openapi: 3.2.0
info:
  title: Merchant-0 A2A Protocol Server Message API
  description: Agent-to-Agent Commerce API for the 2026 Agentic Economy
  version: '2026.1'
tags:
- name: Message
paths:
  /message/send:
    post:
      summary: A2A Message Send
      description: 'Minimal JSON-RPC 2.0 handler for A2A ``message/send`` (registry health / discovery).


        **No database, no outbound HTTP** -- only reads the request body, parses JSON when

        present, and returns a fixed payload. Accepts full JSON-RPC 2.0 or simpler JSON

        bodies; always HTTP **200**. Non-JSON-RPC payloads get ``id: null``.'
      operationId: a2a_message_send_message_send_post
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema: {}
      tags:
      - Message