scaffold

crates/theme/src/lib.rs

@@ -0,0 +1,68 @@
+//! The theme engine: reads the running system theme and resolves it into the
+//! semantic tokens every component paints from.
+//!
+//! Phase B replaces the bundled light/dark presets with platform adapters
+//! (`NSColor` / `UISettings` / portal / Omarchy) behind a `ThemeSource` seam.
+
+mod colors;
+
+pub use colors::ColorTokens;
+
+use gpui::{App, Global, WindowAppearance};
+
+/// Light or dark, resolved from the system appearance.
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+pub enum ThemeVariant {
+    #[default]
+    Light,
+    Dark,
+}
+
+impl ThemeVariant {
+    fn from_appearance(appearance: WindowAppearance) -> Self {
+        match appearance {
+            WindowAppearance::Light | WindowAppearance::VibrantLight => Self::Light,
+            WindowAppearance::Dark | WindowAppearance::VibrantDark => Self::Dark,
+        }
+    }
+}
+
+/// The resolved theme, installed as the app-wide global.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Theme {
+    pub variant: ThemeVariant,
+    pub colors: ColorTokens,
+}
+
+impl Global for Theme {}
+
+impl Theme {
+    /// Reads the theme global. Panics before `init`.
+    pub fn global(cx: &App) -> &Self {
+        cx.global::<Self>()
+    }
+
+    pub fn for_variant(variant: ThemeVariant) -> Self {
+        Self {
+            variant,
+            colors: match variant {
+                ThemeVariant::Light => ColorTokens::light(),
+                ThemeVariant::Dark => ColorTokens::dark(),
+            },
+        }
+    }
+
+    /// Installs the theme global for the current system appearance.
+    pub fn init(cx: &mut App) {
+        let variant = ThemeVariant::from_appearance(cx.window_appearance());
+        cx.set_global(Self::for_variant(variant));
+    }
+
+    /// Re-installs the global when a window's appearance differs from it.
+    pub fn sync_from_window(window: &gpui::Window, cx: &mut App) {
+        let variant = ThemeVariant::from_appearance(window.appearance());
+        if cx.global::<Self>().variant != variant {
+            cx.set_global(Self::for_variant(variant));
+        }
+    }
+}