feat(desktop): Windows taskbar overlay icon for unread badge

Red-dot overlay drawn as raw RGBA (no extra resource bundled).
Shown on Windows when unread count > 0, cleared when 0.
macOS keeps numeric Dock badge; Linux has no cross-DE badge API.

Bumps version 0.10.0 -> 0.10.1.

apps/desktop/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@chat-app/desktop",
-  "version": "0.10.0",
+  "version": "0.10.1",
   "private": true,
   "description": "Tauri v2 desktop client (Windows / macOS / Linux)",
   "type": "module",

apps/desktop/src-tauri/Cargo.lock

@@ -726,7 +726,7 @@ dependencies = [
 
 [[package]]
 name = "chat-app-desktop"
-version = "0.10.0"
+version = "0.10.1"
 dependencies = [
  "base64 0.22.1",
  "dryoc",

apps/desktop/src-tauri/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "chat-app-desktop"
-version = "0.10.0"
+version = "0.10.1"
 description = "ChatApp desktop client"
 authors = ["Dennis"]
 edition = "2021"

apps/desktop/src-tauri/src/lib.rs

@@ -22,6 +22,33 @@ struct TrayUnreadPayload {
     count: u32,
 }
 
+// Red-dot overlay icon for the Windows taskbar. Drawn as raw RGBA instead of
+// shipping a PNG so we don't add another resource to the bundle. Kept small
+// (32x32) since Windows scales the overlay down anyway.
+#[cfg(target_os = "windows")]
+fn unread_overlay_rgba() -> Vec<u8> {
+    const SIZE: u32 = 32;
+    let r = SIZE as f32 / 2.0;
+    let mut buf = Vec::with_capacity((SIZE * SIZE * 4) as usize);
+    for y in 0..SIZE {
+        for x in 0..SIZE {
+            let dx = x as f32 - r + 0.5;
+            let dy = y as f32 - r + 0.5;
+            let d = (dx * dx + dy * dy).sqrt();
+            let edge = r - 1.0;
+            if d <= edge {
+                buf.extend_from_slice(&[0xDC, 0x26, 0x26, 0xFF]);
+            } else if d <= r {
+                let alpha = (255.0 * (r - d)).clamp(0.0, 255.0) as u8;
+                buf.extend_from_slice(&[0xDC, 0x26, 0x26, alpha]);
+            } else {
+                buf.extend_from_slice(&[0, 0, 0, 0]);
+            }
+        }
+    }
+    buf
+}
+
 #[cfg(not(any(target_os = "android", target_os = "ios")))]
 fn show_main_window(app: &AppHandle) {
     if let Some(win) = app.get_webview_window("main") {
@@ -171,9 +198,9 @@ pub fn run() {
                     format!("ChatApp · {} neu", payload.count)
                 };
                 let _ = tray_handle.set_tooltip(Some(tooltip));
-                // Dock/taskbar badge. `set_badge_label` is macOS-only.
-                // Windows taskbar uses an overlay icon (different API).
-                // Linux has no cross-DE badge API — skip.
+                // Dock/taskbar badge. macOS uses a numeric label; Windows uses
+                // an overlay icon (red dot = unread). Linux has no cross-DE
+                // badge API — skip.
                 #[cfg(target_os = "macos")]
                 if let Some(win) = badge_window.as_ref() {
                     let badge = if payload.count == 0 {
@@ -183,7 +210,17 @@ pub fn run() {
                     };
                     let _ = win.set_badge_label(badge);
                 }
-                #[cfg(not(target_os = "macos"))]
+                #[cfg(target_os = "windows")]
+                if let Some(win) = badge_window.as_ref() {
+                    if payload.count == 0 {
+                        let _ = win.set_overlay_icon(None);
+                    } else {
+                        let rgba = unread_overlay_rgba();
+                        let img = tauri::image::Image::new_owned(rgba, 32, 32);
+                        let _ = win.set_overlay_icon(Some(img));
+                    }
+                }
+                #[cfg(not(any(target_os = "macos", target_os = "windows")))]
                 let _ = &badge_window;
             });
 

apps/desktop/src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "ChatApp",
-  "version": "0.10.0",
+  "version": "0.10.1",
   "identifier": "com.meinname.chatapp",
   "build": {
     "beforeDevCommand": "pnpm vite:dev",