Fix FloatBar DPI-aware content sizing

apps/desktop-tauri/src-tauri/src/floatbar/window.rs

@@ -447,8 +447,11 @@ pub fn resize(
     height: f64,
     click_through: bool,
 ) -> Result<(), String> {
+    let width = width.ceil().clamp(1.0, u32::MAX as f64) as u32;
+    let height = height.ceil().clamp(1.0, u32::MAX as f64) as u32;
+
     window
-        .set_size(LogicalSize::new(width, height))
+        .set_size(PhysicalSize::new(width, height))
         .map_err(|e| e.to_string())?;
     apply_no_activate(window);
     apply_click_through(window, click_through);

apps/desktop-tauri/src/floatbar/FloatBar.css

@@ -22,6 +22,7 @@ body.floatbar-window #root {
  * group reads like a compact widget sitting on the Windows taskbar. */
 .floatbar {
   display: inline-flex;
+  flex: none;
   align-items: center;
   justify-content: center;
   gap: calc(4px * var(--floatbar-scale, 1));

apps/desktop-tauri/src/floatbar/FloatBar.test.tsx

@@ -358,6 +358,46 @@ describe("FloatBar", () => {
     });
   });
 
+  it("resizes the native window in physical pixels at the WebView DPI", async () => {
+    tauriMocks.getCachedProviders.mockResolvedValue([]);
+    tauriMocks.getSettingsSnapshot.mockResolvedValue(settings());
+    const originalDevicePixelRatio = window.devicePixelRatio;
+    Object.defineProperty(window, "devicePixelRatio", {
+      configurable: true,
+      value: 1.5,
+    });
+    const rectSpy = vi
+      .spyOn(HTMLElement.prototype, "getBoundingClientRect")
+      .mockReturnValue({
+        x: 0,
+        y: 0,
+        width: 100,
+        height: 20,
+        top: 0,
+        right: 100,
+        bottom: 20,
+        left: 0,
+        toJSON: () => ({}),
+      });
+
+    try {
+      renderFloatBar(bootstrap());
+
+      await waitFor(() => {
+        expect(coreMocks.invoke).toHaveBeenCalledWith("resize_float_bar", {
+          width: 162,
+          height: 42,
+        });
+      });
+    } finally {
+      rectSpy.mockRestore();
+      Object.defineProperty(window, "devicePixelRatio", {
+        configurable: true,
+        value: originalDevicePixelRatio,
+      });
+    }
+  });
+
   it("uses the localized reset formatter in pill tooltips", async () => {
     const resetsAt = new Date(Date.now() + 3 * 60 * 60_000 + 42 * 60_000).toISOString();
     tauriMocks.getCachedProviders.mockResolvedValue([

apps/desktop-tauri/src/floatbar/FloatBar.tsx

@@ -381,8 +381,14 @@ export default function FloatBar({ state }: { state: BootstrapState }) {
       resizeRafRef.current = null;
       const rect = el.getBoundingClientRect();
       const padding = 8;
-      const w = Math.ceil(rect.width + padding);
-      const h = Math.ceil(rect.height + padding);
+      const dpr =
+        Number.isFinite(window.devicePixelRatio) && window.devicePixelRatio > 0
+          ? window.devicePixelRatio
+          : 1;
+      // DOM measurements are CSS pixels; the native command accepts physical
+      // pixels so the window remains correctly sized on scaled displays.
+      const w = Math.ceil(Math.ceil(rect.width + padding) * dpr);
+      const h = Math.ceil(Math.ceil(rect.height + padding) * dpr);
       const last = lastResizeRef.current;
       if (last && Math.abs(last.w - w) <= 1 && Math.abs(last.h - h) <= 1) return;
       lastResizeRef.current = { w, h };
@@ -411,6 +417,12 @@ export default function FloatBar({ state }: { state: BootstrapState }) {
     return () => observer.disconnect();
   }, [resizeToContent]);
 
+  useEffect(() => {
+    // Re-measure after moving onto a monitor with a different scale factor.
+    window.addEventListener("resize", resizeToContent);
+    return () => window.removeEventListener("resize", resizeToContent);
+  }, [resizeToContent]);
+
   useEffect(
     () => () => {
       if (resizeRafRef.current !== null) {