diff --git a/projects/aas-portal/src/app/aas/aas.component.html b/projects/aas-portal/src/app/aas/aas.component.html
index cfebf37a..5c2dcc56 100644
--- a/projects/aas-portal/src/app/aas/aas.component.html
+++ b/projects/aas-portal/src/app/aas/aas.component.html
@@ -76,10 +76,10 @@
         </button>
     </div>
     <div class="btn-group me-2" [hidden]="readOnly()">
-        <button type="button" class="btn btn-primary" (click)="undo()" [disabled]="canUndo === false">
+        <button type="button" class="btn btn-primary" (click)="undo()" [disabled]="canUndo() === false">
             <i class="bi bi-arrow-counterclockwise"></i>
         </button>
-        <button type="button" class="btn btn-primary" (click)="redo()" [disabled]="canRedo === false">
+        <button type="button" class="btn btn-primary" (click)="redo()" [disabled]="canRedo() === false">
             <i class="bi bi-arrow-clockwise"></i>
         </button>
     </div>
diff --git a/projects/aas-portal/src/app/aas/aas.component.ts b/projects/aas-portal/src/app/aas/aas.component.ts
index b9c2ac4a..b4109c58 100644
--- a/projects/aas-portal/src/app/aas/aas.component.ts
+++ b/projects/aas-portal/src/app/aas/aas.component.ts
@@ -90,13 +90,9 @@ export class AASComponent implements OnInit, OnDestroy, AfterViewInit {
 
     public readonly selectedElements = signal<aas.Referable[]>([]);
 
-    public get canUndo(): boolean {
-        return this.commandHandler.canUndo;
-    }
+    public readonly canUndo = this.commandHandler.canUndo;
 
-    public get canRedo(): boolean {
-        return this.commandHandler.canRedo;
-    }
+    public readonly canRedo = this.commandHandler.canRedo;
 
     public readonly canPlay = computed(() => {
         const state = this.store.state();
diff --git a/projects/aas-portal/src/app/aas/command-handler.service.ts b/projects/aas-portal/src/app/aas/command-handler.service.ts
index 261df29b..25399bc7 100644
--- a/projects/aas-portal/src/app/aas/command-handler.service.ts
+++ b/projects/aas-portal/src/app/aas/command-handler.service.ts
@@ -6,7 +6,7 @@
  *
  *****************************************************************************/
 
-import { Injectable } from '@angular/core';
+import { Injectable, computed, signal } from '@angular/core';
 import { NotifyService } from 'aas-lib';
 import { Command } from '../types/command';
 
@@ -14,8 +14,8 @@ import { Command } from '../types/command';
     providedIn: 'root',
 })
 export class CommandHandlerService {
-    private commands: Array<Command> = [];
-    private position = -1;
+    private readonly commands = signal<Command[]>([]);
+    private readonly position = signal(-1);
 
     public constructor(private notify: NotifyService) {}
 
@@ -27,30 +27,26 @@ export class CommandHandlerService {
         try {
             command.execute();
 
-            if (this.commands.length > 0 && this.position < this.commands.length - 1) {
-                this.commands.splice(this.position + 1);
+            if (this.commands().length > 0 && this.position() < this.commands().length - 1) {
+                this.commands.update(values => values.filter((_, i) => i <= this.position()));
             }
 
-            this.commands.push(command);
-            ++this.position;
+            this.commands.update(values => [...values, command]);
+            this.position.update(value => value + 1);
         } catch (error) {
             command.abort();
             throw error;
         }
     }
 
-    public get canUndo(): boolean {
-        return this.position >= 0;
-    }
+    public readonly canUndo = computed(() => this.position() >= 0);
 
-    public get canRedo(): boolean {
-        return this.position + 1 < this.commands.length;
-    }
+    public readonly canRedo = computed(() => this.position() + 1 < this.commands().length);
 
     public undo(): void {
         try {
-            this.commands[this.position].undo();
-            --this.position;
+            this.commands()[this.position()].undo();
+            this.position.update(value => value - 1);
         } catch (error) {
             this.notify.error(error);
         }
@@ -58,15 +54,15 @@ export class CommandHandlerService {
 
     public redo(): void {
         try {
-            ++this.position;
-            this.commands[this.position].redo();
+            this.position.update(value => value + 1);
+            this.commands()[this.position()].redo();
         } catch (error) {
             this.notify.error(error);
         }
     }
 
     public clear(): void {
-        this.commands = [];
-        this.position = -1;
+        this.commands.set([]);
+        this.position.set(-1);
     }
 }
diff --git a/projects/aas-portal/src/app/dashboard/dashboard.component.ts b/projects/aas-portal/src/app/dashboard/dashboard.component.ts
index 5f9abcf1..3ab47d39 100644
--- a/projects/aas-portal/src/app/dashboard/dashboard.component.ts
+++ b/projects/aas-portal/src/app/dashboard/dashboard.component.ts
@@ -175,6 +175,10 @@ export class DashboardComponent implements OnInit, OnDestroy, AfterViewInit, Aft
 
     public readonly selectionMode = this.dashboard.selectionMode.asReadonly();
 
+    public readonly canUndo = computed(() => this.editMode() && this.commandHandler.canUndo());
+
+    public readonly canRedo = computed(() => this.editMode() && this.commandHandler.canRedo());
+
     public ngOnInit(): void {
         this.commandHandler.clear();
 
@@ -455,20 +459,12 @@ export class DashboardComponent implements OnInit, OnDestroy, AfterViewInit, Aft
         }
     }
 
-    public canUndo(): boolean {
-        return this.editMode() && this.commandHandler.canUndo;
-    }
-
     public undo(): void {
         if (this.canUndo()) {
             this.commandHandler.undo();
         }
     }
 
-    public canRedo(): boolean {
-        return this.editMode() && this.commandHandler.canRedo;
-    }
-
     public redo(): void {
         if (this.canRedo()) {
             this.commandHandler.redo();
diff --git a/projects/aas-portal/src/test/aas/aas.component.spec.ts b/projects/aas-portal/src/test/aas/aas.component.spec.ts
index 1d48184c..2cfe41d5 100644
--- a/projects/aas-portal/src/test/aas/aas.component.spec.ts
+++ b/projects/aas-portal/src/test/aas/aas.component.spec.ts
@@ -24,7 +24,7 @@ import { provideHttpClientTesting } from '@angular/common/http/testing';
 import { DashboardPage, DashboardService } from '../../app/dashboard/dashboard.service';
 import { DashboardChartType } from '../../app/dashboard/dashboard.service';
 import { Router, provideRouter } from '@angular/router';
-import { Component, Input, input, output, signal } from '@angular/core';
+import { Component, input, output, signal } from '@angular/core';
 import { AASApiService } from '../../app/aas/aas-api.service';
 import { ToolbarService } from '../../app/toolbar.service';
 import { AASStore } from '../../app/aas/aas.store';
@@ -58,16 +58,11 @@ class TestAASTreeComponent {
     standalone: true,
 })
 class TestSecureImageComponent {
-    @Input()
-    public src = '';
-    @Input()
-    public alt?: string;
-    @Input()
-    public classname?: string;
-    @Input()
-    public width = -1;
-    @Input()
-    public height = -1;
+    public readonly src = input.required<string>();
+    public readonly alt = input<string | undefined>();
+    public readonly classname = input<string | undefined>();
+    public readonly width = input<number | undefined>();
+    public readonly height = input<number | undefined>();
 }
 
 describe('AASComponent', () => {
diff --git a/projects/aas-portal/src/test/aas/command-handler.service.spec.ts b/projects/aas-portal/src/test/aas/command-handler.service.spec.ts
index 3c022b55..b1634bf1 100644
--- a/projects/aas-portal/src/test/aas/command-handler.service.spec.ts
+++ b/projects/aas-portal/src/test/aas/command-handler.service.spec.ts
@@ -88,41 +88,41 @@ describe('CommandHandlerService', () => {
         expect(service).toBeTruthy();
     });
 
-    it('indicates that undo is not possible', function () {
-        expect(service.canUndo).toBeFalse();
+    it('indicates that undo is not possible', () => {
+        expect(service.canUndo()).toBeFalse();
     });
 
-    it('indicates that redo is not possible', function () {
-        expect(service.canRedo).toBeFalse();
+    it('indicates that redo is not possible', () => {
+        expect(service.canRedo()).toBeFalse();
     });
 
-    it('can execute a command', function () {
+    it('can execute a command', () => {
         const spy = jasmine.createSpy('execute');
         service.execute(new TestCommand(spy));
         expect(spy).toHaveBeenCalled();
     });
 
-    it('can undo/redo a command', function () {
+    it('can undo/redo a command', () => {
         const undoSpy = jasmine.createSpy('undo');
         const redoSpy = jasmine.createSpy('redo');
         service.execute(new TestCommand(undefined, undoSpy, redoSpy));
-        expect(service.canUndo).toBeTrue();
+        expect(service.canUndo()).toBeTrue();
         service.undo();
         expect(undoSpy).toHaveBeenCalled();
-        expect(service.canRedo).toBeTrue();
+        expect(service.canRedo()).toBeTrue();
         service.redo();
         expect(redoSpy).toHaveBeenCalled();
     });
 
-    it('clears the undo/redo stack', function () {
+    it('clears the undo/redo stack', () => {
         service.execute(new TestCommand());
         service.execute(new TestCommand());
         service.clear();
-        expect(service.canUndo).toBeFalse();
-        expect(service.canRedo).toBeFalse();
+        expect(service.canUndo()).toBeFalse();
+        expect(service.canRedo()).toBeFalse();
     });
 
-    it('aborts a failed command', function () {
+    it('aborts a failed command', () => {
         const abortSpy = jasmine.createSpy('abort');
         expect(() => service.execute(new FailCommand(abortSpy))).toThrowError();
         expect(abortSpy).toHaveBeenCalled();