RESTful QR-to-Order API Spec

I’m ready to have a complete, production-ready API specification written for a new “QR to Order” flow. The backend is not built yet, so the spec needs to be detailed enough for developers to implement immediately and for front-end teams to mock against with confidence. Scope of the system • A customer scans a unique QR code that opens a session, pre-associating the venue/table. • The session exposes endpoints for browsing products, selecting variants, adding customisations, and building a multi-item cart. • Users can upload an image (for personalised items) and crop it in-browser; the server must validate and store the file while enforcing a maximum file size. • Checkout finalises the cart, processes payment, and triggers an email receipt. • All endpoints follow strict REST conventions and return JSON. What I need from you 1. A full OpenAPI 3.0 (Swagger) document that covers every endpoint, request/response schema, error model, and authentication scheme. 2. Clear field-level definitions for QR session initiation, product catalogue queries, cart actions, image handling, payment, and receipt delivery. 3. Payment section written to allow multiple gateways; I will decide later whether to enable cards, PayPal, Apple Pay or others, so the spec should keep this pluggable. 4. Image upload endpoint specifying content-type, multipart handling, size limit enforcement, and crop parameter options. 5. Email receipt webhook/spec including sample payload. 6. Brief accompanying markdown that explains endpoint sequencing and any security considerations (JWT, OAuth, or API key options). Acceptance criteria • The OpenAPI file validates without errors in Swagger Editor. • Every response example contains realistic data. • Max file size for image upload is clearly stated and enforced in the schema. • All endpoint names, verbs, and status codes follow standard REST best practices. If you’ve authored robust API specs before—especially those involving checkout flows or file uploads—I’d love to see a sample. I’m aiming to sign off the final spec quickly so the dev team can get building right away.

Project ID: 40488222