TUI backtrack: can't navigate forward after overshooting

What version of Codex is running?

Built from source at openai/codex@6a57d7980 (codex-rs TUI)

What subscription do you have?

N/A

Which model were you using?

N/A

What platform is your computer?

Linux 5.15.167.4-microsoft-standard-WSL2 x86_64 x86_64

What issue are you seeing?

In the TUI, the "edit previous message" backtrack flow (press Esc, then Esc again to step through older user messages) only allows moving backward.

If you overshoot the message you wanted to edit, there is no way to move forward to a more recent user message; the only workaround is to exit the flow and start over. This makes editing previous prompts error-prone when you have many turns.

What steps can reproduce the bug?

1. Start a TUI session with multiple user messages.
2. Press Esc twice to enter the backtrack preview and select an older user message.
3. Keep pressing Esc to move further back.
4. Try to move forward to the next/newer user message.

What is the expected behavior?

While the backtrack preview is active, provide a key to move to the next/newer user message (e.g. Right arrow), in addition to Esc/Left moving backwards.