> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chance.cc/llms.txt
> Use this file to discover all available pages before exploring further.

# Submit a sponsored transaction

> Step 2. Send one signature per signature request, in order. The server submits the transaction it prepared. Free.



## OpenAPI

````yaml /openapi.json post /api/v1/gas/submit
openapi: 3.0.3
info:
  title: Chance API
  version: 1.0.0
  description: >-
    Verify an agent's proposed action against its rules, manage escrow wallets,
    and buy credits. Every verification returns a signed, hash-chained receipt.
servers:
  - url: https://harness.chance.cc
    description: Production
security:
  - ApiKeyAuth: []
  - BearerAuth: []
tags:
  - name: Verification
    description: Check an action against its rules and fetch past verdicts.
  - name: Credits
    description: Balance and x402 top-ups.
  - name: Escrow wallets
    description: Wallets that only move funds through a verified proposal.
  - name: Trader
    description: Liveness reports from trader containers.
  - name: Gas sponsorship
    description: Sponsored gas for trader instances on Polygon.
  - name: Status
    description: Public deployment facts for checking receipts.
paths:
  /api/v1/gas/submit:
    post:
      tags:
        - Gas sponsorship
      summary: Submit a sponsored transaction
      description: >-
        Step 2. Send one signature per signature request, in order. The server
        submits the transaction it prepared. Free.
      operationId: gasSubmit
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/GasSubmitRequest'
      responses:
        '200':
          description: Submitted.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/GasSubmitResponse'
        '400':
          description: Invalid body or signatures.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
              examples:
                e0:
                  summary: invalid JSON body
                  value:
                    error: invalid JSON body
                e1:
                  summary: bad_signatures
                  value:
                    error: bad_signatures
                    message: signatures must be an array of hex strings
                e2:
                  summary: signature_count_mismatch
                  value:
                    error: signature_count_mismatch
                    message: expected 2 signature(s), got 1
        '401':
          description: No API key, or the key is unknown or revoked.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
              examples:
                e0:
                  summary: missing API key (send x-api-key)
                  value:
                    error: missing API key (send x-api-key)
                e1:
                  summary: invalid or revoked API key
                  value:
                    error: invalid or revoked API key
        '403':
          description: Nothing to submit for this verification.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
              examples:
                e0:
                  summary: sponsorship_not_found
                  value:
                    error: sponsorship_not_found
                    message: prepare this scan before submitting
                e1:
                  summary: already_sponsored
                  value:
                    error: already_sponsored
                    message: this scan has already been sponsored
                e2:
                  summary: not_prepared
                  value:
                    error: not_prepared
                    message: this sponsorship is not awaiting signatures
        '409':
          description: Gas sponsorship is not configured on this deployment.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
              example:
                error: gas_not_configured
        '502':
          description: The sponsorship provider failed.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
              examples:
                e0:
                  summary: alchemy_error
                  value:
                    error: alchemy_error
                    message: …
                e1:
                  summary: submit_failed
                  value:
                    error: submit_failed
                    message: …
components:
  schemas:
    GasSubmitRequest:
      type: object
      required:
        - scanId
        - signatures
      properties:
        scanId:
          type: string
        signatures:
          type: array
          items:
            type: string
          description: One hex signature per signature request, in order.
    GasSubmitResponse:
      type: object
      properties:
        callIds:
          type: array
          items:
            type: string
    Error:
      type: object
      required:
        - error
      properties:
        error:
          type: string
          description: >-
            An error code (for example `out_of_credits`) or a short sentence
            (for example `intent is required`).
        message:
          type: string
          description: Detail, when present.
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: x-api-key
      description: An API key (`chance_sk_live_…`) from https://harness.chance.cc/keys.
    BearerAuth:
      type: http
      scheme: bearer
      description: >-
        The same API key sent as `Authorization: Bearer <key>`. If both headers
        are sent, `x-api-key` is used.

````