> ## Documentation Index > Fetch the complete documentation index at: https://docs.arcuserp.com/llms.txt > Use this file to discover all available pages before exploring further. # Probe whether a serial is valid for a return > Non-destructive check: verifies that the scanned serial number was on the original shipment for the given order. Returns a verdict object without throwing. Useful for inline scanner UI feedback before submitting a receive. Response shapes: - `valid: true` -- serial is sold, linked to the original order, and not yet returned. - `valid: false` -- serial exists but fails one of: wrong order, not sold, already returned. - `valid: null` -- no `original_order_id` supplied; cannot validate. This endpoint honors the entity's `settings.returns.serial_validation_mode` in the sense that its verdict is for informational use; the actual gate is enforced by `POST /v1/returns/:id/receive` and `POST /v1/returns/:id/disposition` when `serial_validation_mode` is `hard`. Requires the `serials:read` scope. ## OpenAPI ````yaml /openapi.yaml post /serials/validate-for-return openapi: 3.1.0 info: title: Arcus ERP Public API version: 1.0.0 description: > Arcus ERP public REST API. Designed for external integrations and data migration. **Authentication.** Bearer token (API key) via the `Authorization` header. Format: `Authorization: Bearer ark_live_ent__` (or `ark_test_*` for sandbox). API keys are issued per-entity in **Settings > Developers > API Keys**. **Entity scoping.** The entity is encoded in the API key prefix; routes are flat (e.g. `/v1/accounts`, `/v1/orders`, `/v1/products`). A small set of platform endpoints (migration, reconciliation, events, webhook endpoints, API keys) use the `/v1/entities/{entity_id}/...` form -- those are noted in their tags. **Key capabilities.** - Related-resource hydration via `?expand[]=` (see `x-arcus-expand` on each resource). - Cursor-based pagination (`starting_after` / `ending_before` / `limit`). - Idempotency via the `Idempotency-Key` header. - Webhook events for asynchronous notification. - Conditional requests / ETag for cache validation. servers: - url: https://api.arcuserp.com/v1 description: Arcus ERP API (accepts both live `ark_live_*` and test `ark_test_*` keys) - url: https://dev-api.arcuserp.com/v1 description: >- Dev sandbox API (test-only data, accepts `ark_test_*` keys against dev RDS) security: [] paths: /serials/validate-for-return: post: tags: - Serials summary: Probe whether a serial is valid for a return description: > Non-destructive check: verifies that the scanned serial number was on the original shipment for the given order. Returns a verdict object without throwing. Useful for inline scanner UI feedback before submitting a receive. Response shapes: - `valid: true` -- serial is sold, linked to the original order, and not yet returned. - `valid: false` -- serial exists but fails one of: wrong order, not sold, already returned. - `valid: null` -- no `original_order_id` supplied; cannot validate. This endpoint honors the entity's `settings.returns.serial_validation_mode` in the sense that its verdict is for informational use; the actual gate is enforced by `POST /v1/returns/:id/receive` and `POST /v1/returns/:id/disposition` when `serial_validation_mode` is `hard`. Requires the `serials:read` scope. operationId: validateSerialForReturnV1 requestBody: required: true content: application/json: schema: type: object required: - serial_number properties: serial_number: type: string description: The serial number to validate. original_order_id: type: string format: uuid nullable: true description: The order the RMA is being raised against. Omit if unknown. product_id: type: string format: uuid nullable: true description: Scope validation to a specific product (optional). responses: '200': description: >- Validation verdict (never 4xx from this endpoint; check `valid` field) content: application/json: schema: type: object properties: data: type: object properties: valid: oneOf: - type: boolean - type: 'null' description: >- `true` = OK, `false` = mismatch, `null` = cannot determine reason: type: string nullable: true description: Set to `no_original_order` when `valid` is null. code: type: string nullable: true description: >- Machine code when `valid` is false (serial_not_found / serial_not_on_original_order / serial_not_sold / serial_already_returned). hint: type: string nullable: true description: Human-readable explanation when valid is false. serial_id: type: string format: uuid nullable: true description: DB id of the serial record when valid is true. status: type: string nullable: true description: Current serial_status when valid is true. order_number: type: string nullable: true description: >- Order number of the original shipment when valid is true. '400': $ref: '#/components/responses/Error' '401': $ref: '#/components/responses/Error' '403': $ref: '#/components/responses/Error' security: - ApiKeyAuth: - serials:read components: responses: Error: description: Error response (400/401/403/404/409/422/429/500) content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' schemas: ErrorEnvelope: type: object description: | Canonical error response envelope. All API errors use this shape. required: - error - code properties: error: type: string description: Machine-readable error key example: not_found code: type: string description: Machine-readable error code (often same as error) example: not_found type: type: string enum: - validation_error - permission_error - not_found - conflict - rate_limit - internal - expand_error - not_implemented example: not_found hint: type: string description: Human-readable one-sentence explanation (English) example: >- The requested order does not exist or does not belong to this entity. param: type: string description: The parameter that caused the error, if applicable example: expand[0] required: type: string description: The scope required (only on insufficient_scope errors) example: accounts:read request_id: type: string description: >- Unique request ID for support tracing (maps to CloudWatch log stream) example: req_abc123 securitySchemes: ApiKeyAuth: type: http scheme: bearer description: | API key issued per entity via Settings > Developers > API Keys. Each key carries scopes (e.g. orders:read, products:write). Bearer token format: Authorization: Bearer ark_live_ent__ Test keys use ark_test_ent__. Both are issued per entity via Settings > Developers > API Keys. ````