The logic for toggling the theme is duplicated here and in App::toggle_theme. Additionally, there is a naming discrepancy for the palette constant: this file uses UI_THEME_LIGHT (line 522), while crates/tui/src/tui/app.rs uses LIGHT_UI_THEME (line 3706). This inconsistency will likely cause a compilation error. It is better to delegate the toggle logic to the App method to ensure consistency and maintainability.

pub fn theme(app: &mut App) -> CommandResult {
    app.toggle_theme();
    let label = if crate::deepseek_theme::active_theme().variant == crate::deepseek_theme::Variant::Light {
        "light"
    } else {
        "dark"
    };
    CommandResult::message(format!("Theme switched to {label}."))
}

When the --theme CLI flag is provided, app.ui_theme is not updated to match the requested theme. This will result in an inconsistent UI state where some components use the new theme (via the global active_theme()) while others remain in the default theme (via app.ui_theme). Ensure app.ui_theme is updated here as well.

    if let Some(theme_arg) = options.theme.as_ref() {
        let theme = match theme_arg {
            crate::deepseek_theme::ThemeArg::Dark => crate::deepseek_theme::Theme::dark(),
            crate::deepseek_theme::ThemeArg::Light => crate::deepseek_theme::Theme::light(),
        };
        crate::deepseek_theme::set_active_theme(theme);
        app.ui_theme = if theme.variant == crate::deepseek_theme::Variant::Light {
            crate::palette::LIGHT_UI_THEME
        } else {
            crate::palette::UI_THEME
        };
    }

Spawning a new thread for every theme change to persist preferences is inefficient and potentially prone to race conditions if TuiPrefs::load() and save() are called concurrently (e.g., if a user toggles the theme rapidly). Since this is a TUI application, consider using a more robust persistence mechanism, such as a background worker or an async task if the runtime is available.

The KbToggleTheme message ID is added and translated across multiple languages, but it is not used in crates/tui/src/tui/keybindings.rs or elsewhere in the current changes. If a keybinding for toggling the theme was intended, it should be added to the keybindings list; otherwise, this appears to be dead code.