From ca0a3f05277b5dd04f4b2fbc85a79bdb0de5b882 Mon Sep 17 00:00:00 2001
From: andreivieru <andreivieru@microsoft.com_msteamsmdb>
Date: Wed, 4 Nov 2026 22:51:27 -0500
Subject: [PATCH] Restore tracked aria-hidden attributes when disposing
 modalizer

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 37912007-07c2-40e4-81bd-df708aa99fe2
---
 src/Modalizer.ts                |   7 ++
 tests/ModalizerDispose.test.tsx | 157 ++++++++++++++++++++++++++++++++
 2 files changed, 164 insertions(+)
 create mode 100644 tests/ModalizerDispose.test.tsx

diff --git a/src/Modalizer.ts b/src/Modalizer.ts
index 9fcf3d18..7ee65168 100644
--- a/src/Modalizer.ts
+++ b/src/Modalizer.ts
@@ -401,6 +401,13 @@ export class ModalizerAPI implements Types.ModalizerAPI {
         delete this.activeId;
         this.activeElements = [];
 
+        this._aug.forEach((reference) => {
+            const element = reference.get();
+            if (element) {
+                augmentAttribute(this._tabster, element, "aria-hidden");
+            }
+        });
+
         this._augMap = new WeakMap();
         this._aug = [];
 
diff --git a/tests/ModalizerDispose.test.tsx b/tests/ModalizerDispose.test.tsx
new file mode 100644
index 00000000..59b06de3
--- /dev/null
+++ b/tests/ModalizerDispose.test.tsx
@@ -0,0 +1,157 @@
+/*!
+ * Copyright (c) Microsoft Corporation. All rights reserved.
+ * Licensed under the MIT License.
+ */
+
+import * as React from "react";
+import { getTabsterAttribute } from "tabster";
+import * as BroTest from "./utils/BroTest";
+
+describe("Modalizer disposal", () => {
+    beforeEach(async () => {
+        await BroTest.bootstrapTabsterPage({ modalizer: true });
+    });
+
+    const fixture = (original?: "false" | "true") => (
+        <div {...getTabsterAttribute({ root: {} })}>
+            <section id="outside" aria-hidden={original}>
+                <button>Outside</button>
+            </section>
+            <section {...getTabsterAttribute({ modalizer: { id: "modal" } })}>
+                <button id="modal-button">Modal</button>
+            </section>
+        </div>
+    );
+
+    it.each([undefined, "false", "true"] as const)(
+        "restores the original aria-hidden value on last-wrapper disposal (%s)",
+        async (original) => {
+            await new BroTest.BroTest(fixture(original))
+                .focusElement("#modal-button")
+                .wait(300)
+                .eval(() => {
+                    const vars = getTabsterTestVariables();
+                    const outside = vars.dom!.getElementById(
+                        document,
+                        "outside"
+                    )!;
+                    const handle = vars.core!;
+                    const borrowed = vars.getTabster!(window)!;
+                    const hidden = outside.getAttribute("aria-hidden");
+
+                    vars.disposeTabster!(handle);
+
+                    return {
+                        hidden,
+                        restored: outside.getAttribute("aria-hidden"),
+                        borrowedSharesCore: borrowed.core === handle.core,
+                        newBorrowedHandle: !!vars.getTabster!(window),
+                    };
+                })
+                .check((result) => {
+                    expect(result).toEqual({
+                        hidden: "true",
+                        restored: original ?? null,
+                        borrowedSharesCore: true,
+                        newBorrowedHandle: false,
+                    });
+                });
+        }
+    );
+
+    it.each([undefined, "false"] as const)(
+        "does not restore until the final counted wrapper is disposed (%s)",
+        async (original) => {
+            await new BroTest.BroTest(fixture(original))
+                .focusElement("#modal-button")
+                .wait(300)
+                .eval(() => {
+                    const vars = getTabsterTestVariables();
+                    const outside = vars.dom!.getElementById(
+                        document,
+                        "outside"
+                    )!;
+                    const keeper = vars.createTabster!(window);
+                    vars.disposeTabster!(vars.core!);
+                    const retained = outside.getAttribute("aria-hidden");
+                    const coreRetained = !!vars.getTabster!(window);
+
+                    vars.disposeTabster!(keeper);
+
+                    return {
+                        retained,
+                        coreRetained,
+                        restored: outside.getAttribute("aria-hidden"),
+                        coreGone: !vars.getTabster!(window),
+                    };
+                })
+                .check((result) => {
+                    expect(result).toEqual({
+                        retained: "true",
+                        coreRetained: true,
+                        restored: original ?? null,
+                        coreGone: true,
+                    });
+                });
+        }
+    );
+
+    it.each([undefined, "false"] as const)(
+        "restores a still-live detached element before storage is discarded (%s)",
+        async (original) => {
+            await new BroTest.BroTest(fixture(original))
+                .focusElement("#modal-button")
+                .wait(300)
+                .eval(() => {
+                    const vars = getTabsterTestVariables();
+                    const outside = vars.dom!.getElementById(
+                        document,
+                        "outside"
+                    )!;
+                    const hidden = outside.getAttribute("aria-hidden");
+                    outside.remove();
+                    vars.disposeTabster!(vars.core!);
+
+                    return {
+                        hidden,
+                        connected: outside.isConnected,
+                        restored: outside.getAttribute("aria-hidden"),
+                    };
+                })
+                .check((result) => {
+                    expect(result).toEqual({
+                        hidden: "true",
+                        connected: false,
+                        restored: original ?? null,
+                    });
+                });
+        }
+    );
+
+    it("preserves normal deactivation before disposal", async () => {
+        await new BroTest.BroTest(fixture("false"))
+            .focusElement("#modal-button")
+            .wait(300)
+            .eval(() => {
+                getTabsterTestVariables().modalizer!.setActive(undefined);
+            })
+            .wait(300)
+            .eval(() => {
+                const vars = getTabsterTestVariables();
+                const outside = vars.dom!.getElementById(document, "outside")!;
+                const deactivated = outside.getAttribute("aria-hidden");
+                vars.disposeTabster!(vars.core!);
+
+                return {
+                    deactivated,
+                    disposed: outside.getAttribute("aria-hidden"),
+                };
+            })
+            .check((result) => {
+                expect(result).toEqual({
+                    deactivated: "false",
+                    disposed: "false",
+                });
+            });
+    });
+});