event sequence integrity audit derived

{
  "input": {
    "body": {
      "events": [
        {
          "type": "order.created",
          "total": 42.5,
          "offset": 101,
          "stream": "orders-0",
          "event_id": "evt-1",
          "order_id": "o-1",
          "schema_version": "2"
        },
        {
          "type": "order.created",
          "total": 19.99,
          "offset": 102,
          "stream": "orders-0",
          "event_id": "evt-2",
          "order_id": "o-2",
          "schema_version": "2"
        },
        {
          "type": "order.created",
          "total": 7,
          "offset": 104,
          "stream": "orders-0",
          "event_id": "evt-4",
          "order_id": "o-4",
          "schema_version": "2"
        },
        {
          "type": "order.created",
          "total": 7.5,
          "offset": 105,
          "stream": "orders-0",
          "event_id": "evt-4",
          "order_id": "o-4",
          "schema_version": "2"
        },
        {
          "type": "order.created",
          "total": "12.00",
          "offset": 106,
          "stream": "orders-0",
          "event_id": "evt-5",
          "order_id": "o-5",
          "schema_version": "1"
        },
        {
          "type": "order.cancelled",
          "offset": 1,
          "reason": "customer",
          "stream": "orders-1",
          "event_id": "evt-6",
          "order_id": "o-1",
          "schema_version": "2"
        },
        {
          "type": "order.cancelled",
          "offset": 2,
          "reason": "fraud",
          "stream": "orders-1",
          "order_id": "o-2",
          "schema_version": "2"
        }
      ],
      "sequence_field": "offset",
      "partition_field": "stream"
    },
    "type": "http",
    "method": "POST",
    "bodyType": "json"
  },
  "output": {
    "type": "json",
    "example": {
      "intact": false,
      "limits": {
        "maxEvents": 2000,
        "maxSchemas": 100,
        "maxFindings": 500,
        "maxAttributes": 500,
        "maxPartitions": 500,
        "cardinalityWarning": 100
      },
      "passed": false,
      "complete": true,
      "findings": [
        {
          "code": "SEQUENCE_GAP",
          "event": 2,
          "detail": "Partition orders-0: 102 is followed by 104, so 1 value(s) are missing.",
          "missing": 1,
          "partition": "orders-0"
        }
      ],
      "gap_count": 1,
      "partitions": [
        {
          "last": 106,
          "first": 101,
          "events": 5,
          "partition": "orders-0"
        },
        {
          "last": 2,
          "first": 1,
          "events": 2,
          "partition": "orders-1"
        }
      ],
      "request_id": "example-request",
      "service_id": "event_sequence_integrity_audit",
      "assumptions": [
        "A sequence is only meaningful inside the stream that produced it, so without a partition field the whole batch is treated as one stream. Auditing a merged multi-partition batch as one sequence would r...",
        "Contiguity is only checked between integral sequence values; a non-integral sequence is reported as unchecked rather than guessed at.",
        "Ordering is judged on the order events appear in the batch, and gaps on their values. They are different questions and are reported separately."
      ],
      "limitations": [
        "Sequence integrity only. Whether the events themselves are valid is event_batch_contract_audit.",
        "intact is true only when every event was placed and no gap, duplicate or ordering violation was found."
      ],
      "observed_at": "2026-10-02T00:00:00.000Z",
      "not_examined": [],
      "finding_count": 1,
      "duplicate_count": 0,
      "partition_count": 2,
      "service_version": "1.0.0",
      "findings_by_code": {
        "SEQUENCE_GAP": 1
      },
      "out_of_order_count": 0,
      "examined_event_count": 7,
      "supplied_event_count": 7,
      "unsequenced_event_count": 0
    }
  }
}