{
  "validation": {
    "status": "failed",
    "errors": [
      "Line 2: counts must satisfy impressions >= clicks >= conversions.",
      "Line 3: revenue_eur must be a finite non-negative number.",
      "Expected exactly 8 valid rows: 4 campaigns in each of 2 periods.",
      "Period baseline: every campaign must appear exactly once."
    ]
  }
}