> ## Documentation Index > Fetch the complete documentation index at: https://docs.fluid.app/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > For new direct REST integrations, use the v2026-04 surfaces. The @fluid-app FairShare SDK continues to use its own published public-v2025-06 contract. > Authenticate with the header Authorization: Bearer ; public storefront read endpoints require no auth. > Lists use cursor pagination via the page[cursor] and page[limit] query params; follow meta.pagination.next_cursor until it is null. > Never use /api/company/v1 or /api/v1 paths, page/per_page params, or offset pagination — they are legacy. > The OpenAPI specs under api-reference/ are the authoritative contracts; prefer them over prose when in doubt. api-reference/storefront-v2026-04.yaml covers the v2026-04 storefront surface (/api/v202604/... paths); api-reference/auth-v0.yaml covers the unversioned auth surface (/api/... paths — authentication, MFA, social auth, and token exchange); api-reference/checkout-v2026-04.yaml covers the v2026-04 checkout surface (/api/checkout/v2026-04/... paths — carts, cart auth, discounts, items, subscriptions, orders, enrollments, and store config); api-reference/public-v2025-06.yaml covers the Public SDK surface used by the @fluid-app FairShare SDK, including its parallel cart lifecycle, browser integrations, versioned payment callbacks, unversioned public utilities, and the cart price-override operation; api-reference/payment-v2026-04.yaml covers the v2026-04 payment gateway admin surface (/api/payment/v2026-04/... paths, bearer-authenticated — gateway CRUD, gateway purchase/authorize/$0-verify, transaction list/show and capture/void/credit, and merchant payment configuration); api-reference/payments-v2026-04.yaml covers the v2026-04 cart payment surface (/api/payments/v2026-04/carts/{cart_token}/... paths, authenticated by the cart token in the path with no bearer — payment-method selection, VGS card tokenization, 3D Secure verification, and PayPal/Braintree/Klarna/Apple Pay flows); api-reference/commerce-v2026-04.yaml covers the v2026-04 commerce order-editing surface (/api/v202604/orders/{order_id}/edits paths, bearer-authenticated — post-checkout order edits that atomically insert items and add adjustments/discounts, with an optional dry-run preview); api-reference/webhooks-v0.yaml covers the unversioned webhooks surface (/api/... paths — webhook registration, delivery payloads, callback registrations, company events, and webhook/callback schemas). > Successful responses wrap the resource payload alongside a top-level integer status and a meta object. # Query product > Returns a single product and its purchasable variants for the checkout surface. `{id}` accepts a product id or slug. Uses POST because the request body carries the shop, locale negotiation, and session context under `metadata` — here `metadata.fluid_shop` is the full host (e.g. `acme.fluid.app`), unlike the bare subdomain used in `create_cart` / `send_magic_link`. Public — no bearer token is required. Note the error envelope: this operation's `404` (product not found) uses the legacy `{ status: "fail", data: { error } }` shape, whereas its `422` — and every other operation on this surface — uses the standard `ErrorResponse` (`{ error_message, errors, meta }`), so a uniform error parser must special-case this `404`. ## OpenAPI ````yaml /api-reference/checkout-v2026-04.yaml post /api/checkout/v2026-04/products/{id} openapi: 3.1.0 info: title: Fluid Checkout API description: >- **Fluid Checkout API — for building a checkout directly against REST.** Use this surface if you are integrating server-to-server or building your own checkout UI. It covers the full order lifecycle (cart → address → shipping → discount → complete → order) plus the logged-in customer's account: saved addresses, saved payment methods, order history, loyalty points, and subscription management (pause, resume, skip, cancel, retry). **The cart token in the URL scopes cart access** — creating a cart, adding items, applying a discount, and completing a cart need no bearer token. Among the cart operations, a Bearer token is required only for `carts/{cart_token}/sync`, `carts/{cart_token}/volume_rep`, and `carts/{cart_token}/discount/manual`. Off the cart, a token is required for everything under `customers/me` and `subscriptions`, and for the store and directory lookups (`store/config`, `store/languages`, `reps`, `users`) and `subscription_bundles`. `store/countries` accepts a token but does not require one — it returns the same list either way. **If you are using the `@fluid-app` FairShare SDK in a theme or storefront, you are not calling this surface** — the SDK calls the Fluid Public SDK API (`public-v2025-06`). Do not mix the two against one cart: they share the same cart records and services, but their request shapes differ. See [Choosing a cart surface](https://docs.fluid.app/api/choosing-a-cart-surface) for the operation map and boundary. version: v2026-04 contact: email: support@fluid.app license: name: Proprietary identifier: LicenseRef-Proprietary servers: - url: https://api.fluid.app security: [] tags: - name: carts description: >- Create, read, and mutate checkout carts (email, address, country, language, shipping, recalculation, completion). - name: cart-auth description: >- Cart-scoped customer authentication — magic-link challenge, verification, identity, and logout. - name: cart-discount description: >- Apply, list, and remove cart discount codes, including admin manual discounts. - name: cart-items description: Add, update, and remove line items on a cart. - name: cart-points description: Apply and remove loyalty points on a cart. - name: customers description: The authenticated customer's profile and company memberships. - name: customer-addresses description: The authenticated customer's saved shipping/billing addresses. - name: customer-orders description: The authenticated customer's order history. - name: customer-payment-methods description: The authenticated customer's saved payment methods and tokenization. - name: customer-points description: The authenticated customer's loyalty point balances. - name: directory description: Company rep and user directory lookups. - name: enrollments description: >- Public enrollment forms — retrieve a form and submit, update, or upload field answers. - name: orders description: Public order lookup by token. - name: products description: Public product queries for the storefront checkout. - name: store description: >- Store-level checkout configuration — countries, languages, address fields, agreements, drop zones, and Apple Pay domain verification. - name: subscriptions description: >- Manage subscriptions — pause, resume, skip, cancel, reactivate, retry, and failed-cycle waivers. - name: subscription-bundles description: List and create subscription bundles. paths: /api/checkout/v2026-04/products/{id}: post: tags: - products summary: Query product description: > Returns a single product and its purchasable variants for the checkout surface. `{id}` accepts a product id or slug. Uses POST because the request body carries the shop, locale negotiation, and session context under `metadata` — here `metadata.fluid_shop` is the full host (e.g. `acme.fluid.app`), unlike the bare subdomain used in `create_cart` / `send_magic_link`. Public — no bearer token is required. Note the error envelope: this operation's `404` (product not found) uses the legacy `{ status: "fail", data: { error } }` shape, whereas its `422` — and every other operation on this surface — uses the standard `ErrorResponse` (`{ error_message, errors, meta }`), so a uniform error parser must special-case this `404`. operationId: checkout_v2026_04_query_product parameters: - name: id in: path required: true description: Product ID or slug schema: type: string requestBody: content: application/json: examples: by_slug: summary: Resolve a product by slug for a given shop value: metadata: fluid_shop: acme.fluid.app fluid_locale: en schema: type: object additionalProperties: false required: - metadata properties: metadata: type: object additionalProperties: false required: - fluid_shop properties: fluid_shop: type: string description: Fluid shop identifier example: acme.fluid.app fluid_locale: type: - string - 'null' description: Locale for product content example: en fluid_session: type: - string - 'null' description: Session identifier responses: '200': description: Product details content: application/json: schema: $ref: '#/components/schemas/CheckoutProductQueryResponse' '404': description: Product not found content: application/json: schema: type: object additionalProperties: false required: - status - data properties: status: type: string enum: - fail data: type: object additionalProperties: false required: - error properties: error: type: string '422': description: Unprocessable entity content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' security: [] components: schemas: CheckoutProductQueryResponse: type: object properties: metadata: type: object properties: fluid_locale: type: string fluid_session: type: - string - 'null' fluid_shop: type: string request_uuid: type: string timestamp: type: string format: date-time required: - fluid_locale - fluid_session - fluid_shop - request_uuid - timestamp additionalProperties: false product: type: object properties: canonical_url: type: string cv: type: string format: decimal cv_in_currency: type: string external_id: type: - string - 'null' id: type: integer image_path: type: - string - 'null' image_url: type: string introduction: type: - string - 'null' metadata: type: - object - 'null' metafields: type: array items: type: object additionalProperties: false required: - id - namespace - key - value - value_type - description - owner_type - owner_id - created_at - updated_at - metafield_definition properties: id: type: integer namespace: type: string key: type: string value: $ref: '#/components/schemas/JsonValue' value_type: type: string description: type: - string - 'null' owner_type: type: string owner_id: type: integer created_at: type: string format: date-time updated_at: type: string format: date-time metafield_definition: type: - object - 'null' additionalProperties: false required: - id - company_id - namespace - key - name - description - value_type - validation_rules - owner_resource - pinned - position - locked - created_at - updated_at - list_type - reference_type - supported_validations - validation_description - category_ids properties: id: type: integer company_id: type: integer namespace: type: string key: type: string name: type: string description: type: - string - 'null' value_type: type: string validation_rules: type: - object - 'null' additionalProperties: $ref: '#/components/schemas/JsonValue' owner_resource: type: string pinned: type: - boolean - 'null' position: type: - integer - 'null' locked: type: - boolean - 'null' created_at: type: string format: date-time updated_at: type: string format: date-time list_type: type: boolean reference_type: type: boolean supported_validations: type: array items: type: string validation_description: type: - string - 'null' category_ids: type: array items: type: integer price: type: - string - number - 'null' price_in_currency: type: string sku: type: string tax: type: string tax_in_currency: type: string title: type: string required: - canonical_url - cv - cv_in_currency - external_id - id - image_path - image_url - introduction - metadata - metafields - price - price_in_currency - sku - tax - tax_in_currency - title additionalProperties: false status: type: integer subscription_plans: type: array items: type: object additionalProperties: false required: - id - name - billing_interval - billing_interval_unit - billing_frequency_in_words - shipping_interval - shipping_interval_unit - volume_interval - volume_interval_unit - trial_period - trial_period_unit - split_volume - allow_skipping - max_skips - allow_max_billing_cycles - max_billing_cycles - price_adjustment_type - price_adjustment_amount - savings_display_mode - active - company_default - created_at - updated_at - products_count - subscribers_count properties: id: type: integer name: type: string billing_interval: type: integer billing_interval_unit: type: string enum: - day - week - month - year billing_frequency_in_words: type: string shipping_interval: type: integer shipping_interval_unit: type: string enum: - day - week - month - year volume_interval: type: integer volume_interval_unit: type: string enum: - day - week - month - year trial_period: type: - integer - 'null' trial_period_unit: type: - string - 'null' split_volume: type: boolean allow_skipping: type: - boolean - 'null' max_skips: type: - integer - 'null' allow_max_billing_cycles: type: boolean max_billing_cycles: type: - integer - 'null' price_adjustment_type: type: - string - 'null' price_adjustment_amount: type: number description: Serialized via to_f — nil becomes 0.0, so never null. savings_display_mode: type: string active: type: - boolean - 'null' company_default: type: - boolean - 'null' created_at: type: string format: date-time updated_at: type: string format: date-time products_count: type: integer subscribers_count: type: integer variants: type: array items: $ref: '#/components/schemas/CheckoutProductVariant' required: - metadata - product - status - subscription_plans - variants additionalProperties: false ErrorResponse: type: object additionalProperties: false required: - error_message - errors - meta properties: error_message: type: string errors: $ref: '#/components/schemas/ErrorBag' meta: $ref: '#/components/schemas/CheckoutMeta' JsonValue: description: >- Any valid JSON value for provider, integration, theme, metadata, or other dynamic payloads whose keys are not fixed by the API contract. anyOf: - type: string - type: number - type: boolean - type: 'null' - type: array items: $ref: '#/components/schemas/JsonValue' - type: object additionalProperties: $ref: '#/components/schemas/JsonValue' CheckoutProductVariant: type: object properties: id: type: integer title: type: string display_name: type: - string - 'null' image_url: type: - string - 'null' image_path: type: - string - 'null' sku: type: - string - 'null' primary_image: type: - string - 'null' price: type: - number - string - 'null' price_in_currency: type: string currency_code: type: - string - 'null' options: type: array items: $ref: '#/components/schemas/CheckoutProductVariantOption' required: - id - title - display_name - image_url - image_path - sku - primary_image - price - price_in_currency - currency_code - options additionalProperties: false ErrorBag: description: >- Validation errors keyed by field, a list of errors, a single error message, or null when no structured error details are available. anyOf: - type: string - type: array items: $ref: '#/components/schemas/ErrorValue' - type: object additionalProperties: $ref: '#/components/schemas/ErrorValue' - type: 'null' CheckoutMeta: type: object additionalProperties: false required: - request_id - timestamp properties: request_id: type: - string - 'null' timestamp: type: string format: date-time CheckoutProductVariantOption: type: object properties: title: type: string value: type: string required: - title - value additionalProperties: false ErrorValue: description: A validation or API error value. anyOf: - type: string - type: array items: type: string - type: object additionalProperties: $ref: '#/components/schemas/JsonValue' ````