• Session-level entries: when a session was added (who created it and when), instructor swaps, reschedules (date/time), room changes, cancellations, hours-returned overrides — the full lifecycle, so a class that was created then cancelled shows both, not just the cancellation.
• Each entry shows what changed in plain English ("Time changed 6:00 PM–7:00 PM → 6:30 PM–7:30 PM"), who made the change, and how long ago — the audit trail you need for contracted-hours calculations.