{
  "kind": "cohort",
  "synthetic": true,
  "definition": "Use the first observed activity month per text customer ID as the cohort. Count each customer once per calendar month. Retention is 100 *active customers/cohort customers. Fill zero-activity ages only through the selected observation end; omit later ages. Filter qualifying events before import. This is observed activity retention, not subscription MRR retention.",
  "columns": [
    "cohort_month",
    "month_number",
    "cohort_customers",
    "active_customers",
    "retention_pct"
  ],
  "expected_rows": [
    [
      "2026-01",
      0,
      2,
      2,
      100
    ],
    [
      "2026-01",
      1,
      2,
      1,
      50
    ],
    [
      "2026-01",
      2,
      2,
      0,
      0
    ],
    [
      "2026-02",
      0,
      1,
      1,
      100
    ],
    [
      "2026-02",
      1,
      1,
      1,
      100
    ]
  ],
  "options": {
    "throughMonth": "2026-03"
  }
}