Customizable Session Background / Context Window Colors

What variant of Codex are you using?

GUI App

What feature would you like to see?

Description

Please add an option to customize the visual appearance of individual Codex sessions or context windows, such as:

Background color
Accent/window color
Optional background image

A good reference for this functionality is Windows Terminal, where different terminal profiles can have distinct colors, themes, or background images.

Ideally, these appearance settings could be configured per project, workspace, or session.

Motivation

This would make it much easier to visually distinguish between different projects when switching between Codex sessions.

When several sessions are open at the same time, their interfaces currently look very similar. It is therefore quite easy to switch to the wrong session and accidentally enter a prompt or reply that was intended for another project.

For example:

Project A could use a blue background.
Project B could use a dark green background.
Project C could use a custom background image or accent color.

The visual difference would provide an immediate indication of which project/session is currently active, without needing to repeatedly check the session title or context.

Benefits
Reduces accidental prompts being sent to the wrong project/session.
Makes switching between multiple active Codex sessions much safer and faster.
Provides an immediate visual indication of the current project context.
Particularly useful for users working across several repositories or projects simultaneously.
Possible Implementation

Similar to Windows Terminal profiles, Codex could allow appearance settings to be associated with a project or session, for example:

Appearance
├── Background color
├── Accent color
├── Background image
├── Background image opacity
└── Use project-specific appearance

Even basic support for assigning a different background or accent color to each project would already make a significant difference.

Additional information

No response

No files, tests, or entry points are identified in the issue. Start by locating the GUI session or workspace appearance code and determine how project or session settings are stored. Done means users can configure distinct background or accent appearance per project or session without confusing which context is active.