feat: permanently delete archived lists

frontend/src/lib/list-purge.test.ts

@@ -0,0 +1,15 @@
+import { describe, expect, it } from 'vitest'
+import { nextDialogFocusIndex } from './list-purge'
+
+describe('archived list purge dialog behavior', () => {
+  it('wraps Tab focus between the cancel and destructive actions', () => {
+    expect(nextDialogFocusIndex(0, 2, true)).toBe(1)
+    expect(nextDialogFocusIndex(1, 2, false)).toBe(0)
+  })
+
+  it('leaves focus alone while moving between interior controls', () => {
+    expect(nextDialogFocusIndex(1, 3, true)).toBeNull()
+    expect(nextDialogFocusIndex(1, 3, false)).toBeNull()
+    expect(nextDialogFocusIndex(0, 0, false)).toBeNull()
+  })
+})

frontend/src/lib/list-purge.ts

@@ -0,0 +1,6 @@
+export function nextDialogFocusIndex(currentIndex: number, controlCount: number, shiftKey: boolean) {
+  if (controlCount < 2) return null
+  if (shiftKey && currentIndex === 0) return controlCount - 1
+  if (!shiftKey && currentIndex === controlCount - 1) return 0
+  return null
+}