scaffold

crates/theme/Cargo.toml

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+[package]
+name = "gpui-native-theme"
+version = "0.1.0"
+edition = "2024"
+description = "Native theme engine: reads the OS theme and resolves it into semantic tokens"
+
+[dependencies]
+gpui = { workspace = true }

crates/theme/src/colors.rs

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+//! Semantic color roles. This module is the only place in the workspace
+//! allowed to hold color literals.
+
+use gpui::{Hsla, rgb};
+
+fn hex(hex: u32) -> Hsla {
+    rgb(hex).into()
+}
+
+/// The semantic color roles components paint from.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct ColorTokens {
+    pub background: Hsla,
+    pub foreground: Hsla,
+    pub surface: Hsla,
+    pub surface_foreground: Hsla,
+    pub primary: Hsla,
+    pub primary_foreground: Hsla,
+    pub secondary: Hsla,
+    pub secondary_foreground: Hsla,
+    pub muted: Hsla,
+    pub muted_foreground: Hsla,
+    pub accent: Hsla,
+    pub accent_foreground: Hsla,
+    pub destructive: Hsla,
+    pub destructive_foreground: Hsla,
+    pub border: Hsla,
+    pub input: Hsla,
+    pub ring: Hsla,
+    pub selection: Hsla,
+}
+
+impl ColorTokens {
+    /// Neutral light palette; the fallback when no system theme applies.
+    pub fn light() -> Self {
+        Self {
+            background: hex(0xffffff),
+            foreground: hex(0x18181b),
+            surface: hex(0xfafafa),
+            surface_foreground: hex(0x18181b),
+            primary: hex(0x2563eb),
+            primary_foreground: hex(0xffffff),
+            secondary: hex(0xf4f4f5),
+            secondary_foreground: hex(0x18181b),
+            muted: hex(0xf4f4f5),
+            muted_foreground: hex(0x71717a),
+            accent: hex(0x2563eb),
+            accent_foreground: hex(0xffffff),
+            destructive: hex(0xdc2626),
+            destructive_foreground: hex(0xffffff),
+            border: hex(0xe4e4e7),
+            input: hex(0xe4e4e7),
+            ring: hex(0x93c5fd),
+            selection: hex(0xdbeafe),
+        }
+    }
+
+    /// Neutral dark palette; the fallback when no system theme applies.
+    pub fn dark() -> Self {
+        Self {
+            background: hex(0x09090b),
+            foreground: hex(0xfafafa),
+            surface: hex(0x18181b),
+            surface_foreground: hex(0xfafafa),
+            primary: hex(0x3b82f6),
+            primary_foreground: hex(0xffffff),
+            secondary: hex(0x27272a),
+            secondary_foreground: hex(0xfafafa),
+            muted: hex(0x27272a),
+            muted_foreground: hex(0xa1a1aa),
+            accent: hex(0x3b82f6),
+            accent_foreground: hex(0xffffff),
+            destructive: hex(0xef4444),
+            destructive_foreground: hex(0xffffff),
+            border: hex(0x27272a),
+            input: hex(0x27272a),
+            ring: hex(0x1d4ed8),
+            selection: hex(0x1e3a8a),
+        }
+    }
+}

crates/theme/src/lib.rs

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+//! 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));
+        }
+    }
+}