Copilot CLI colors don't respect terminal theme in Warp

[cadin]

Describe the bug

In Warp terminal (Mac), Copilot CLI changes text colors based on the system light/dark mode setting, regardless of the terminal color theme. This means if you have light mode set at the OS level, but use a dark theme in Warp the text colors assume a light background and are unreadable on the dark background. There does not seem to be a way to force dark mode through the /theme settings.

Affected version

GitHub Copilot CLI 1.0.84-6

Steps to reproduce the behavior

1. Set the Mac OS-level appearance to light mode.
2. Choose a dark theme in the Warp terminal settings.
3. Start Copilot.

Results:
Copilot launches in the correct (dark) theme, then switches to light mode colors. The text is difficult (in some cases impossible) to read.

Expected behavior

Copilot CLI should use a text theme appropriate to the terminal color theme, not the OS color theme.
If the terminal is set to a dark theme, use a dark text color theme regardless of the OS setting.

Additional context

Mac OS 15.7.9
Warp v0.2026.09.09.08.26.stable_02
Warp theme "Fancy Dracula"
GitHub Copilot CLI 1.0.84-6

Workarounds:

• Changing the system-level appearance to dark causes Copilot to switch to the proper colors
• Changing Warp to use a light theme makes the text readable again
• Using the default Mac terminal seems to work as expected.
• Reverting to Copilot v1.0.84-5 works as expected.

[akashsinghal]

I'm seeing this same issue with Windows Terminal

[orcame]

I can reproduce a closely related regression on Windows with Copilot CLI 1.0.84-8. Rolling back to 1.0.84-5 restores normal colors, matching the working version reported here.

Environment and symptoms

• Reproduces in both Windows Terminal and standalone PowerShell.
• Windows application appearance is Light, while the shell uses a readable dark background.
• Launching Copilot changes the background to white, making some light-colored text difficult to read.
• Switching among all available /theme options does not resolve it.
• Changing the terminal color scheme provides only temporary relief; the white background returns during Copilot interaction.

The visual symptom differs slightly from the original report—my background turns white rather than remaining dark with incorrect text colors—but the appearance mismatch and working baseline align.

Verified comparisons

Configuration	Result
1.0.84-8, normal launch	White background / poor contrast
1.0.84-8 with --no-color	Same problem
1.0.84-8 with TERM=dumb and --no-color	White-background issue disappears
copilot --prefer-version 1.0.84-5 --no-auto-update	Normal colors restored, without either workaround

Diagnostic evidence

Startup logs repeatedly show:

[DEBUG] queryTerminalColors: failed to assemble colors (bg=failed, fg=failed)
[DEBUG] OS theme changed to light

Local update logs confirm an upgrade from 1.0.84-5 to 1.0.84-8 on September 15, 2026, shortly before the problem was observed.

These results suggest investigating the failed terminal-color query and subsequent OS-appearance fallback, including why --no-color alone does not prevent the background change. The exact root cause and whether both platforms share it remain unconfirmed.

[copilot-cli-bot]

This appears to be resolved as of GitHub Copilot CLI v1.0.88. Please update to that release or a newer stable version. We're closing this as completed. If it still happens, please comment with your version and reproduction steps.