> ## 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. > When the same operation exists on more than one surface, use the newest: dated API versions are newer than unversioned ones, and later dates win (v2026-04 > v2025-06 > unversioned v0/v1.1). Fall back to a legacy or unversioned operation only when no newer versioned equivalent exists — the company-v0 notes below list the known superseded operations. /api/company/v1 and /api/v1/... paths are documented in no spec here and must never be used (/api/v1.1/... is distinct and documented in company-v0). Use page/per_page offset pagination only where a spec documents it — in practice the unversioned company-v0 admin surface; every versioned surface uses cursor pagination. > 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); api-reference/company-v0.yaml covers the legacy unversioned company admin surface (/api/... paths, bearer-authenticated — company settings and management, customers, users, roles, subscription plans, subscription bundles, subscriptions, media, pages, catch-ups, inventory levels, domains, agreements, and admin order actions). company-v0 caveats: it is the legacy v0 admin contract and its lists use flat page/per_page offset pagination, which is expected there despite the general cursor-pagination rule; where an operation exists in both company-v0 and a versioned spec, prefer the versioned spec — the subscriptions lifecycle (list/create/show/update, cancel, pause, reactivate, resume, retry, skip, failed-cycle-waiver, discounts) and subscription bundles are superseded by checkout-v2026-04, and company pages/media CRUD plus the public pages, categories, products, and media list endpoints are superseded by storefront-v2026-04. Subscription plan management (/api/subscription_plans, resource-wrapped {"subscription_plan": {...}} bodies) exists only in company-v0. > Successful responses wrap the resource payload alongside a top-level integer status and a meta object. # Paymentrefunded > Sent when a refund created through this API succeeds (full or partial). Same delivery, signature, and retry contract as `payment.completed`. ## OpenAPI ````yaml /api-reference/payment-v2026-04.yaml webhook payment.refunded openapi: 3.1.0 info: title: Fluid Payment API version: v2026-04 description: | Payment gateway and transaction management API — the standalone Fluid Payments surface for external platforms. Two credentials are accepted on every operation: - **API keys** (`fp_live_*` / `fp_test_*`), scoped to a payments merchant. Live and sandbox keys are separate credentials; `fp_live_*` keys also require the merchant's API access to be enabled. Requests authenticated with an `fp_test_*` key run in sandbox mode: transactions are created with a sandbox source and never move real funds. - **JWT bearer tokens** at admin tier (company admin or root admin). A non-admin JWT is rejected with `403`. Transactions created outside this API (checkout, storefront, admin) are not visible to its read endpoints and cannot be captured, voided, or credited here. API-key-authenticated operations emit signed webhooks to the merchant's configured webhook URL (see the `webhooks` section). contact: email: support@fluid.app license: name: Proprietary identifier: LicenseRef-Proprietary servers: - url: https://api.fluid.app security: - bearer_auth: [] tags: - name: Gateways description: >- Manage payment gateways and run gateway-level transactions — purchase, authorize, and $0 verification. - name: Transactions description: >- Read transactions and run transaction lifecycle operations — capture, void, and refund. Scoped to transactions created through this API (live or sandbox); transactions from checkout, storefront, or admin flows are not visible here. - name: Merchant Configuration description: >- Root-admin-only access to a merchant's VGS, Kount, 3DS acquirer, payout, and platform-fee settings. - name: Webhooks description: >- Signed payment-event notifications POSTed to the merchant's configured webhook URL. Fired only for transactions created through API-key-authenticated requests. paths: {} components: securitySchemes: bearer_auth: type: http scheme: bearer description: | Merchant API key (`fp_live_*` for live, `fp_test_*` for sandbox) or an admin-tier JWT (company admin or root admin). Non-admin JWTs are rejected with `403`; live API keys additionally require the merchant's API access to be enabled. ````