From b05f0a237b9a56c45c15f8ed592648c04399cedf Mon Sep 17 00:00:00 2001
From: Pavel Pomerantsev <pomerantsevp@gmail.com>
Date: Sun, 30 Nov 2025 22:04:45 -0500
Subject: [PATCH 1/3] [WIP] Add shadow host instead of ignoring the shadow root

Resolves #4941
---
 lib/core/base/context/parse-selector-array.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/core/base/context/parse-selector-array.js b/lib/core/base/context/parse-selector-array.js
index 4435664f41..08388e2a65 100644
--- a/lib/core/base/context/parse-selector-array.js
+++ b/lib/core/base/context/parse-selector-array.js
@@ -16,6 +16,8 @@ export function parseSelectorArray(context, type) {
     if (item instanceof window.Node) {
       if (item.documentElement instanceof window.Node) {
         result.push(context.flatTree[0]);
+      } else if (item.host instanceof window.Node) {
+        result.push(getNodeFromTree(item.host));
       } else {
         result.push(getNodeFromTree(item));
       }

From d2f48cf1dee4dc361aa16899a4fff6406988659e Mon Sep 17 00:00:00 2001
From: Pavel Pomerantsev <pomerantsevp@gmail.com>
Date: Tue, 2 Dec 2025 21:46:57 -0500
Subject: [PATCH 2/3] Push children instead of the host

---
 lib/core/base/context/parse-selector-array.js |  8 +++++++-
 test/core/base/context.js                     | 17 +++++++++++++++--
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/lib/core/base/context/parse-selector-array.js b/lib/core/base/context/parse-selector-array.js
index 08388e2a65..d237508fb5 100644
--- a/lib/core/base/context/parse-selector-array.js
+++ b/lib/core/base/context/parse-selector-array.js
@@ -17,7 +17,13 @@ export function parseSelectorArray(context, type) {
       if (item.documentElement instanceof window.Node) {
         result.push(context.flatTree[0]);
       } else if (item.host instanceof window.Node) {
-        result.push(getNodeFromTree(item.host));
+        // Item is a shadow root. We only cache instances of `Element`,
+        // not `DocumentFragment`, so instead of the shadow root itself,
+        // we'll push all of its children to context.
+        const children = Array.from(item.children).map(child =>
+          getNodeFromTree(child)
+        );
+        result.push(...children);
       } else {
         result.push(getNodeFromTree(item));
       }
diff --git a/test/core/base/context.js b/test/core/base/context.js
index 3a28ad0baa..d0ee8b5e00 100644
--- a/test/core/base/context.js
+++ b/test/core/base/context.js
@@ -16,7 +16,7 @@ describe('Context', () => {
   it('should not mutate exclude in input', () => {
     fixture.innerHTML = '<div id="foo"></div>';
     const context = { exclude: [['iframe', '#foo']] };
-    // eslint-disable-next-line no-new
+     
     new Context(context);
     assert.deepEqual(context, { exclude: [['iframe', '#foo']] });
   });
@@ -24,7 +24,7 @@ describe('Context', () => {
   it('should not mutate its include input', () => {
     fixture.innerHTML = '<div id="foo"></div>';
     const context = { include: [['#foo']] };
-    // eslint-disable-next-line no-new
+     
     new Context(context);
     assert.deepEqual(context, { include: [['#foo']] });
   });
@@ -109,6 +109,19 @@ describe('Context', () => {
       assert.equal(result.include[0].props.id, 'target');
     });
 
+    it('accepts a reference to a ShadowRoot', () => {
+      createNestedShadowDom(
+        fixture,
+        '<article id="shadowHost"></article>',
+        `<h1 id="h1">Heading</h1>
+				<p id="p">Content</p>`
+      );
+      const shadowHost = fixture.querySelector('#shadowHost');
+      const shadowRoot = shadowHost.shadowRoot;
+      const result = new Context(shadowRoot);
+      assert.deepEqual(selectors(result.include), ['#h1', '#p']);
+    });
+
     it('accepts a node reference consisting of nested divs', () => {
       const div1 = document.createElement('div');
       const div2 = document.createElement('div');

From 2a272c1df283e52969896503cfaeba3576c2ac18 Mon Sep 17 00:00:00 2001
From: Pavel Pomerantsev <pomerantsevp@gmail.com>
Date: Wed, 3 Dec 2025 19:22:03 -0500
Subject: [PATCH 3/3] Format

---
 test/core/base/context.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/core/base/context.js b/test/core/base/context.js
index d0ee8b5e00..410bfe09ab 100644
--- a/test/core/base/context.js
+++ b/test/core/base/context.js
@@ -16,7 +16,7 @@ describe('Context', () => {
   it('should not mutate exclude in input', () => {
     fixture.innerHTML = '<div id="foo"></div>';
     const context = { exclude: [['iframe', '#foo']] };
-     
+
     new Context(context);
     assert.deepEqual(context, { exclude: [['iframe', '#foo']] });
   });
@@ -24,7 +24,7 @@ describe('Context', () => {
   it('should not mutate its include input', () => {
     fixture.innerHTML = '<div id="foo"></div>';
     const context = { include: [['#foo']] };
-     
+
     new Context(context);
     assert.deepEqual(context, { include: [['#foo']] });
   });