Single Instance + argv

Typical flow: user double-clicks the app icon while it’s already open. You want:

The second launch exits silently (no duplicate window).
The primary window focuses + unminimizes.
The primary receives the launch argv (e.g. a file path).


import { singleInstance, tyndWindow } from "@tynd/core/client";
 
const { acquired } = await singleInstance.acquire("com.example.myapp");
if (!acquired) {
  // Second instance — host already forwarded argv+cwd and focused the primary.
  process.exit(0);
}
 
// Only the primary reaches here. Handle forwarded launches:
singleInstance.onSecondLaunch(({ argv, cwd }) => {
  // First argv entry is the exe path; look at argv[1..] for args
  const file = argv.slice(1).find((a) => a.endsWith(".myapp"));
  if (file) {
    openFile(file);
  }
});

Host auto-focus + unminimize is built in — no IPC round-trip needed. Your code only handles what to do with the forwarded args.

Combine with deep links


singleInstance.onOpenUrl((url) => {
  // Fires on cold start (argv has the URL) AND duplicate launch (forwarded)
  const parsed = new URL(url);
  router.navigate(parsed.pathname);
});

onOpenUrl and onSecondLaunch can coexist — the URL-scheme detection happens in the host, custom-scheme URLs fire onOpenUrl, plain paths fire onSecondLaunch.

Use stable, reverse-DNS ids


singleInstance.acquire("com.example.myapp");   // ✓
singleInstance.acquire("MyApp-v1.0.0");         // ✗ — version breaks upgrade UX

Related: Single Instance guide · singleInstance API.