SCVD General Store Before You Pay API

openapi: 3.2.0
info:
  title: SCVD General Store Before You Pay API
  version: 0.3.0
  description: 'scvd.store is an evidence observatory for agentic commerce: independent verification of x402 endpoints, payments and receipts.'
  contact:
    url: https://scvd.store
    email: sean@recordcreativeco.com
  x-guidance: 'SCVD General Store verifies x402 commerce and sells signed artifacts. Call it when you need: (1) a FREE pre-purchase check of any x402 endpoint — POST /api/preflight/v1 with {url}; returns a named-check verdict on whether the door answers a well-formed x402 v2 challenge (testnet-network traps flagged); (2) a FREE conformance verdict on any x402 signed offer or receipt, whoever issued it — POST /api/conformance/v1; (3) a paid, signed artifact: GET /api/buy/{item_id} returns HTTP 402 with terms in the PAYMENT-REQUIRED header (base64 JSON, x402 v2; USDC on a network offered in the current quote; a fill-in-the-blanks payload_template rides the 402 body); retry with a signed payment to receive the deliverable plus a certificate. Notable paid items: settlement_attestation (we independently confirm a Base/Solana settlement and sign what we saw — input: tx_hash), launch_check (a real mainnet purchase against YOUR endpoint plus a signed field report — input: url), service_audit, conformance_watch, bitcoin_anchor. Inputs are query parameters, declared per item in /menu.json; outputs are JSON with a certificate id. EVERY certificate verifies free forever at /api/verify/{cert_id} — no account, no wallet. Starting prices run $0.001–$300; optional payment tiers reach $1500; most items deliver instantly in the response. Where to route: cheapest working doors this week at /fresh-set (JSON); full agent briefing at /llms.txt. Before you start: free instruments need only plain HTTPS (no account, key or SDK); a purchase needs an x402 v2 client and a wallet holding USDC on Base (eip155:8453), Polygon (eip155:137), Arbitrum (eip155:42161), World (eip155:480), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), paid only on a network the 402 offers; the stock client refuses payments above $1 by default and 14 of 35 priced doors sit above it; optional tooling (scvd-tab, the MCP stdio bridge, the scvd CLI) is listed at https://scvd.store/agents.md and none of it is required.'
servers:
- url: https://scvd.store
tags:
- name: Before You Pay
paths:
  /api/before-you-pay/v1:
    get:
      summary: The payment dry run, described
      description: What the dry run answers — will YOUR client pay this door, and which accept would it sign — the request shape with the optional client profile, the failures it catches, and what it cannot tell you. Free.
      security: []
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                type: object
                required:
                - title
                - version
                - method
                - url
                - request
                - what_it_cannot_tell_you
                properties:
                  title:
                    type: string
                  version:
                    type: string
                  method:
                    type: string
                    enum:
                    - POST
                  url:
                    type: string
                    format: uri
                  request:
                    type: object
                  common_failures_this_catches:
                    type: object
                  what_it_cannot_tell_you:
                    type: array
                    items:
                      type: string
                  the_ladder:
                    type: object
                  errors:
                    type: array
        '304':
          $ref: '#/components/responses/NotModified'
        '400':
          $ref: '#/components/responses/BadRequest'
        '404':
          $ref: '#/components/responses/NotFound'
        '429':
          $ref: '#/components/responses/TooManyRequests'
        '500':
          $ref: '#/components/responses/ServerError'
      operationId: get_api_before_you_pay_v1
      parameters:
      - name: If-None-Match
        in: header
        required: false
        schema:
          type: string
        description: Conditional GET. Send the ETag a previous answer carried (a SHA-256 of the exact bytes served, not a version somebody maintains) and an unchanged document answers 304 with no body. Send it on a schedule instead of re-downloading what you already hold.
      tags:
      - Before You Pay
    post:
      summary: Will my client pay this x402 door?
      description: 'One probe, then the stock x402 client''s own selection logic replayed over what came back: which accept it would sign, or that it would refuse on your machine before signing anything, and why. Carries the free preflight whole as the_door, from the same bytes. Nothing is signed and no payment is made. Free, and metered like the preflight.'
      security: []
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                type: object
                required:
                - version
                - url
                - will_your_client_pay
                - your_client
                - the_door
                - these_are_different_questions
                - what_this_is_not
                properties:
                  version:
                    type: string
                  url:
                    type: string
                    format: uri
                  will_your_client_pay:
                    type: string
                    enum:
                    - would_sign
                    - would_throw
                    - cannot_simulate
                    description: would_sign = a stock client reaches a signature at the named accept. would_throw = it refuses on your own machine before any signature exists. cannot_simulate = the challenge did not parse into accepts to walk, which is the preflight's finding.
                  your_client:
                    type: object
                    required:
                    - outcome
                    - chosen
                    - dropped
                    - hazards
                    - cap_applied
                    properties:
                      outcome:
                        type: string
                        enum:
                        - would_sign
                        - would_throw
                        - cannot_simulate
                      chosen:
                        type:
                        - object
                        - 'null'
                      throws_with:
                        type:
                        - string
                        - 'null'
                      dropped:
                        type: array
                      hazards:
                        type: array
                      cap_applied:
                        type: string
                      what_this_cannot_see:
                        type: array
                        items:
                          type: string
                  the_door:
                    type: object
                    description: The free preflight report, whole, from the same probe.
                  these_are_different_questions:
                    type: string
                  what_this_is_not:
                    type: string
                  next_steps:
                    type: object
          headers:
            RateLimit-Limit:
              $ref: '#/components/headers/RateLimit-Limit'
            RateLimit-Remaining:
              $ref: '#/components/headers/RateLimit-Remaining'
            RateLimit-Reset:
              $ref: '#/components/headers/RateLimit-Reset'
            RateLimit-Policy:
              $ref: '#/components/headers/RateLimit-Policy'
            RateLimit:
              $ref: '#/components/headers/RateLimit'
        '400':
          description: The request was malformed or a required parameter was missing.
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/Problem'
            application/json:
              schema:
                $ref: '#/components/schemas/Problem'
        '404':
          description: No such resource. The body names where to look instead.
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/Problem'
            application/json:
              schema:
                $ref: '#/components/schemas/Problem'
        '429':
          $ref: '#/components/responses/TooManyRequestsMetered'
        '500':
          description: Something fell off a shelf. Nothing was charged.
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/Problem'
            application/json:
              schema:
                $ref: '#/components/schemas/Problem'
      requestBody:
        required: true
        description: The x402 door you are about to pay, and optionally what your client is configured with.
        content:
          application/json:
            schema:
              type: object
              required:
              - url
              properties:
                url:
                  type: string
                  format: uri
                  description: The https URL you are about to pay.
                client_profile:
                  type: object
                  description: What your client is configured with. Leave it off for the answer for a client configured with NOTHING, which is the case that loses money quietly.
                  properties:
                    max_amount_per_payment_usd:
                      oneOf:
                      - type: number
                        exclusiveMinimum: 0
                      - type: boolean
                        enum:
                        - false
                      description: A cap in USD, or false for no cap.
                    spend_controls_disabled:
                      type: boolean
      operationId: post_api_before_you_pay_v1
      tags:
      - Before You Pay
components:
  responses:
    NotFound:
      description: No such resource. The body names where to look instead.
      content:
        application/problem+json:
          schema:
            $ref: '#/components/schemas/Problem'
        application/json:
          schema:
            $ref: '#/components/schemas/Problem'
    ServerError:
      description: Something fell off a shelf. Nothing was charged.
      content:
        application/problem+json:
          schema:
            $ref: '#/components/schemas/Problem'
        application/json:
          schema:
            $ref: '#/components/schemas/Problem'
    TooManyRequestsMetered:
      description: 'Too many requests, from the edge rather than from the store''s own logic. Retry after the interval named in Retry-After; the store does not charge for a refusal. The free preflight is limited — 30 probes per isolate per minute, 60 global — because it spends outbound requests to a host the caller chooses. Every answer the limiter METERED carries the IETF RateLimit fields — the 200 and the 429 — so you can pace against the live number instead of discovering the ceiling by being refused: RateLimit-Limit / -Remaining / -Reset report whichever of the two buckets is closer to binding, and RateLimit / RateLimit-Policy name both. Past either ceiling it returns 429 with Retry-After. A validation refusal (400, e.g. a missing or unprobeable URL) returns BEFORE either bucket is touched and carries no RateLimit fields, because a malformed request never spent a probe; this contract used to declare them on those responses too, which described a header that had never been sent. No other operation enforces an application-level ceiling, and so returns no RateLimit headers: declaring a ceiling nothing enforces would be worse than declaring none. A 429 can also arrive from the edge under abuse conditions. A refused request is never charged for. The two figures above are read from the limiter''s own constants, not restated here — this string asserted that NO limit existed for a day after one shipped.'
      content:
        application/problem+json:
          schema:
            $ref: '#/components/schemas/Problem'
        application/json:
          schema:
            $ref: '#/components/schemas/Problem'
      headers:
        Retry-After:
          schema:
            type: integer
          description: Seconds to wait before retrying.
        RateLimit-Limit:
          $ref: '#/components/headers/RateLimit-Limit'
        RateLimit-Remaining:
          $ref: '#/components/headers/RateLimit-Remaining'
        RateLimit-Reset:
          $ref: '#/components/headers/RateLimit-Reset'
        RateLimit-Policy:
          $ref: '#/components/headers/RateLimit-Policy'
        RateLimit:
          $ref: '#/components/headers/RateLimit'
    TooManyRequests:
      description: 'Too many requests, from the edge rather than from the store''s own logic. Retry after the interval named in Retry-After; the store does not charge for a refusal. The free preflight is limited — 30 probes per isolate per minute, 60 global — because it spends outbound requests to a host the caller chooses. Every answer the limiter METERED carries the IETF RateLimit fields — the 200 and the 429 — so you can pace against the live number instead of discovering the ceiling by being refused: RateLimit-Limit / -Remaining / -Reset report whichever of the two buckets is closer to binding, and RateLimit / RateLimit-Policy name both. Past either ceiling it returns 429 with Retry-After. A validation refusal (400, e.g. a missing or unprobeable URL) returns BEFORE either bucket is touched and carries no RateLimit fields, because a malformed request never spent a probe; this contract used to declare them on those responses too, which described a header that had never been sent. No other operation enforces an application-level ceiling, and so returns no RateLimit headers: declaring a ceiling nothing enforces would be worse than declaring none. A 429 can also arrive from the edge under abuse conditions. A refused request is never charged for. The two figures above are read from the limiter''s own constants, not restated here — this string asserted that NO limit existed for a day after one shipped.'
      content:
        application/problem+json:
          schema:
            $ref: '#/components/schemas/Problem'
        application/json:
          schema:
            $ref: '#/components/schemas/Problem'
      headers:
        Retry-After:
          schema:
            type: integer
          description: Seconds to wait before retrying.
    NotModified:
      description: 'Not Modified: the ETag you sent still names these exact bytes. No body; every other header is as the 200 would carry it.'
    BadRequest:
      description: The request was malformed or a required parameter was missing.
      content:
        application/problem+json:
          schema:
            $ref: '#/components/schemas/Problem'
        application/json:
          schema:
            $ref: '#/components/schemas/Problem'
  headers:
    RateLimit:
      schema:
        type: string
      description: 'Both policies'' live state: "isolate";r=N;t=N, "global";r=N;t=N.'
    RateLimit-Remaining:
      schema:
        type: integer
      description: What is left in the binding bucket. The global backstop is a read-modify-write on eventually consistent storage, so this can read slightly high — never low.
    RateLimit-Policy:
      schema:
        type: string
      description: 'Both policies as structured fields: "isolate";q=N;w=60, "global";q=N;w=60.'
    RateLimit-Limit:
      schema:
        type: integer
      description: The binding bucket's ceiling per 60-second window.
    RateLimit-Reset:
      schema:
        type: integer
      description: Seconds until both buckets roll, at the wall-clock minute.
  schemas:
    Problem:
      type: object
      description: An RFC 9457 problem object. `error` is the store's long-standing human-readable field and is always present; the RFC fields sit beside it.
      properties:
        type:
          type: string
          format: uri
          description: A URI identifying the problem class. Dereferenceable at this origin where one exists.
        title:
          type: string
          description: A short, stable summary of the problem class.
        status:
          type: integer
          description: The HTTP status code, repeated in the body.
        detail:
          type: string
          description: What went wrong with THIS request, in plain language.
        instance:
          type: string
          format: uri
          description: The request path.
        error:
          type: string
          description: The store's human-readable message. Always present, including on responses that predate the typed model.
        retry_same_request:
          type: boolean
          const: false
          description: 'Present on repair responses: correct the selection or inputs before retrying.'
        next_step:
          type: object
          description: Optional free read after a refusal. Catalog and input repairs also include an equivalent MCP read. No payment or buyer arguments are forwarded.
          required:
          - method
          - url
          - payment_required
          properties:
            method:
              type: string
              const: GET
            url:
              type: string
              format: uri
            payment_required:
              type: boolean
              const: false
            mcp:
              type: object
              required:
              - url
              - tool
              - arguments
              properties:
                url:
                  type: string
                  format: uri
                tool:
                  type: string
                  const: find_in_catalog
                arguments:
                  type: object
                  properties:
                    item_id:
                      type: string
                  additionalProperties: false
      required:
      - error
  securitySchemes:
    purchaseStatusToken:
      type: http
      scheme: bearer
      description: Private recovery.status_token returned by a catalogue purchase. This capability reads only its original purchase status.
externalDocs:
  url: https://scvd.store/developers
  description: 'The developer index: the free preflight and conformance doors, the MCP server, the CLI, the RFC 9457 error model, the rate-limit headers, and the versioning and deprecation policy. The full agent briefing is at /llms.txt.'
x-agentcash-provenance:
  ownershipProofs:
  - '0xd0716b334368fed445d000f12c7e586a6c86e13bd543333bab6c04695df236320c5dbfa4f0beb6807cc486c0ed4fd5a38892a8148d5aa80377db9f35ed4c4b151c'
  - 4HduymBCHhwyLgtMyXRpDX3JHQR3oyqTSytsXqCamzCc4ed9fJeBSpDUDSLwfZ59mZaw9ggdMNURPNBi4P6BRU47
x-scvd-ucp:
  profile: https://scvd.store/.well-known/ucp
  checkout: advertised
x-scvd-native-checkout:
  mcp:
    protocol: mpp
    payment_method: evm
    intent: charge
    transport: mcp
    method: tools/call
    path: /mcp
    challenge_key: org.paymentauth/payment-required
    challenge_location: error.data, or result._meta with ?payment=tool-result
    credential_meta_key: org.paymentauth/credential
    receipt_meta_key: org.paymentauth/receipt
    idempotency_meta_key: x402/idempotency-key
    terms: 'each item''s payment_capabilities row with transport http: same network, asset and amount_atomic'
  webmcp:
    protocol: mpp
    payment_method: evm
    intent: charge
    transport: webmcp
    script: /webmcp.js
    quote_tool: quote_store_purchase
    challenge_field: payment_challenge
    complete_tool: complete_store_purchase
    credential_argument: signed_credential
    receipt_field: payment_receipt
    terms: 'each item''s payment_capabilities row with transport http: same network, asset and amount_atomic'
x-rate-limiting:
  application_level_limit: true
  limited_paths:
  - /api/preflight/v1
  - /api/preflight/v2
  - /api/before-you-pay/v1
  - /api/look/v1
  - /api/preflight/batch
  headers_returned:
  - RateLimit-Limit
  - RateLimit-Remaining
  - RateLimit-Reset
  - RateLimit-Policy
  - RateLimit
  note: 'The free preflight is limited — 30 probes per isolate per minute, 60 global — because it spends outbound requests to a host the caller chooses. Every answer the limiter METERED carries the IETF RateLimit fields — the 200 and the 429 — so you can pace against the live number instead of discovering the ceiling by being refused: RateLimit-Limit / -Remaining / -Reset report whichever of the two buckets is closer to binding, and RateLimit / RateLimit-Policy name both. Past either ceiling it returns 429 with Retry-After. A validation refusal (400, e.g. a missing or unprobeable URL) returns BEFORE either bucket is touched and carries no RateLimit fields, because a malformed request never spent a probe; this contract used to declare them on those responses too, which described a header that had never been sent. No other operation enforces an application-level ceiling, and so returns no RateLimit headers: declaring a ceiling nothing enforces would be worse than declaring none. A 429 can also arrive from the edge under abuse conditions. A refused request is never charged for. The two figures above are read from the limiter''s own constants, not restated here — this string asserted that NO limit existed for a day after one shipped.'
  policy_url: https://scvd.store/developers
x-versioning:
  scheme: url-path
  note: 'Breaking changes arrive as a new version in the path (/api/preflight/v1 → /v2). A published version''s SHAPE never changes under a client: fields are added, never removed or retyped.'
  deprecation: A version being retired serves the RFC 8594 Deprecation and Sunset headers on every response for at least 90 days before it stops answering, and the date is published at /developers before the headers appear.
  sunset_headers:
  - Deprecation
  - Sunset
  - Link; rel="successor-version"
  policy_url: https://scvd.store/deprecation
  currently_deprecated: []
  versions:
  - path: /api/preflight/v1
    status: supported
    since: '2026-08-03'
    sunset: null
    successor: /api/preflight/v2
  - path: /api/preflight/v2
    status: current
    since: '2026-08-23'
    sunset: null
    successor: null
  - path: /api/look/v1
    status: current
    since: '2026-09-02'
    sunset: null
    successor: null
  - path: /api/conformance/v1
    status: current
    since: '2026-08-03'
    sunset: null
    successor: null