Every opened file registered its preview pane with dock dir 'right', so
each open split a new zone off the right edge — three file opens made
three ever-narrower columns (#93610). The first preview still opens its
own zone docked beside main; every subsequent preview now anchors to an
existing preview-tile pane with dir 'center', so it stacks as a tab in
the same preview zone. Covers files, artifacts, and the Browser tab
alike (all flow through openPreview/$previewTabs); session tiles are
untouched.
Fixes#93610
Teknium
4d030a37c7