원화와 스테이블코인 사이를, 규제 안에서

# Payment API는 JSON + Bearer 인증입니다
POST /v0.1/payment/onramp/sessions
Host: api.inexkr.com
Authorization: Bearer <secret_key>
Idempotency-Key: 3f9a1c2e-8b40-4d2a-9f11-...
Content-Type: application/json

{
  "partner_id":         "PARTNER-XXXX-001",
  "customer_reference": "CUST-88210",
  "fiat_currency":      "KRW",
  "fiat_amount":        "1000000",   // 문자열 · 최소단위
  "target_stablecoin":  "USDT",
  "destination_wallet": "INEX-WALLET-88210",
  "kyc_level":          "TIER2",
  "vasp_purpose_code":  "FIAT_TO_STABLE"
}

// 201 Created
{
  "object":       "onramp_session",
  "id":           "onramp_7F2A91C3",
  "status":       "pending_payment",
  "redirect_url": "https://pay.inexkr.com/s/7F2A91C3",
  "quote": {
    "fiat_amount":       "1000000",
    "stablecoin_amount": "745.86",
    "rate":              "1340.50",
    "expires_at":        "2026-08-04T09:25:00Z"
  },
  "created_at":   "2026-08-04T09:15:00Z"
}

// 4xx 오류 응답 (공통 형식)
{
  "error": {
    "code":    "ECompliance:KYC level insufficient",
    "message": "TIER2 이상 필요",
    "request_id": "req_5c81f0"
  }
}