Add keyboard navigation (PageUp/PageDown/j/k) to VS Code Codex chat view

What variant of Codex are you using?

IDE Extension (VSCode)

What feature would you like to see?

I would like to request improved keyboard navigation in the Codex VS Code extension chat view.

When the chat view is clicked and has focus:

• Pressing Page Up should scroll up by one full viewport.
• Pressing Page Down should scroll down by one full viewport.
• Pressing j should scroll so that the nearest previous user message below the current top of the viewport becomes aligned to the top.
• Pressing k should scroll so that the nearest previous user message above the current top of the viewport becomes aligned to the top.

This would enable efficient navigation through long chat histories using only the keyboard.

Expected behavior

When the chat panel is focused:

• PageUp/PageDown perform viewport-based scrolling (similar to editors and text viewers).
• j/k jump between user-authored messages, positioning the selected user message at the top of the viewport.

This behavior is inspired by common keyboard-driven navigation patterns (e.g., vim-style movement and structured navigation between logical blocks).

Why is this important?

Many developers prefer keyboard-centric workflows. Long Codex conversations can become difficult to navigate efficiently with mouse-only scrolling.

Providing consistent keyboard navigation would:

• Improve usability for power users
• Reduce reliance on mouse input
• Make reviewing past prompts and iterations significantly faster
• Improve accessibility

Additional context

Previous issues discussed scrolling limitations (e.g., #2919), but this request specifically focuses on structured keyboard navigation and viewport-aware scrolling behavior.

Thank you for considering this enhancement.

Additional information

_No response_