From 84585b2930a9c4ca7590908faf8ef643a44646df Mon Sep 17 00:00:00 2001
From: Stef Stachow <stef@stachow.co.uk>
Date: Wed, 30 Sep 2026 10:38:30 +0100
Subject: [PATCH] #FCT2-22209 - prevent footer switching for non-page footers

---
 e2e/tests/footer.test.ts                      | 40 +++++++++++++++++++
 .../services/browser/dom/footer-subscriber.ts |  9 ++++-
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/e2e/tests/footer.test.ts b/e2e/tests/footer.test.ts
index 9c1491104..6464164e7 100644
--- a/e2e/tests/footer.test.ts
+++ b/e2e/tests/footer.test.ts
@@ -112,4 +112,44 @@ describe("Footer", () => {
 
     expect(hasLink).toBe(false);
   });
+
+  it("leaves footers marked .cps-component-footer alone and anchors to the page footer", async () => {
+    await arrange({});
+    await act();
+
+    // A host app using <footer> inside a modal alongside the real page footer.
+    // The modal footer carries the opt-out class, so the shim must neither hide
+    // it nor anchor cps-global-footer next to it.
+    await page.evaluate(() => {
+      const modal = document.createElement("div");
+      modal.id = "host-modal";
+      const modalFooter = document.createElement("footer");
+      modalFooter.id = "host-modal-footer";
+      modalFooter.className = "cps-component-footer";
+      modalFooter.textContent = "modal footer";
+      modal.appendChild(modalFooter);
+      document.body.appendChild(modal);
+
+      const pageFooter = document.createElement("footer");
+      pageFooter.id = "host-page-footer";
+      pageFooter.textContent = "page footer";
+      document.body.appendChild(pageFooter);
+    });
+
+    // The page footer being hidden is our signal that the subscriber has run.
+    await page.waitForFunction(() => document.getElementById("host-page-footer")?.style.display === "none", { timeout: 5000, polling: 100 });
+
+    const result = await page.evaluate(() => {
+      const modalFooter = document.getElementById("host-modal-footer")!;
+      return {
+        modalFooterDisplay: window.getComputedStyle(modalFooter).display,
+        modalFooterObserved: !!modalFooter.dataset.cpsFooterEmailObserved,
+        globalFooterPrevSiblingId: document.querySelector("cps-global-footer")?.previousElementSibling?.id,
+      };
+    });
+
+    expect(result.modalFooterDisplay).not.toBe("none");
+    expect(result.modalFooterObserved).toBe(false);
+    expect(result.globalFooterPrevSiblingId).toBe("host-page-footer");
+  });
 });
diff --git a/packages/cps-global-components/src/services/browser/dom/footer-subscriber.ts b/packages/cps-global-components/src/services/browser/dom/footer-subscriber.ts
index bdf543a6b..97c3c7f37 100644
--- a/packages/cps-global-components/src/services/browser/dom/footer-subscriber.ts
+++ b/packages/cps-global-components/src/services/browser/dom/footer-subscriber.ts
@@ -9,6 +9,8 @@ import { DomMutationObserver } from "./DomMutationObserver";
 const EMAIL_REGEX = /[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}/;
 const OBSERVED_MARKER = "cpsFooterEmailObserved";
 
+const IGNORED_FOOTER_CLASS = "cps-component-footer";
+
 // During a host SPA route transition the header is briefly hidden or
 // zero-sized (display:none flash, parent collapsing, mid-paint state). The
 // ResizeObserver faithfully fires with that tiny rect and — left unguarded —
@@ -97,7 +99,12 @@ export const footerSubscriber: DomMutationObserver = ({ preview, flags, config,
   isActiveForContext: FEATURE_FLAGS.shouldShimFooter({ config, preview, flags }),
   subscriptions: [
     {
-      cssSelector: "footer",
+      // Host apps can use <footer> for things that aren't the page footer
+      // (sidebars, modals, cards). Agreed contract: host apps mark those with
+      // `.cps-component-footer` and we leave them alone. The class must be
+      // present when the element is rendered - if it's added later we'll
+      // already have hidden it and re-anchored cps-global-footer next to it.
+      cssSelector: `footer:not(.${IGNORED_FOOTER_CLASS})`,
       handler: (element: HTMLElement) => {
         let cpsGlobalFooter = element.ownerDocument.querySelector<HTMLCpsGlobalFooterElement>("cps-global-footer");
         if (!cpsGlobalFooter) {