{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://design-council.local/schemas/exchange-credit-ledger.schema.json",
  "title": "Future Exchange research-credit ledger contract",
  "description": "Schema boundary only. V1 performs no payments, balances, pricing, or ledger writes.",
  "type": "object",
  "additionalProperties": false,
  "required": ["ledger_version", "feature_status", "currency", "account_id", "balance", "entries"],
  "properties": {
    "ledger_version": {"const": "1.0.0"},
    "feature_status": {"enum": ["FUTURE_FEATURE", "NOT_CONFIGURED", "ACTIVE"]},
    "currency": {"const": "EXCHANGE_CREDITS"},
    "account_id": {"type": ["string", "null"]},
    "balance": {"type": ["number", "null"], "minimum": 0},
    "entries": {
      "type": "array",
      "items": {
        "type": "object",
        "additionalProperties": false,
        "required": ["id", "transaction_type", "amount", "study_id", "participant_id", "created_at"],
        "properties": {
          "id": {"type": "string", "pattern": "^XCL-[0-9]{3,}$"},
          "transaction_type": {"enum": ["EARN", "SPEND", "PURCHASE", "ADJUSTMENT"]},
          "amount": {"type": "number", "exclusiveMinimum": 0},
          "study_id": {"type": ["string", "null"], "pattern": "^STUDY-[0-9]{3,}$"},
          "participant_id": {"type": ["string", "null"], "pattern": "^P-[0-9]{3,}$"},
          "created_at": {"type": "string", "format": "date-time"}
        }
      }
    },
    "pricing_model": {"type": "null"}
  }
}