feat: Linear 风格 UI 主题（近黑/纯白扁平调色板、靛蓝主色、14px 密度与 6px 圆角）

gpui-app/src/ui/app.rs

@@ -11,7 +11,7 @@ use gpui_kit::component::menu::{DropdownMenu as _, PopupMenuItem};
 use gpui_kit::component::tab::{Tab, TabBar};
 use gpui_kit::component::{
     h_flex, notification::Notification, v_flex, ActiveTheme as _, Selectable as _, Sizable as _,
-    StyledExt as _, Theme, ThemeMode, TitleBar, WindowExt as _,
+    StyledExt as _, Theme, ThemeMode, ThemeRegistry, TitleBar, WindowExt as _,
 };
 use gpui_kit::prelude::FluentBuilder as _;
 use gpui_kit::{
@@ -816,7 +816,14 @@ impl MqttXApp {
 /// 应用主题偏好。
 ///
 /// 「跟随系统」读取 gpui 的窗口外观（`App::window_appearance`）；系统深浅色变化由
+/// Linear 风格主题（内嵌 JSON，模式与 gpui-component 默认主题同构）。
+const LINEAR_THEME: &str = include_str!("linear-theme.json");
+
 /// `MqttXApp::new` 里注册的 `Window::observe_window_appearance` 监听并重应用本函数。
+///
+/// 流程：先 `change` 确保 Theme 全局已建立（注册表 observer 依赖它）→ 注册
+/// Linear Light/Dark（重名跳过，幂等）→ 把当前明暗对指向 Linear → 再 `change`
+/// 应用其颜色/字号/圆角。
 pub fn apply_theme(pref: ThemeModePref, cx: &mut App) {
     let mode = match pref {
         ThemeModePref::Light => ThemeMode::Light,
@@ -824,6 +831,22 @@ pub fn apply_theme(pref: ThemeModePref, cx: &mut App) {
         ThemeModePref::System => ThemeMode::from(cx.window_appearance()),
     };
     Theme::change(mode, None, cx);
+    if let Err(e) = ThemeRegistry::global_mut(cx).load_themes_from_str(LINEAR_THEME) {
+        eprintln!("加载 Linear 主题失败，回退默认主题: {e}");
+    }
+    {
+        let reg = ThemeRegistry::global(cx);
+        let light = reg.themes().get("Linear Light").cloned();
+        let dark = reg.themes().get("Linear Dark").cloned();
+        let theme = Theme::global_mut(cx);
+        if let Some(l) = light {
+            theme.light_theme = l;
+        }
+        if let Some(d) = dark {
+            theme.dark_theme = d;
+        }
+    }
+    Theme::change(mode, None, cx);
 }
 
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