The TUI's preview attached without checking status, so after a host reboot —
every session dormant — moving the sidebar highlight tried a live attach on
each one in turn; the daemon has no bridge to answer, so it 404/409s.
Gate every attach (preview, committed AttachHighlighted, and the reconciling
poll after a resume completes) on status == Running, and show a metadata +
resume placeholder in the pane instead, per docs/PREVIEW.md.