# A Treatment Case snapshots its areas

The areas a service covers are derived from the catalog category graph, which the clinic manager can
edit at any time. Because a session's area records are a medical record, a Treatment Case copies its
area list at creation and never re-derives it; editing the category graph afterwards affects only
cases opened from then on.

## Consequences

An in-flight case will not pick up a category change. If a clinic genuinely needs that, it has to be
an explicit re-sync action, not a silent side effect of editing settings.
