From 90a337b8196863c55de16531c8df62b6179efa21 Mon Sep 17 00:00:00 2001
From: rxm <xmari0@icloud.com>
Date: Sun, 14 Jun 2026 22:10:42 +0200
Subject: [PATCH] feat(main): prevent multiple app instances with
 single-instance lock

Acquire app.requestSingleInstanceLock() before startup. A second launch
(double-clicking the exe while DropPilot is in the tray, or auto-start
firing alongside a manual launch) fails to acquire the lock and quits
before creating a window or starting any Twitch/IPC services. Electron
forwards that launch to the running process via the "second-instance"
event, which restores the existing window from the tray and focuses it.

A close-to-tray default means the running instance usually has a hidden
but alive window, so the handler calls show()/restore() before focus().

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 src/main/index.ts | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/main/index.ts b/src/main/index.ts
index 1760c98..ae6345c 100644
--- a/src/main/index.ts
+++ b/src/main/index.ts
@@ -15,6 +15,26 @@ import { loadStats, saveStats, bumpStats, resetStats } from "./core/stats";
 
 const isDev = !app.isPackaged;
 
+// Single-instance guard: only one DropPilot process may run at a time. A second
+// launch (double-clicking the exe while it's already in the tray, or auto-start
+// firing alongside a manual launch) fails to acquire the lock and exits before
+// doing any startup work. Electron forwards that launch to the first process via
+// the "second-instance" event, which we use to surface the running window.
+const gotSingleInstanceLock = app.requestSingleInstanceLock();
+if (!gotSingleInstanceLock) {
+  app.quit();
+} else {
+  app.on("second-instance", () => {
+    const [win] = BrowserWindow.getAllWindows();
+    if (!win) return;
+    if (win.isMinimized()) win.restore();
+    // Default close-to-tray hides the window rather than destroying it, so a
+    // running instance often has a hidden-but-alive window to reveal.
+    if (!win.isVisible()) win.show();
+    win.focus();
+  });
+}
+
 /**
  * Behavior flags read on every close/minimize event. Seeded from settings
  * at startup; refreshed whenever the IPC layer saves new settings (see
@@ -458,6 +478,9 @@ function setupAutoUpdater() {
 }
 
 app.whenReady().then(async () => {
+  // Losing instance: the lock guard above already called app.quit(); bail before
+  // creating a window or starting any Twitch/IPC services.
+  if (!gotSingleInstanceLock) return;
   const startHidden = process.argv.includes("--start-in-tray");
   // Read settings before creating the window so we can restore bounds + seed
   // behavior flags before any close/minimize event can fire.