Refactor-Loop-Imperative-Reduce

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 refactor, rationale, tests. Refactor a for-loop that iterates over an array of numbers and accumulates a running sum into a single Array.prototype.reduce call. Preserve the exact numeric result for all inputs including an empty array.

{
  "metrics": {
    "visible": {
      "checks": [
        {
          "contains": [
            "reduce"
          ]
        },
        {
          "contains": [
            "accumulator"
          ]
        },
        {
          "contains": [
            "for loop"
          ]
        }
      ]
    },
    "hidden": {
      "checks": [
        {
          "contains": [
            "empty array"
          ]
        },
        {
          "contains": [
            "initial value"
          ]
        },
        {
          "contains": [
            "same result"
          ]
        }
      ]
    },
    "intent": {
      "checks": [
        {
          "contains": [
            "readability"
          ]
        },
        {
          "contains": [
            "declarative"
          ]
        },
        {
          "contains": [
            "eliminate mutation"
          ]
        }
      ]
    }
  }
}