diff --git a/src/lib/api/bookings.ts b/src/lib/api/bookings.ts
new file mode 100644
index 0000000..d5bbfa5
--- /dev/null
+++ b/src/lib/api/bookings.ts
@@ -0,0 +1,265 @@
+/**
+ * Booking Admin API Client
+ *
+ * API client for booking management operations (cancel, move, attendees).
+ * Supports ETag optimistic concurrency and idempotency headers.
+ */
+
+import type {
+  BookingDetail,
+  CancelBookingRequest,
+  CancelBookingResponse,
+  MoveBookingRequest,
+  MoveBookingResponse,
+  MoveDryRunResponse,
+  UpdateAttendeesRequest,
+  UpdateAttendeesResponse,
+  BookingError,
+  BookingApiResult,
+} from '@/src/types/bookings';
+
+const API_BASE_URL = process.env.NEXT_PUBLIC_API_BASE_URL || 'https://api.playchoo.com';
+
+/**
+ * Generate a unique idempotency key for request retries
+ */
+function generateIdempotencyKey(): string {
+  return crypto.randomUUID();
+}
+
+/**
+ * Extract ETag from response headers
+ */
+function extractETag(headers: Headers): string | undefined {
+  return headers.get('ETag') || undefined;
+}
+
+/**
+ * GET /admin/bookings/{id}
+ * Fetch complete booking details
+ */
+export async function getBooking(bookingId: number): Promise<BookingApiResult<BookingDetail>> {
+  try {
+    const response = await fetch(`${API_BASE_URL}/admin/bookings/${bookingId}`, {
+      method: 'GET',
+      credentials: 'include',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+    });
+
+    if (!response.ok) {
+      const error: BookingError = await response.json();
+      return { success: false, error };
+    }
+
+    const data: BookingDetail = await response.json();
+    const etag = extractETag(response.headers);
+
+    return {
+      success: true,
+      data: { ...data, etag },
+      etag,
+    };
+  } catch (error) {
+    return {
+      success: false,
+      error: {
+        type: 'about:blank',
+        title: 'Network Error',
+        status: 0,
+        detail: 'Failed to fetch booking details. Please check your connection.',
+        code: 'internal_error',
+      },
+    };
+  }
+}
+
+/**
+ * PATCH /admin/bookings/{id}/cancel
+ * Cancel a booking with optional reason and notification control
+ */
+export async function cancelBooking(
+  bookingId: number,
+  request: Omit<CancelBookingRequest, 'status'>,
+  etag?: string
+): Promise<BookingApiResult<CancelBookingResponse>> {
+  try {
+    const headers: HeadersInit = {
+      'Content-Type': 'application/json',
+      'X-Idempotency-Key': generateIdempotencyKey(),
+    };
+
+    // Prefer ETag for optimistic concurrency
+    if (etag) {
+      headers['If-Match'] = etag;
+    }
+
+    const response = await fetch(`${API_BASE_URL}/admin/bookings/${bookingId}/cancel`, {
+      method: 'PATCH',
+      credentials: 'include',
+      headers,
+      body: JSON.stringify({
+        status: 'cancelled',
+        ...request,
+      }),
+    });
+
+    if (!response.ok) {
+      const error: BookingError = await response.json();
+      return { success: false, error };
+    }
+
+    const data: CancelBookingResponse = await response.json();
+    return { success: true, data };
+  } catch (error) {
+    return {
+      success: false,
+      error: {
+        type: 'about:blank',
+        title: 'Network Error',
+        status: 0,
+        detail: 'Failed to cancel booking. Please check your connection.',
+        code: 'internal_error',
+      },
+    };
+  }
+}
+
+/**
+ * PATCH /admin/bookings/{id}/move?dry_run=true
+ * Validate move operation without committing (for slot picker)
+ */
+export async function validateMoveBooking(
+  bookingId: number,
+  request: Pick<MoveBookingRequest, 'new_slot_instance_id'>
+): Promise<BookingApiResult<MoveDryRunResponse>> {
+  try {
+    const response = await fetch(
+      `${API_BASE_URL}/admin/bookings/${bookingId}/move?dry_run=true`,
+      {
+        method: 'PATCH',
+        credentials: 'include',
+        headers: {
+          'Content-Type': 'application/json',
+        },
+        body: JSON.stringify(request),
+      }
+    );
+
+    if (!response.ok) {
+      const error: BookingError = await response.json();
+      return { success: false, error };
+    }
+
+    const data: MoveDryRunResponse = await response.json();
+    return { success: true, data };
+  } catch (error) {
+    return {
+      success: false,
+      error: {
+        type: 'about:blank',
+        title: 'Network Error',
+        status: 0,
+        detail: 'Failed to validate move. Please check your connection.',
+        code: 'internal_error',
+      },
+    };
+  }
+}
+
+/**
+ * PATCH /admin/bookings/{id}/move
+ * Move booking to a different slot
+ */
+export async function moveBooking(
+  bookingId: number,
+  request: MoveBookingRequest,
+  etag?: string
+): Promise<BookingApiResult<MoveBookingResponse>> {
+  try {
+    const headers: HeadersInit = {
+      'Content-Type': 'application/json',
+      'X-Idempotency-Key': generateIdempotencyKey(),
+    };
+
+    // Prefer ETag for optimistic concurrency
+    if (etag) {
+      headers['If-Match'] = etag;
+    }
+
+    const response = await fetch(`${API_BASE_URL}/admin/bookings/${bookingId}/move`, {
+      method: 'PATCH',
+      credentials: 'include',
+      headers,
+      body: JSON.stringify(request),
+    });
+
+    if (!response.ok) {
+      const error: BookingError = await response.json();
+      return { success: false, error };
+    }
+
+    const data: MoveBookingResponse = await response.json();
+    return { success: true, data };
+  } catch (error) {
+    return {
+      success: false,
+      error: {
+        type: 'about:blank',
+        title: 'Network Error',
+        status: 0,
+        detail: 'Failed to move booking. Please check your connection.',
+        code: 'internal_error',
+      },
+    };
+  }
+}
+
+/**
+ * PATCH /admin/bookings/{id}/attendees
+ * Update booking attendee list
+ */
+export async function updateBookingAttendees(
+  bookingId: number,
+  request: UpdateAttendeesRequest,
+  etag?: string
+): Promise<BookingApiResult<UpdateAttendeesResponse>> {
+  try {
+    const headers: HeadersInit = {
+      'Content-Type': 'application/json',
+      'X-Idempotency-Key': generateIdempotencyKey(),
+    };
+
+    // Prefer ETag for optimistic concurrency
+    if (etag) {
+      headers['If-Match'] = etag;
+    }
+
+    const response = await fetch(`${API_BASE_URL}/admin/bookings/${bookingId}/attendees`, {
+      method: 'PATCH',
+      credentials: 'include',
+      headers,
+      body: JSON.stringify(request),
+    });
+
+    if (!response.ok) {
+      const error: BookingError = await response.json();
+      return { success: false, error };
+    }
+
+    const data: UpdateAttendeesResponse = await response.json();
+    return { success: true, data };
+  } catch (error) {
+    return {
+      success: false,
+      error: {
+        type: 'about:blank',
+        title: 'Network Error',
+        status: 0,
+        detail: 'Failed to update attendees. Please check your connection.',
+        code: 'internal_error',
+      },
+    };
+  }
+}
diff --git a/src/types/bookings.ts b/src/types/bookings.ts
new file mode 100644
index 0000000..4ea71c0
--- /dev/null
+++ b/src/types/bookings.ts
@@ -0,0 +1,304 @@
+/**
+ * Booking Admin Types
+ *
+ * Types for booking management operations (cancel, move, attendees).
+ * Based on Booking Admin API v1.1 contract.
+ */
+
+/**
+ * Provider information for club/booking
+ */
+export interface ProviderInfo {
+  type: 'local' | 'fairplay';
+  manages_slot_storage: boolean;
+}
+
+/**
+ * Attendee in a booking
+ */
+export interface Attendee {
+  position: number; // 1, 2, 3, 4...
+  type: 'app_user' | 'guest' | 'remote_member';
+  app_user_id?: number; // if type=app_user
+  remote_member_id?: number; // if type=remote_member
+  email?: string;
+  display_name: string;
+}
+
+/**
+ * Slot information within booking
+ */
+export interface BookingSlot {
+  slot_instance_id: number;
+  starts_at: string; // ISO 8601
+  ends_at: string; // ISO 8601
+  capacity: number;
+  booked_count: number;
+  capacity_remaining: number;
+  status: 'open' | 'held' | 'booked' | 'cancelled';
+  court: {
+    court_id: number;
+    name: string;
+    club_id: number;
+    club_name: string;
+  };
+}
+
+/**
+ * User who created the booking
+ */
+export interface BookedBy {
+  app_user_id: number;
+  email: string;
+  display_name: string;
+}
+
+/**
+ * Complete booking details
+ */
+export interface BookingDetail {
+  booking_id: number;
+  status: 'confirmed' | 'cancelled' | 'no_show';
+  slot: BookingSlot;
+  booked_by: BookedBy;
+  attendees: Attendee[];
+  created_at: string; // ISO 8601
+  updated_at: string; // ISO 8601
+  provider?: ProviderInfo;
+  etag?: string; // from ETag response header
+  // Optional policy fields (if backend adds them)
+  policies?: {
+    cancel_grace_minutes?: number;
+    cancel_grace_anchor?: 'start' | 'end';
+    move_window_days?: number;
+  };
+}
+
+/**
+ * Request to cancel a booking
+ */
+export interface CancelBookingRequest {
+  status: 'cancelled';
+  reason?: string;
+  notify_players?: boolean; // default: true
+  prev_updated_at?: string; // for optimistic concurrency (fallback to ETag)
+}
+
+/**
+ * Response from cancel operation
+ */
+export interface CancelBookingResponse {
+  booking_id: number;
+  status: 'cancelled';
+  cancelled_reason?: string;
+  updated_at: string;
+}
+
+/**
+ * Request to move a booking to a different slot
+ */
+export interface MoveBookingRequest {
+  new_slot_instance_id: number;
+  reason?: string;
+  notify_players?: boolean; // default: true
+  prev_updated_at?: string; // for optimistic concurrency (fallback to ETag)
+  // Note: dry_run is sent as query parameter ?dry_run=true, not in body
+}
+
+/**
+ * Response from move operation
+ */
+export interface MoveBookingResponse {
+  booking_id: number;
+  status: 'confirmed';
+  old_slot: {
+    slot_instance_id: number;
+    starts_at: string;
+    ends_at: string;
+  };
+  new_slot: {
+    slot_instance_id: number;
+    starts_at: string;
+    ends_at: string;
+    court: {
+      court_id: number;
+      name: string;
+    };
+  };
+  move_reason?: string;
+  updated_at: string;
+}
+
+/**
+ * Response from move dry-run validation
+ */
+export interface MoveDryRunResponse {
+  ok: boolean;
+  reasons?: string[]; // error codes if validation failed
+}
+
+/**
+ * Request to update booking attendees
+ */
+export interface UpdateAttendeesRequest {
+  attendees: Attendee[];
+  reason?: string;
+  notify_players?: boolean; // default: true
+  prev_updated_at?: string; // for optimistic concurrency (fallback to ETag)
+}
+
+/**
+ * Response from attendees update operation
+ */
+export interface UpdateAttendeesResponse {
+  booking_id: number;
+  status: 'confirmed';
+  attendees: Attendee[];
+  updated_at: string;
+}
+
+/**
+ * Booking-specific error codes
+ */
+export type BookingErrorCode =
+  | 'validation_error'
+  | 'not_found'
+  | 'not_admin_for_club'
+  | 'booking_already_cancelled'
+  | 'invalid_status_transition'
+  | 'slot_full'
+  | 'slot_wrong_status'
+  | 'slot_different_club'
+  | 'slot_different_sport' // product-type mismatch (singles/doubles)
+  | 'product_type_mismatch' // alternative naming
+  | 'slot_in_past'
+  | 'exceeds_capacity'
+  | 'capacity_exceeded' // alternative naming
+  | 'past_slot_locked' // beyond cancel grace period
+  | 'remote_provider_managed' // FairPlay clubs (read-only)
+  | 'capacity_conflict' // race condition (retry signal)
+  | 'booking_already_exists' // unique constraint
+  | 'duplicate_attendee'
+  | 'invalid_attendee' // user not found
+  | 'move_window_exceeded' // beyond move day limit
+  | 'precondition_failed' // ETag mismatch (412)
+  | 'precondition_required' // missing concurrency token
+  | 'insufficient_capacity' // target slot full
+  | 'internal_error';
+
+/**
+ * RFC-7807 Problem Details for booking errors
+ */
+export interface BookingError {
+  type: string;
+  title: string;
+  status: number;
+  detail: string;
+  code: BookingErrorCode;
+  errors?: Array<{
+    field: string;
+    message: string;
+  }>;
+  // Extension fields for specific errors
+  grace_minutes?: number; // for past_slot_locked
+  limit_days?: number; // for move_window_exceeded
+}
+
+/**
+ * API result wrapper for booking operations
+ */
+export type BookingApiResult<T> =
+  | { success: true; data: T; etag?: string }
+  | { success: false; error: BookingError };
+
+/**
+ * User-friendly error messages for booking error codes
+ */
+export const BOOKING_ERROR_MESSAGES: Record<BookingErrorCode, (error?: BookingError) => string> = {
+  remote_provider_managed: () =>
+    'Edits are disabled for this club. This club is managed by an external provider; changes must be made in the provider\'s system.',
+
+  capacity_conflict: () =>
+    'Someone just took that spot. The slot\'s capacity changed while you were editing. Pick another slot and try again.',
+
+  booking_already_exists: () =>
+    'This slot already has a booking. Choose a different time or court.',
+
+  slot_different_sport: () =>
+    'Wrong format for this booking. Select a slot that matches the booking\'s format (singles/doubles).',
+
+  product_type_mismatch: () =>
+    'Wrong format for this booking. Select a slot that matches the booking\'s format (singles/doubles).',
+
+  slot_different_club: () =>
+    'Different club. You can only move bookings within the same club.',
+
+  slot_wrong_status: () =>
+    'That slot isn\'t open. Choose an open slot.',
+
+  slot_full: () =>
+    'That slot is full. Select a different time.',
+
+  insufficient_capacity: () =>
+    'That slot is full. Select a different time.',
+
+  past_slot_locked: (error) => {
+    const minutes = error?.grace_minutes || 15;
+    return `Too late to change this booking. Changes allowed until ${minutes} minutes after start.`;
+  },
+
+  move_window_exceeded: (error) => {
+    const days = error?.limit_days || 14;
+    return `Move not allowed that far out. You can move within the next ${days} days.`;
+  },
+
+  precondition_failed: () =>
+    'This booking changed while you were editing. We reloaded the latest details.',
+
+  precondition_required: () =>
+    'Outdated data. Please retry from the latest booking details.',
+
+  validation_error: () =>
+    'Please fix the highlighted fields.',
+
+  not_admin_for_club: () =>
+    'No admin access. You don\'t have permission for this club.',
+
+  booking_already_cancelled: () =>
+    'This booking is already cancelled.',
+
+  invalid_status_transition: () =>
+    'Invalid operation for this booking status.',
+
+  slot_in_past: () =>
+    'This slot is in the past and cannot be modified.',
+
+  exceeds_capacity: () =>
+    'Too many attendees for this slot\'s capacity.',
+
+  capacity_exceeded: () =>
+    'Too many attendees for this slot\'s capacity.',
+
+  duplicate_attendee: () =>
+    'Duplicate attendee detected.',
+
+  invalid_attendee: () =>
+    'One or more attendees could not be found.',
+
+  not_found: () =>
+    'Booking not found.',
+
+  internal_error: () =>
+    'An unexpected error occurred. Please try again.',
+};
+
+/**
+ * Get user-friendly error message from booking error
+ */
+export function getBookingErrorMessage(error: BookingError): string {
+  const messageGetter = BOOKING_ERROR_MESSAGES[error.code];
+  if (messageGetter) {
+    return messageGetter(error);
+  }
+  return error.detail || 'An error occurred';
+}