AlgoVoi Checkout API

openapi: 3.2.0
info:
  title: AlgoVoi Gateway Checkout API
  description: Public-facing x402 payment gateway.
  version: 1.0.0-phase1c
  x-guidance: To access payment-gated resources, send the required payment proof header. Use GET /mpp/{resource_id} for MPP or GET /protected/{resource_id} for x402.
tags:
- name: Checkout
paths:
  /checkout/{token}/verify:
    post:
      tags:
      - Checkout
      summary: Verify Checkout
      description: 'Verify the payer''s on-chain transaction and mark the payment link paid.


        The payer must have sent exactly the required amount to the receiver address

        on the correct chain. The facilitator performs the on-chain verification.


        Returns the redirect_url on success so the browser JS can redirect.

        Returns 422 if the transaction is invalid or cannot be verified.

        Returns 409 if the link is already paid.

        Returns 410 if the link is expired or cancelled.'
      operationId: verify_checkout_checkout__token__verify_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CheckoutVerifyRequest'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CheckoutVerifyResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/qr:
    get:
      tags:
      - Checkout
      summary: Checkout Qr
      description: 'Generate a QR code PNG for any short string (used for WalletConnect pairing URIs).

        Returns image/png so the browser can use it as without any JS QR library.'
      operationId: checkout_qr_checkout__token__qr_get
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      - name: data
        in: query
        required: true
        schema:
          type: string
          title: Data
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/build-txn:
    get:
      tags:
      - Checkout
      summary: Checkout Build Txn
      description: 'Build an unsigned Algorand/VOI transaction for WalletConnect signing.

        Caller supplies ?sender=. Returns {unsigned_txn: } ready

        to pass straight to algo_signTxn — no algosdk needed in the browser.'
      operationId: checkout_build_txn_checkout__token__build_txn_get
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      - name: sender
        in: query
        required: true
        schema:
          type: string
          title: Sender
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/submit-txn:
    post:
      tags:
      - Checkout
      summary: Checkout Submit Txn
      description: 'Accept a base64-encoded signed Algorand/VOI transaction, submit it to algod,

        and return the tx_id for verification via the existing /verify endpoint.'
      operationId: checkout_submit_txn_checkout__token__submit_txn_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/detect:
    get:
      tags:
      - Checkout
      summary: Detect Payment
      description: 'Auto-detect inbound payment by polling the chain''s indexer/mirror node.


        Supports all chains:

        - Algorand/VOI: queries indexer /v2/transactions?address=...¬e-prefix=...

        - Hedera: queries Mirror Node /api/v1/transactions?account.id=...


        Returns {"found": true, "tx_id": "..."} when detected, or {"found": false}.'
      operationId: detect_payment_checkout__token__detect_get
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/submit-sponsored:
    post:
      tags:
      - Checkout
      summary: Submit Sponsored
      description: 'Accept a customer''s signed 0-fee transaction and submit it via the

        tenant''s sponsor wallet (atomic group fee pooling).


        Body: { "signed_tx": base64, "chain": "algorand-mainnet" | "voi-mainnet" }


        If the tenant has no sponsor wallet configured, returns

        {"error": "not_sponsored", "fallback": true} so the client can fall back

        to normal payment flow.'
      operationId: submit_sponsored_checkout__token__submit_sponsored_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              additionalProperties: true
              title: Body
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/abandon:
    post:
      tags:
      - Checkout
      summary: Abandon Checkout
      description: 'Customer-initiated checkout abandonment.


        No `cancel_secret` required: anyone who has the checkout URL can already

        walk away from their own checkout. This endpoint just makes the

        abandonment EXPLICIT to the platform — without it, the merchant order

        stays in `Pending` indefinitely, and OpenCart''s `algovoi.callback`

        polling our `/status` would still see `active`, leading to confusing

        UX where a cancelled checkout returns to the merchant''s checkout page

        instead of the merchant''s "order cancelled" page.


        Only `active` links can be abandoned:

        * `paid` → 409 Conflict (let the JS show "Payment confirmed" instead)

        * `cancelled`→ 200 (idempotent — already cancelled)

        * `expired` → 410 Gone


        On success: marks `link.status = ''cancelled''` AND notifies the merchant

        platform (OpenCart etc.) to mark the order as Cancelled on their side.

        Always returns the redirect_url so the JS can wire the "Return to store"

        link target.'
      operationId: abandon_checkout_checkout__token__abandon_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/cancel:
    post:
      tags:
      - Checkout
      summary: Cancel Checkout
      description: 'Cancel an active checkout link. Sets status to ''cancelled''.


        F5 security fix: requires cancel_secret in the request body. The secret

        is generated at link-creation time and returned to the merchant only —

        it is never embedded in the public checkout page. This prevents an

        attacker who merely knows the checkout URL from cancelling the link.


        Only active links can be cancelled. Paid/expired/already-cancelled links

        return 409/410. Returns redirect_url so callers can redirect customers.'
      operationId: cancel_checkout_checkout__token__cancel_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CancelCheckoutRequest'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/xchain/bridge-info:
    get:
      tags:
      - Checkout
      summary: Xchain Bridge Info
      description: 'Return all EVM chains Allbridge supports as bridge SOURCES for the

        tenant''s configured destination chain (Algorand USDCa or Solana USDC),

        pre-computed with the exact send amount (checkout amount + bridge fee).


        Also returns the destination metadata so the frontend can render the

        right "USDC on " label without a second round-trip.'
      operationId: xchain_bridge_info_checkout__token__xchain_bridge_info_get
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/xchain/bridge-send:
    post:
      tags:
      - Checkout
      summary: Xchain Bridge Send
      description: 'Build the swapAndBridge calldata server-side and return it for MetaMask to sign.


        Body schema:

        Required: evm_address, chain_id, usdc_address, bridge_amount

        One of: algo_address (legacy field name, used for Algorand destination)

        recipient_address (preferred — works for any destination)


        Returns: { to, data, value } — pass directly to eth_sendTransaction.


        The destination chain is taken from the tenant''s xchain_destination_chain

        setting; the frontend doesn''t pass it (and shouldn''t be allowed to,

        because that would let a hostile shopper redirect bridge inflow to a

        different chain).'
      operationId: xchain_bridge_send_checkout__token__xchain_bridge_send_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/xchain/source-tx-recorded:
    post:
      tags:
      - Checkout
      summary: Xchain Source Tx Recorded
      description: 'Called by the frontend immediately after MetaMask returns a tx hash for

        the swapAndBridge call. Records the source_tx_hash on the bridge-attempt

        row, advancing its state from `pending_signature` to `pending_bridge`.


        Body: { attempt_id: int, source_tx_hash: str }


        Idempotent: re-POSTing with the same source_tx_hash for the same

        attempt is a no-op. Mismatched source_tx_hash on a row that already has

        one is rejected with 400 — exactly one source tx per attempt.


        Per Comet review 2026-05-04 — without this, AlgoVoi can''t reconcile

        Allbridge''s destination tx back to the shopper''s checkout.'
      operationId: xchain_source_tx_recorded_checkout__token__xchain_source_tx_recorded_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/xchain/bridge-status/{tx_hash}:
    get:
      tags:
      - Checkout
      summary: Xchain Bridge Status
      description: 'Poll Allbridge for cross-chain transfer completion + advance the

        bridge-attempt lifecycle.


        Reads `tx_hash` as the SOURCE-chain tx (the one MetaMask returned).

        Looks up the persisted attempt by source_tx_hash, polls Allbridge,

        and on completion records the destination tx hash on the attempt

        row so the verifier can run against the SPECIFIC dest tx (not "any

        matching tx in window").


        Idempotent — repeated polls only update DB state on transitions.'
      operationId: xchain_bridge_status_checkout__token__xchain_bridge_status__tx_hash__get
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      - name: tx_hash
        in: path
        required: true
        schema:
          type: string
          title: Tx Hash
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/xchain/prepare:
    post:
      tags:
      - Checkout
      summary: Xchain Prepare
      description: 'Derive the Algorand LogicSig address for an EVM wallet and check funding.

        If sufficiently funded, builds the unsigned payment tx ready for EIP-712 signing.

        Body: { "evm_address": "0x..." }'
      operationId: xchain_prepare_checkout__token__xchain_prepare_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/xchain/prepare-optin:
    post:
      tags:
      - Checkout
      summary: Xchain Prepare Optin
      description: 'Fund the LogicSig address from the platform sponsor wallet and build an

        unsigned USDCa opt-in transaction for EIP-712 signing.

        Body: { "evm_address": "0x..." }

        Returns: { "eip712_message": {...} }'
      operationId: xchain_prepare_optin_checkout__token__xchain_prepare_optin_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/xchain/optin-submit:
    post:
      tags:
      - Checkout
      summary: Xchain Optin Submit
      description: 'Sign and submit the pending USDCa opt-in transaction.

        Body: { "evm_address": "0x...", "signature": "0x..." }

        Returns: { "optin_tx_id": "..." }'
      operationId: xchain_optin_submit_checkout__token__xchain_optin_submit_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/xchain/submit:
    post:
      tags:
      - Checkout
      summary: Xchain Submit
      description: 'Sign and submit the pending xChain transaction using the EVM wallet''s EIP-712 signature.

        Body: { "evm_address": "0x...", "signature": "0x..." }

        Returns { "tx_id": "..." }'
      operationId: xchain_submit_checkout__token__xchain_submit_post
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
  /checkout/{token}/status:
    get:
      tags:
      - Checkout
      summary: Checkout Status
      description: 'Polling endpoint — returns whether the link has been paid.


        Safe to call repeatedly; does not mutate state.

        Returns { "status": "active"|"paid"|"expired"|"cancelled", "redirect_url": str|null }'
      operationId: checkout_status_checkout__token__status_get
      parameters:
      - name: token
        in: path
        required: true
        schema:
          type: string
          title: Token
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      x-payment-info:
        authMode: api_key
components:
  schemas:
    CheckoutVerifyRequest:
      properties:
        tx_id:
          type: string
          maxLength: 100
          minLength: 10
          title: Tx Id
        chain:
          anyOf:
          - type: string
          - type: 'null'
          title: Chain
      type: object
      required:
      - tx_id
      title: CheckoutVerifyRequest
      description: Body for POST /checkout/{token}/verify (gateway-side, unauthenticated).
    ValidationError:
      properties:
        loc:
          items:
            anyOf:
            - type: string
            - type: integer
          type: array
          title: Location
        msg:
          type: string
          title: Message
        type:
          type: string
          title: Error Type
        input:
          title: Input
        ctx:
          type: object
          title: Context
      type: object
      required:
      - loc
      - msg
      - type
      title: ValidationError
    HTTPValidationError:
      properties:
        detail:
          items:
            $ref: '#/components/schemas/ValidationError'
          type: array
          title: Detail
      type: object
      title: HTTPValidationError
    CheckoutVerifyResponse:
      properties:
        payment_ledger_id:
          anyOf:
          - type: string
            format: uuid
          - type: 'null'
          title: Payment Ledger Id
        status:
          type: string
          title: Status
        redirect_url:
          anyOf:
          - type: string
          - type: 'null'
          title: Redirect Url
        settlement_attestation:
          anyOf:
          - additionalProperties: true
            type: object
          - type: 'null'
          title: Settlement Attestation
        settlement_attestation_jws:
          anyOf:
          - type: string
          - type: 'null'
          title: Settlement Attestation Jws
      type: object
      required:
      - status
      title: CheckoutVerifyResponse
      description: Successful verification response.
    CancelCheckoutRequest:
      properties:
        cancel_secret:
          type: string
          maxLength: 128
          minLength: 1
          title: Cancel Secret
      type: object
      required:
      - cancel_secret
      title: CancelCheckoutRequest
      description: 'Body for POST /checkout/{token}/cancel (gateway-side).


        F5 security fix: the cancel endpoint now requires cancel_secret so that

        only the merchant (who received cancel_secret at link-creation time) can

        cancel a link programmatically. Customers use the in-browser ''abandon''

        flow which navigates them away without touching the backend.'
x-discovery:
  ownershipProofs:
  - eb10b2d7fb1e2fcbea7a4c5b031e339daacc7cf37d1fb569c58849287c121633
  resources:
  - https://api.algovoi.co.uk/mpp/probe
  resourcesCatalog: https://api.algovoi.co.uk/discovery/resources