# HARN-RMD-008
**Variant:** `Code::ReminderUnsupportedHookEvent`
A hook handler returned a reminder effect from a lifecycle event that cannot
inject reminders. Worker lifecycle events are observational and must not mutate
the active transcript with reminder effects.
Move the reminder to a session, tool, step, or persona hook that runs at a
turn-boundary mutation point.
Example fix:
```harn
register_session_hook("post_turn", { _event ->
return {reminder: {body: "Review worker progress before continuing."}}
})
```