fx rates latest derived

{
  "input": {
    "type": "http",
    "method": "GET",
    "queryParams": {
      "base": "ISO 4217 code to rebase the table on.",
      "symbols": "Comma-separated ISO 4217 codes to restrict the table to."
    }
  },
  "output": {
    "type": "object",
    "required": [
      "rateType",
      "found",
      "rateDate",
      "staleDays",
      "base",
      "rates",
      "source",
      "disclaimer"
    ],
    "properties": {
      "base": {
        "type": "string",
        "description": "Rebase currency (default EUR)."
      },
      "about": {
        "type": "string",
        "description": "What this response is and where its data comes from, in one sentence."
      },
      "found": {
        "type": "boolean",
        "description": "False when we answered definitively and the answer is that no such rate exists (see why). A definitive miss is a complete paid answer, never a 404."
      },
      "rates": {
        "type": "object",
        "description": "Currency code → rate (1 base = N quote), 6 decimals."
      },
      "source": {
        "enum": [
          "European Central Bank"
        ],
        "type": "string"
      },
      "related": {
        "type": "object",
        "description": "Next steps as paths on this origin. Each is priced by its own 402 challenge; GET /.well-known/x402 prices the whole origin in one free call.",
        "additionalProperties": {
          "type": "string"
        }
      },
      "rateDate": {
        "type": [
          "string",
          "null"
        ],
        "description": "ECB fixing date (YYYY-MM-DD) backing this answer; null when no fixing was consulted."
      },
      "rateType": {
        "enum": [
          "ecb-daily-reference"
        ],
        "type": "string",
        "description": "Daily reference rates — NOT live trading rates."
      },
      "freshness": {
        "type": "object",
        "required": [
          "tier",
          "as_of",
          "age_seconds",
          "max_age_seconds"
        ],
        "properties": {
          "note": {
            "type": "string"
          },
          "tier": {
            "type": "string",
            "example": "nightly"
          },
          "as_of": {
            "type": "string",
            "description": "Newest datum this answer is based on (ISO 8601)."
          },
          "age_seconds": {
            "type": "integer",
            "minimum": 0
          },
          "max_age_seconds": {
            "type": [
              "integer",
              "null"
            ],
            "minimum": 0
          }
        },
        "description": "How fresh the data is, measured when you called. `age_seconds` is the number to act on; `max_age_seconds` is the refresh cadence (null = deterministic, cannot go stale)."
      },
      "staleDays": {
        "type": [
          "integer",
          "null"
        ],
        "description": "Weekdays since the fixing; 0 = current. Null on a miss."
      },
      "disclaimer": {
        "type": "string"
      }
    }
  }
}