Colors are completely off in tmux

Describe the bug

When having a light theme, Copilot CLI light theme's colors are completely wrong when running in tmux. Outside tmux, everything's fine.

tmux vs regular shell:

The problem isn't just the aesthetics, some text is genuinely unreadable (like bright yellow on light background in the screenshot above).

Affected version

GitHub Copilot CLI 1.0.61

Steps to reproduce the behavior

• Set a light terminal theme
• Set the theme to "light" or "auto" in Copilot CLI
• Spawn the command menu with "/"

Expected behavior

Exactly the same color in and outside tmux.

Additional context

Env:

• WSL2, NixOS
• Terminal emulator: Windows Terminal
• Fish shell

In tmux:

❯ echo TERM=$TERM; tput colors
TERM=tmux-direct
16777216

❯ echo $COLORTERM
truecolor

Relevant tmux config:

# Enable true color support
set-option -as terminal-features ',*:RGB'
set -ga update-environment "COLORTERM"
set -ga update-environment "COLORFGBG"
set-environment -g COLORTERM "truecolor"

Issue #4212 seems related but I'm not sure if it's exactly the same. There is also issue #135 but it hasn't received any attention in months.

按照列出的 WSL2、NixOS、Windows Terminal 和 Fish 设置，使用 Copilot CLI 1.0.61 在 tmux 内外复现浅色主题的颜色不一致问题。首先将 tmux 的环境值和配置与 issue #4212 及 issue #135 进行比较。当在 tmux 内外使用 "/" 打开命令菜单时，浅色或自动主题显示相同的易读颜色，即视为完成。