Schema Status

Return the last-run migration report.

Response shape::

{
  "attempted": bool,
  "applied":   [migration_id, ...],
  "skipped":   [migration_id, ...],
  "failed":    [{"id": ..., "error": ...}, ...],
  "error":     None | str,
  "last_attempt_at": ISO-8601 UTC | None,
  "clickhouse_reachable": bool,
  "pending":   [migration_id, ...]
}

pending is derived on-the-fly from the MIGRATIONS list minus what's recorded in the tracker — this is what an operator wants to see, not just what the last apply attempted.