From 1c01f3efe679aef8b6503477a7120bcfa86493c9 Mon Sep 17 00:00:00 2001
From: Nikita Guryev <nikgurv@gmail.com>
Date: Thu, 2 Jul 2026 14:37:43 +0300
Subject: [PATCH 1/3] fix(tags): prevent focus-back loop in eventCoalescing
 mode (#DS-5236)

---
 .../tags/tag-list.component.spec.ts           | 33 +++++++++++++++++++
 .../components/tags/tag-list.component.ts     |  1 +
 2 files changed, 34 insertions(+)

diff --git a/packages/components/tags/tag-list.component.spec.ts b/packages/components/tags/tag-list.component.spec.ts
index f6392b536..ed756100d 100644
--- a/packages/components/tags/tag-list.component.spec.ts
+++ b/packages/components/tags/tag-list.component.spec.ts
@@ -1414,6 +1414,39 @@ describe(KbqTagList.name, () => {
         );
     });
 
+    it('should synchronously set native tabIndex to -1 on tabOut to prevent focus-back loop', fakeAsync(() => {
+        const fixture = createStandaloneComponent(TestTagList);
+        const { debugElement, componentInstance } = fixture;
+        const tagListEl = getTagListElement(debugElement);
+
+        expect(tagListEl.tabIndex).toBe(0);
+
+        componentInstance.tagList().keyManager.onKeydown(createKeyboardEvent('keydown', TAB));
+
+        // Native DOM must be -1 immediately — before any CD cycle — so the browser does not see
+        // the list host as a tab stop when processing the Tab key event. Without this, sync writes
+        // the host holds `tabIndex=0`, and the browser re-focuses it, triggering
+        // (focus) → setFirstItemActive() loop (reproducible with provideZoneChangeDetection({ eventCoalescing: true })).
+        expect(tagListEl.tabIndex).toBe(-1);
+    }));
+
+    it('should restore tabIndex to userTabIndex after tabOut', fakeAsync(() => {
+        const fixture = createStandaloneComponent(TestTagList);
+        const { componentInstance } = fixture;
+        const tagList = componentInstance.tagList();
+
+        tagList.tabIndex = 3;
+        fixture.detectChanges();
+
+        tagList.keyManager.onKeydown(createKeyboardEvent('keydown', TAB));
+
+        expect(tagList.tabIndex).toBe(-1);
+
+        tick();
+
+        expect(tagList.tabIndex).toBe(3);
+    }));
+
     it('should be draggable when draggable is enabled', () => {
         const fixture = createStandaloneComponent(TestTagList);
         const { debugElement, componentInstance } = fixture;
diff --git a/packages/components/tags/tag-list.component.ts b/packages/components/tags/tag-list.component.ts
index fbd2de623..2cdf64617 100644
--- a/packages/components/tags/tag-list.component.ts
+++ b/packages/components/tags/tag-list.component.ts
@@ -457,6 +457,7 @@ export class KbqTagList
         // it back to the first tag when the user tabs out.
         this.keyManager.tabOut.pipe(takeUntilDestroyed(this.destroyRef)).subscribe(() => {
             this._tabIndex = -1;
+            this.elementRef.nativeElement.tabIndex = -1;
 
             setTimeout(() => {
                 this._tabIndex = this.userTabIndex || 0;

From 2a640f467eca02423df9ec6be5e9d082a2653868 Mon Sep 17 00:00:00 2001
From: Nikita Guryev <nikgurv@gmail.com>
Date: Thu, 2 Jul 2026 17:25:07 +0300
Subject: [PATCH 2/3] chore: after review

---
 packages/components/tags/tag-list.component.spec.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/packages/components/tags/tag-list.component.spec.ts b/packages/components/tags/tag-list.component.spec.ts
index ed756100d..0480a1da5 100644
--- a/packages/components/tags/tag-list.component.spec.ts
+++ b/packages/components/tags/tag-list.component.spec.ts
@@ -1428,6 +1428,8 @@ describe(KbqTagList.name, () => {
         // the host holds `tabIndex=0`, and the browser re-focuses it, triggering
         // (focus) → setFirstItemActive() loop (reproducible with provideZoneChangeDetection({ eventCoalescing: true })).
         expect(tagListEl.tabIndex).toBe(-1);
+
+        tick();
     }));
 
     it('should restore tabIndex to userTabIndex after tabOut', fakeAsync(() => {

From c275dcce773e0dcb6e8876b2fe9666370ade1f34 Mon Sep 17 00:00:00 2001
From: Nikita Guryev <nikgurv@gmail.com>
Date: Fri, 3 Jul 2026 10:15:10 +0300
Subject: [PATCH 3/3] chore: after review

---
 packages/components/tags/tag-list.component.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/components/tags/tag-list.component.ts b/packages/components/tags/tag-list.component.ts
index 2cdf64617..bf8e21b6f 100644
--- a/packages/components/tags/tag-list.component.ts
+++ b/packages/components/tags/tag-list.component.ts
@@ -457,6 +457,7 @@ export class KbqTagList
         // it back to the first tag when the user tabs out.
         this.keyManager.tabOut.pipe(takeUntilDestroyed(this.destroyRef)).subscribe(() => {
             this._tabIndex = -1;
+            // Direct DOM write since the binding update is deferred with eventCoalescing.
             this.elementRef.nativeElement.tabIndex = -1;
 
             setTimeout(() => {