agent_ui: Fix ACP toggle thinking with keybinds and Zed agent thinking traversal

[David3u]

Self-Review Checklist:

• I've reviewed my own diff for quality, security, and reliability
• Unsafe blocks (if any) have justifying comments
• The content is consistent with the UI/UX checklist
• Tests cover the new/changed behavior
• Performance impact has been considered and is acceptable

Closes #56074

Release Notes:

• Added ability to use cycle thinking mode and open thinking menu keybinds for ACP agents (at least for Codex)
• Fixed the bug where opening the Zed agent's thinking effort panel did not set the current thinking level as active. The new change allows using up and down arrows without having to press the arrows once to select the current mode.

Before: pressing up arrow once does nothing, and the second up arrow changes the thinking mode.
After: pressing up arrow once actually changes

Screen.Recording.2026-05-15.at.5.27.42.PM.mov

Screen.Recording.2026-05-15.at.5.29.14.PM.mov

[ask4fusora]

Hi, I think you attached the same video twice.
Can you attach a video regarding codex?

[David3u]

Hi. In the first video, I press the up arrow key twice to change the active thinking effort. I'm the bottom one, I only press it once. For the codex change, I think it doesn't need a video, the key bind just opens the menu like it's supposed to. Let me know what you think

[ask4fusora]

Firstly, thank you, grateful for your contribution.

About the duplicated video problem, my bad, I didn't pay enough attention.

About the codex problem, if you sure it works, I don't have any complain.

Again, thank you.

[bennetbo]

Hey, thanks for working on this. This branch has conflicts as we recently changed how we handle defaults. Also some of the changes on this branch did not make sense to me. So I opened a new PR (#58223) that handles the thinking effort selector keybindings, and also adds the shortcuts to the tooltips. If I missed anything please let me know