Problem

In the Aggregations tab in Compass, each document preview has an expand/collapse caret at the top of the card. When a document is long and you scroll down inside the preview, this caret (and the _id row) scrolls out of view. To collapse the document or jump back to the top, you have to scroll all the way up again, which is annoying when inspecting multiple long documents.

Solution
Make the document header row (containing the expand/collapse caret and _id) sticky within the scrollable document card so it remains visible while scrolling. This ensures the caret is always accessible for collapsing or navigating, without needing to scroll back to the top of the document preview.

Acceptance criteria : Sticky header applies only inside each Aggregations document preview’s own scroll area; caret + _id stay usable while scrolling long previews.

Check: If e2e or shared preview components are touched, run or adjust the smallest relevant test(s)—no broad refactors unless needed for this behavior.