diff --git a/docs/menus.md b/docs/menus.md
index e66c1213..9e4c47b3 100644
--- a/docs/menus.md
+++ b/docs/menus.md
@@ -29,7 +29,7 @@ dev surface without worrying about duplicates.
 `createPopover(trigger, render, options)` wires focus management, aria
 attributes, collision detection, and auto updates. The render callback receives
 a portal `container` inside the overlay root. Return the panel element so the
-engine can toggle `data-popover-state` values while it opens and closes.
+engine toggles `data-popover-state` / `data-state` values while it opens and closes.
 
 ```js
 import createPopover from "../js/ui/overlay/popoverEngine.js";
diff --git a/js/ui/overlay/popoverEngine.js b/js/ui/overlay/popoverEngine.js
index 494d3961..f3764129 100644
--- a/js/ui/overlay/popoverEngine.js
+++ b/js/ui/overlay/popoverEngine.js
@@ -756,6 +756,7 @@ export function createPopover(trigger, render, options = {}) {
     panelElement.hidden = false;
     panelElement.setAttribute("aria-hidden", "false");
     panelElement.dataset.popoverState = "open";
+    panelElement.dataset.state = "open";
     setExpandedAttribute(anchor, true);
 
     bindGlobalHandlers();
@@ -809,6 +810,7 @@ export function createPopover(trigger, render, options = {}) {
       panel.setAttribute("aria-hidden", "true");
       panel.hidden = true;
       panel.dataset.popoverState = "closed";
+      panel.dataset.state = "closed";
       updateAriaActiveDescendant(panel, null);
       if (menuState.items.length) {
         menuState.items.forEach((item) => {
diff --git a/tests/position-floating-panel.test.mjs b/tests/position-floating-panel.test.mjs
index 8afe224c..27a9ef72 100644
--- a/tests/position-floating-panel.test.mjs
+++ b/tests/position-floating-panel.test.mjs
@@ -151,6 +151,7 @@ test("flips placement when bottom placement would collide with viewport", async
   const panel = documentRef.querySelector('[data-test-panel="collision"]');
   assert.ok(panel, "panel should render");
   assert.equal(panel.dataset.popoverState, "open");
+  assert.equal(panel.dataset.state, "open");
   assert.equal(panel.dataset.popoverPlacement, "top-start");
   assert.equal(panel.style.position, "fixed");
   assert.equal(panel.style.maxWidth, "calc(100vw - var(--space-xl))");
@@ -254,15 +255,18 @@ test("closes previously open popovers without restoring focus", async () => {
   assert.equal(popoverA.isOpen(), true);
   assert.equal(triggerA.getAttribute("aria-expanded"), "true");
   assert.equal(panelA?.dataset.popoverState, "open");
+  assert.equal(panelA?.dataset.state, "open");
 
   await popoverB.open();
   assert.equal(popoverB.isOpen(), true);
   assert.equal(triggerB.getAttribute("aria-expanded"), "true");
   assert.equal(panelB?.dataset.popoverState, "open");
+  assert.equal(panelB?.dataset.state, "open");
 
   assert.equal(popoverA.isOpen(), false, "first popover should close");
   assert.equal(triggerA.getAttribute("aria-expanded"), "false");
   assert.equal(panelA?.dataset.popoverState, "closed");
+  assert.equal(panelA?.dataset.state, "closed");
   assert.notEqual(active.active, triggerA, "focus should not jump back to first trigger");
 
   popoverA.destroy();
diff --git a/tests/ui/popoverEngine.test.mjs b/tests/ui/popoverEngine.test.mjs
index e91c7bb7..f6303f50 100644
--- a/tests/ui/popoverEngine.test.mjs
+++ b/tests/ui/popoverEngine.test.mjs
@@ -124,6 +124,7 @@ test("opens a popover in the overlay root and positions the panel", async () =>
   assert.ok(panel, "panel should be rendered");
   assert.equal(trigger.getAttribute("aria-controls"), panel.id);
   assert.equal(panel.dataset.popoverState, "open");
+  assert.equal(panel.dataset.state, "open");
   assert.equal(panel.dataset.popoverPlacement, "bottom-start");
   assert.equal(panel.style.position, "fixed");
   assert.equal(panel.style.left, "100px");
@@ -134,6 +135,7 @@ test("opens a popover in the overlay root and positions the panel", async () =>
 
   popover.close();
   assert.equal(panel.dataset.popoverState, "closed");
+  assert.equal(panel.dataset.state, "closed");
   assert.equal(trigger.getAttribute("aria-expanded"), "false");
 
   popover.destroy();
@@ -369,6 +371,7 @@ test("escape closes the popover and restores trigger focus", async () => {
 
   assert.equal(popover.isOpen(), false);
   assert.equal(panel.dataset.popoverState, "closed");
+  assert.equal(panel.dataset.state, "closed");
   assert.equal(panel.getAttribute("aria-activedescendant"), null);
   assert.equal(documentRef.activeElement, trigger);
 
@@ -496,6 +499,8 @@ test("ensures only one popover is open at a time", async () => {
   const panelB = documentRef.getElementById("panel-b");
   assert.equal(panelA.dataset.popoverState, "closed");
   assert.equal(panelB.dataset.popoverState, "open");
+  assert.equal(panelA.dataset.state, "closed");
+  assert.equal(panelB.dataset.state, "open");
 
   popoverA.destroy();
   popoverB.destroy();