Honor macOS title bar double-click setting

docs/shell-design.md

@@ -62,10 +62,14 @@ lights have a reserved 104px left area before the community switcher only in the
 macOS desktop runtime. This inset does not move the centered tabs. Web gets no
 inset or imitation window controls. Other
 platforms retain their native decorations. Drag regions are limited to the
-header background; controls remain clickable. The main-window capability grants
-only titlebar dragging and the internal native maximize action used by Tauri's drag
-handler, plus scoped HTTP(S) opening for [external links](channels.md#run-the-integration).
-See [Tauri window customization](https://v2.tauri.app/learn/window-customization/).
+header background; controls remain clickable. On macOS, double-clicking that
+background follows the current system title-bar preference (Fill/Zoom, Minimize,
+or no action); changing the preference does not require restarting Buzz. Other
+platforms retain Tauri's native drag-region behavior. The main-window capability
+grants only titlebar dragging and the internal maximize action used by that
+handler, plus scoped HTTP(S) opening for
+[external links](channels.md#run-the-integration). See
+[Tauri window customization](https://v2.tauri.app/learn/window-customization/).
 
 The top-right group contains enabled plugin launchers (Bestie supplies the snake),
 a page finder, and the local avatar. `ProfileButton.tsx` subscribes to the community
@@ -103,7 +107,8 @@ behind, never over, opaque cards; it makes no relay request at runtime.
 Run `just iterate` for UI changes and `just scan` for the broader review checks.
 Check Home, Messages, and Settings; toggle a bundled plugin off/on and confirm its
 navigation entry follows; inspect a narrow viewport. On macOS, verify titlebar
-alignment, dragging, double-click zoom, and Settings access in a built app.
+alignment, dragging, each macOS title-bar double-click preference, and Settings
+access in a built app.
 
 ## Messages
 

src-tauri/Cargo.toml

@@ -27,6 +27,7 @@ libc = "0.2"
 
 [target.'cfg(target_os = "macos")'.dependencies]
 mac-notification-sys = "=0.6.15"
+objc2-foundation = { version = "0.3", default-features = false, features = ["NSString", "NSUserDefaults"] }
 
 [target.'cfg(target_os = "windows")'.dependencies]
 tauri-winrt-notification = "=0.7.3"

src-tauri/src/lib.rs

@@ -17,6 +17,52 @@ use tauri_plugin_dialog::DialogExt;
 #[derive(Clone, Default)]
 struct Imports(Arc<Mutex<Option<PreparedImport>>>);
 
+#[derive(Debug, PartialEq, Eq)]
+enum TitleBarDoubleClickAction {
+    Maximize,
+    Minimize,
+    None,
+}
+
+fn title_bar_double_click_action(preference: Option<&str>) -> TitleBarDoubleClickAction {
+    match preference {
+        Some("Maximize" | "Zoom" | "Fill") => TitleBarDoubleClickAction::Maximize,
+        Some("Minimize") => TitleBarDoubleClickAction::Minimize,
+        _ => TitleBarDoubleClickAction::None,
+    }
+}
+
+#[tauri::command]
+fn title_bar_double_click(window: tauri::Window) -> Result<(), String> {
+    #[cfg(target_os = "macos")]
+    {
+        use objc2_foundation::{ns_string, NSUserDefaults};
+
+        let preference = NSUserDefaults::standardUserDefaults()
+            .stringForKey(ns_string!("AppleActionOnDoubleClick"))
+            .map(|value| value.to_string());
+        match title_bar_double_click_action(preference.as_deref()) {
+            TitleBarDoubleClickAction::Maximize => {
+                if window.is_maximized().map_err(|error| error.to_string())? {
+                    window.unmaximize()
+                } else {
+                    window.maximize()
+                }
+                .map_err(|error| error.to_string())?;
+            }
+            TitleBarDoubleClickAction::Minimize => {
+                window.minimize().map_err(|error| error.to_string())?;
+            }
+            TitleBarDoubleClickAction::None => {}
+        }
+    }
+
+    #[cfg(not(target_os = "macos"))]
+    let _ = window;
+
+    Ok(())
+}
+
 async fn prepare_import(
     imports: Imports,
     operation: impl FnOnce() -> Result<Option<PreparedImport>, String> + Send + 'static,
@@ -163,6 +209,7 @@ pub fn run() {
         .manage(Notifications::default())
         .manage(PluginManager(Manager::from_env()))
         .invoke_handler(tauri::generate_handler![
+            title_bar_double_click,
             notification_show,
             terminal_create_owner,
             terminal_spawn,
@@ -190,3 +237,32 @@ pub fn run() {
             }
         });
 }
+
+#[cfg(test)]
+mod tests {
+    use super::{title_bar_double_click_action, TitleBarDoubleClickAction};
+
+    #[test]
+    fn title_bar_double_click_preferences_map_to_native_actions() {
+        assert_eq!(
+            title_bar_double_click_action(Some("Maximize")),
+            TitleBarDoubleClickAction::Maximize
+        );
+        assert_eq!(
+            title_bar_double_click_action(Some("Fill")),
+            TitleBarDoubleClickAction::Maximize
+        );
+        assert_eq!(
+            title_bar_double_click_action(Some("Minimize")),
+            TitleBarDoubleClickAction::Minimize
+        );
+        assert_eq!(
+            title_bar_double_click_action(Some("None")),
+            TitleBarDoubleClickAction::None
+        );
+        assert_eq!(
+            title_bar_double_click_action(None),
+            TitleBarDoubleClickAction::None
+        );
+    }
+}

src/app/shell/AppShell.tsx

@@ -8,8 +8,10 @@ import { ProfileButton } from "./ProfileButton";
 import { PageSearch } from "./PageSearch";
 import { orderPages, pagePresentation } from "./presentation";
 import { PanelFrame } from "../../features/panels/PanelFrame";
+import { macTitleBarDragHandlers } from "./title-bar";
 
 const macDesktop = isTauri() && /Mac/i.test(navigator.platform);
+const titleBarDragProps = macDesktop ? macTitleBarDragHandlers : {};
 
 export function AppShell({
   pages,
@@ -54,10 +56,15 @@ export function AppShell({
         Skip to content
       </a>
       <header
-        data-tauri-drag-region
+        data-tauri-drag-region={macDesktop ? undefined : true}
+        {...titleBarDragProps}
         className={`shell-header ${macDesktop ? "shell-header-mac" : ""}`}
       >
-        <div className="shell-communities" data-tauri-drag-region>
+        <div
+          className="shell-communities"
+          data-tauri-drag-region={macDesktop ? undefined : true}
+          {...titleBarDragProps}
+        >
           {navigationControls}
           <CommunitySwitcher
             communities={communities}
@@ -90,7 +97,11 @@ export function AppShell({
             );
           })}
         </nav>
-        <div className="shell-actions" data-tauri-drag-region>
+        <div
+          className="shell-actions"
+          data-tauri-drag-region={macDesktop ? undefined : true}
+          {...titleBarDragProps}
+        >
           {launchers}
           <PageSearch pages={pages} onSelect={onSelect} />
           <ProfileButton

src/app/shell/title-bar.test.ts

@@ -0,0 +1,76 @@
+import { describe, expect, it, vi } from "vitest";
+import { createTitleBarDragHandlers } from "./title-bar";
+
+function mouseEvent(
+  detail: number,
+  overrides: Partial<{
+    button: number;
+    clientX: number;
+    clientY: number;
+    sameTarget: boolean;
+  }> = {},
+) {
+  const currentTarget = {};
+  return {
+    button: overrides.button ?? 0,
+    clientX: overrides.clientX ?? 40,
+    clientY: overrides.clientY ?? 12,
+    currentTarget,
+    detail,
+    preventDefault: vi.fn(),
+    target: overrides.sameTarget === false ? {} : currentTarget,
+  } as unknown as Parameters<
+    ReturnType<typeof createTitleBarDragHandlers>["onMouseDown"]
+  >[0];
+}
+
+describe("macOS title bar dragging", () => {
+  it("starts dragging on a primary single click of the region itself", () => {
+    const actions = { startDragging: vi.fn(), doubleClick: vi.fn() };
+    const handlers = createTitleBarDragHandlers(actions);
+    const event = mouseEvent(1);
+
+    handlers.onMouseDown(event);
+
+    expect(event.preventDefault).toHaveBeenCalledOnce();
+    expect(actions.startDragging).toHaveBeenCalledOnce();
+    expect(actions.doubleClick).not.toHaveBeenCalled();
+  });
+
+  it("runs the native preference action after an unmoved double click", () => {
+    const actions = { startDragging: vi.fn(), doubleClick: vi.fn() };
+    const handlers = createTitleBarDragHandlers(actions);
+    const down = mouseEvent(2);
+    const up = mouseEvent(2);
+
+    handlers.onMouseDown(down);
+    handlers.onMouseUp(up);
+
+    expect(up.preventDefault).toHaveBeenCalledOnce();
+    expect(actions.doubleClick).toHaveBeenCalledOnce();
+    expect(actions.startDragging).not.toHaveBeenCalled();
+  });
+
+  it("cancels the double-click action after movement", () => {
+    const actions = { startDragging: vi.fn(), doubleClick: vi.fn() };
+    const handlers = createTitleBarDragHandlers(actions);
+
+    handlers.onMouseDown(mouseEvent(2));
+    handlers.onMouseUp(mouseEvent(2, { clientX: 41 }));
+
+    expect(actions.doubleClick).not.toHaveBeenCalled();
+  });
+
+  it("ignores interactive descendants and non-primary clicks", () => {
+    const actions = { startDragging: vi.fn(), doubleClick: vi.fn() };
+    const handlers = createTitleBarDragHandlers(actions);
+
+    handlers.onMouseDown(mouseEvent(1, { sameTarget: false }));
+    handlers.onMouseDown(mouseEvent(1, { button: 1 }));
+    handlers.onMouseDown(mouseEvent(2, { sameTarget: false }));
+    handlers.onMouseUp(mouseEvent(2, { sameTarget: false }));
+
+    expect(actions.startDragging).not.toHaveBeenCalled();
+    expect(actions.doubleClick).not.toHaveBeenCalled();
+  });
+});

src/app/shell/title-bar.ts

@@ -0,0 +1,64 @@
+import type { MouseEventHandler } from "react";
+import { invoke } from "@tauri-apps/api/core";
+import { getCurrentWindow } from "@tauri-apps/api/window";
+
+type TitleBarActions = Readonly<{
+  startDragging: () => void;
+  doubleClick: () => void;
+}>;
+
+export type TitleBarDragHandlers = Readonly<{
+  onMouseDown: MouseEventHandler<HTMLElement>;
+  onMouseUp: MouseEventHandler<HTMLElement>;
+}>;
+
+export function createTitleBarDragHandlers(
+  actions: TitleBarActions,
+): TitleBarDragHandlers {
+  let doubleClickStart: Readonly<{ x: number; y: number }> | undefined;
+
+  return {
+    onMouseDown(event) {
+      if (
+        event.button !== 0 ||
+        event.target !== event.currentTarget ||
+        (event.detail !== 1 && event.detail !== 2)
+      ) {
+        return;
+      }
+
+      if (event.detail === 2) {
+        doubleClickStart = { x: event.clientX, y: event.clientY };
+        return;
+      }
+
+      event.preventDefault();
+      actions.startDragging();
+    },
+    onMouseUp(event) {
+      const start = doubleClickStart;
+      doubleClickStart = undefined;
+      if (
+        event.button !== 0 ||
+        event.detail !== 2 ||
+        event.target !== event.currentTarget ||
+        start?.x !== event.clientX ||
+        start.y !== event.clientY
+      ) {
+        return;
+      }
+
+      event.preventDefault();
+      actions.doubleClick();
+    },
+  };
+}
+
+export const macTitleBarDragHandlers = createTitleBarDragHandlers({
+  startDragging: () => {
+    void getCurrentWindow().startDragging();
+  },
+  doubleClick: () => {
+    void invoke("title_bar_double_click");
+  },
+});