Theme turns light over night

Describe the bug

Upon starting copilot at e.g. 8 am. the color theme/tint is dark. Letting the computer go to sleep and reopening the computer the next day at the same time, the color theme/tint is now light. As if it changes between dark and light mode depending on the color scheme of the macOS.

I have attempted to force the terminal application to stay in macOS dark mode, to no avail. Only discovered fix is to exit copilot and reopen it. This resets the color theme/tint back to dark.

Changing the theme to "default" results in the background turning dark again, but code fences stay light gray as does the input field and the tabs at the top. Not all text is visible on the dark background.

Unsure if this actually is a copilot CLI problem or it has to do with the terminal emulator.

Affected version

1.0.79

Steps to reproduce the behavior

1. Start copilot CLI
2. Sleep computer
3. Wait 24 hours (to pass through a day/night cycle)
4. Open computer
5. Observe the copilot CLI is now all light colors

Expected behavior

That the copilot CLI stays the same colors even after sleeping the computer for a longer duration.

Additional context

• Operating system: macOS 26.6.1 (25G76)
• CPU architecture: ARM, Apple M4 Pro
• Terminal emulator: iTerm2, Build 3.6.11
• Shell: zsh

macOS 上で iTerm2 と zsh を使って Copilot CLI を開始し、報告されているスリープして再度開く再現手順に従います。スリープ前と昼夜サイクル後のテーマを比較し、次に CLI のテーマ処理を追跡して、macOS の外観に応じて変化するかどうかを判断します。復帰後も色が一貫していれば完了です。