chore: import upstream snapshot with attribution

apps/sim/lib/core/utils/background.test.ts

@@ -0,0 +1,36 @@
+/**
+ * @vitest-environment node
+ */
+import { sleep } from '@sim/utils/helpers'
+import { describe, expect, it, vi } from 'vitest'
+import { runDetached } from '@/lib/core/utils/background'
+
+const flushMicrotasks = () => sleep(0)
+
+describe('runDetached', () => {
+  it('runs the work without the caller awaiting it', async () => {
+    const work = vi.fn().mockResolvedValue(undefined)
+
+    runDetached('test', work)
+
+    await flushMicrotasks()
+    expect(work).toHaveBeenCalledTimes(1)
+  })
+
+  it('swallows rejections so they do not surface as unhandled', async () => {
+    const work = vi.fn().mockRejectedValue(new Error('boom'))
+
+    expect(() => runDetached('test', work)).not.toThrow()
+    await flushMicrotasks()
+    expect(work).toHaveBeenCalledTimes(1)
+  })
+
+  it('swallows synchronous throws from work', async () => {
+    const work = vi.fn(() => {
+      throw new Error('sync boom')
+    })
+
+    expect(() => runDetached('test', work)).not.toThrow()
+    await flushMicrotasks()
+  })
+})