Good point to make a commit

tp-rtb-base-extension.js

@@ -0,0 +1,76 @@
+import { LitElement, html, css } from 'lit';
+
+export class TpRtbBaseExtension extends LitElement {
+  static get styles() {
+    return css`
+      :host {
+        display: inline-block;
+      }
+      
+      button {
+        margin: 0 2px;
+        padding: 4px 8px;
+        background: none;
+        border: 1px solid #ccc;
+        border-radius: 3px;
+        cursor: pointer;
+      }
+      
+      button:hover {
+        background-color: #f0f0f0;
+      }
+      
+      button.active {
+        background-color: #e0e0e0;
+      }
+    `;
+  }
+
+  static get properties() {
+    return {
+      label: { type: String },
+      active: { type: Boolean, reflect: true }
+    };
+  }
+
+  constructor() {
+    super();
+    this.label = '';
+    this.active = false;
+  }
+
+  render() {
+    return html`
+      <button class="${this.active ? 'active' : ''}" @click=${this._handleClick}>
+        ${this.label}
+      </button>
+    `;
+  }
+
+  connectedCallback() {
+    super.connectedCallback();
+    this._findParentEditor();
+  }
+
+  _findParentEditor() {
+    this.parentEditor = this.closest('tp-rich-text-box');
+  }
+
+  _editorReady(editorInstance) {
+    this.parentEditor.editor = editorInstance;
+    this._setupEditorListeners();
+  }
+
+  _setupEditorListeners() {
+    // To be implemented by child classes
+  }
+
+  _handleClick() {
+    // To be implemented by child classes
+  }
+
+  getExtension() {
+    // To be implemented by child classes
+    return null;
+  }
+}