Add restart-to-update banner: waiting SW detected via watchForWaitingUpdate, explicit user opt-in applies SKIP_WAITING + reload (no auto mid-session claim, ARCH §8)

tests/unit/update-banner.test.ts

@@ -0,0 +1,54 @@
+/**
+ * @vitest-environment jsdom
+ * "Restart to update" banner — appears once, apply fires the opt-in,
+ * Later removes it. Pure DOM: no SW, no storage, no network.
+ */
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { showUpdateBanner } from "../../src/ui/components/update-banner.js";
+
+beforeEach(() => {
+  document.body.replaceChildren();
+});
+
+function root(): HTMLElement {
+  const el = document.createElement("div");
+  document.body.append(el);
+  return el;
+}
+
+describe("update banner", () => {
+  it("renders banner with apply and dismiss once (idempotent)", () => {
+    const host = root();
+    showUpdateBanner(host, () => undefined);
+    showUpdateBanner(host, () => undefined);
+    expect(document.querySelectorAll(".update-banner").length).toBe(1);
+    expect(host.textContent).toContain("new version");
+    expect(host.querySelector(".update-banner__apply")?.textContent).toBe("Restart to update");
+  });
+
+  it("apply invokes the opt-in callback exactly once per click", () => {
+    const host = root();
+    const onApply = vi.fn();
+    showUpdateBanner(host, onApply);
+    host.querySelector(".update-banner__apply")?.dispatchEvent(new MouseEvent("click"));
+    expect(onApply).toHaveBeenCalledTimes(1);
+  });
+
+  it("Later removes the banner without calling apply", () => {
+    const host = root();
+    const onApply = vi.fn();
+    showUpdateBanner(host, onApply);
+    host.querySelector(".update-banner__dismiss")?.dispatchEvent(new MouseEvent("click"));
+    expect(document.querySelector(".update-banner")).toBeNull();
+    expect(onApply).not.toHaveBeenCalled();
+    // Re-show after dismiss is allowed (a later update can re-offer).
+    showUpdateBanner(host, onApply);
+    expect(document.querySelectorAll(".update-banner").length).toBe(1);
+  });
+
+  it("renders no raw HTML from anywhere (textContent-only)", () => {
+    const host = root();
+    showUpdateBanner(host, () => undefined);
+    expect(host.querySelector(".update-banner")?.innerHTML).not.toMatch(/<img|<script/);
+  });
+});