dead letter batch audit derived

{
  "input": {
    "body": {
      "entries": [
        {
          "error": "UPSTREAM_TIMEOUT",
          "failed_at": "2026-10-01T00:00:00Z",
          "message_id": "m-1"
        },
        {
          "error": "UPSTREAM_TIMEOUT",
          "failed_at": "2026-10-01T00:00:05Z",
          "message_id": "m-2"
        },
        {
          "error": "UPSTREAM_TIMEOUT",
          "failed_at": "2026-10-01T00:00:09Z",
          "message_id": "m-3"
        },
        {
          "error": "UPSTREAM_TIMEOUT",
          "failed_at": "2026-10-01T00:05:00Z",
          "message_id": "m-1"
        },
        {
          "error": {
            "code": "SCHEMA_REJECTED",
            "detail": "total was a string"
          },
          "message_id": "m-4"
        },
        {
          "message_id": "m-5"
        }
      ],
      "id_field": "message_id",
      "reason_field": "error",
      "retryable_reasons": [
        "UPSTREAM_TIMEOUT",
        "RATE_LIMITED"
      ]
    },
    "type": "http",
    "method": "POST",
    "bodyType": "json"
  },
  "output": {
    "type": "json",
    "example": {
      "limits": {
        "maxEvents": 2000,
        "maxSchemas": 100,
        "maxFindings": 500,
        "maxAttributes": 500,
        "maxPartitions": 500,
        "cardinalityWarning": 100
      },
      "passed": false,
      "reasons": [
        {
          "reason": "UPSTREAM_TIMEOUT",
          "entries": 4,
          "example_ids": [
            "m-1",
            "m-2",
            "m-3"
          ],
          "first_entry": 0
        },
        {
          "reason": "(unstated)",
          "entries": 1,
          "example_ids": [
            "m-5"
          ],
          "first_entry": 5
        },
        {
          "reason": "SCHEMA_REJECTED",
          "entries": 1,
          "example_ids": [
            "m-4"
          ],
          "first_entry": 4
        }
      ],
      "triaged": false,
      "complete": true,
      "findings": [
        {
          "code": "REASON_MISSING",
          "entry": 5,
          "detail": "Entry 5 states no error, so it cannot be triaged."
        },
        {
          "code": "DOMINANT_FAILURE_CAUSE",
          "detail": "4 of 6 entries share the reason UPSTREAM_TIMEOUT, so this queue is mostly one problem rather than many.",
          "reason": "UPSTREAM_TIMEOUT",
          "entries": 4
        },
        {
          "id": "m-1",
          "code": "REPEATED_ENTRY",
          "detail": "message_id m-1 appears 2 times in the queue, so the same item failed more than once.",
          "occurrences": 2
        }
      ],
      "request_id": "example-request",
      "service_id": "dead_letter_batch_audit",
      "assumptions": [
        "A reason is read from a string, or from a code property when it is an object, because both shapes are common in a dead letter payload.",
        "Retryability is decided by substring against the list supplied. Without a list, entries are grouped and counted but not classified.",
        "A queue where one reason accounts for half the entries is one problem rather than many, which changes what to do about it."
      ],
      "limitations": [
        "Triage of the entries supplied. Nothing is replayed, requeued or deleted.",
        "triaged is true only when every entry was readable, stated a reason, and nothing permanent or repeated was found."
      ],
      "observed_at": "2026-10-02T00:00:00.000Z",
      "not_examined": [],
      "finding_count": 5,
      "dominant_share": 0.666667,
      "dominant_reason": "UPSTREAM_TIMEOUT",
      "service_version": "1.0.0",
      "findings_by_code": {
        "REASON_MISSING": 1,
        "REPEATED_ENTRY": 1,
        "PERMANENT_FAILURE": 2,
        "DOMINANT_FAILURE_CAUSE": 1
      },
      "entries_without_id": 0,
      "examined_entry_count": 6,
      "supplied_entry_count": 6,
      "distinct_reason_count": 3,
      "permanent_entry_count": 2,
      "retryable_entry_count": 4,
      "entries_without_reason": 1
    }
  }
}