Resume screen needs a structural bottom split to preview the conversation tail

Summary

The resume screen needs a bottom split that previews the conversation tail.

This should be structural, not decorative:

• one row per conversation entry
• each row rendered as an ellipsized head [...] tail summary within the available terminal width
• a shortcut to toggle the bottom preview split on/off

Right now the resume experience is too blind. You cannot tell what anything is, which makes the screen much dumber than it needs to be.

Problem

The current resume UI does not provide enough information to identify sessions confidently.

That is a serious UX failure.

When resuming a conversation, users need to see at least the recent tail of the thread in a compact structured form. Without that, the resume screen becomes guesswork.

Requested behavior

Add a toggleable bottom split to the resume screen that previews the currently selected conversation/session.

Requirements:

• the preview occupies a bottom pane / split
• the pane shows the tail of the selected conversation
• rendering is one row per conversation entry
• each row is width-aware and ellipsized as:
• head [...] tail
• rows should fit the current terminal width cleanly
• the split should have a keyboard shortcut to toggle visibility

Why this needs to be structural

This should not be implemented as a blob of wrapped text.

Each conversation entry should stay a distinct object/row so the user can:

• scan role boundaries
• understand turn rhythm
• distinguish one session from another

The whole point is to make the resume screen legible at a glance.

Why this matters

Resume is currently missing critical context.

That makes session selection feel dumb and unsafe. Users should not have to reopen sessions blindly just to remember what they are.

This is not a nice-to-have. It is baseline competence for a resume UI.

Additional notes

• preview should track the currently highlighted resume entry
• the toggle shortcut should be discoverable in the UI
• if space is tight, the split can shrink, but the row structure should remain intact
• future extension: separate styling for user / assistant / tool rows

Invitation

Would be good to discuss:

• the best default toggle key
• how many tail entries to show by default
• whether the split should be resizable later