Finding a sleeve without its record creates an odd catalogue problem: you own part of the release, but cannot play it. A clear entry keeps that distinction visible.
Describe the pieces actually present
List the outer sleeve, inner sleeve, booklet and disc separately where necessary. Avoid marking the album simply owned if that label makes you expect a playable copy. A status such as sleeve only is more useful than a private abbreviation you may later forget.
Photograph identifying details and note where the sleeve is stored. If a matching disc appears later, compare its release information before assuming the two pieces belong together.
Keep a future match provisional
A second-hand disc placed inside an empty sleeve becomes your assembled copy; it does not prove that the pieces originally travelled together. Preserve that distinction if the history matters to your collection.
You can still enjoy the artwork or use the sleeve as a reminder to hear the recording elsewhere. A partial object need not become an urgent shopping task. The catalogue’s job is to tell you what is on the shelf and what you know about it, including the empty space.