> ## Documentation Index > Fetch the complete documentation index at: https://docs.omnicommerce.sg/llms.txt > Use this file to discover all available pages before exploring further. # Complete Agentic Checkout Session > Settle the selected rail and create a native `agentic` order. Settlement failures return 402 and leave the session in `ready_for_payment`. ## OpenAPI ````yaml /openapi.json post /api/v1/checkout-sessions/{sessionId}/complete openapi: 3.1.0 info: title: OmniCommerce API version: 1.0.0 license: name: Proprietary url: https://omnicommerce.sg/terms description: >- OmniCommerce API surface for agents and developer integrations. Includes public endpoints (merchant discovery, product search, compare, catalog, ACO retrieval) and authenticated endpoints (product management via API key Bearer tokens). servers: - url: https://omnicommerce.sg description: Production - url: http://localhost:3000 description: Local development security: [] tags: - name: agentic-checkout description: Merchant-fulfilled agentic checkout x-group: Agentic Checkout - name: commerce description: Root commerce discovery x-group: Commerce - name: developer-platform description: Authenticated developer platform APIs x-group: Developer Platform - name: looks description: AI-styled product looks x-group: Looks - name: oauth description: OAuth token endpoints x-group: OAuth - name: orders description: Workspace and agentic orders x-group: Orders - name: organizations description: Organization management x-group: Organizations - name: price-books description: Marketplace list-price markup rules x-group: Price Books - name: products description: Product CRUD, bulk import, and publish x-group: Products - name: promotions description: Central promotions and marketplace sync x-group: Promotions - name: public-agent description: Public agent discovery and catalog APIs x-group: Public Agent - name: settlements description: settlements x-group: Settlements - name: ucp description: Universal Commerce Protocol x-group: UCP paths: /api/v1/checkout-sessions/{sessionId}/complete: post: tags: - agentic-checkout summary: Complete Agentic Checkout Session description: >- Settle the selected rail and create a native `agentic` order. Settlement failures return 402 and leave the session in `ready_for_payment`. operationId: post_v1_checkout_sessions_by_sessionid_complete parameters: - name: sessionId in: path required: true schema: type: string - name: organizationId in: query required: false description: >- Optional organization scope for OAuth clients that can access multiple organizations. schema: type: string maxLength: 120 - name: Idempotency-Key in: header required: false description: Optional idempotency key for completion retries. schema: type: string maxLength: 180 requestBody: required: true content: application/json: schema: type: object additionalProperties: false required: - paymentProof properties: idempotencyKey: type: string maxLength: 180 paymentProof: type: object additionalProperties: true description: >- Rail-specific payment proof. ACP uses `{ sharedPaymentTokenId: string }`; x402 uses `{ paymentPayload: object }` or `{ xPayment: object }`. Local testing may use `{ test: true, testPaymentToken: string }` when test settlement is enabled. responses: '200': description: Checkout completed and native order created. content: application/json: schema: type: object properties: ok: type: boolean apiVersion: type: string default: agentic_checkout_v1 session: type: object required: - id - organizationId - status - paymentRail - currency - totalAmount - paymentRequirements - expiresAt properties: id: type: string organizationId: type: string status: type: string enum: - ready_for_payment - completed - cancelled - expired paymentRail: type: string enum: - acp_stripe - x402 currency: type: string subtotalAmount: type: number shippingAmount: type: number taxAmount: type: number discountAmount: type: number totalAmount: type: number cartVersion: type: integer buyer: type: object additionalProperties: true shippingAddress: type: object additionalProperties: true billingAddress: type: object additionalProperties: true paymentRequirements: type: object additionalProperties: true orderId: type: - string - 'null' expiresAt: type: string completedAt: type: - string - 'null' createdAt: type: string updatedAt: type: string items: type: array items: type: object properties: id: type: string productId: type: string sku: type: - string - 'null' title: type: string quantity: type: integer unitAmount: type: number currency: type: string imageUrl: type: - string - 'null' productSnapshot: type: object additionalProperties: true settlement: type: object additionalProperties: true properties: ok: type: boolean providerPaymentId: type: - string - 'null' settlementReference: type: - string - 'null' errorCode: type: string errorMessage: type: string '400': description: Bad Request '401': description: Unauthorized '402': description: Settlement failed; the checkout remains ready for payment. content: application/json: schema: type: object properties: ok: type: boolean apiVersion: type: string default: agentic_checkout_v1 session: type: object required: - id - organizationId - status - paymentRail - currency - totalAmount - paymentRequirements - expiresAt properties: id: type: string organizationId: type: string status: type: string enum: - ready_for_payment - completed - cancelled - expired paymentRail: type: string enum: - acp_stripe - x402 currency: type: string subtotalAmount: type: number shippingAmount: type: number taxAmount: type: number discountAmount: type: number totalAmount: type: number cartVersion: type: integer buyer: type: object additionalProperties: true shippingAddress: type: object additionalProperties: true billingAddress: type: object additionalProperties: true paymentRequirements: type: object additionalProperties: true orderId: type: - string - 'null' expiresAt: type: string completedAt: type: - string - 'null' createdAt: type: string updatedAt: type: string items: type: array items: type: object properties: id: type: string productId: type: string sku: type: - string - 'null' title: type: string quantity: type: integer unitAmount: type: number currency: type: string imageUrl: type: - string - 'null' productSnapshot: type: object additionalProperties: true settlement: type: object additionalProperties: true properties: ok: type: boolean providerPaymentId: type: - string - 'null' settlementReference: type: - string - 'null' errorCode: type: string errorMessage: type: string '403': description: Forbidden or checkout not enabled '404': description: Checkout session not found '409': description: Terminal or expired checkout session '500': description: Internal Server Error security: - bearerAuth: [] components: securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: API Key description: >- Bearer API key for server-to-server access. Session auth is also supported in first-party UI flows. ````