Debug-Concurrent-Map-Delete-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 cleanup routine deletes entries from a Map while another async iterator over the same Map expects every entry to exist. Identify the concurrent mutation and fix.

{
  "metrics": {
    "repro": {
      "checks": [
        {
          "contains": [
            "delete"
          ]
        },
        {
          "contains": [
            "Map"
          ]
        },
        {
          "contains": [
            "async iterator"
          ]
        },
        {
          "contains": [
            "entry"
          ]
        }
      ]
    },
    "hidden": {
      "checks": [
        {
          "contains": [
            "snapshot entries"
          ]
        },
        {
          "contains": [
            "lock"
          ]
        },
        {
          "contains": [
            "two phase cleanup"
          ]
        }
      ]
    },
    "diagnose": {
      "checks": [
        {
          "contains": [
            "concurrent"
          ]
        },
        {
          "contains": [
            "mutation"
          ]
        },
        {
          "contains": [
            "cleanup"
          ]
        }
      ]
    }
  }
}