fix Vesktop being registered as html mime handler

This is actually a bug in xdg-settings that was already fixed years ago, but Ubuntu
still ships 7 (!!!!!) years out of date xdg-utils. Please just switch to Fedora what
are we doing man

src/main/index.ts

@@ -15,6 +15,7 @@ import { createWindows, mainWin } from "./mainWindow";
 import { registerMediaPermissionsHandler } from "./mediaPermissions";
 import { registerScreenShareHandler } from "./screenShare";
 import { Settings, State } from "./settings";
+import { setAsDefaultProtocolClient } from "./utils/setAsDefaultProtocolClient";
 import { isDeckGameMode } from "./utils/steamOS";
 
 if (!IS_DEV) {
@@ -31,7 +32,7 @@ const isLinux = process.platform === "linux";
 export let enableHardwareAcceleration = true;
 
 function init() {
-    app.setAsDefaultProtocolClient("discord");
+    setAsDefaultProtocolClient("discord");
 
     const { disableSmoothScroll, hardwareAcceleration, hardwareVideoAcceleration } = Settings.store;
 

src/main/utils/setAsDefaultProtocolClient.ts

@@ -0,0 +1,29 @@
+/*
+ * Vesktop, a desktop app aiming to give you a snappier Discord Experience
+ * Copyright (c) 2025 Vendicated and Vesktop contributors
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+import { execFile } from "child_process";
+import { app } from "electron";
+
+export async function setAsDefaultProtocolClient(protocol: string) {
+    if (process.platform !== "linux") {
+        return app.setAsDefaultProtocolClient(protocol);
+    }
+
+    // electron setAsDefaultProtocolClient uses xdg-settings instead of xdg-mime.
+    // xdg-settings had a bug where it would also register the app as a handler for text/html,
+    // aka become your browser. This bug was fixed years ago (xdg-utils 1.2.0) but Ubuntu ships
+    // 7 (YES, SEVEN) years out of date xdg-utils which STILL has the bug.
+    // FIXME: remove this workaround when Ubuntu updates their xdg-utils or electron switches to xdg-mime.
+
+    const { CHROME_DESKTOP } = process.env;
+    if (!CHROME_DESKTOP) return false;
+
+    return new Promise<boolean>(resolve => {
+        execFile("xdg-mime", ["default", CHROME_DESKTOP, `x-scheme-handler/${protocol}`], err => {
+            resolve(err == null);
+        });
+    });
+}