Debug-Timezone-Dst-Bucket-V2

The model receives the prompt (and optional system message). The run uses scorer rubric_json_metrics with the JSON configuration below. Pass/fail and partial credit are determined entirely by that scorer against the model output; no human grading.

Return JSON only with keys diagnosis, fix, tests. A daily bucket function adds 24 hours in milliseconds across daylight saving transitions, misclassifying records near midnight. Identify the bug and fix.

{
  "metrics": {
    "repro": {
      "checks": [
        {
          "contains": [
            "24 hours"
          ]
        },
        {
          "contains": [
            "daylight saving"
          ]
        },
        {
          "contains": [
            "midnight"
          ]
        },
        {
          "contains": [
            "bucket"
          ]
        }
      ]
    },
    "hidden": {
      "checks": [
        {
          "contains": [
            "calendar day"
          ]
        },
        {
          "contains": [
            "UTC"
          ]
        },
        {
          "contains": [
            "timezone aware"
          ]
        }
      ]
    },
    "diagnose": {
      "checks": [
        {
          "contains": [
            "DST"
          ]
        },
        {
          "contains": [
            "daily bucket"
          ]
        },
        {
          "contains": [
            "milliseconds"
          ]
        }
      ]
    }
  }
}