feat(split-screen): redesign split screen with free-form panes and pane picker

src/ui/tests/lib/create-id.test.ts

@@ -0,0 +1,19 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { createId } from "@/lib/create-id";
+
+afterEach(() => vi.unstubAllGlobals());
+
+describe("createId", () => {
+  it("uses randomUUID when available", () => {
+    vi.stubGlobal("crypto", { randomUUID: () => "uuid-1" });
+    expect(createId()).toBe("uuid-1");
+  });
+
+  it("falls back without randomUUID, e.g. over plain http", () => {
+    vi.stubGlobal("crypto", {});
+    const first = createId();
+    const second = createId();
+    expect(first).toBeTruthy();
+    expect(second).not.toBe(first);
+  });
+});