Halluc-Api-Array-Flat

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 answer, supported_facts, uncertainty. In JavaScript, what does [1,[2,[3]]].flat() return? State the default depth and the exact result. Avoid claiming flat() does not exist natively.

{
  "metrics": {
    "accuracy": {
      "checks": [
        {
          "contains": [
            "depth"
          ]
        },
        {
          "contains": [
            "[1, 2, [3]]"
          ]
        },
        {
          "contains": [
            "ES2019"
          ]
        }
      ]
    },
    "fabricated": {
      "checks": [
        {
          "contains": [
            "natively available"
          ]
        },
        {
          "contains": [
            "default depth is 1"
          ]
        },
        {
          "contains": [
            "does not recursively flatten"
          ]
        }
      ]
    }
  }
}