> ## Documentation Index > Fetch the complete documentation index at: https://partner.headout.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Validate - Seatmap For products with `inventorySelectionType: SEATMAP`. Performs a live availability and pricing check on a set of seats before checkout. **Always check the `validationErrors` array even on 200 responses.** A 200 response does not mean all seats are available — business-level failures (seat sold, seat not recognised) are returned as 200 with non-empty `validationErrors`. HTTP 4xx errors are returned for system-level failures (bad input, auth, product not found). Validate is recommended but not required before booking. Prices can change between the Inventory response and booking time — use the prices returned by this endpoint in the booking request. **Seat count** must satisfy the product's `minPax`/`maxPax` constraint. Hard ceiling is 20 seats per request. ## Validation error codes | Code | Description | | -------------------------- | -------------------------------------------- | | `SEAT_UNAVAILABLE` | Seat exists but cannot be booked | | `SEAT_NOT_FOUND` | Seat code does not exist in this venue | | `ADJACENCY_RULE_VIOLATION` | Seat selection violates a venue seating rule | ## Adjacency rules Some venues enforce rules about which seats can be selected together. These are returned with `code: ADJACENCY_RULE_VIOLATION`. The seat itself is available — it is the combination of selected seats that violates the venue's rule. Prompt the customer to adjust their selection. | Message | What it means | How to fix | | ------------------------------------------- | ----------------------------------------------------------------------- | ----------------------------------------------------------- | | "Selected seats must be consecutive" | Seats must be next to each other in the same row — no gaps | Remove the seat causing the gap | | "Left adjacent seat must also be selected" | Selecting an end seat that would leave a single unsold seat to its left | Also select the seat to the left, or pick a different seat | | "Right adjacent seat must also be selected" | Same but to the right | Also select the seat to the right, or pick a different seat | | "All seats at the table must be selected" | For table-style venues, all seats at a table must be booked together | Select all remaining seats at that table | ```json 200 (ALL_AVAILABLE) theme={"theme":{"light":"github-light","dark":"github-dark"}} { "productId": 3023, "variantId": 4700, "inventoryId": 489560432, "currencyCode": "GBP", "date": "2026-03-25", "startTime": "19:30", "seats": [ { "seatCode": "SE-B8223499-CF01-562C-97DC-62F72E232FEC-E-11", "sectionName": "Grand Circle", "row": "E", "seatNumber": "11", "seatType": "STANDARD", "isAvailable": true, "pricing": { "currency": "GBP", "headoutSellingPrice": 58.43, "netPrice": 50.83 } } ], "validationErrors": [] } ``` ## OpenAPI ````yaml POST /api/public/v2/seatmap/products/{productId}/variants/{variantId}/validate/ openapi: 3.1.0 info: title: Headout API Docs - API Partner v2 version: 0.0.1 servers: - url: https://www.headout.com description: Production server - url: https://www.sandbox-headout.com description: Sandbox server security: [] paths: /api/public/v2/seatmap/products/{productId}/variants/{variantId}/validate/: post: tags: - Seatmap summary: Validate - Seatmap operationId: validateSeatmapSeats parameters: - name: productId in: path required: true schema: type: integer - name: variantId in: path required: true schema: type: integer - name: currencyCode in: query required: false schema: type: string description: ISO 4217 currency code. Defaults to `USD`. requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/SeatmapValidateRequest' responses: '200': description: >- Validation result. Check validationErrors array even on 200 responses. content: application/json: schema: $ref: '#/components/schemas/SeatmapValidateResponse' '400': description: >- Seat count violates product minPax/maxPax, exceeds hard ceiling of 20, `inventoryId` is not an integer, or unknown/malformed request body field '403': description: Partner not authorised, or partner type is Affiliate '404': description: Product not found or not a seatmap product '413': description: Request payload too large '415': description: Content-Type is not application/json '503': description: >- Supplier validation service unavailable. Do not proceed to booking — retry the request. security: - apiKeyAuth: [] components: schemas: SeatmapValidateRequest: type: object required: - inventoryId - seatCodes properties: inventoryId: type: integer format: int64 description: >- Show-level inventory identifier. Must be an integer — strings and floats are rejected with 400. seatCodes: type: array maxItems: 20 items: type: string SeatmapValidateResponse: type: object properties: productId: type: integer variantId: type: integer inventoryId: type: integer format: int64 currencyCode: type: string date: type: string format: date startTime: type: string seats: type: array items: $ref: '#/components/schemas/SeatmapValidatedSeat' validationErrors: type: array description: >- Non-empty when one or more seats failed validation. Check this even on 200 responses. items: $ref: '#/components/schemas/SeatmapValidationError' SeatmapValidatedSeat: type: object properties: seatCode: type: string sectionName: type: - string - 'null' row: type: - string - 'null' seatNumber: type: - string - 'null' seatType: type: - string - 'null' isAvailable: type: boolean pricing: description: Null when isAvailable is false. oneOf: - $ref: '#/components/schemas/SeatmapPrice' - type: 'null' SeatmapValidationError: type: object properties: code: type: string enum: - SEAT_UNAVAILABLE - SEAT_NOT_FOUND - ADJACENCY_RULE_VIOLATION message: type: string seatCode: type: string SeatmapPrice: type: object properties: currency: type: string profileType: type: string headoutSellingPrice: type: number netPrice: type: - number - 'null' securitySchemes: apiKeyAuth: type: apiKey in: header name: Headout-Auth ````