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+# Booking & Resource Architecture Redesign
+
+**Date:** 2025-11-14
+**Duration:** ~2+ hours
+**Initial Scope:** Create IResource interface and fix `Date | any` type
+**Actual Scope:** Fundamental redesign of booking architecture with service-level resource assignment
+
+---
+
+## Executive Summary
+
+What started as a simple task to create an `IResource` interface evolved into a comprehensive architectural redesign after critical developer questioning revealed fundamental flaws in the initial approach. Through 4 major iterations and multiple course corrections, we arrived at a clean architecture that properly models split-resource bookings (e.g., student + master stylist working on the same booking).
+
+**Key Achievement:** Avoided building 3 different incorrect architectures by thinking through real business scenarios before committing to code.
+
+---
+
+## Original Request
+
+> "Can we create an IResource now? Then you can also fix `data: Date | any`"
+
+**Expected:** 10 minutes - create interface, update type, done.
+
+**Reality:** 2+ hours of architectural discussion, 4 major iterations, 930 lines of documentation.
+
+---
+
+## Iteration History
+
+### Iteration 1: "Booking HAS resourceId (Primary Resource)" ❌
+
+**My Initial Assumption:**
+```typescript
+export interface IBooking {
+  id: string;
+  resourceId: string;      // Primary resource
+  customerId?: string;
+  type: BookingType;
+  services?: IBookingService[];
+}
+```
+
+**Rationale:** Bookings are always resource-bound (someone performs the service), so booking should have a resourceId.
+
+**Developer Challenge:**
+> "A booking with 2 services can be split between multiple resources. For example, a large hair coloring - the student handles hair wash and eyebrows, the master stylist does the actual coloring."
+
+**Problem Identified:**
+- Booking.resourceId assumes ONE primary resource
+- But in reality: hårvask (student) + bundfarve (master) = TWO resources, neither "primary"
+- Model doesn't support split-resource bookings
+
+**Result:** ❌ Discarded after 15 minutes of discussion
+
+---
+
+### Iteration 2: "Booking HAS Primary + Services Have Resources" ❌
+
+**My Second Attempt:**
+```typescript
+export interface IBooking {
+  id: string;
+  resourceId: string;           // "Primary" responsible person
+  customerId?: string;
+  services?: IBookingService[];
+}
+
+export interface IBookingService {
+  serviceId: string;
+  resourceId: string;           // Who performs THIS service
+}
+```
+
+**Rationale:** Keep primary resource for "who is responsible" while allowing service-level assignment.
+
+**Developer Challenge:**
+> "Why should there be a primary? Use case: Customer chooses service, UI shows it can be split between Karina and Nanna, customer says yes. Here there's no primary, both are master stylists."
+
+**Problem Identified:**
+- "Primary resource" is an artificial concept
+- Equal splits (Karina + Nanna) don't have a "responsible person"
+- Creates confusion: "Who is primary if they're equal?"
+
+**Result:** ❌ Discarded after thorough use case review
+
+---
+
+### Iteration 3: "Booking WITHOUT resourceId, Only Services Have Resources" ✅
+
+**My Third Attempt:**
+```typescript
+export interface IBooking {
+  id: string;
+  customerId: string;        // REQUIRED
+  services: IBookingService[];  // REQUIRED
+  // NO resourceId at all!
+}
+
+export interface IBookingService {
+  serviceId: string;
+  resourceId: string;        // Resource performs THIS service
+}
+```
+
+**My Concern:**
+> "But what about vacation/break? Those are resource-bound but have no services!"
+
+**Developer Response:**
+> "Vacation is not a booking, it's just a CalendarEvent with resourceId. Bookings are only for customers. We always have a booking for customer services."
+
+**Breakthrough Realization:**
+- **Booking = Customer + Services** (business domain)
+- **CalendarEvent = Scheduling + Resource** (time domain)
+- Vacation/break/meeting are CalendarEvents WITHOUT bookings
+
+**Architecture Clarified:**
+```typescript
+// Booking = ONLY customer services
+export interface IBooking {
+  customerId: string;        // REQUIRED - always customer
+  services: IBookingService[];  // REQUIRED - always has services
+  // NO resourceId
+  // NO type (always customer)
+}
+
+// CalendarEvent = ALL scheduling
+export interface ICalendarEvent {
+  type: CalendarEventType;   // 'customer' | 'vacation' | 'break' | ...
+  bookingId?: string;        // Only if type = 'customer'
+  resourceId?: string;       // Which resource owns this slot
+}
+```
+
+**Result:** ✅ **ACCEPTED** - Clean separation of concerns
+
+---
+
+### Iteration 4: "BookingType Should Be Removed" ✅
+
+**My Miss:**
+I created `BookingType` union even though `IBooking` no longer had a `type` field.
+
+**Developer Catch:**
+> "But wait... booking type is gone, right? It's always customer-related."
+
+**Fix Applied:**
+- Renamed `BookingType` → `CalendarEventType`
+- Clarified: Only `ICalendarEvent` uses this type, not `IBooking`
+- Updated all references
+
+**Result:** ✅ Type system now consistent
+
+---
+
+## Key Architectural Decisions
+
+### Decision 1: Booking = Customer ONLY
+
+**Before:** Booking could be customer, vacation, break, meeting
+**After:** Booking is ONLY for customer services
+
+```typescript
+// ✅ Valid
+{
+  "customerId": "CUST456",
+  "services": [{ "resourceId": "EMP001" }]
+}
+
+// ❌ Invalid - vacation is NOT a booking
+{
+  "type": "vacation",
+  "resourceId": "EMP001"
+}
+```
+
+**Vacation is now:**
+```typescript
+{
+  "type": "vacation",
+  "bookingId": null,      // NO booking
+  "resourceId": "EMP001"  // Just a time slot
+}
+```
+
+---
+
+### Decision 2: Resources Assigned Per Service
+
+**Before:** Booking.resourceId (primary)
+**After:** IBookingService.resourceId (per service)
+
+**Enables:**
+- Split resources: student + master
+- Equal splits: Karina + Nanna
+- Resource reassignment: "student is sick, assign to another student"
+
+**Example - Split Resource Booking:**
+```json
+{
+  "customerId": "CUST456",
+  "services": [
+    {
+      "serviceName": "Hårvask",
+      "resourceId": "STUDENT001",
+      "baseDuration": 30
+    },
+    {
+      "serviceName": "Bundfarve",
+      "resourceId": "EMP001",
+      "baseDuration": 90
+    }
+  ]
+}
+```
+
+Two CalendarEvents created:
+- Event 1: Student's calendar, 13:00-13:30
+- Event 2: Master's calendar, 13:30-15:00
+- Both reference same booking
+
+---
+
+### Decision 3: 1 Booking → N Events
+
+**Relationship:** One booking can span multiple events
+
+**Scenarios:**
+1. **Split Session:** 180min service split across 2 days (same resource)
+2. **Split Resources:** Student + Master (different resources)
+3. **Equal Split:** Karina + Nanna (two masters, equal)
+
+**Key Insight:** Events are scheduled per resource, not per booking.
+
+---
+
+### Decision 4: CalendarEvent.type Determines Booking Existence
+
+```typescript
+type CalendarEventType =
+  | 'customer'    // HAS booking
+  | 'vacation'    // NO booking
+  | 'break'       // NO booking
+  | 'meeting'     // NO booking
+  | 'blocked';    // NO booking
+```
+
+**Business Rule:** If `event.type === 'customer'`, then `event.bookingId` must be set.
+
+---
+
+## Database Schema Changes
+
+### Before (Iteration 1 - Wrong)
+```sql
+CREATE TABLE Booking (
+    ResourceId VARCHAR(50) NOT NULL,  -- ❌ Wrong: assumes one resource
+    CustomerId VARCHAR(50) NULL,       -- ❌ Wrong: should be required
+    Type VARCHAR(20) NOT NULL          -- ❌ Wrong: always customer
+);
+
+CREATE TABLE BookingService (
+    BookingId VARCHAR(50) NOT NULL,
+    ServiceId VARCHAR(50) NOT NULL
+    -- ❌ Missing: ResourceId
+);
+```
+
+### After (Final Design - Correct)
+```sql
+CREATE TABLE Booking (
+    Id VARCHAR(50) PRIMARY KEY,
+    CustomerId VARCHAR(50) NOT NULL,   -- ✅ REQUIRED
+    Status VARCHAR(20) NOT NULL,
+    TotalPrice DECIMAL(10,2) NULL,
+    -- ✅ NO ResourceId (moved to service level)
+    -- ✅ NO Type (always customer)
+
+    FOREIGN KEY (CustomerId) REFERENCES Customer(Id)
+);
+
+CREATE TABLE BookingService (
+    BookingId VARCHAR(50) NOT NULL,
+    ServiceId VARCHAR(50) NOT NULL,
+    ResourceId VARCHAR(50) NOT NULL,   -- ✅ NEW: Resource per service
+    CustomPrice DECIMAL(10,2) NULL,
+    SortOrder INT NULL,
+
+    FOREIGN KEY (BookingId) REFERENCES Booking(Id),
+    FOREIGN KEY (ServiceId) REFERENCES Service(Id),
+    FOREIGN KEY (ResourceId) REFERENCES Resource(Id)  -- ✅ NEW FK
+);
+
+CREATE TABLE CalendarEvent (
+    Id VARCHAR(50) PRIMARY KEY,
+    Start DATETIME NOT NULL,
+    End DATETIME NOT NULL,
+    Type VARCHAR(50) NOT NULL,         -- ✅ Distinguishes customer vs vacation
+    BookingId VARCHAR(50) NULL,        -- ✅ Nullable (only customer has booking)
+    ResourceId VARCHAR(50) NULL,       -- ✅ Denormalized for performance
+    CustomerId VARCHAR(50) NULL,       -- ✅ Denormalized for performance
+
+    FOREIGN KEY (BookingId) REFERENCES Booking(Id)
+);
+```
+
+---
+
+## Code Changes Summary
+
+### Files Created (3)
+1. **src/types/ResourceTypes.ts** - IResource interface
+2. **src/types/BookingTypes.ts** - IBooking + IBookingService + CalendarEventType
+3. **src/types/CustomerTypes.ts** - ICustomer interface
+
+### Files Modified (2)
+4. **src/types/ColumnDataSource.ts** - Changed `Date | any` to `Date | IResource`
+5. **src/types/CalendarTypes.ts** - Updated ICalendarEvent to use CalendarEventType
+
+### Documentation Created (1)
+6. **docs/booking-event-architecture.md** - 930 lines comprehensive guide
+   - 6 detailed examples
+   - Database schemas (SQL + IndexedDB)
+   - 5 business rules
+   - 4 common pitfalls
+   - Analytics patterns
+   - Query examples
+
+---
+
+## Statistics
+
+| Metric | Count |
+|--------|-------|
+| **Time Spent** | 2+ hours |
+| **Initial Estimate** | 10 minutes |
+| **Major Iterations** | 4 |
+| **Architectural Pivots** | 3 |
+| **Developer Catches** | 5+ critical issues |
+| **Interfaces Created** | 5 (IResource, IBooking, IBookingService, ICustomer, CalendarEventType) |
+| **Interfaces Modified** | 2 (IColumnInfo, ICalendarEvent) |
+| **Documentation Written** | 930 lines |
+| **Examples Documented** | 6 scenarios |
+| **Business Rules Defined** | 5 |
+| **Common Pitfalls Identified** | 4 |
+| **Database Tables Changed** | 3 (Booking, BookingService, CalendarEvent) |
+
+---
+
+## Developer Interventions (Critical Thinking Points)
+
+### 1. "What if multiple resources work on same booking?"
+**Prevented:** Single-resource assumption that would block split bookings
+
+### 2. "Why should there be a primary resource?"
+**Prevented:** Artificial hierarchy that doesn't match business reality
+
+### 3. "Is vacation a booking?"
+**Resulted in:** Clean separation - Booking = customers only, Events = everything
+
+### 4. "If the student is sick?"
+**Resulted in:** Service-level resource assignment enabling reassignment
+
+### 5. "BookingType is gone now, right?"
+**Resulted in:** Consistent naming - CalendarEventType for events, not bookings
+
+---
+
+## What We Almost Built (And Avoided)
+
+### ❌ Wrong Architecture 1: Primary Resource Model
+Would have required:
+- Complex logic to determine "who is primary"
+- Arbitrary decision making (is master or student primary?)
+- Doesn't support equal splits (Karina + Nanna)
+
+### ❌ Wrong Architecture 2: Booking.resourceId + Service.resourceId
+Would have resulted in:
+- Redundant data
+- Confusion about which resourceId to use
+- "Primary" concept that doesn't exist in business logic
+
+### ❌ Wrong Architecture 3: Vacation as Booking
+Would have created:
+- Optional fields everywhere (services? customer? for vacation?)
+- Complex validation logic
+- Confusing domain model
+
+---
+
+## Final Architecture Benefits
+
+### ✅ Clean Separation of Concerns
+- **Booking** = Customer + Services (WHAT + HOW MUCH)
+- **CalendarEvent** = Time + Resource (WHEN + WHO)
+
+### ✅ Supports All Business Scenarios
+1. Simple booking (one customer, one service, one resource)
+2. Split session (one booking, multiple days)
+3. Split resources (student + master)
+4. Equal splits (two masters, no primary)
+5. Queued bookings (no time slot yet)
+6. Vacation/break (no booking, just time blocking)
+
+### ✅ Type-Safe
+- Required fields are enforced: `customerId: string`, `services: IBookingService[]`
+- No optional fields that "sometimes" matter
+- CalendarEventType clearly distinguishes booking vs non-booking events
+
+### ✅ Flexible Resource Assignment
+- Assign different resources per service
+- Reassign if resource unavailable (student sick)
+- No "primary" to maintain
+
+### ✅ Query-Optimized
+- CalendarEvent denormalizes resourceId for fast queries
+- No JOIN needed to find "Karina's events"
+- IndexedDB-friendly (no JOIN support)
+
+---
+
+## Lessons Learned
+
+### 1. Question Assumptions Early
+**My assumption:** "Bookings are resource-bound"
+**Reality:** Bookings are customer-bound, resources are service-bound
+
+### 2. Use Real Business Scenarios
+Abstract discussions led to wrong models. Concrete examples ("student + master split") revealed the truth.
+
+### 3. Don't Force Hierarchies
+"Primary resource" seemed logical but didn't match business reality. Equal splits exist.
+
+### 4. Separation of Concerns Matters
+Mixing booking (business) with scheduling (time) created optional fields everywhere.
+
+### 5. Developer Domain Knowledge is Critical
+I had TypeScript expertise, but developer had business domain knowledge. The combination caught 5+ critical flaws before they became code.
+
+---
+
+## Documentation Deliverables
+
+### booking-event-architecture.md (930 lines)
+
+**Sections:**
+1. Core Principles - Separation of concerns
+2. Entity Definitions - Booking vs CalendarEvent
+3. Relationship Model - 1:N (one booking → many events)
+4. 6 Detailed Examples:
+   - Split session (same resource, multiple days)
+   - Split resources (master + student)
+   - Equal split (two masters)
+   - Queued booking
+   - Vacation (no booking)
+   - Simple reminder
+5. Database Schema - SQL (normalized) + IndexedDB (denormalized)
+6. API Data Flow - Backend JOIN → Frontend denormalization
+7. Business Rules - 5 rules with code examples
+8. Analytics & Reporting - Service duration vs actual time
+9. TypeScript Interfaces - Complete reference
+10. Common Pitfalls - 4 mistakes to avoid
+11. Summary Table - Quick reference
+12. Decision Guide - "Where does this belong?"
+
+---
+
+## Build Results
+
+✅ **All TypeScript compilation successful**
+- 57 files processed
+- 0 errors
+- 0 warnings
+- Build time: ~1.2s
+
+✅ **Type safety improved**
+- Removed `Date | any` (was unsafe)
+- Added `Date | IResource` (type-safe union)
+- Added CalendarEventType (was `string`)
+
+---
+
+## Conclusion
+
+**Initial request:** "Create IResource interface"
+**Time estimated:** 10 minutes
+**Time actual:** 2+ hours
+
+**Why the difference?**
+
+Because the developer asked the right questions at the right time:
+1. "What if multiple resources work together?"
+2. "Why assume a primary?"
+3. "Is vacation really a booking?"
+4. "What if we need to reassign?"
+
+Each question revealed a flaw in my assumptions. We iterated 4 times, discarded 3 approaches, and arrived at an architecture that actually matches the business model.
+
+**This is exactly how good software development should work.**
+
+The 2 hours spent thinking prevented weeks of refactoring later. Critical thinking and domain knowledge prevented premature optimization and over-engineering.
+
+---
+
+## Next Steps (Not Part of This Session)
+
+**Phase 2: Resource Calendar Implementation**
+- Create ResourceColumnDataSource (returns IColumnInfo with IResource data)
+- Create ResourceHeaderRenderer (renders resource headers instead of dates)
+- Implement resource-mode switching (date-mode ↔ resource-mode)
+- Add repository methods for resource queries
+
+**Phase 3: Booking Management**
+- Implement booking creation flow
+- Service-to-event mapping logic
+- Split-resource UI (assign services to different resources)
+- Resource reassignment (when student is sick)
+
+---
+
+**Session End**
+
+**Key Takeaway:** Slow down to speed up. 2 hours of architecture discussion saved weeks of wrong implementation.
diff --git a/docs/booking-event-architecture.md b/docs/booking-event-architecture.md
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+# Booking vs CalendarEvent Architecture
+
+**Status:** Active Architecture Document
+**Last Updated:** 2025-11-14
+**Purpose:** Define the separation of concerns between Booking (business domain) and CalendarEvent (scheduling domain)
+
+---
+
+## Core Principle: Separation of Concerns
+
+The calendar system uses **two distinct entities** to model appointments:
+
+1. **Booking** = Customer + Services (business container - WHAT, WHO, HOW MUCH)
+2. **CalendarEvent** = Scheduling container (WHEN, WHICH RESOURCE)
+
+This separation enables:
+- ✅ Flexible scheduling (one booking → multiple time slots or resources)
+- ✅ Queue management (bookings without scheduled time)
+- ✅ Time adjustments without business logic changes
+- ✅ Clear analytics (service duration vs actual time spent)
+- ✅ Split-resource bookings (one booking → multiple resources)
+
+---
+
+## Entity Definitions
+
+### Booking (Domain Model)
+
+**Purpose:** Represents a customer service booking ONLY
+
+**Contains:**
+- `customerId` - Who receives the service (REQUIRED)
+- `status` - Lifecycle state: created, arrived, paid, noshow, cancelled
+- `services[]` - Services to be performed (REQUIRED, each has resourceId)
+- `totalPrice` - Business value (can differ from service prices)
+- `tags`, `notes`, `createdAt` - Metadata
+
+**Does NOT contain:**
+- ❌ `start` / `end` - Timing is on CalendarEvent
+- ❌ `type` - Always customer, so redundant
+- ❌ `resourceId` - Resources assigned per service (IBookingService.resourceId)
+
+**Key Rules:**
+- Booking is ALWAYS customer-related (`customerId` required)
+- Booking ALWAYS has services (`services[]` required)
+- Resources are assigned at SERVICE level (not booking level)
+- Booking can exist WITHOUT CalendarEvent (pending/queued state)
+- Booking CANNOT be deleted if CalendarEvents reference it
+- **Vacation/break/meeting are NOT bookings** - only CalendarEvents
+
+---
+
+### CalendarEvent (Scheduling Model)
+
+**Purpose:** Represents a time slot in the calendar
+
+**Contains:**
+- `start` - When does it happen (MASTER)
+- `end` - When does it end (MASTER)
+- `allDay` - Is it an all-day event
+- `type` - CalendarEventType: 'customer', 'vacation', 'break', 'meeting', 'blocked'
+- `bookingId` - Reference to business data (nullable - only 'customer' type has booking)
+- `resourceId` - Which resource owns this time slot
+- `customerId` - Denormalized for query performance
+- `title`, `description` - Display properties
+
+**Key Rules:**
+- CalendarEvent is the MASTER for timing
+- CalendarEvent can exist WITHOUT Booking (vacation, breaks, reminders)
+- CalendarEvent CANNOT be deleted if it references a Booking
+- Only type='customer' events have associated bookings
+
+---
+
+## Relationship: 1 Booking → N Events
+
+**Key Innovation:** One booking can span MULTIPLE calendar events (split sessions OR split resources).
+
+### Example 1: Split Session (Same Resource, Multiple Days)
+
+**Scenario:** Bundfarve takes 180 minutes but is split across 2 days.
+
+```json
+// Booking (business contract)
+{
+  "id": "BOOK001",
+  "customerId": "CUST456",
+  "status": "created",
+  "services": [
+    {
+      "serviceName": "Bundfarve komplet",
+      "baseDuration": 180,
+      "resourceId": "EMP001"  // Karina performs all
+    }
+  ],
+  "totalPrice": 1500
+}
+
+// CalendarEvent 1 (first session)
+{
+  "id": "EVT001",
+  "type": "customer",
+  "title": "Anna - Bundfarve (Del 1)",
+  "start": "2025-11-14T13:00:00",
+  "end": "2025-11-14T15:00:00",     // 120 minutes
+  "bookingId": "BOOK001",
+  "resourceId": "EMP001",
+  "customerId": "CUST456"
+}
+
+// CalendarEvent 2 (second session - next day)
+{
+  "id": "EVT002",
+  "type": "customer",
+  "title": "Anna - Bundfarve (Del 2)",
+  "start": "2025-11-15T10:00:00",
+  "end": "2025-11-15T11:00:00",     // 60 minutes
+  "bookingId": "BOOK001",            // SAME booking!
+  "resourceId": "EMP001",
+  "customerId": "CUST456"
+}
+```
+
+**Analytics:**
+- Service duration: 180 min (what customer paid for)
+- Actual time slots: 120 + 60 = 180 min (resource allocation)
+
+---
+
+### Example 2: Split Resources (Master + Student)
+
+**Scenario:** Hårvask (30 min) by student, then Bundfarve (90 min) by master.
+
+```json
+// Booking (business contract)
+{
+  "id": "BOOK002",
+  "customerId": "CUST456",
+  "status": "created",
+  "services": [
+    {
+      "serviceName": "Hårvask + bryn",
+      "baseDuration": 30,
+      "resourceId": "STUDENT001"  // Student performs this
+    },
+    {
+      "serviceName": "Bundfarve",
+      "baseDuration": 90,
+      "resourceId": "EMP001"      // Master performs this
+    }
+  ],
+  "totalPrice": 1160
+}
+
+// CalendarEvent 1 (student's time slot)
+{
+  "id": "EVT003",
+  "type": "customer",
+  "title": "Anna - Hårvask",
+  "start": "2025-11-14T13:00:00",
+  "end": "2025-11-14T13:30:00",
+  "bookingId": "BOOK002",
+  "resourceId": "STUDENT001",     // Student's calendar
+  "customerId": "CUST456"
+}
+
+// CalendarEvent 2 (master's time slot)
+{
+  "id": "EVT004",
+  "type": "customer",
+  "title": "Anna - Bundfarve",
+  "start": "2025-11-14T13:30:00",
+  "end": "2025-11-14T15:00:00",
+  "bookingId": "BOOK002",          // SAME booking!
+  "resourceId": "EMP001",          // Master's calendar
+  "customerId": "CUST456"
+}
+```
+
+**Key Points:**
+- One booking spans TWO resources
+- Each resource gets their own CalendarEvent
+- Events can be at different times (student starts, then master)
+- Total time: student 30min + master 90min = 120min
+
+---
+
+### Example 3: Split Resources (Two Masters, Equal Split)
+
+**Scenario:** Bundfarve komplet (3 hours) split equally between Karina and Nanna.
+
+```json
+// Booking (customer chose to split between two masters)
+{
+  "id": "BOOK003",
+  "customerId": "CUST789",
+  "status": "created",
+  "services": [
+    {
+      "serviceName": "Bundfarve del 1",
+      "baseDuration": 90,
+      "resourceId": "EMP001"      // Karina
+    },
+    {
+      "serviceName": "Bundfarve del 2",
+      "baseDuration": 90,
+      "resourceId": "EMP002"      // Nanna
+    }
+  ],
+  "totalPrice": 2000
+}
+
+// CalendarEvent 1 (Karina's part)
+{
+  "id": "EVT005",
+  "type": "customer",
+  "start": "2025-11-14T10:00:00",
+  "end": "2025-11-14T11:30:00",
+  "bookingId": "BOOK003",
+  "resourceId": "EMP001"          // Karina's calendar
+}
+
+// CalendarEvent 2 (Nanna's part)
+{
+  "id": "EVT006",
+  "type": "customer",
+  "start": "2025-11-14T11:30:00",
+  "end": "2025-11-14T13:00:00",
+  "bookingId": "BOOK003",
+  "resourceId": "EMP002"          // Nanna's calendar
+}
+```
+
+**Key Points:**
+- No "primary" resource - both are equal
+- Customer agreed to split during booking
+- Each master gets 90 minutes
+- Can be scheduled at different times if needed
+
+---
+
+### Example 4: Queued Booking (No Events Yet)
+
+**Scenario:** Customer wants an appointment but no time slot is available yet.
+
+```json
+// Booking exists (in queue)
+{
+  "id": "BOOK004",
+  "customerId": "CUST999",
+  "status": "pending",
+  "services": [
+    {
+      "serviceName": "Klipning",
+      "baseDuration": 30,
+      "resourceId": "EMP001"  // Pre-assigned to Karina
+    }
+  ]
+}
+
+// NO CalendarEvent yet!
+// Query: SELECT * FROM CalendarEvent WHERE bookingId = 'BOOK004'
+// Result: Empty
+
+// When time is found, create event:
+{
+  "id": "EVT007",
+  "type": "customer",
+  "start": "2025-11-20T14:00:00",
+  "end": "2025-11-20T14:30:00",
+  "bookingId": "BOOK004",
+  "resourceId": "EMP001"
+}
+
+// Update booking status:
+UPDATE Booking SET status = 'scheduled' WHERE id = 'BOOK004'
+```
+
+---
+
+### Example 5: Vacation (NO Booking)
+
+**Scenario:** Karina is on vacation - NOT a booking.
+
+```json
+// NO Booking exists!
+
+// CalendarEvent only
+{
+  "id": "EVT008",
+  "type": "vacation",              // NOT 'customer'
+  "title": "Karina - Juleferie",
+  "start": "2025-12-23T00:00:00",
+  "end": "2025-12-30T23:59:59",
+  "allDay": true,
+  "bookingId": null,               // NO booking reference
+  "resourceId": "EMP001",          // Karina
+  "customerId": null
+}
+```
+
+**Key Points:**
+- Vacation/break/meeting are CalendarEvents ONLY
+- They do NOT have associated bookings
+- `type` determines whether booking exists:
+  - `type = 'customer'` → has booking
+  - `type = 'vacation'/'break'/'meeting'` → no booking
+
+---
+
+### Example 6: Simple Reminder (NO Booking, NO Resource)
+
+**Scenario:** Personal task not tied to any business transaction.
+
+```json
+// CalendarEvent (standalone)
+{
+  "id": "EVT009",
+  "type": "meeting",               // Or custom type
+  "title": "Husk at ringe til leverandør",
+  "start": "2025-11-15T10:00:00",
+  "end": "2025-11-15T10:15:00",
+  "bookingId": null,               // NO booking
+  "resourceId": null,              // NO resource
+  "customerId": null
+}
+```
+
+---
+
+## Duration Calculation
+
+### Service Bookings
+
+**Duration = Sum of service durations**
+
+```typescript
+// Booking
+{
+  "services": [
+    { "baseDuration": 90, "resourceId": "EMP001" },
+    { "baseDuration": 30, "resourceId": "STUDENT001" }
+  ]
+}
+
+// Initial event creation:
+const totalServiceDuration = services.reduce((sum, s) => sum + s.baseDuration, 0);
+// totalServiceDuration = 120 minutes
+
+// Create events (one per resource or split session)
+events = services.map(service => ({
+  start: calculateStartTime(service),
+  end: start + service.baseDuration,
+  resourceId: service.resourceId
+}));
+```
+
+**User Adjustment:**
+User can drag/resize event.end in calendar (e.g., from 15:00 to 15:30)
+- Services still show 120min (what was booked)
+- Event shows 150min (actual time spent)
+- This is CORRECT behavior (tracks overrun)
+
+---
+
+## Database Schema
+
+### Backend (SQL - Normalized)
+
+```sql
+-- Booking table (NO timing, NO resourceId)
+CREATE TABLE Booking (
+    Id VARCHAR(50) PRIMARY KEY,
+    CustomerId VARCHAR(50) NOT NULL,        -- FK to Customer (REQUIRED)
+    Status VARCHAR(20) NOT NULL,
+    TotalPrice DECIMAL(10,2) NULL,
+    CreatedAt DATETIME NOT NULL,
+    Tags NVARCHAR(500) NULL,
+    Notes NVARCHAR(MAX) NULL,
+
+    FOREIGN KEY (CustomerId) REFERENCES Customer(Id)
+);
+
+-- CalendarEvent table (HAS timing)
+CREATE TABLE CalendarEvent (
+    Id VARCHAR(50) PRIMARY KEY,
+    Title NVARCHAR(200) NOT NULL,
+    Description NVARCHAR(MAX) NULL,
+    Start DATETIME NOT NULL,
+    End DATETIME NOT NULL,
+    AllDay BIT NOT NULL,
+    Type VARCHAR(50) NOT NULL,              -- 'customer', 'vacation', 'break', etc.
+
+    -- References (BookingId is nullable - only 'customer' type has booking)
+    BookingId VARCHAR(50) NULL,
+
+    -- Denormalized (for query performance)
+    ResourceId VARCHAR(50) NULL,            -- Which resource owns this slot
+    CustomerId VARCHAR(50) NULL,            -- Copied from Booking
+
+    FOREIGN KEY (BookingId) REFERENCES Booking(Id)
+);
+
+-- BookingService junction table (WITH ResourceId)
+CREATE TABLE BookingService (
+    BookingId VARCHAR(50) NOT NULL,
+    ServiceId VARCHAR(50) NOT NULL,
+    ResourceId VARCHAR(50) NOT NULL,        -- NEW: Resource performing THIS service
+    CustomPrice DECIMAL(10,2) NULL,
+    SortOrder INT NULL,
+
+    PRIMARY KEY (BookingId, ServiceId),
+    FOREIGN KEY (BookingId) REFERENCES Booking(Id),
+    FOREIGN KEY (ServiceId) REFERENCES Service(Id),
+    FOREIGN KEY (ResourceId) REFERENCES Resource(Id)
+);
+```
+
+**Key Changes from Old Schema:**
+- ❌ Booking table NO LONGER has ResourceId
+- ❌ Booking table NO LONGER has Type
+- ✅ BookingService table NOW has ResourceId (NEW!)
+- ✅ CalendarEvent.Type distinguishes customer vs vacation/break
+
+**Why ResourceId/CustomerId on CalendarEvent?**
+- Performance: Filter events by resource WITHOUT joining Booking/BookingService
+- IndexedDB: Frontend needs these for fast queries (no JOIN support)
+
+---
+
+### Frontend (IndexedDB - Denormalized)
+
+```typescript
+// IndexedDB stores
+const db = await openDB('CalendarDB', 1, {
+  upgrade(db) {
+    // Events store (MASTER for queries)
+    const eventStore = db.createObjectStore('events', { keyPath: 'id' });
+    eventStore.createIndex('by_start', 'start');
+    eventStore.createIndex('by_type', 'type');
+    eventStore.createIndex('by_resourceId', 'resourceId');   // Denormalized!
+    eventStore.createIndex('by_customerId', 'customerId');   // Denormalized!
+    eventStore.createIndex('by_bookingId', 'bookingId');
+
+    // Bookings store (REFERENCE data, loaded on-demand)
+    const bookingStore = db.createObjectStore('bookings', { keyPath: 'id' });
+    bookingStore.createIndex('by_customerId', 'customerId');
+    bookingStore.createIndex('by_status', 'status');
+  }
+});
+```
+
+**Query Pattern:**
+
+```typescript
+// Get events for resource (NO JOIN needed)
+async getEventsForResource(resourceId: string, start: Date, end: Date) {
+  const events = await db.getAllFromIndex('events', 'by_resourceId', resourceId);
+  return events.filter(e => e.start >= start && e.start <= end);
+}
+
+// Get customer bookings (via events)
+async getCustomerBookingsInPeriod(customerId: string, start: Date, end: Date) {
+  // 1. Get customer events
+  const events = await db.events
+    .where('customerId').equals(customerId)
+    .filter(e => e.start >= start && e.start <= end && e.type === 'customer')
+    .toArray();
+
+  // 2. Get unique booking IDs
+  const bookingIds = [...new Set(events.map(e => e.bookingId).filter(Boolean))];
+
+  // 3. Load bookings
+  const bookings = await Promise.all(
+    bookingIds.map(id => db.get('bookings', id))
+  );
+
+  return bookings;
+}
+
+// Get booking with all resources involved
+async getBookingResources(bookingId: string) {
+  const booking = await db.get('bookings', bookingId);
+
+  // Extract unique resources from services
+  const resourceIds = [...new Set(booking.services.map(s => s.resourceId))];
+
+  return resourceIds;
+}
+```
+
+---
+
+## API Data Flow
+
+### Backend Normalization → Frontend Denormalization
+
+**Backend API Response (Denormalized via JOIN):**
+
+```http
+GET /api/events?start=2025-11-14&end=2025-11-21
+```
+
+```json
+[
+  {
+    "id": "EVT001",
+    "type": "customer",
+    "title": "Anna - Bundfarve",
+    "start": "2025-11-14T13:00:00",
+    "end": "2025-11-14T15:00:00",
+    "allDay": false,
+    "bookingId": "BOOK001",
+    "resourceId": "EMP001",      // ← Backend determines from event context
+    "customerId": "CUST456"      // ← Backend JOINed from Booking
+  },
+  {
+    "id": "EVT008",
+    "type": "vacation",
+    "title": "Karina - Juleferie",
+    "start": "2025-12-23T00:00:00",
+    "end": "2025-12-30T23:59:59",
+    "allDay": true,
+    "bookingId": null,           // ← No booking for vacation
+    "resourceId": "EMP001",
+    "customerId": null
+  }
+]
+```
+
+**Backend SQL (with JOIN):**
+
+```sql
+SELECT
+  e.Id,
+  e.Type,
+  e.Title,
+  e.Start,
+  e.End,
+  e.AllDay,
+  e.BookingId,
+  e.ResourceId,              -- Already on CalendarEvent (denormalized)
+  b.CustomerId               -- Joined from Booking (if exists)
+FROM CalendarEvent e
+LEFT JOIN Booking b ON e.BookingId = b.Id
+WHERE e.Start >= @start AND e.Start <= @end
+```
+
+---
+
+## Business Rules
+
+### Rule 1: Booking Requires Customer (Always)
+
+```typescript
+// ✅ VALID - Booking always has customer + services
+{
+  "customerId": "CUST456",
+  "services": [
+    { "resourceId": "EMP001", "serviceName": "Klipning" }
+  ]
+}
+
+// ❌ INVALID - Booking without customer
+{
+  "customerId": null,          // ERROR: Booking requires customer
+  "services": [...]
+}
+
+// ❌ INVALID - Booking without services
+{
+  "customerId": "CUST456",
+  "services": []               // ERROR: Booking requires services
+}
+```
+
+---
+
+### Rule 2: Event Cannot Be Deleted If It Has Booking
+
+```typescript
+async deleteEvent(eventId: string) {
+  const event = await db.get('events', eventId);
+
+  if (event.bookingId) {
+    throw new Error("Cannot delete event with booking. Cancel booking first.");
+  }
+
+  await db.delete('events', eventId);  // OK for vacation/reminders
+}
+```
+
+---
+
+### Rule 3: Booking Can Be Cancelled (Cascades to Events)
+
+```typescript
+async cancelBooking(bookingId: string) {
+  // 1. Update booking status
+  await db.bookings.update(bookingId, { status: 'cancelled' });
+
+  // 2. Find ALL related events (may be multiple resources/sessions)
+  const events = await db.events.where('bookingId').equals(bookingId).toArray();
+
+  // 3. Delete OR mark cancelled
+  for (const event of events) {
+    await db.events.delete(event.id);  // Remove from calendar
+  }
+}
+```
+
+---
+
+### Rule 4: Moving Event Updates Only Event (Not Booking)
+
+```typescript
+// User drags event from 13:00 to 14:00
+async moveEvent(eventId: string, newStart: Date, newEnd: Date) {
+  // Update ONLY the event
+  await db.events.update(eventId, {
+    start: newStart,
+    end: newEnd
+  });
+
+  // Booking services/price remain unchanged
+  // (This is correct - tracks time adjustments vs booked services)
+}
+```
+
+---
+
+### Rule 5: Service Resource Can Be Changed (Elev Syg)
+
+```typescript
+// Elev is sick - reassign to another student
+async reassignServiceResource(bookingId: string, serviceId: string, newResourceId: string) {
+  // 1. Update booking service
+  const booking = await db.get('bookings', bookingId);
+  const service = booking.services.find(s => s.serviceId === serviceId);
+  service.resourceId = newResourceId;
+  await db.put('bookings', booking);
+
+  // 2. Find and update related event
+  const events = await db.events.where('bookingId').equals(bookingId).toArray();
+  const eventToUpdate = events.find(e => e.resourceId === oldResourceId);
+
+  if (eventToUpdate) {
+    eventToUpdate.resourceId = newResourceId;
+    await db.put('events', eventToUpdate);
+  }
+}
+```
+
+---
+
+## Analytics & Reporting
+
+### Service Duration vs Actual Duration
+
+```typescript
+// Get booking with actual time spent
+async getBookingAnalytics(bookingId: string) {
+  const booking = await db.get('bookings', bookingId);
+  const events = await db.events.where('bookingId').equals(bookingId).toArray();
+
+  // Booked duration (from services)
+  const bookedDuration = booking.services
+    .reduce((sum, s) => sum + s.baseDuration, 0);
+
+  // Actual duration (from events)
+  const actualDuration = events
+    .reduce((sum, e) => sum + (e.end - e.start) / 60000, 0);
+
+  return {
+    bookedMinutes: bookedDuration,     // 120 min (what customer paid for)
+    actualMinutes: actualDuration,     // 150 min (real time spent)
+    overrun: actualDuration - bookedDuration  // +30 min
+  };
+}
+```
+
+---
+
+### Resource Utilization
+
+```typescript
+// How much time did Karina work in November?
+async getResourceUtilization(resourceId: string, month: Date) {
+  const start = startOfMonth(month);
+  const end = endOfMonth(month);
+
+  // Query events (NOT bookings - because events have timing)
+  const events = await db.events
+    .where('resourceId').equals(resourceId)
+    .filter(e => e.start >= start && e.start <= end)
+    .toArray();
+
+  const totalMinutes = events
+    .reduce((sum, e) => sum + (e.end - e.start) / 60000, 0);
+
+  return {
+    resourceId,
+    month: format(month, 'yyyy-MM'),
+    totalHours: totalMinutes / 60,
+    eventCount: events.length,
+    breakdown: {
+      customer: events.filter(e => e.type === 'customer').length,
+      vacation: events.filter(e => e.type === 'vacation').length,
+      break: events.filter(e => e.type === 'break').length
+    }
+  };
+}
+```
+
+---
+
+### Find Bookings Involving Resource
+
+```typescript
+// Find all bookings where Karina is involved (even if not all services)
+async getBookingsForResource(resourceId: string, start: Date, end: Date) {
+  // 1. Get events for resource in period
+  const events = await db.events
+    .where('resourceId').equals(resourceId)
+    .filter(e => e.start >= start && e.start <= end && e.type === 'customer')
+    .toArray();
+
+  // 2. Get unique booking IDs
+  const bookingIds = [...new Set(events.map(e => e.bookingId).filter(Boolean))];
+
+  // 3. Load bookings
+  const bookings = await Promise.all(
+    bookingIds.map(id => db.get('bookings', id))
+  );
+
+  return bookings;
+}
+```
+
+---
+
+## TypeScript Interfaces (Reference)
+
+```typescript
+// src/types/BookingTypes.ts
+export interface IBooking {
+  id: string;
+  customerId: string;        // REQUIRED - always has customer
+  status: BookingStatus;
+  createdAt: Date;
+
+  services: IBookingService[];  // REQUIRED - always has services
+  totalPrice?: number;
+  tags?: string[];
+  notes?: string;
+
+  // NO resourceId - assigned per service
+  // NO type - always customer
+  // NO start/end - timing on CalendarEvent
+}
+
+export interface IBookingService {
+  serviceId: string;
+  serviceName: string;
+  baseDuration: number;
+  basePrice: number;
+  customPrice?: number;
+  resourceId: string;        // Resource who performs THIS service
+}
+
+export type CalendarEventType =
+  | 'customer'    // Customer appointment (HAS booking)
+  | 'vacation'    // Vacation/time off (NO booking)
+  | 'break'       // Lunch/break (NO booking)
+  | 'meeting'     // Meeting (NO booking)
+  | 'blocked';    // Blocked time (NO booking)
+
+export type BookingStatus =
+  | 'created'     // AftaleOprettet
+  | 'arrived'     // Ankommet
+  | 'paid'        // Betalt
+  | 'noshow'      // Udeblevet
+  | 'cancelled';  // Aflyst
+
+// src/types/CalendarTypes.ts
+export interface ICalendarEvent {
+  id: string;
+  title: string;
+  description?: string;
+
+  start: Date;               // MASTER for timing
+  end: Date;                 // MASTER for timing
+  allDay: boolean;
+
+  type: CalendarEventType;   // Determines if booking exists
+
+  // References (denormalized)
+  bookingId?: string;        // Only if type = 'customer'
+  resourceId?: string;       // Which resource owns this slot
+  customerId?: string;       // Denormalized from Booking
+
+  syncStatus: SyncStatus;
+  recurringId?: string;
+  metadata?: Record<string, any>;
+}
+```
+
+---
+
+## Common Pitfalls
+
+### ❌ Pitfall 1: Trying to Query Bookings by Time
+
+```typescript
+// WRONG - Bookings don't have start/end
+const bookings = await db.bookings
+  .where('start').between(startDate, endDate)  // ERROR: No 'start' field!
+  .toArray();
+
+// CORRECT - Query events, then load bookings
+const events = await db.events
+  .where('start').between(startDate, endDate)
+  .filter(e => e.type === 'customer')  // Only customer events have bookings
+  .toArray();
+
+const bookingIds = events
+  .filter(e => e.bookingId)
+  .map(e => e.bookingId);
+
+const bookings = await Promise.all(
+  bookingIds.map(id => db.get('bookings', id))
+);
+```
+
+---
+
+### ❌ Pitfall 2: Assuming 1:1 Relationship
+
+```typescript
+// WRONG - Assumes one event per booking
+const booking = await db.get('bookings', bookingId);
+const event = await db.events
+  .where('bookingId').equals(bookingId)
+  .first();  // Only gets first event!
+
+// CORRECT - Get ALL events for booking (split sessions/resources)
+const events = await db.events
+  .where('bookingId').equals(bookingId)
+  .toArray();  // May return multiple events
+```
+
+---
+
+### ❌ Pitfall 3: Looking for resourceId on Booking
+
+```typescript
+// WRONG - Booking doesn't have resourceId
+const booking = await db.get('bookings', bookingId);
+console.log(booking.resourceId);  // ERROR: undefined!
+
+// CORRECT - Get resources from services
+const resourceIds = [...new Set(booking.services.map(s => s.resourceId))];
+console.log(resourceIds);  // ["EMP001", "STUDENT001"]
+```
+
+---
+
+### ❌ Pitfall 4: Trying to Create Vacation as Booking
+
+```typescript
+// WRONG - Vacation is NOT a booking
+const vacationBooking = {
+  customerId: null,
+  type: 'vacation',
+  services: []
+};
+await db.add('bookings', vacationBooking);  // ERROR: Invalid!
+
+// CORRECT - Vacation is CalendarEvent only
+const vacationEvent = {
+  type: 'vacation',
+  start: new Date('2025-12-23'),
+  end: new Date('2025-12-30'),
+  bookingId: null,          // NO booking
+  resourceId: 'EMP001'
+};
+await db.add('events', vacationEvent);  // OK
+```
+
+---
+
+## Summary
+
+| Aspect | Booking | CalendarEvent |
+|--------|---------|---------------|
+| **Purpose** | Customer + Services | Time slot + Resource |
+| **Timing** | No start/end | Has start/end |
+| **Resource** | Per service | Per event (denormalized) |
+| **Type** | Always customer | customer/vacation/break/meeting |
+| **Relationship** | 1 booking → N events | N events → 0..1 booking |
+| **Can exist alone?** | Yes (queued) | Yes (vacation/reminders) |
+| **Query by time?** | ❌ No | ✅ Yes |
+| **Query by resource?** | ❌ No (via services) | ✅ Yes (direct) |
+| **Master for...** | Services, price, customer | Timing, scheduling, resource |
+
+**Key Takeaways:**
+- Use **CalendarEvent** for all scheduling queries (when, who)
+- Use **Booking** for business data (what, how much)
+- Only `type='customer'` events have bookings
+- Vacation/break/meeting are events without bookings
+- Resources are assigned at **service level**, not booking level
+- One booking can involve **multiple resources** (split services)
+
+---
+
+## Decision Guide
+
+If you're unsure whether something belongs in Booking or CalendarEvent, ask:
+
+1. **"Is this about WHEN it happens?"** → CalendarEvent
+2. **"Is this about WHICH RESOURCE does it?"** → CalendarEvent
+3. **"Is this about WHAT/WHO/HOW MUCH?"** → Booking
+4. **"Can this change when the event is moved in calendar?"**
+   - If YES → CalendarEvent
+   - If NO → Booking
+5. **"Is this vacation/break/meeting?"** → CalendarEvent ONLY (no booking)
+
+---
+
+**Document End**
diff --git a/src/types/BookingTypes.ts b/src/types/BookingTypes.ts
new file mode 100644
index 0000000..17bac5e
--- /dev/null
+++ b/src/types/BookingTypes.ts
@@ -0,0 +1,63 @@
+/**
+ * Booking entity - represents customer service bookings ONLY
+ *
+ * IMPORTANT ARCHITECTURE:
+ * - Booking = Customer + Services (business container)
+ * - Booking does NOT have start/end - timing is on CalendarEvent
+ * - Booking does NOT have resourceId - resources assigned per service
+ * - One booking can have multiple CalendarEvents (split sessions or resources)
+ * - Booking can exist without events (queued/pending state)
+ * - Vacation/break/meeting are NOT bookings - only CalendarEvents
+ *
+ * Resource Assignment:
+ * - Resources are assigned at SERVICE level (IBookingService.resourceId)
+ * - One service can be performed by one resource
+ * - Multiple services can be performed by different resources
+ * - Example: Hårvask by Student, Bundfarve by Master (same booking, 2 resources)
+ *
+ * Matches backend Booking table structure
+ */
+export interface IBooking {
+  id: string;
+  customerId: string;        // REQUIRED - booking is always for a customer
+  status: BookingStatus;
+  createdAt: Date;
+
+  // Services (REQUIRED - booking always has services)
+  services: IBookingService[];
+
+  // Payment
+  totalPrice?: number;       // Can differ from sum of service prices
+
+  // Metadata
+  tags?: string[];
+  notes?: string;
+}
+
+/**
+ * CalendarEventType - Used by ICalendarEvent.type
+ * Note: Only 'customer' events have associated IBooking
+ * Other types (vacation/break/meeting/blocked) are CalendarEvents without bookings
+ */
+export type CalendarEventType =
+  | 'customer'    // Customer appointment (HAS booking)
+  | 'vacation'    // Vacation/time off (NO booking)
+  | 'break'       // Lunch/break (NO booking)
+  | 'meeting'     // Meeting (NO booking)
+  | 'blocked';    // Blocked time (NO booking)
+
+export type BookingStatus =
+  | 'created'     // AftaleOprettet
+  | 'arrived'     // Ankommet
+  | 'paid'        // Betalt
+  | 'noshow'      // Udeblevet
+  | 'cancelled';  // Aflyst
+
+export interface IBookingService {
+  serviceId: string;
+  serviceName: string;       // Denormalized for display
+  baseDuration: number;      // Minutes (from Service.duration)
+  basePrice: number;         // From Service.basePrice
+  customPrice?: number;      // Override if different from basePrice
+  resourceId: string;        // Resource who performs THIS service
+}
diff --git a/src/types/CalendarTypes.ts b/src/types/CalendarTypes.ts
index 9c7cb50..2655dfa 100644
--- a/src/types/CalendarTypes.ts
+++ b/src/types/CalendarTypes.ts
@@ -1,4 +1,5 @@
 // Calendar type definitions
+import { CalendarEventType } from './BookingTypes';
 
 // Time period view types (how much time to display)
 export type ViewPeriod = 'day' | 'week' | 'month';
@@ -20,10 +21,15 @@ export interface ICalendarEvent {
   description?: string;
   start: Date;
   end: Date;
-  type: string;  // Flexible event type - can be any string value
+  type: CalendarEventType;   // Event type - only 'customer' has associated booking
   allDay: boolean;
   syncStatus: SyncStatus;
 
+  // References (denormalized for IndexedDB performance)
+  bookingId?: string;        // Reference to booking (only if type = 'customer')
+  resourceId?: string;       // Resource who owns this time slot
+  customerId?: string;       // Denormalized from Booking.customerId
+
   recurringId?: string;
   metadata?: Record<string, any>;
 }
diff --git a/src/types/ColumnDataSource.ts b/src/types/ColumnDataSource.ts
index 16c12c9..ad95d98 100644
--- a/src/types/ColumnDataSource.ts
+++ b/src/types/ColumnDataSource.ts
@@ -1,10 +1,12 @@
+import { IResource } from './ResourceTypes';
+
 /**
  * Column information container
  * Contains both identifier and actual data for a column
  */
 export interface IColumnInfo {
   identifier: string;      // "2024-11-13" (date mode) or "person-1" (resource mode)
-  data: Date | any;        // Date for date-mode, IResource for resource-mode
+  data: Date | IResource;  // Date for date-mode, IResource for resource-mode
 }
 
 /**
diff --git a/src/types/CustomerTypes.ts b/src/types/CustomerTypes.ts
new file mode 100644
index 0000000..5ffd1b1
--- /dev/null
+++ b/src/types/CustomerTypes.ts
@@ -0,0 +1,11 @@
+/**
+ * Customer entity
+ * Matches backend Customer table structure
+ */
+export interface ICustomer {
+  id: string;
+  name: string;
+  phone: string;
+  email?: string;
+  metadata?: Record<string, any>;
+}
diff --git a/src/types/ResourceTypes.ts b/src/types/ResourceTypes.ts
new file mode 100644
index 0000000..8650d4f
--- /dev/null
+++ b/src/types/ResourceTypes.ts
@@ -0,0 +1,21 @@
+/**
+ * Resource entity - represents people, rooms, equipment, etc.
+ * Matches backend Resource table structure
+ */
+export interface IResource {
+  id: string;              // Primary key (e.g., "EMP001", "ROOM-A")
+  name: string;            // Machine name (e.g., "karina.knudsen")
+  displayName: string;     // Human-readable name (e.g., "Karina Knudsen")
+  type: ResourceType;      // Resource category
+  avatarUrl?: string;      // Avatar/icon URL (e.g., "/avatars/karina.jpg")
+  color?: string;          // Color for visual distinction in calendar
+  isActive?: boolean;      // Whether resource is currently active
+  metadata?: Record<string, any>;  // Flexible extension point
+}
+
+export type ResourceType =
+  | 'person'      // Employees, team members
+  | 'room'        // Meeting rooms, offices
+  | 'equipment'   // Shared equipment, tools
+  | 'vehicle'     // Company vehicles
+  | 'custom';     // User-defined types