{
  "context": "Checks whether the solution uses github.com/prometheus/client_model/go to build and serialize a gauge histogram payload. It focuses on correct histogram field choices, float overrides, and exemplar placement rather than general code quality.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "Gauge type",
      "description": "Sets MetricFamily.Type to client_model.MetricType_GAUGE_HISTOGRAM and populates Metric.Histogram while leaving other metric payloads unset.",
      "max_score": 20
    },
    {
      "name": "Spans encoded",
      "description": "Uses Histogram.PositiveSpan and NegativeSpan with offsets/lengths matching provided span inputs and aligns PositiveDelta/PositiveCount and NegativeDelta/NegativeCount arrays to those spans instead of conventional Bucket entries.",
      "max_score": 25
    },
    {
      "name": "Counts and sum",
      "description": "Fills Histogram.SampleSum plus Histogram.SampleCount or SampleCountFloat as given, and sets ZeroCount or ZeroCountFloat with float fields taking precedence when provided.",
      "max_score": 20
    },
    {
      "name": "Bucket values",
      "description": "Encodes the provided bucket deltas so that Histogram.PositiveDelta/PositiveCount and NegativeDelta/NegativeCount represent the requested populations (e.g., positive deltas [2,3] yielding cumulative 2 then 5, negative delta [1]).",
      "max_score": 20
    },
    {
      "name": "Exemplar attached",
      "description": "Attaches a client_model.Exemplar with the trace_id label, value 0.34, and timestamp 1700000000000 to the first positive bucket via Histogram.Exemplars aligned to that bucket or the corresponding Bucket.Exemplar entry.",
      "max_score": 15
    }
  ]
}