| JournalInterface | The append-only log a capture writes to and a flush drains. |
| DatabaseJournal | A journal backed by a database table. |
| FlushPolicy | Decides when a window of captured operations should be sealed into a segment. |
| JournalFactory | Chooses the journal backend, and falls back rather than failing. |
| JournalOp | One captured mutation, and the only shape the journal appends. |
| MemoryJournal | A journal held in memory. |
| RedisJournal | A journal backed by a Redis stream. |