diff --git a/Sources/UntoldEditor/Editor/Window/EditorMainMenuKeeper.swift b/Sources/UntoldEditor/Editor/Window/EditorMainMenuKeeper.swift
new file mode 100644
index 0000000..d130c62
--- /dev/null
+++ b/Sources/UntoldEditor/Editor/Window/EditorMainMenuKeeper.swift
@@ -0,0 +1,106 @@
+//
+//  EditorMainMenuKeeper.swift
+//  UntoldEditor
+//
+// Copyright (C) Untold Engine Studios
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+//
+
+import AppKit
+import UntoldEngine
+
+/// Keeps the editor's menus in the menu bar. The editor is a SwiftUI `App`,
+/// for the space the Apple Vision Pro preview shows, with its menus built by
+/// its AppKit delegate. SwiftUI installs a menu bar of its own, from its
+/// default commands, and on macOS 26 it does so after the delegate has set
+/// the editor's, and again whenever it updates: the bar then reads Edit,
+/// View, Window and Help, without the editor's File menu and View items.
+///
+/// The keeper does not fight over which `NSMenu` is the main menu: it moves
+/// the editor's menus into whatever menu bar is installed and takes that
+/// bar's own items out, so SwiftUI keeps the object it installed and the
+/// user sees the editor's menus. It looks again whenever the main menu
+/// changes and after every event the application handles. Made and used on
+/// the main thread, where AppKit sets the menu bar.
+final class EditorMainMenuKeeper: @unchecked Sendable {
+    /// The editor's menus, in order: the app menu first.
+    let items: [NSMenuItem]
+    /// The editor's Window menu, which lists the open windows.
+    let windowsMenu: NSMenu?
+    /// How many times the editor's menus were put back; for the tests and the log.
+    private(set) var restorations = 0
+    private let application: NSApplication
+    private var observation: NSKeyValueObservation?
+    private var observers: [NSObjectProtocol] = []
+    private var checkIsScheduled = false
+
+    init(menu: NSMenu, windowsMenu: NSMenu? = nil, application: NSApplication = .shared) {
+        items = menu.items
+        self.windowsMenu = windowsMenu
+        self.application = application
+        install(into: application.mainMenu ?? menu)
+        observation = application.observe(\.mainMenu, options: [.new]) { [weak self] _, _ in
+            self?.scheduleCheck()
+        }
+        let center = NotificationCenter.default
+        for name in [NSApplication.didUpdateNotification, NSApplication.didBecomeActiveNotification, NSWindow.didBecomeKeyNotification] {
+            observers.append(center.addObserver(forName: name, object: nil, queue: nil) { [weak self] _ in
+                self?.checkNow()
+            })
+        }
+    }
+
+    deinit {
+        for observer in observers {
+            NotificationCenter.default.removeObserver(observer)
+        }
+    }
+
+    /// True while the menu bar shows the editor's menus and nothing else.
+    var isInPlace: Bool {
+        guard let bar = application.mainMenu else { return false }
+        return bar.items.count == items.count && zip(bar.items, items).allSatisfy { $0 === $1 }
+    }
+
+    /// Outside the setter that is replacing the menu bar.
+    private func scheduleCheck() {
+        guard checkIsScheduled == false else { return }
+        checkIsScheduled = true
+        DispatchQueue.main.async { [weak self] in
+            self?.checkIsScheduled = false
+            self?.checkNow()
+        }
+    }
+
+    /// Puts the editor's menus back when the menu bar shows something else.
+    func checkNow() {
+        guard isInPlace == false else { return }
+        restorations += 1
+        if restorations == 1 {
+            Logger.log(message: "The menu bar was replaced; the editor's menus are put back.")
+        }
+        install(into: application.mainMenu ?? NSMenu())
+    }
+
+    /// Makes `bar` the menu bar, with the editor's menus and nothing else.
+    private func install(into bar: NSMenu) {
+        // A menu bar of SwiftUI's fills itself in through its delegate.
+        bar.delegate = nil
+        for item in items {
+            item.menu?.removeItem(item)
+        }
+        bar.removeAllItems()
+        for item in items {
+            bar.addItem(item)
+        }
+        if application.mainMenu !== bar {
+            application.mainMenu = bar
+        }
+        if let windowsMenu, application.windowsMenu !== windowsMenu {
+            application.windowsMenu = windowsMenu
+        }
+    }
+}
diff --git a/Sources/UntoldEditor/UntoldEditorApp.swift b/Sources/UntoldEditor/UntoldEditorApp.swift
index b820dda..0ad5d81 100644
--- a/Sources/UntoldEditor/UntoldEditorApp.swift
+++ b/Sources/UntoldEditor/UntoldEditorApp.swift
@@ -54,6 +54,8 @@ class AppDelegate: NSObject, NSApplicationDelegate, NSMenuDelegate {
     private var splatBlendCapItems: [SplatBlendCapOption: NSMenuItem] = [:]
     private var splatWorkingSetItems: [EditorSplatWorkingSet: NSMenuItem] = [:]
     private var splatLevelModeItems: [SplatLevelModeOption: NSMenuItem] = [:]
+    /// Puts the editor's menus in the menu bar and keeps them there (SwiftUI installs its own bar).
+    private var mainMenuKeeper: EditorMainMenuKeeper?
 
     func applicationDidFinishLaunching(_: Notification) {
         Logger.log(message: "Launching \(appName) v\(Self.editorVersion) as \(Bundle.main.bundleIdentifier ?? "an executable without an identity")")
@@ -344,7 +346,7 @@ class AppDelegate: NSObject, NSApplicationDelegate, NSMenuDelegate {
         windowMenu.addItem(withTitle: "Zoom", action: #selector(NSWindow.zoom(_:)), keyEquivalent: "")
         NSApp.windowsMenu = windowMenu
 
-        NSApp.mainMenu = mainMenu
+        mainMenuKeeper = EditorMainMenuKeeper(menu: mainMenu, windowsMenu: windowMenu)
     }
 
     /// A menu item that shows or hides a panel of the docking layout; its
diff --git a/Tests/UntoldEditorTests/EditorMainMenuKeeperTests.swift b/Tests/UntoldEditorTests/EditorMainMenuKeeperTests.swift
new file mode 100644
index 0000000..bbb4843
--- /dev/null
+++ b/Tests/UntoldEditorTests/EditorMainMenuKeeperTests.swift
@@ -0,0 +1,202 @@
+//
+//  EditorMainMenuKeeperTests.swift
+//  UntoldEditor
+//
+// Copyright (C) Untold Engine Studios
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+//
+import AppKit
+@testable import UntoldEditor
+import XCTest
+
+/// The editor's menus stay in the menu bar when SwiftUI, or anything else,
+/// installs another one or fills the installed one with its own items.
+@MainActor
+final class EditorMainMenuKeeperTests: XCTestCase {
+    private var menuBefore: NSMenu?
+    private var windowsMenuBefore: NSMenu?
+
+    override func setUp() {
+        super.setUp()
+        menuBefore = NSApplication.shared.mainMenu
+        windowsMenuBefore = NSApplication.shared.windowsMenu
+    }
+
+    override func tearDown() {
+        NSApplication.shared.mainMenu = menuBefore
+        NSApplication.shared.windowsMenu = windowsMenuBefore
+        super.tearDown()
+    }
+
+    /// Turns the run loop until the keeper has looked (two seconds at most, for a
+    /// busy machine), or for a moment when nothing is expected to happen.
+    private func turnTheRunLoop(until done: (() -> Bool)? = nil) {
+        guard let done else {
+            RunLoop.main.run(until: Date().addingTimeInterval(0.2))
+            return
+        }
+        let deadline = Date().addingTimeInterval(2)
+        repeat {
+            RunLoop.main.run(until: Date().addingTimeInterval(0.02))
+        } while done() == false && Date() < deadline
+    }
+
+    /// A menu bar as the editor builds it: three menus, the last the Window menu.
+    private func editorsMenu() -> (menu: NSMenu, items: [NSMenuItem], windows: NSMenu) {
+        let menu = NSMenu(title: "Editor")
+        let windows = NSMenu(title: "Window")
+        for title in ["Untold Engine Editor", "File", "View"] {
+            let item = NSMenuItem()
+            item.submenu = NSMenu(title: title)
+            menu.addItem(item)
+        }
+        let windowItem = NSMenuItem()
+        windowItem.submenu = windows
+        menu.addItem(windowItem)
+        return (menu, menu.items, windows)
+    }
+
+    /// A menu bar as SwiftUI installs it: its own menus, filled in by a delegate.
+    private final class FillingDelegate: NSObject, NSMenuDelegate {
+        func menuNeedsUpdate(_ menu: NSMenu) {
+            menu.addItem(withTitle: "Help", action: nil, keyEquivalent: "")
+        }
+    }
+
+    private func swiftUIsMenu() -> NSMenu {
+        let menu = NSMenu(title: "SwiftUI")
+        for title in ["Untold Engine Studio", "Edit", "View", "Window", "Help"] {
+            let item = NSMenuItem()
+            item.submenu = NSMenu(title: title)
+            menu.addItem(item)
+        }
+        return menu
+    }
+
+    private func titles(_ menu: NSMenu?) -> [String] {
+        menu?.items.map { $0.submenu?.title ?? $0.title } ?? []
+    }
+
+    func test_withNoMenuBar_theEditorsMenuIsInstalled() {
+        NSApplication.shared.mainMenu = nil
+        let editors = editorsMenu()
+
+        let keeper = EditorMainMenuKeeper(menu: editors.menu, windowsMenu: editors.windows)
+
+        XCTAssertTrue(NSApplication.shared.mainMenu === editors.menu)
+        XCTAssertTrue(keeper.isInPlace)
+        XCTAssertTrue(NSApplication.shared.windowsMenu === editors.windows)
+        XCTAssertEqual(keeper.restorations, 0)
+    }
+
+    func test_aMenuBarInstalledBefore_getsTheEditorsMenusAndKeepsItsIdentity() {
+        let swiftUIs = swiftUIsMenu()
+        NSApplication.shared.mainMenu = swiftUIs
+        let editors = editorsMenu()
+
+        let keeper = EditorMainMenuKeeper(menu: editors.menu, windowsMenu: editors.windows)
+
+        XCTAssertTrue(NSApplication.shared.mainMenu === swiftUIs)
+        XCTAssertEqual(titles(NSApplication.shared.mainMenu), ["Untold Engine Editor", "File", "View", "Window"])
+        XCTAssertTrue(keeper.isInPlace)
+        XCTAssertEqual(editors.menu.items.count, 0, "the editor's items moved into the installed bar")
+    }
+
+    func test_aMenuBarInstalledLater_getsTheEditorsMenus() {
+        NSApplication.shared.mainMenu = nil
+        let editors = editorsMenu()
+        let keeper = EditorMainMenuKeeper(menu: editors.menu, windowsMenu: editors.windows)
+
+        let swiftUIs = swiftUIsMenu()
+        NSApplication.shared.mainMenu = swiftUIs
+        turnTheRunLoop { keeper.isInPlace }
+
+        XCTAssertTrue(NSApplication.shared.mainMenu === swiftUIs)
+        XCTAssertEqual(titles(NSApplication.shared.mainMenu), ["Untold Engine Editor", "File", "View", "Window"])
+        XCTAssertEqual(keeper.restorations, 1)
+    }
+
+    func test_aMenuBarRefilledWithoutBeingReplaced_isPutBackAfterTheNextEvent() throws {
+        NSApplication.shared.mainMenu = nil
+        let editors = editorsMenu()
+        let keeper = EditorMainMenuKeeper(menu: editors.menu, windowsMenu: editors.windows)
+        let bar = try XCTUnwrap(NSApplication.shared.mainMenu)
+
+        // What a menu bar's owner may do on an update of its own: no setter runs.
+        bar.removeAllItems()
+        for title in ["Edit", "Help"] {
+            bar.addItem(withTitle: title, action: nil, keyEquivalent: "")
+        }
+        XCTAssertFalse(keeper.isInPlace)
+        NotificationCenter.default.post(name: NSApplication.didUpdateNotification, object: NSApplication.shared)
+
+        XCTAssertEqual(titles(NSApplication.shared.mainMenu), ["Untold Engine Editor", "File", "View", "Window"])
+        XCTAssertEqual(keeper.restorations, 1)
+    }
+
+    func test_aMenuBarThatFillsItselfInThroughItsDelegate_isStopped() {
+        let swiftUIs = swiftUIsMenu()
+        let filling = FillingDelegate()
+        swiftUIs.delegate = filling
+        NSApplication.shared.mainMenu = swiftUIs
+        let editors = editorsMenu()
+
+        _ = EditorMainMenuKeeper(menu: editors.menu, windowsMenu: editors.windows)
+
+        XCTAssertNil(swiftUIs.delegate)
+    }
+
+    func test_theWindowsMenu_staysTheEditors() {
+        NSApplication.shared.mainMenu = nil
+        let editors = editorsMenu()
+        let keeper = EditorMainMenuKeeper(menu: editors.menu, windowsMenu: editors.windows)
+
+        let swiftUIs = swiftUIsMenu()
+        NSApplication.shared.windowsMenu = swiftUIs.items[3].submenu
+        NSApplication.shared.mainMenu = swiftUIs
+        turnTheRunLoop { keeper.isInPlace }
+
+        XCTAssertTrue(NSApplication.shared.windowsMenu === editors.windows)
+    }
+
+    func test_theEditorsMenusInPlace_countAsNothing() {
+        NSApplication.shared.mainMenu = nil
+        let editors = editorsMenu()
+        let keeper = EditorMainMenuKeeper(menu: editors.menu, windowsMenu: editors.windows)
+
+        NotificationCenter.default.post(name: NSApplication.didUpdateNotification, object: NSApplication.shared)
+        NotificationCenter.default.post(name: NSApplication.didBecomeActiveNotification, object: NSApplication.shared)
+        NSApplication.shared.mainMenu = editors.menu
+        turnTheRunLoop()
+
+        XCTAssertEqual(keeper.restorations, 0)
+    }
+
+    func test_everyReplacement_isUndone() {
+        NSApplication.shared.mainMenu = nil
+        let editors = editorsMenu()
+        let keeper = EditorMainMenuKeeper(menu: editors.menu, windowsMenu: editors.windows)
+
+        for _ in 0 ..< 3 {
+            NSApplication.shared.mainMenu = swiftUIsMenu()
+            turnTheRunLoop { keeper.isInPlace }
+        }
+
+        XCTAssertEqual(titles(NSApplication.shared.mainMenu), ["Untold Engine Editor", "File", "View", "Window"])
+        XCTAssertEqual(keeper.restorations, 3)
+    }
+
+    func test_withoutAKeeper_anotherMenuBarStays() {
+        let editors = editorsMenu()
+        NSApplication.shared.mainMenu = editors.menu
+        let swiftUIs = swiftUIsMenu()
+
+        NSApplication.shared.mainMenu = swiftUIs
+        turnTheRunLoop()
+
+        XCTAssertEqual(titles(NSApplication.shared.mainMenu), ["Untold Engine Studio", "Edit", "View", "Window", "Help"])
+    }
+}