel-pro/shared",
+      "version": "0.1.0",
+      "dependencies": {
+        "zod": "^3.22.4"
+      },
+      "devDependencies": {
+        "typescript": "^5.3.3"
+      }
+    },
+    "node_modules/typescript": {
+      "version": "5.9.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.9.3.tgz",
+      "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=14.17"
+      }
+    },
+    "node_modules/zod": {
+      "version": "3.25.76",
+      "resolved": "https://registry.npmjs.org/zod/-/zod-3.25.76.tgz",
+      "integrity": "sha512-gzUt/qt81nXsFGKIFcC3YnfEAx5NkunCfnDlvuBSSFS02bcXu4Lmea0AFIUwbLWxWPx3d9p8S5QoaujKcNQxcQ==",
+      "license": "MIT",
+      "funding": {
+        "url": "https://github.com/sponsors/colinhacks"
+      }
+    }
+  }
+}
diff --git a/packages/shared/package.json b/packages/shared/package.json
new file mode 100644
index 0000000..2366022
--- /dev/null
+++ b/packages/shared/package.json
@@ -0,0 +1,17 @@
+{
+  "name": "@padel-pro/shared",
+  "version": "0.1.0",
+  "private": true,
+  "main": "./src/index.ts",
+  "types": "./src/index.ts",
+  "scripts": {
+    "type-check": "tsc --noEmit",
+    "lint": "eslint src/"
+  },
+  "dependencies": {
+    "zod": "^3.22.4"
+  },
+  "devDependencies": {
+    "typescript": "^5.3.3"
+  }
+}
diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
new file mode 100644
index 0000000..dc6be05
--- /dev/null
+++ b/packages/shared/src/index.ts
@@ -0,0 +1,5 @@
+// Re-export all types
+export * from './types/index';
+
+// Re-export all validations
+export * from './validations/index';
diff --git a/packages/shared/src/types/index.ts b/packages/shared/src/types/index.ts
new file mode 100644
index 0000000..8de861e
--- /dev/null
+++ b/packages/shared/src/types/index.ts
@@ -0,0 +1,531 @@
+// ==========================================
+// Enums
+// ==========================================
+
+export type UserRole = 'super_admin' | 'org_admin' | 'site_admin' | 'staff' | 'coach' | 'client';
+
+export type CourtType = 'indoor' | 'outdoor' | 'covered';
+
+export type CourtStatus = 'active' | 'maintenance' | 'inactive';
+
+export type BookingStatus = 'pending' | 'confirmed' | 'cancelled' | 'completed' | 'no_show';
+
+export type PaymentType = 'cash' | 'card' | 'transfer' | 'membership' | 'pending';
+
+export type MembershipStatus = 'active' | 'expired' | 'cancelled' | 'suspended';
+
+export type TournamentType = 'single_elimination' | 'double_elimination' | 'round_robin' | 'swiss';
+
+export type TournamentStatus = 'draft' | 'registration_open' | 'registration_closed' | 'in_progress' | 'completed' | 'cancelled';
+
+export type MatchStatus = 'scheduled' | 'in_progress' | 'completed' | 'cancelled' | 'walkover';
+
+export type CashRegisterStatus = 'open' | 'closed';
+
+// ==========================================
+// Core Interfaces
+// ==========================================
+
+export interface Organization {
+  id: string;
+  name: string;
+  slug: string;
+  logo?: string;
+  primaryColor?: string;
+  secondaryColor?: string;
+  email?: string;
+  phone?: string;
+  address?: string;
+  taxId?: string;
+  settings: OrganizationSettings;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface OrganizationSettings {
+  timezone: string;
+  currency: string;
+  dateFormat: string;
+  timeFormat: '12h' | '24h';
+  defaultBookingDuration: number; // in minutes
+  cancellationPolicy: {
+    allowCancellation: boolean;
+    hoursBeforeBooking: number;
+    refundPercentage: number;
+  };
+  bookingRules: {
+    minAdvanceBooking: number; // hours
+    maxAdvanceBooking: number; // days
+    requirePayment: boolean;
+  };
+}
+
+export interface Site {
+  id: string;
+  organizationId: string;
+  name: string;
+  slug: string;
+  address: string;
+  city: string;
+  state?: string;
+  country: string;
+  postalCode?: string;
+  latitude?: number;
+  longitude?: number;
+  phone?: string;
+  email?: string;
+  openingHours: WeeklySchedule;
+  amenities: string[];
+  images: string[];
+  isActive: boolean;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface WeeklySchedule {
+  monday: DaySchedule;
+  tuesday: DaySchedule;
+  wednesday: DaySchedule;
+  thursday: DaySchedule;
+  friday: DaySchedule;
+  saturday: DaySchedule;
+  sunday: DaySchedule;
+}
+
+export interface DaySchedule {
+  isOpen: boolean;
+  openTime?: string; // HH:mm format
+  closeTime?: string; // HH:mm format
+  breaks?: TimeSlot[];
+}
+
+export interface TimeSlot {
+  startTime: string; // HH:mm format
+  endTime: string; // HH:mm format
+}
+
+export interface Court {
+  id: string;
+  siteId: string;
+  name: string;
+  type: CourtType;
+  status: CourtStatus;
+  description?: string;
+  features: string[];
+  hourlyRate: number;
+  peakHourlyRate?: number;
+  peakHours?: TimeSlot[];
+  images: string[];
+  position?: number; // for ordering
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+// ==========================================
+// User & Client Interfaces
+// ==========================================
+
+export interface User {
+  id: string;
+  email: string;
+  passwordHash?: string;
+  firstName: string;
+  lastName: string;
+  phone?: string;
+  avatar?: string;
+  role: UserRole;
+  organizationId?: string;
+  siteIds: string[]; // sites user has access to
+  permissions: string[];
+  isActive: boolean;
+  emailVerified: boolean;
+  lastLoginAt?: Date;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface Client {
+  id: string;
+  userId?: string; // linked user account (optional)
+  organizationId: string;
+  firstName: string;
+  lastName: string;
+  email: string;
+  phone?: string;
+  dateOfBirth?: Date;
+  gender?: 'male' | 'female' | 'other' | 'prefer_not_to_say';
+  avatar?: string;
+  address?: string;
+  city?: string;
+  postalCode?: string;
+  country?: string;
+  notes?: string;
+  tags: string[];
+  preferredSiteId?: string;
+  skillLevel?: 'beginner' | 'intermediate' | 'advanced' | 'professional';
+  emergencyContact?: EmergencyContact;
+  marketingConsent: boolean;
+  isActive: boolean;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface EmergencyContact {
+  name: string;
+  relationship: string;
+  phone: string;
+}
+
+// ==========================================
+// Booking Interfaces
+// ==========================================
+
+export interface Booking {
+  id: string;
+  courtId: string;
+  siteId: string;
+  organizationId: string;
+  clientId: string;
+  createdByUserId?: string;
+  startTime: Date;
+  endTime: Date;
+  duration: number; // in minutes
+  status: BookingStatus;
+  paymentType: PaymentType;
+  paymentStatus: 'pending' | 'paid' | 'refunded' | 'partial';
+  amount: number;
+  paidAmount: number;
+  currency: string;
+  participants: BookingParticipant[];
+  notes?: string;
+  internalNotes?: string;
+  isRecurring: boolean;
+  recurringId?: string;
+  cancellationReason?: string;
+  cancelledAt?: Date;
+  cancelledByUserId?: string;
+  checkInAt?: Date;
+  checkOutAt?: Date;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface BookingParticipant {
+  clientId?: string;
+  name: string;
+  email?: string;
+  phone?: string;
+  isPayer: boolean;
+}
+
+export interface RecurringBooking {
+  id: string;
+  courtId: string;
+  siteId: string;
+  organizationId: string;
+  clientId: string;
+  createdByUserId?: string;
+  dayOfWeek: number; // 0-6 (Sunday-Saturday)
+  startTime: string; // HH:mm format
+  endTime: string; // HH:mm format
+  startDate: Date;
+  endDate?: Date;
+  isActive: boolean;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+// ==========================================
+// Membership Interfaces
+// ==========================================
+
+export interface MembershipPlan {
+  id: string;
+  organizationId: string;
+  siteIds: string[]; // applicable sites
+  name: string;
+  description?: string;
+  durationMonths: number;
+  price: number;
+  currency: string;
+  benefits: MembershipBenefit[];
+  bookingDiscount?: number; // percentage
+  maxActiveBookings?: number;
+  priorityBooking: boolean;
+  guestPasses?: number;
+  isActive: boolean;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface MembershipBenefit {
+  type: 'discount' | 'free_hours' | 'priority' | 'guest_pass' | 'product_discount' | 'custom';
+  description: string;
+  value?: number;
+  conditions?: string;
+}
+
+export interface Membership {
+  id: string;
+  clientId: string;
+  planId: string;
+  organizationId: string;
+  startDate: Date;
+  endDate: Date;
+  status: MembershipStatus;
+  autoRenew: boolean;
+  paymentMethod?: string;
+  remainingGuestPasses: number;
+  usedHours: number;
+  notes?: string;
+  suspendedAt?: Date;
+  suspensionReason?: string;
+  cancelledAt?: Date;
+  cancellationReason?: string;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+// ==========================================
+// Product & Sales Interfaces
+// ==========================================
+
+export interface ProductCategory {
+  id: string;
+  organizationId: string;
+  name: string;
+  description?: string;
+  parentId?: string;
+  position: number;
+  isActive: boolean;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface Product {
+  id: string;
+  organizationId: string;
+  siteIds: string[]; // available at these sites
+  categoryId?: string;
+  name: string;
+  description?: string;
+  sku?: string;
+  barcode?: string;
+  price: number;
+  cost?: number;
+  currency: string;
+  taxRate: number;
+  trackInventory: boolean;
+  images: string[];
+  isActive: boolean;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface ProductInventory {
+  id: string;
+  productId: string;
+  siteId: string;
+  quantity: number;
+  minQuantity?: number;
+  location?: string;
+  updatedAt: Date;
+}
+
+export interface Sale {
+  id: string;
+  siteId: string;
+  organizationId: string;
+  clientId?: string;
+  userId: string; // staff who made the sale
+  cashRegisterId?: string;
+  items: SaleItem[];
+  subtotal: number;
+  taxAmount: number;
+  discountAmount: number;
+  total: number;
+  currency: string;
+  paymentType: PaymentType;
+  paymentReference?: string;
+  notes?: string;
+  voidedAt?: Date;
+  voidedByUserId?: string;
+  voidReason?: string;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface SaleItem {
+  productId?: string;
+  bookingId?: string;
+  membershipId?: string;
+  description: string;
+  quantity: number;
+  unitPrice: number;
+  taxRate: number;
+  discountAmount: number;
+  total: number;
+}
+
+export interface CashRegister {
+  id: string;
+  siteId: string;
+  name: string;
+  status: CashRegisterStatus;
+  openedAt?: Date;
+  openedByUserId?: string;
+  openingBalance?: number;
+  closedAt?: Date;
+  closedByUserId?: string;
+  closingBalance?: number;
+  expectedBalance?: number;
+  notes?: string;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+// ==========================================
+// Tournament Interfaces
+// ==========================================
+
+export interface Tournament {
+  id: string;
+  siteId: string;
+  organizationId: string;
+  name: string;
+  description?: string;
+  type: TournamentType;
+  status: TournamentStatus;
+  startDate: Date;
+  endDate: Date;
+  registrationStartDate: Date;
+  registrationEndDate: Date;
+  maxTeams: number;
+  minTeams: number;
+  teamSize: number; // players per team (1 for singles, 2 for doubles)
+  entryFee: number;
+  currency: string;
+  prizePool?: number;
+  prizes?: TournamentPrize[];
+  rules?: string;
+  courtIds: string[];
+  categories: TournamentCategory[];
+  images: string[];
+  isPublic: boolean;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface TournamentCategory {
+  id: string;
+  name: string;
+  description?: string;
+  minSkillLevel?: string;
+  maxSkillLevel?: string;
+  minAge?: number;
+  maxAge?: number;
+  gender?: 'male' | 'female' | 'mixed' | 'any';
+}
+
+export interface TournamentPrize {
+  position: number;
+  description: string;
+  amount?: number;
+  currency?: string;
+}
+
+export interface TournamentTeam {
+  id: string;
+  tournamentId: string;
+  categoryId: string;
+  name: string;
+  players: TournamentPlayer[];
+  seed?: number;
+  status: 'registered' | 'confirmed' | 'withdrawn' | 'disqualified';
+  paidAt?: Date;
+  notes?: string;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface TournamentPlayer {
+  clientId: string;
+  firstName: string;
+  lastName: string;
+  email?: string;
+  phone?: string;
+  isCaptain: boolean;
+}
+
+export interface TournamentMatch {
+  id: string;
+  tournamentId: string;
+  categoryId: string;
+  round: number;
+  matchNumber: number;
+  courtId?: string;
+  scheduledAt?: Date;
+  team1Id?: string;
+  team2Id?: string;
+  winnerId?: string;
+  score?: MatchScore;
+  status: MatchStatus;
+  notes?: string;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+export interface MatchScore {
+  sets: SetScore[];
+  winner: 'team1' | 'team2';
+  duration?: number; // in minutes
+}
+
+export interface SetScore {
+  team1Score: number;
+  team2Score: number;
+  tiebreak?: TiebreakScore;
+}
+
+export interface TiebreakScore {
+  team1Score: number;
+  team2Score: number;
+}
+
+// ==========================================
+// Utility Types
+// ==========================================
+
+export type WithTimestamps<T> = T & {
+  createdAt: Date;
+  updatedAt: Date;
+};
+
+export type CreateInput<T> = Omit<T, 'id' | 'createdAt' | 'updatedAt'>;
+
+export type UpdateInput<T> = Partial<Omit<T, 'id' | 'createdAt' | 'updatedAt'>>;
+
+export type PaginationParams = {
+  page?: number;
+  limit?: number;
+  sortBy?: string;
+  sortOrder?: 'asc' | 'desc';
+};
+
+export type PaginatedResponse<T> = {
+  data: T[];
+  total: number;
+  page: number;
+  limit: number;
+  totalPages: number;
+};
+
+export type ApiResponse<T> = {
+  success: boolean;
+  data?: T;
+  error?: {
+    code: string;
+    message: string;
+    details?: Record<string, unknown>;
+  };
+};
diff --git a/packages/shared/src/validations/index.ts b/packages/shared/src/validations/index.ts
new file mode 100644
index 0000000..bc8fa0f
--- /dev/null
+++ b/packages/shared/src/validations/index.ts
@@ -0,0 +1,575 @@
+import { z } from 'zod';
+
+// ==========================================
+// Common Schemas
+// ==========================================
+
+export const emailSchema = z.string().email('Invalid email address');
+
+export const phoneSchema = z.string().regex(
+  /^[+]?[(]?[0-9]{1,4}[)]?[-\s./0-9]*$/,
+  'Invalid phone number'
+).optional();
+
+export const passwordSchema = z
+  .string()
+  .min(8, 'Password must be at least 8 characters')
+  .regex(/[A-Z]/, 'Password must contain at least one uppercase letter')
+  .regex(/[a-z]/, 'Password must contain at least one lowercase letter')
+  .regex(/[0-9]/, 'Password must contain at least one number');
+
+export const timeSchema = z.string().regex(
+  /^([01]?[0-9]|2[0-3]):[0-5][0-9]$/,
+  'Invalid time format (HH:mm)'
+);
+
+export const slugSchema = z
+  .string()
+  .min(2, 'Slug must be at least 2 characters')
+  .max(50, 'Slug must be at most 50 characters')
+  .regex(/^[a-z0-9]+(?:-[a-z0-9]+)*$/, 'Slug must be lowercase and contain only letters, numbers, and hyphens');
+
+// ==========================================
+// Auth Schemas
+// ==========================================
+
+export const loginSchema = z.object({
+  email: emailSchema,
+  password: z.string().min(1, 'Password is required'),
+  rememberMe: z.boolean().optional().default(false),
+});
+
+export type LoginInput = z.infer<typeof loginSchema>;
+
+export const registerClientSchema = z.object({
+  email: emailSchema,
+  password: passwordSchema,
+  confirmPassword: z.string(),
+  firstName: z.string().min(1, 'First name is required').max(50),
+  lastName: z.string().min(1, 'Last name is required').max(50),
+  phone: phoneSchema,
+  dateOfBirth: z.coerce.date().optional(),
+  gender: z.enum(['male', 'female', 'other', 'prefer_not_to_say']).optional(),
+  marketingConsent: z.boolean().optional().default(false),
+  termsAccepted: z.boolean().refine(val => val === true, {
+    message: 'You must accept the terms and conditions',
+  }),
+}).refine(data => data.password === data.confirmPassword, {
+  message: 'Passwords do not match',
+  path: ['confirmPassword'],
+});
+
+export type RegisterClientInput = z.infer<typeof registerClientSchema>;
+
+export const forgotPasswordSchema = z.object({
+  email: emailSchema,
+});
+
+export type ForgotPasswordInput = z.infer<typeof forgotPasswordSchema>;
+
+export const resetPasswordSchema = z.object({
+  token: z.string().min(1, 'Reset token is required'),
+  password: passwordSchema,
+  confirmPassword: z.string(),
+}).refine(data => data.password === data.confirmPassword, {
+  message: 'Passwords do not match',
+  path: ['confirmPassword'],
+});
+
+export type ResetPasswordInput = z.infer<typeof resetPasswordSchema>;
+
+// ==========================================
+// Booking Schemas
+// ==========================================
+
+export const createBookingSchema = z.object({
+  courtId: z.string().uuid('Invalid court ID'),
+  clientId: z.string().uuid('Invalid client ID'),
+  startTime: z.coerce.date(),
+  endTime: z.coerce.date(),
+  participants: z.array(z.object({
+    clientId: z.string().uuid().optional(),
+    name: z.string().min(1, 'Participant name is required'),
+    email: emailSchema.optional(),
+    phone: phoneSchema,
+    isPayer: z.boolean().default(false),
+  })).optional().default([]),
+  paymentType: z.enum(['cash', 'card', 'transfer', 'membership', 'pending']).default('pending'),
+  notes: z.string().max(500).optional(),
+}).refine(data => data.endTime > data.startTime, {
+  message: 'End time must be after start time',
+  path: ['endTime'],
+});
+
+export type CreateBookingInput = z.infer<typeof createBookingSchema>;
+
+export const updateBookingStatusSchema = z.object({
+  bookingId: z.string().uuid('Invalid booking ID'),
+  status: z.enum(['pending', 'confirmed', 'cancelled', 'completed', 'no_show']),
+  cancellationReason: z.string().max(500).optional(),
+});
+
+export type UpdateBookingStatusInput = z.infer<typeof updateBookingStatusSchema>;
+
+export const createRecurringBookingSchema = z.object({
+  courtId: z.string().uuid('Invalid court ID'),
+  clientId: z.string().uuid('Invalid client ID'),
+  dayOfWeek: z.number().int().min(0).max(6),
+  startTime: timeSchema,
+  endTime: timeSchema,
+  startDate: z.coerce.date(),
+  endDate: z.coerce.date().optional(),
+  paymentType: z.enum(['cash', 'card', 'transfer', 'membership', 'pending']).default('pending'),
+  notes: z.string().max(500).optional(),
+}).refine(data => {
+  const [startH, startM] = data.startTime.split(':').map(Number);
+  const [endH, endM] = data.endTime.split(':').map(Number);
+  return endH * 60 + endM > startH * 60 + startM;
+}, {
+  message: 'End time must be after start time',
+  path: ['endTime'],
+});
+
+export type CreateRecurringBookingInput = z.infer<typeof createRecurringBookingSchema>;
+
+// ==========================================
+// Site & Court Schemas
+// ==========================================
+
+const dayScheduleSchema = z.object({
+  isOpen: z.boolean(),
+  openTime: timeSchema.optional(),
+  closeTime: timeSchema.optional(),
+  breaks: z.array(z.object({
+    startTime: timeSchema,
+    endTime: timeSchema,
+  })).optional(),
+}).refine(data => {
+  if (data.isOpen) {
+    return data.openTime !== undefined && data.closeTime !== undefined;
+  }
+  return true;
+}, {
+  message: 'Open and close times are required when the day is open',
+});
+
+const weeklyScheduleSchema = z.object({
+  monday: dayScheduleSchema,
+  tuesday: dayScheduleSchema,
+  wednesday: dayScheduleSchema,
+  thursday: dayScheduleSchema,
+  friday: dayScheduleSchema,
+  saturday: dayScheduleSchema,
+  sunday: dayScheduleSchema,
+});
+
+export const createSiteSchema = z.object({
+  name: z.string().min(1, 'Site name is required').max(100),
+  slug: slugSchema,
+  address: z.string().min(1, 'Address is required').max(200),
+  city: z.string().min(1, 'City is required').max(100),
+  state: z.string().max(100).optional(),
+  country: z.string().min(1, 'Country is required').max(100),
+  postalCode: z.string().max(20).optional(),
+  latitude: z.number().min(-90).max(90).optional(),
+  longitude: z.number().min(-180).max(180).optional(),
+  phone: phoneSchema,
+  email: emailSchema.optional(),
+  openingHours: weeklyScheduleSchema,
+  amenities: z.array(z.string()).optional().default([]),
+  images: z.array(z.string().url()).optional().default([]),
+  isActive: z.boolean().optional().default(true),
+});
+
+export type CreateSiteInput = z.infer<typeof createSiteSchema>;
+
+export const updateSiteSchema = createSiteSchema.partial();
+
+export type UpdateSiteInput = z.infer<typeof updateSiteSchema>;
+
+export const createCourtSchema = z.object({
+  siteId: z.string().uuid('Invalid site ID'),
+  name: z.string().min(1, 'Court name is required').max(50),
+  type: z.enum(['indoor', 'outdoor', 'covered']),
+  status: z.enum(['active', 'maintenance', 'inactive']).default('active'),
+  description: z.string().max(500).optional(),
+  features: z.array(z.string()).optional().default([]),
+  hourlyRate: z.number().positive('Hourly rate must be positive'),
+  peakHourlyRate: z.number().positive().optional(),
+  peakHours: z.array(z.object({
+    startTime: timeSchema,
+    endTime: timeSchema,
+  })).optional(),
+  images: z.array(z.string().url()).optional().default([]),
+  position: z.number().int().min(0).optional(),
+});
+
+export type CreateCourtInput = z.infer<typeof createCourtSchema>;
+
+export const updateCourtSchema = createCourtSchema.partial().omit({ siteId: true });
+
+export type UpdateCourtInput = z.infer<typeof updateCourtSchema>;
+
+// ==========================================
+// Product & Sales Schemas
+// ==========================================
+
+export const createProductCategorySchema = z.object({
+  name: z.string().min(1, 'Category name is required').max(100),
+  description: z.string().max(500).optional(),
+  parentId: z.string().uuid().optional(),
+  position: z.number().int().min(0).optional().default(0),
+  isActive: z.boolean().optional().default(true),
+});
+
+export type CreateProductCategoryInput = z.infer<typeof createProductCategorySchema>;
+
+export const createProductSchema = z.object({
+  categoryId: z.string().uuid().optional(),
+  siteIds: z.array(z.string().uuid()).min(1, 'At least one site is required'),
+  name: z.string().min(1, 'Product name is required').max(100),
+  description: z.string().max(1000).optional(),
+  sku: z.string().max(50).optional(),
+  barcode: z.string().max(50).optional(),
+  price: z.number().nonnegative('Price must be non-negative'),
+  cost: z.number().nonnegative().optional(),
+  currency: z.string().length(3, 'Currency must be a 3-letter code').default('EUR'),
+  taxRate: z.number().min(0).max(100).default(21),
+  trackInventory: z.boolean().optional().default(false),
+  images: z.array(z.string().url()).optional().default([]),
+  isActive: z.boolean().optional().default(true),
+});
+
+export type CreateProductInput = z.infer<typeof createProductSchema>;
+
+export const updateProductSchema = createProductSchema.partial();
+
+export type UpdateProductInput = z.infer<typeof updateProductSchema>;
+
+const saleItemSchema = z.object({
+  productId: z.string().uuid().optional(),
+  bookingId: z.string().uuid().optional(),
+  membershipId: z.string().uuid().optional(),
+  description: z.string().min(1, 'Item description is required').max(200),
+  quantity: z.number().int().positive('Quantity must be positive'),
+  unitPrice: z.number().nonnegative('Unit price must be non-negative'),
+  taxRate: z.number().min(0).max(100).default(21),
+  discountAmount: z.number().nonnegative().optional().default(0),
+});
+
+export const createSaleSchema = z.object({
+  siteId: z.string().uuid('Invalid site ID'),
+  clientId: z.string().uuid().optional(),
+  cashRegisterId: z.string().uuid().optional(),
+  items: z.array(saleItemSchema).min(1, 'At least one item is required'),
+  discountAmount: z.number().nonnegative().optional().default(0),
+  paymentType: z.enum(['cash', 'card', 'transfer', 'membership', 'pending']),
+  paymentReference: z.string().max(100).optional(),
+  notes: z.string().max(500).optional(),
+});
+
+export type CreateSaleInput = z.infer<typeof createSaleSchema>;
+
+// ==========================================
+// Tournament Schemas
+// ==========================================
+
+const tournamentCategorySchema = z.object({
+  id: z.string().uuid().optional(),
+  name: z.string().min(1, 'Category name is required').max(50),
+  description: z.string().max(200).optional(),
+  minSkillLevel: z.enum(['beginner', 'intermediate', 'advanced', 'professional']).optional(),
+  maxSkillLevel: z.enum(['beginner', 'intermediate', 'advanced', 'professional']).optional(),
+  minAge: z.number().int().min(0).max(100).optional(),
+  maxAge: z.number().int().min(0).max(100).optional(),
+  gender: z.enum(['male', 'female', 'mixed', 'any']).optional(),
+});
+
+const tournamentPrizeSchema = z.object({
+  position: z.number().int().positive(),
+  description: z.string().min(1).max(200),
+  amount: z.number().nonnegative().optional(),
+  currency: z.string().length(3).optional(),
+});
+
+export const createTournamentSchema = z.object({
+  siteId: z.string().uuid('Invalid site ID'),
+  name: z.string().min(1, 'Tournament name is required').max(100),
+  description: z.string().max(2000).optional(),
+  type: z.enum(['single_elimination', 'double_elimination', 'round_robin', 'swiss']),
+  startDate: z.coerce.date(),
+  endDate: z.coerce.date(),
+  registrationStartDate: z.coerce.date(),
+  registrationEndDate: z.coerce.date(),
+  maxTeams: z.number().int().min(2, 'Minimum 2 teams required').max(256),
+  minTeams: z.number().int().min(2, 'Minimum 2 teams required').default(2),
+  teamSize: z.number().int().min(1).max(4).default(2),
+  entryFee: z.number().nonnegative().default(0),
+  currency: z.string().length(3, 'Currency must be a 3-letter code').default('EUR'),
+  prizePool: z.number().nonnegative().optional(),
+  prizes: z.array(tournamentPrizeSchema).optional(),
+  rules: z.string().max(5000).optional(),
+  courtIds: z.array(z.string().uuid()).min(1, 'At least one court is required'),
+  categories: z.array(tournamentCategorySchema).min(1, 'At least one category is required'),
+  images: z.array(z.string().url()).optional().default([]),
+  isPublic: z.boolean().optional().default(true),
+}).refine(data => data.endDate >= data.startDate, {
+  message: 'End date must be on or after start date',
+  path: ['endDate'],
+}).refine(data => data.registrationEndDate >= data.registrationStartDate, {
+  message: 'Registration end date must be on or after registration start date',
+  path: ['registrationEndDate'],
+}).refine(data => data.registrationEndDate <= data.startDate, {
+  message: 'Registration must end before or on tournament start date',
+  path: ['registrationEndDate'],
+}).refine(data => data.minTeams <= data.maxTeams, {
+  message: 'Minimum teams cannot exceed maximum teams',
+  path: ['minTeams'],
+});
+
+export type CreateTournamentInput = z.infer<typeof createTournamentSchema>;
+
+// Base tournament schema without refinements for partial updates
+const baseTournamentSchema = z.object({
+  name: z.string().min(1, 'Tournament name is required').max(100),
+  description: z.string().max(2000).optional(),
+  type: z.enum(['single_elimination', 'double_elimination', 'round_robin', 'swiss']),
+  startDate: z.coerce.date(),
+  endDate: z.coerce.date(),
+  registrationStartDate: z.coerce.date(),
+  registrationEndDate: z.coerce.date(),
+  maxTeams: z.number().int().min(2, 'Minimum 2 teams required').max(256),
+  minTeams: z.number().int().min(2, 'Minimum 2 teams required').default(2),
+  teamSize: z.number().int().min(1).max(4).default(2),
+  entryFee: z.number().nonnegative().default(0),
+  currency: z.string().length(3, 'Currency must be a 3-letter code').default('EUR'),
+  prizePool: z.number().nonnegative().optional(),
+  prizes: z.array(tournamentPrizeSchema).optional(),
+  rules: z.string().max(5000).optional(),
+  courtIds: z.array(z.string().uuid()).min(1, 'At least one court is required'),
+  categories: z.array(tournamentCategorySchema).min(1, 'At least one category is required'),
+  images: z.array(z.string().url()).optional().default([]),
+  isPublic: z.boolean().optional().default(true),
+  status: z.enum(['draft', 'registration_open', 'registration_closed', 'in_progress', 'completed', 'cancelled']).optional(),
+});
+
+export const updateTournamentSchema = baseTournamentSchema.partial();
+
+export type UpdateTournamentInput = z.infer<typeof updateTournamentSchema>;
+
+export const registerTournamentTeamSchema = z.object({
+  tournamentId: z.string().uuid('Invalid tournament ID'),
+  categoryId: z.string().uuid('Invalid category ID'),
+  name: z.string().min(1, 'Team name is required').max(50),
+  players: z.array(z.object({
+    clientId: z.string().uuid('Invalid client ID'),
+    firstName: z.string().min(1).max(50),
+    lastName: z.string().min(1).max(50),
+    email: emailSchema.optional(),
+    phone: phoneSchema,
+    isCaptain: z.boolean().default(false),
+  })).min(1, 'At least one player is required'),
+});
+
+export type RegisterTournamentTeamInput = z.infer<typeof registerTournamentTeamSchema>;
+
+export const updateMatchScoreSchema = z.object({
+  matchId: z.string().uuid('Invalid match ID'),
+  score: z.object({
+    sets: z.array(z.object({
+      team1Score: z.number().int().min(0),
+      team2Score: z.number().int().min(0),
+      tiebreak: z.object({
+        team1Score: z.number().int().min(0),
+        team2Score: z.number().int().min(0),
+      }).optional(),
+    })).min(1, 'At least one set is required'),
+    winner: z.enum(['team1', 'team2']),
+    duration: z.number().int().positive().optional(),
+  }),
+});
+
+export type UpdateMatchScoreInput = z.infer<typeof updateMatchScoreSchema>;
+
+// ==========================================
+// Membership Schemas
+// ==========================================
+
+const membershipBenefitSchema = z.object({
+  type: z.enum(['discount', 'free_hours', 'priority', 'guest_pass', 'product_discount', 'custom']),
+  description: z.string().min(1, 'Benefit description is required').max(200),
+  value: z.number().optional(),
+  conditions: z.string().max(500).optional(),
+});
+
+export const createMembershipPlanSchema = z.object({
+  siteIds: z.array(z.string().uuid()).min(1, 'At least one site is required'),
+  name: z.string().min(1, 'Plan name is required').max(100),
+  description: z.string().max(1000).optional(),
+  durationMonths: z.number().int().positive('Duration must be at least 1 month'),
+  price: z.number().nonnegative('Price must be non-negative'),
+  currency: z.string().length(3, 'Currency must be a 3-letter code').default('EUR'),
+  benefits: z.array(membershipBenefitSchema).optional().default([]),
+  bookingDiscount: z.number().min(0).max(100).optional(),
+  maxActiveBookings: z.number().int().positive().optional(),
+  priorityBooking: z.boolean().optional().default(false),
+  guestPasses: z.number().int().nonnegative().optional(),
+  isActive: z.boolean().optional().default(true),
+});
+
+export type CreateMembershipPlanInput = z.infer<typeof createMembershipPlanSchema>;
+
+export const updateMembershipPlanSchema = createMembershipPlanSchema.partial();
+
+export type UpdateMembershipPlanInput = z.infer<typeof updateMembershipPlanSchema>;
+
+export const createMembershipSchema = z.object({
+  clientId: z.string().uuid('Invalid client ID'),
+  planId: z.string().uuid('Invalid plan ID'),
+  startDate: z.coerce.date(),
+  autoRenew: z.boolean().optional().default(false),
+  paymentMethod: z.string().max(50).optional(),
+  notes: z.string().max(500).optional(),
+});
+
+export type CreateMembershipInput = z.infer<typeof createMembershipSchema>;
+
+export const updateMembershipStatusSchema = z.object({
+  membershipId: z.string().uuid('Invalid membership ID'),
+  status: z.enum(['active', 'expired', 'cancelled', 'suspended']),
+  reason: z.string().max(500).optional(),
+});
+
+export type UpdateMembershipStatusInput = z.infer<typeof updateMembershipStatusSchema>;
+
+// ==========================================
+// Client Schemas
+// ==========================================
+
+export const createClientSchema = z.object({
+  firstName: z.string().min(1, 'First name is required').max(50),
+  lastName: z.string().min(1, 'Last name is required').max(50),
+  email: emailSchema,
+  phone: phoneSchema,
+  dateOfBirth: z.coerce.date().optional(),
+  gender: z.enum(['male', 'female', 'other', 'prefer_not_to_say']).optional(),
+  address: z.string().max(200).optional(),
+  city: z.string().max(100).optional(),
+  postalCode: z.string().max(20).optional(),
+  country: z.string().max(100).optional(),
+  notes: z.string().max(1000).optional(),
+  tags: z.array(z.string()).optional().default([]),
+  preferredSiteId: z.string().uuid().optional(),
+  skillLevel: z.enum(['beginner', 'intermediate', 'advanced', 'professional']).optional(),
+  emergencyContact: z.object({
+    name: z.string().min(1).max(100),
+    relationship: z.string().min(1).max(50),
+    phone: z.string().min(1),
+  }).optional(),
+  marketingConsent: z.boolean().optional().default(false),
+});
+
+export type CreateClientInput = z.infer<typeof createClientSchema>;
+
+export const updateClientSchema = createClientSchema.partial();
+
+export type UpdateClientInput = z.infer<typeof updateClientSchema>;
+
+// ==========================================
+// Organization Schemas
+// ==========================================
+
+export const createOrganizationSchema = z.object({
+  name: z.string().min(1, 'Organization name is required').max(100),
+  slug: slugSchema,
+  logo: z.string().url().optional(),
+  primaryColor: z.string().regex(/^#[0-9A-Fa-f]{6}$/, 'Invalid color format').optional(),
+  secondaryColor: z.string().regex(/^#[0-9A-Fa-f]{6}$/, 'Invalid color format').optional(),
+  email: emailSchema.optional(),
+  phone: phoneSchema,
+  address: z.string().max(200).optional(),
+  taxId: z.string().max(50).optional(),
+  settings: z.object({
+    timezone: z.string().default('Europe/Madrid'),
+    currency: z.string().length(3).default('EUR'),
+    dateFormat: z.string().default('DD/MM/YYYY'),
+    timeFormat: z.enum(['12h', '24h']).default('24h'),
+    defaultBookingDuration: z.number().int().positive().default(90),
+    cancellationPolicy: z.object({
+      allowCancellation: z.boolean().default(true),
+      hoursBeforeBooking: z.number().int().nonnegative().default(24),
+      refundPercentage: z.number().min(0).max(100).default(100),
+    }).optional(),
+    bookingRules: z.object({
+      minAdvanceBooking: z.number().int().nonnegative().default(0),
+      maxAdvanceBooking: z.number().int().positive().default(14),
+      requirePayment: z.boolean().default(false),
+    }).optional(),
+  }).optional(),
+});
+
+export type CreateOrganizationInput = z.infer<typeof createOrganizationSchema>;
+
+export const updateOrganizationSchema = createOrganizationSchema.partial().omit({ slug: true });
+
+export type UpdateOrganizationInput = z.infer<typeof updateOrganizationSchema>;
+
+// ==========================================
+// User Schemas
+// ==========================================
+
+export const createUserSchema = z.object({
+  email: emailSchema,
+  password: passwordSchema,
+  firstName: z.string().min(1, 'First name is required').max(50),
+  lastName: z.string().min(1, 'Last name is required').max(50),
+  phone: phoneSchema,
+  role: z.enum(['super_admin', 'org_admin', 'site_admin', 'staff', 'coach', 'client']),
+  organizationId: z.string().uuid().optional(),
+  siteIds: z.array(z.string().uuid()).optional().default([]),
+  permissions: z.array(z.string()).optional().default([]),
+  isActive: z.boolean().optional().default(true),
+});
+
+export type CreateUserInput = z.infer<typeof createUserSchema>;
+
+export const updateUserSchema = createUserSchema.partial().omit({ password: true });
+
+export type UpdateUserInput = z.infer<typeof updateUserSchema>;
+
+export const changePasswordSchema = z.object({
+  currentPassword: z.string().min(1, 'Current password is required'),
+  newPassword: passwordSchema,
+  confirmPassword: z.string(),
+}).refine(data => data.newPassword === data.confirmPassword, {
+  message: 'Passwords do not match',
+  path: ['confirmPassword'],
+}).refine(data => data.currentPassword !== data.newPassword, {
+  message: 'New password must be different from current password',
+  path: ['newPassword'],
+});
+
+export type ChangePasswordInput = z.infer<typeof changePasswordSchema>;
+
+// ==========================================
+// Pagination & Filter Schemas
+// ==========================================
+
+export const paginationSchema = z.object({
+  page: z.coerce.number().int().positive().optional().default(1),
+  limit: z.coerce.number().int().positive().max(100).optional().default(20),
+  sortBy: z.string().optional(),
+  sortOrder: z.enum(['asc', 'desc']).optional().default('desc'),
+});
+
+export type PaginationInput = z.infer<typeof paginationSchema>;
+
+export const dateRangeSchema = z.object({
+  startDate: z.coerce.date(),
+  endDate: z.coerce.date(),
+}).refine(data => data.endDate >= data.startDate, {
+  message: 'End date must be on or after start date',
+  path: ['endDate'],
+});
+
+export type DateRangeInput = z.infer<typeof dateRangeSchema>;
diff --git a/packages/shared/tsconfig.json b/packages/shared/tsconfig.json
new file mode 100644
index 0000000..b146cdb
--- /dev/null
+++ b/packages/shared/tsconfig.json
@@ -0,0 +1,19 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "lib": ["ES2020"],
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "declaration": true,
+    "declarationMap": true,
+    "noEmit": true,
+    "resolveJsonModule": true,
+    "isolatedModules": true
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules"]
+}