[FEATURE] Add an "auto-daltonized" theme mode (easy change)

Problem Statement

I use the daltonized themes because they are easier on my eyes. I also switch my terminal between light and dark during the day.

The auto theme mode follows that switch, but it only targets light and dark. There is no auto mode for the daltonized pair, so I have to pick one of two bad options:

• Use auto. I lose the daltonized colors.
• Use light-daltonized or dark-daltonized. I run /theme again after every terminal change.

For me this is a comfort problem. For a colorblind user it is worse, and it is an accessibility problem, because the default palette is the one they cannot read.

The daltonized themes exist for accessibility, and today they are the only themes locked out of automatic switching.

Proposed Solution

Add auto-daltonized to the /theme picker. Accept it as a value of the theme setting.

It works the same way as auto and uses the same terminal background detection. On a light terminal it resolves to light-daltonized, and on a dark terminal to dark-daltonized.

Alternative Solutions

I checked whether a custom theme in ~/.claude/themes/ can do this. It cannot. Three things block it in v2.1.261:

1. Custom themes use their own namespace. The stored value is custom:<slug>. A built-in theme uses the bare name. A file named dark.json becomes custom:dark, so it does not replace dark.
2. The palette lookup is a hardcoded switch over the six built-in themes. It does not read user theme files.
3. The auto path resolves to the bare string light or dark, then skips custom overrides. While the setting is auto, the active custom theme is undefined.

I found no setting that changes what auto targets.

Today I run /theme by hand after each terminal change.

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

1. I start work in the morning. My terminal is light.
2. I set the theme to auto-daltonized one time.
3. Claude Code shows light-daltonized.
4. My system switches to dark mode in the evening. My terminal follows it.
5. Claude Code switches to dark-daltonized on its own.
6. I never open /theme again.

Additional Context

I have no knowledge of your source code, but this should be an easy and quick change. The auto mode already does the detection. The new mode needs that same detection pointed at a different pair of themes.

I am happy to open a PR if contributors can get the source.

Related

#50179 asks for the same thing. The stale bot closed it as not planned after 4 months of inactivity, and its closing comment asks people to open a new issue if the request is still relevant. Three other people commented there that they want it. I am filing this as that new issue.