Upgrade Alt+Up queue navigation into a first-class queued-message selector/editor

Summary

Upgrade the current Alt+Up queued-message mechanic into a first-class queued-message selector/editor.

The ideal interaction:

• Alt+Up / Alt+Down navigates queued messages
• releasing Alt enters edit mode on the currently selected queued message
• Alt+Down past the newest queued message returns selection to the composer

This should make queued messages feel like a real editable stack instead of a hidden one-off mechanic.

Problem

Queued messages are useful, but the interaction surface feels underpowered.

Right now the queue exists more like a narrow convenience than a manipulable object. If users are stacking follow-up prompts while a turn is running, they should be able to:

• move through queued messages quickly
• edit them directly
• return to the composer naturally
• eventually reorder them

That feels like the obvious terminal-native shape.

Requested behavior

Selector behavior

• Alt+Up selects older queued messages
• Alt+Down selects newer queued messages
• going past the newest queued message with Alt+Down returns focus/selection to the live composer
• the selected queued message is visibly highlighted

Edit behavior

• while Alt is held, user can move through the queue
• on releasing Alt, Codex opens the selected queued message for editing

That gives the queue a direct “peek, choose, drop into edit” flow.

Future extension: reordering

Once queued messages are true selectable objects, reordering feels natural too.

For example:

• Alt+Shift+Up / Alt+Shift+Down to reorder queued messages

Terminal limitation / fallback

I do not know whether all supported terminals expose Alt as a reliable modifier with distinct key-down / key-release behavior.

If reliable release semantics are not possible, the fallback should still preserve the same idea:

• one shortcut enters a queue selection modal
• Up / Down navigates queued messages
• a second key edits the selected queued message
• Esc or equivalent returns to the composer

That would be less elegant than release-to-edit, but still much better than leaving the queue as a weakly operable feature.

Why this matters

Queued prompts should feel like a real stack/workbench, not a hidden buffer.

This would make Codex better at:

• iterative follow-up planning
• stacking multiple unrelated follow-ons while a turn is still running
• refining queued prompts before they fire

It is also a natural sibling to broader terminal/editor expectations around selectable objects, modal navigation, and first-class keyboard control.

Related issues

• queueing follow-up messages after a turn ends: #11212
• configurable hotkeys: #3049

Invitation

Would be good to discuss:

• whether Alt release semantics are practical across supported terminals
• whether the fallback should be modal or inline
• good default reordering bindings
• whether queued messages should eventually support multi-select / batch actions too