diff --git a/apps/web/src/index.css b/apps/web/src/index.css
index 0f9942e3295ee..0cddb76a05ba2 100644
--- a/apps/web/src/index.css
+++ b/apps/web/src/index.css
@@ -151,16 +151,19 @@ html[data-mobile-composer-route-transition="true"]::view-transition-old(t3-mobil
   }
 }
 
+/* env() goes undefined in a minimized window, so Windows supplies --wco-fallback-* below. */
 .wco {
-  --native-titlebar-height: env(titlebar-area-height, 0px);
-  --workspace-topbar-height: max(40px, env(titlebar-area-height, 52px));
+  --native-titlebar-height: env(titlebar-area-height, var(--wco-fallback-height, 0px));
+  --workspace-topbar-height: max(40px, env(titlebar-area-height, var(--wco-fallback-height, 52px)));
   --workspace-controls-top: env(titlebar-area-y, 0px);
   --workspace-controls-left: calc(env(titlebar-area-x, 0px) + 0.75rem);
   --workspace-controls-right: calc(
-    100vw - env(titlebar-area-width, 100vw) - env(titlebar-area-x, 0px) + 0.75rem
+    100vw - env(titlebar-area-width, calc(100vw - var(--wco-fallback-controls-width, 0px))) -
+      env(titlebar-area-x, 0px) + 0.75rem
   );
   --workspace-native-controls-inset: calc(
-    100vw - env(titlebar-area-width, 100vw) - env(titlebar-area-x, 0px) + 0.75rem
+    100vw - env(titlebar-area-width, calc(100vw - var(--wco-fallback-controls-width, 0px))) -
+      env(titlebar-area-x, 0px) + 0.75rem
   );
 }
 
@@ -1756,6 +1759,9 @@ body {
 
 .electron-windows {
   --desktop-window-right-resize-inset: 6px;
+  /* Matches DesktopWindow TITLEBAR_HEIGHT and the width of the native window buttons at 100% zoom. */
+  --wco-fallback-height: 40px;
+  --wco-fallback-controls-width: 137px;
 }
 
 /* App-chrome grain. Baked into each surface's own background (behind
diff --git a/apps/web/src/lib/windowControlsOverlay.browser.test.ts b/apps/web/src/lib/windowControlsOverlay.browser.test.ts
new file mode 100644
index 0000000000000..18386647d3f26
--- /dev/null
+++ b/apps/web/src/lib/windowControlsOverlay.browser.test.ts
@@ -0,0 +1,60 @@
+import { expect, it, vi } from "vite-plus/test";
+
+import "~/index.css";
+import {
+  syncDocumentElectronPlatformClasses,
+  syncDocumentWindowControlsOverlayClass,
+} from "./windowControlsOverlay";
+
+vi.mock("~/env", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("~/env")>()),
+  isElectron: true,
+}));
+
+function paintedTitlebarLayout() {
+  const probe = document.createElement("div");
+  probe.style.cssText =
+    "height: var(--workspace-topbar-height); width: var(--workspace-native-controls-inset)";
+  document.body.append(probe);
+  try {
+    const { height, width } = probe.getBoundingClientRect();
+    return { height, width };
+  } finally {
+    probe.remove();
+  }
+}
+
+// The test page has no overlay, so env(titlebar-area-*) is undefined just as in a minimized window.
+it("keeps the titlebar layout while a minimized Windows window reports an empty overlay", () => {
+  const overlay = Object.assign(new EventTarget(), { visible: true });
+  let fullscreen = false;
+  const bridgeWindow = window as { desktopBridge?: unknown };
+  bridgeWindow.desktopBridge = { getWindowFullscreenState: () => fullscreen };
+  using _platform = vi.spyOn(navigator, "platform", "get").mockReturnValue("Win32");
+  using _overlay = vi
+    .spyOn(
+      navigator as unknown as { windowControlsOverlay: unknown },
+      "windowControlsOverlay",
+      "get",
+    )
+    .mockReturnValue(overlay);
+  const root = document.documentElement;
+  const stopPlatformClasses = syncDocumentElectronPlatformClasses("Win32");
+  const stop = syncDocumentWindowControlsOverlayClass();
+  try {
+    overlay.visible = false;
+    overlay.dispatchEvent(new Event("geometrychange"));
+
+    expect(root.classList.contains("wco")).toBe(true);
+    expect(paintedTitlebarLayout()).toEqual({ height: 40, width: 137 + 12 });
+
+    fullscreen = true;
+    window.dispatchEvent(new Event("resize"));
+    expect(root.classList.contains("wco")).toBe(false);
+  } finally {
+    delete bridgeWindow.desktopBridge;
+    stop();
+    stopPlatformClasses();
+    root.classList.remove("wco");
+  }
+});
diff --git a/apps/web/src/lib/windowControlsOverlay.ts b/apps/web/src/lib/windowControlsOverlay.ts
index 9b2e90e6a754f..d17fa744ff5fa 100644
--- a/apps/web/src/lib/windowControlsOverlay.ts
+++ b/apps/web/src/lib/windowControlsOverlay.ts
@@ -53,12 +53,30 @@ export function syncDocumentWindowControlsOverlayClass(): () => void {
   }
 
   const overlay = getWindowControlsOverlay();
+  // Windows also empties the overlay while minimized; dropping the class then shifts the layout
+  // on restore. Fullscreen empties it for real, so only fullscreen may drop it there.
+  const keepsClassUnlessFullscreen = isElectron && isWindowsPlatform(navigator.platform);
   const update = () => {
-    document.documentElement.classList.toggle(WCO_CLASS_NAME, overlay !== null && overlay.visible);
+    const visible = overlay !== null && overlay.visible;
+    if (
+      !visible &&
+      keepsClassUnlessFullscreen &&
+      !window.desktopBridge?.getWindowFullscreenState()
+    ) {
+      return;
+    }
+    document.documentElement.classList.toggle(WCO_CLASS_NAME, visible);
   };
 
   update();
-  return onWindowControlsOverlayGeometryChange(update);
+  const stopGeometry = onWindowControlsOverlayGeometryChange(update);
+  if (!keepsClassUnlessFullscreen) return stopGeometry;
+  // The overlay can hide before the window reports fullscreen; the fullscreen resize settles it.
+  window.addEventListener("resize", update);
+  return () => {
+    stopGeometry();
+    window.removeEventListener("resize", update);
+  };
 }
 
 function subscribeTitlebarArea(listener: () => void): () => void {