{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "Conversation",
  "type": "object",
  "required": ["conversation_id", "product_id", "character_id", "messages"],
  "properties": {
    "conversation_id": { "type": "string" },
    "product_id": { "type": "string" },
    "character_id": { "type": "string" },
    "status": { "type": "string" },
    "messages": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "role": { "type": "string", "enum": ["user", "assistant"] },
          "text": { "type": "string" },
          "audio_url": { "type": ["string", "null"] }
        }
      }
    }
  }
}