{
  "schema": "kaldenframe.column-schema.v1",
  "dataset_id": "customer_retention_training_v1",
  "data_values_present": false,
  "columns": [
    {"name": "account_id", "type": "string", "role": "identity", "nullable": false},
    {"name": "snapshot_time", "type": "string", "role": "time", "nullable": false},
    {"name": "support_tickets_30d", "type": "integer", "role": "candidate", "nullable": false},
    {"name": "active_days_30d", "type": "integer", "role": "candidate", "nullable": false},
    {"name": "plan_family", "type": "category", "role": "candidate", "nullable": false},
    {"name": "internal_note", "type": "string", "role": "metadata", "nullable": true},
    {"name": "retained_90d", "type": "boolean", "role": "target", "nullable": false}
  ]
}