# MetricAggregation

One aggregation declaration inside an anomaly rule.

**Type**: `object`

## Properties

- name: aggregations (optional)
  type: array of `AggregationDecl`
  description: Aggregations to emit. Null = dimension view.

- name: filters (optional)
  type: `FilterPrimitive`

- name: groupBy (required)
  type: array of string
  description: Group-by tokens: 'object', 'cohort', 'series', or a level-prefixed attribute path. Empty list = global aggregation.

- name: source (optional)
  type: string
  description: Exact metric name or nested-aggregation alias. Mutually exclusive with filters.metricName. Null for dimension views (when filters is also unset).

- name: window (optional)
  type: string
  description: Aggregation window. Defaults to timeGranularity.duration.