From 9dd6f8e92f505a381510a9d5042e2fb61224fdec Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Fri, 17 Apr 2026 20:55:33 +0100
Subject: [PATCH 01/15] feat(eventbus): create CopyUIEvent entity

---
 .../EventBus/events/ui/CopyUIEvent.ts         | 28 +++++++++++++++++++
 .../src/entities/EventBus/events/ui/index.ts  |  1 +
 2 files changed, 29 insertions(+)
 create mode 100644 packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts

diff --git a/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts b/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts
new file mode 100644
index 00000000..2472dcfe
--- /dev/null
+++ b/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts
@@ -0,0 +1,28 @@
+import { UIEventBase } from './UIEventBase.js';
+
+/**
+ * Name of the copy UI event (dispatched as `ui:copy`)
+ */
+export const CopyUIEventName = 'copy';
+
+/**
+ * Payload @todo update doc
+ */
+export interface CopyUIEventPayload {
+  /**
+   * @todo update doc
+   */
+  nativeEvent: ClipboardEvent;
+}
+
+/**
+ * Delegated copy event from the editor @todo update doc
+ */
+export class CopyUIEvent extends UIEventBase<CopyUIEventPayload> {
+  /**
+   * @param payload - carries the original DOM `ClipboardEvent` as `nativeEvent` for providing rich clipboard data
+   */
+  constructor(payload: CopyUIEventPayload) {
+    super(CopyUIEventName, payload);
+  }
+}
diff --git a/packages/sdk/src/entities/EventBus/events/ui/index.ts b/packages/sdk/src/entities/EventBus/events/ui/index.ts
index 69856918..c4770540 100644
--- a/packages/sdk/src/entities/EventBus/events/ui/index.ts
+++ b/packages/sdk/src/entities/EventBus/events/ui/index.ts
@@ -1,3 +1,4 @@
 export * from './UIEventBase.js';
 export * from './BeforeInputUIEvent.js';
 export * from './KeydownUIEvent.js';
+export * from './CopyUIEvent.js';

From b53c482f26f21768c06b98f8e948579507fddb03 Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Fri, 17 Apr 2026 21:19:53 +0100
Subject: [PATCH 02/15] feat(ui-blocks): subscribe for copy event and pass
 native event object to eventbus

---
 packages/ui/src/Blocks/Blocks.ts | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/packages/ui/src/Blocks/Blocks.ts b/packages/ui/src/Blocks/Blocks.ts
index 30df927a..e2c367fb 100644
--- a/packages/ui/src/Blocks/Blocks.ts
+++ b/packages/ui/src/Blocks/Blocks.ts
@@ -1,13 +1,14 @@
-import type { BlockAddedCoreEvent,
-  BlockRemovedCoreEvent,
-  EditorjsPlugin,
-  EditorjsPluginParams } from '@editorjs/sdk';
+import { CopyUIEvent } from '@editorjs/sdk';
 import {
   CoreEventType,
   UiComponentType,
   BeforeInputUIEvent
 } from '@editorjs/sdk';
-import type { EventBus } from '@editorjs/sdk';
+import type { EventBus,
+  BlockAddedCoreEvent,
+  BlockRemovedCoreEvent, CopyUIEventPayload,
+  EditorjsPlugin,
+  EditorjsPluginParams } from '@editorjs/sdk';
 import Style from './Blocks.module.pcss';
 import { isNativeInput, make } from '@editorjs/dom';
 import { BlocksHolderRenderedUIEvent, BlockSelectedUIEvent } from './events/index.js';
@@ -130,6 +131,16 @@ export class BlocksUI implements EditorjsPlugin {
       e.preventDefault();
     });
 
+    blocksHolder.addEventListener('copy', (e) => {
+      const payload: CopyUIEventPayload = {
+        nativeEvent: e,
+      };
+
+      this.#eventBus.dispatchEvent(new CopyUIEvent(payload));
+
+      e.preventDefault();
+    });
+
     return blocksHolder;
   }
 

From 0be2ca499b3ec69198381072431cd934d10db3a2 Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Fri, 17 Apr 2026 21:22:22 +0100
Subject: [PATCH 03/15] feat(core): init clipboard plugin

---
 packages/core/src/plugins/ClipboardPlugin.ts | 32 ++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 packages/core/src/plugins/ClipboardPlugin.ts

diff --git a/packages/core/src/plugins/ClipboardPlugin.ts b/packages/core/src/plugins/ClipboardPlugin.ts
new file mode 100644
index 00000000..fca4af3e
--- /dev/null
+++ b/packages/core/src/plugins/ClipboardPlugin.ts
@@ -0,0 +1,32 @@
+import type { CopyUIEvent, EditorAPI, EditorjsPlugin, EditorjsPluginParams } from '@editorjs/sdk';
+import { CopyUIEventName } from '@editorjs/sdk';
+import { PluginType } from '@editorjs/sdk';
+
+/**
+ * @todo update doc
+ */
+export class ClipboardPlugin implements EditorjsPlugin {
+  public static readonly type = PluginType.Plugin;
+
+  readonly #api: EditorAPI;
+
+  /**
+   * @param params @todo update doc
+   */
+  constructor(params: EditorjsPluginParams) {
+    const { api, eventBus } = params;
+
+    this.#api = api;
+
+    eventBus.addEventListener(`ui:${CopyUIEventName}`, (e: CopyUIEvent) => {
+      console.log('Copied to clipboard plugin', e.detail);
+    });
+  }
+
+  /**
+   * @todo update doc
+   */
+  public destroy(): void {
+    // do nothing
+  }
+}

From 10c1c22e669f0612168268da557951dfd8d8946e Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Fri, 17 Apr 2026 21:23:12 +0100
Subject: [PATCH 04/15] feat(core): use ClipboardPlugin

---
 packages/core/src/index.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index c5f7aa6f..69deda5e 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -21,6 +21,7 @@ import { EditorAPI } from './api/index.js';
 import { generateId } from './utils/uid.js';
 import { Paragraph, BoldInlineTool, LinkInlineTool, ItalicInlineTool } from './tools/internal';
 import { ShortcutsPlugin } from './plugins/ShortcutsPlugin.js';
+import { ClipboardPlugin } from './plugins/ClipboardPlugin.js';
 
 /**
  * If no holder is provided via config, the editor will be appended to the element with this id
@@ -135,6 +136,7 @@ export default class Core {
     this.use(ItalicInlineTool);
     this.use(LinkInlineTool);
     this.use(ShortcutsPlugin);
+    this.use(ClipboardPlugin);
   }
 
   /**

From bc3657c0c55f358f49f4529402fb9dc2487215a1 Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Sun, 24 May 2026 22:29:28 +0100
Subject: [PATCH 05/15] feat: implement clipboard plugin

---
 packages/core/src/api/SelectionAPI.ts         |  9 +++-
 .../core/src/components/SelectionManager.ts   | 30 +++++++++++-
 packages/core/src/plugins/ClipboardPlugin.ts  | 46 ++++++++++++++++++-
 packages/model/src/entities/Index/index.ts    |  8 ++++
 packages/sdk/src/api/SelectionAPI.ts          |  7 ++-
 .../EventBus/events/ui/CopyUIEvent.ts         |  3 +-
 packages/ui/src/Blocks/Blocks.ts              |  2 -
 7 files changed, 98 insertions(+), 7 deletions(-)

diff --git a/packages/core/src/api/SelectionAPI.ts b/packages/core/src/api/SelectionAPI.ts
index 4e139b26..bcbea136 100644
--- a/packages/core/src/api/SelectionAPI.ts
+++ b/packages/core/src/api/SelectionAPI.ts
@@ -2,7 +2,7 @@ import 'reflect-metadata';
 import { injectable } from 'inversify';
 
 import { SelectionManager } from '../components/SelectionManager.js';
-import { createInlineToolName } from '@editorjs/model';
+import { createInlineToolName, BlockNodeSerialized } from '@editorjs/model';
 import { InlineToolFormatData } from '@editorjs/sdk';
 import { SelectionAPI as SelectionApiInterface } from '@editorjs/sdk';
 
@@ -32,4 +32,11 @@ export class SelectionAPI implements SelectionApiInterface {
   public applyInlineToolForCurrentSelection(toolName: string, data?: InlineToolFormatData): void {
     this.#selectionManager.applyInlineToolForCurrentSelection(createInlineToolName(toolName), data);
   }
+
+  /**
+   *
+   */
+  public get selectedBlocks(): BlockNodeSerialized[] | null {
+    return this.#selectionManager.selectedBlocks();
+  }
 }
diff --git a/packages/core/src/components/SelectionManager.ts b/packages/core/src/components/SelectionManager.ts
index 6f2c1ad5..24359efa 100644
--- a/packages/core/src/components/SelectionManager.ts
+++ b/packages/core/src/components/SelectionManager.ts
@@ -4,7 +4,7 @@ import {
   createInlineToolData,
   FormattingAction,
   InlineFragment,
-  InlineToolName
+  InlineToolName, BlockNodeSerialized
 } from '@editorjs/model';
 import { CaretManagerCaretUpdatedEvent, Index, EditorJSModel, createInlineToolName } from '@editorjs/model';
 import { EventType } from '@editorjs/model';
@@ -177,4 +177,32 @@ export class SelectionManager {
       }
     }
   };
+
+  /**
+   *
+   */
+  public selectedBlocks(): BlockNodeSerialized[] | null {
+    const userCaret = this.#model.getCaret(this.#config.userId);
+    const index = userCaret?.index ?? null;
+
+    if (index === null) {
+      return null;
+    }
+
+    if (index.isBlockIndex) {
+      const { blockIndex } = index;
+
+      return [this.#model.serialized.blocks[blockIndex!]];
+    }
+
+    if (index.compositeSegments !== undefined) {
+      return index.compositeSegments.map((segment) => {
+        const { blockIndex } = segment;
+
+        return this.#model.serialized.blocks[blockIndex!];
+      });
+    }
+
+    return null;
+  }
 }
diff --git a/packages/core/src/plugins/ClipboardPlugin.ts b/packages/core/src/plugins/ClipboardPlugin.ts
index fca4af3e..08758228 100644
--- a/packages/core/src/plugins/ClipboardPlugin.ts
+++ b/packages/core/src/plugins/ClipboardPlugin.ts
@@ -19,7 +19,31 @@ export class ClipboardPlugin implements EditorjsPlugin {
     this.#api = api;
 
     eventBus.addEventListener(`ui:${CopyUIEventName}`, (e: CopyUIEvent) => {
-      console.log('Copied to clipboard plugin', e.detail);
+      const { nativeEvent } = e.detail;
+
+      const selectedBlocks = this.#api.selection.selectedBlocks;
+
+      /**
+       * Don't override native event if there are no blocks selected
+       */
+      if (selectedBlocks === null || selectedBlocks.length === 0) {
+        return;
+      }
+
+      nativeEvent.preventDefault();
+
+      const currentDOMSelection = window.getSelection();
+
+      if (!currentDOMSelection) {
+        return;
+      }
+
+      const selectionAsPlainText = currentDOMSelection?.toString() ?? '';
+      const selectionAsHTML = this.#parseDOMSelectionToHTML(currentDOMSelection);
+
+      nativeEvent.clipboardData?.setData('text/plain', selectionAsPlainText);
+      nativeEvent.clipboardData?.setData('text/html', selectionAsHTML);
+      nativeEvent.clipboardData?.setData('application/x-editor-js', JSON.stringify(selectedBlocks));
     });
   }
 
@@ -29,4 +53,24 @@ export class ClipboardPlugin implements EditorjsPlugin {
   public destroy(): void {
     // do nothing
   }
+
+  /**
+   *
+   * @param selection
+   */
+  #parseDOMSelectionToHTML(selection: Selection): string {
+    if (selection.rangeCount === 0) {
+      return '';
+    }
+
+    const container = document.createElement('div');
+
+    for (let i = 0; i < selection.rangeCount; i++) {
+      const range = selection.getRangeAt(i);
+
+      container.appendChild(range.cloneContents());
+    }
+
+    return container.innerHTML;
+  }
 }
diff --git a/packages/model/src/entities/Index/index.ts b/packages/model/src/entities/Index/index.ts
index 91162926..442c6516 100644
--- a/packages/model/src/entities/Index/index.ts
+++ b/packages/model/src/entities/Index/index.ts
@@ -279,4 +279,12 @@ export class Index {
     /* Stryker disable next-line ConditionalExpression, LogicalOperator -- compound data-index predicate; .isDataIndex specs cover field combinations */
     return this.blockIndex !== undefined && this.tuneName === undefined && this.dataKey !== undefined && this.textRange === undefined;
   }
+
+  /**
+   *
+   */
+  public get isCompositeIndex(): boolean {
+    /* Stryker disable next-line ConditionalExpression, LogicalOperator -- compound data-index predicate; .isDataIndex specs cover field combinations */
+    return this.compositeSegments !== undefined && this.compositeSegments.length > 0 && this.blockIndex === undefined && this.tuneName === undefined && this.dataKey === undefined && this.textRange === undefined;
+  }
 }
diff --git a/packages/sdk/src/api/SelectionAPI.ts b/packages/sdk/src/api/SelectionAPI.ts
index 6e12990e..4a417237 100644
--- a/packages/sdk/src/api/SelectionAPI.ts
+++ b/packages/sdk/src/api/SelectionAPI.ts
@@ -1,4 +1,4 @@
-import type { InlineToolName } from '@editorjs/model';
+import type { BlockNodeSerialized, InlineToolName } from '@editorjs/model';
 
 /**
  * Selection API interface
@@ -11,4 +11,9 @@ export interface SelectionAPI {
    * @param data - optional data for the inline tool
    */
   applyInlineToolForCurrentSelection(tool: InlineToolName, data?: Record<string, unknown>): void;
+
+  /**
+   *
+   */
+  get selectedBlocks(): BlockNodeSerialized[] | null;
 }
diff --git a/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts b/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts
index 2472dcfe..f9b65746 100644
--- a/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts
+++ b/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts
@@ -10,7 +10,8 @@ export const CopyUIEventName = 'copy';
  */
 export interface CopyUIEventPayload {
   /**
-   * @todo update doc
+   * Native ClipboardEvent
+   * UI does not call .preventDefault() for this event
    */
   nativeEvent: ClipboardEvent;
 }
diff --git a/packages/ui/src/Blocks/Blocks.ts b/packages/ui/src/Blocks/Blocks.ts
index e2c367fb..75aeaf94 100644
--- a/packages/ui/src/Blocks/Blocks.ts
+++ b/packages/ui/src/Blocks/Blocks.ts
@@ -137,8 +137,6 @@ export class BlocksUI implements EditorjsPlugin {
       };
 
       this.#eventBus.dispatchEvent(new CopyUIEvent(payload));
-
-      e.preventDefault();
     });
 
     return blocksHolder;

From 00d10ac9d205bc44e7178b8aa2c632f4ce652e3a Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Tue, 9 Jun 2026 19:21:18 +0100
Subject: [PATCH 06/15] fix(clipboard-plugin): prevent native event only after
 checking selection for null

---
 packages/core/src/plugins/ClipboardPlugin.ts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/core/src/plugins/ClipboardPlugin.ts b/packages/core/src/plugins/ClipboardPlugin.ts
index 08758228..b03c027b 100644
--- a/packages/core/src/plugins/ClipboardPlugin.ts
+++ b/packages/core/src/plugins/ClipboardPlugin.ts
@@ -30,17 +30,17 @@ export class ClipboardPlugin implements EditorjsPlugin {
         return;
       }
 
-      nativeEvent.preventDefault();
-
       const currentDOMSelection = window.getSelection();
 
       if (!currentDOMSelection) {
         return;
       }
 
-      const selectionAsPlainText = currentDOMSelection?.toString() ?? '';
+      const selectionAsPlainText = currentDOMSelection.toString();
       const selectionAsHTML = this.#parseDOMSelectionToHTML(currentDOMSelection);
 
+      nativeEvent.preventDefault();
+
       nativeEvent.clipboardData?.setData('text/plain', selectionAsPlainText);
       nativeEvent.clipboardData?.setData('text/html', selectionAsHTML);
       nativeEvent.clipboardData?.setData('application/x-editor-js', JSON.stringify(selectedBlocks));

From d426ae486f001f300753f80fcff44cb4381c750c Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Tue, 9 Jun 2026 19:23:38 +0100
Subject: [PATCH 07/15] chore: fix stryker exception description

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
---
 packages/model/src/entities/Index/index.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/model/src/entities/Index/index.ts b/packages/model/src/entities/Index/index.ts
index 442c6516..1ae6b2cd 100644
--- a/packages/model/src/entities/Index/index.ts
+++ b/packages/model/src/entities/Index/index.ts
@@ -281,10 +281,10 @@ export class Index {
   }
 
   /**
-   *
+   * Returns true if index points to a composite index
    */
   public get isCompositeIndex(): boolean {
-    /* Stryker disable next-line ConditionalExpression, LogicalOperator -- compound data-index predicate; .isDataIndex specs cover field combinations */
+    /* Stryker disable next-line ConditionalExpression, LogicalOperator -- compound composite-index predicate; .isCompositeIndex specs cover field combinations */
     return this.compositeSegments !== undefined && this.compositeSegments.length > 0 && this.blockIndex === undefined && this.tuneName === undefined && this.dataKey === undefined && this.textRange === undefined;
   }
 }

From 9f44277b05d0d1787f9fc0fa19731ba0ad74fd71 Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Tue, 7 Jul 2026 21:13:27 +0100
Subject: [PATCH 08/15] feat(clipboard-plugin): update docs, add destroy method
 implementation, replace div with template

---
 packages/core/src/plugins/ClipboardPlugin.ts | 47 +++++++++++++++-----
 1 file changed, 35 insertions(+), 12 deletions(-)

diff --git a/packages/core/src/plugins/ClipboardPlugin.ts b/packages/core/src/plugins/ClipboardPlugin.ts
index b03c027b..02acf39a 100644
--- a/packages/core/src/plugins/ClipboardPlugin.ts
+++ b/packages/core/src/plugins/ClipboardPlugin.ts
@@ -1,24 +1,32 @@
-import type { CopyUIEvent, EditorAPI, EditorjsPlugin, EditorjsPluginParams } from '@editorjs/sdk';
+import type { CopyUIEvent, EditorAPI, EditorjsPlugin, EditorjsPluginParams, EventBus } from '@editorjs/sdk';
 import { CopyUIEventName } from '@editorjs/sdk';
 import { PluginType } from '@editorjs/sdk';
 
 /**
- * @todo update doc
+ * Clipboard plugin handles copy events and provides rich clipboard data for selected blocks.
+ * When a user copies content, this plugin intercepts the event and adds EditorJS-specific data
+ * including the selected blocks metadata alongside plain text and HTML content.
  */
 export class ClipboardPlugin implements EditorjsPlugin {
   public static readonly type = PluginType.Plugin;
 
   readonly #api: EditorAPI;
+  readonly #eventBus: EventBus;
+  #copyEventListener: ((e: CopyUIEvent) => void) | undefined;
 
   /**
-   * @param params @todo update doc
+   * @param params - plugin configuration and dependencies
+   * @param params.config - EditorJS configuration
+   * @param params.api - EditorAPI instance for block and selection access
+   * @param params.eventBus - EventBus for event subscriptions
    */
   constructor(params: EditorjsPluginParams) {
     const { api, eventBus } = params;
 
     this.#api = api;
+    this.#eventBus = eventBus;
 
-    eventBus.addEventListener(`ui:${CopyUIEventName}`, (e: CopyUIEvent) => {
+    this.#copyEventListener = (e: CopyUIEvent) => {
       const { nativeEvent } = e.detail;
 
       const selectedBlocks = this.#api.selection.selectedBlocks;
@@ -44,33 +52,48 @@ export class ClipboardPlugin implements EditorjsPlugin {
       nativeEvent.clipboardData?.setData('text/plain', selectionAsPlainText);
       nativeEvent.clipboardData?.setData('text/html', selectionAsHTML);
       nativeEvent.clipboardData?.setData('application/x-editor-js', JSON.stringify(selectedBlocks));
-    });
+    };
+
+    eventBus.addEventListener(`ui:${CopyUIEventName}`, this.#copyEventListener);
   }
 
   /**
-   * @todo update doc
+   * Destroys the plugin and removes all event listeners
    */
   public destroy(): void {
-    // do nothing
+    this.removeEventListener();
+  }
+
+  /**
+   * Removes the event listener for copy events
+   * @internal
+   */
+  private removeEventListener(): void {
+    if (this.#copyEventListener !== undefined) {
+      this.#eventBus.removeEventListener(`ui:${CopyUIEventName}`, this.#copyEventListener);
+    }
+    this.#copyEventListener = undefined;
   }
 
   /**
-   *
-   * @param selection
+   * Parses DOM selection to HTML string
+   * @internal
+   * @param selection - DOM selection to parse
+   * @returns HTML string representation of the selection
    */
   #parseDOMSelectionToHTML(selection: Selection): string {
     if (selection.rangeCount === 0) {
       return '';
     }
 
-    const container = document.createElement('div');
+    const template = document.createElement('template');
 
     for (let i = 0; i < selection.rangeCount; i++) {
       const range = selection.getRangeAt(i);
 
-      container.appendChild(range.cloneContents());
+      template.content.appendChild(range.cloneContents());
     }
 
-    return container.innerHTML;
+    return template.innerHTML;
   }
 }

From 55b62c80e0187c6122ef76a289477c8244f0e61e Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Tue, 7 Jul 2026 21:56:50 +0100
Subject: [PATCH 09/15] chore: use currentSelection in selection manager

---
 packages/core/src/components/SelectionManager.ts | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/packages/core/src/components/SelectionManager.ts b/packages/core/src/components/SelectionManager.ts
index d1e7b74a..ca19b4e5 100644
--- a/packages/core/src/components/SelectionManager.ts
+++ b/packages/core/src/components/SelectionManager.ts
@@ -231,21 +231,20 @@ export class SelectionManager {
    *
    */
   public selectedBlocks(): BlockNodeSerialized[] | null {
-    const userCaret = this.#model.getCaret(this.#config.userId);
-    const index = userCaret?.index ?? null;
+    const currentSelectionIndex = this.currentSelection;
 
-    if (index === null) {
+    if (currentSelectionIndex === null) {
       return null;
     }
 
-    if (index.isBlockIndex) {
-      const { blockIndex } = index;
+    if (currentSelectionIndex.isBlockIndex) {
+      const { blockIndex } = currentSelectionIndex;
 
       return [this.#model.serialized.blocks[blockIndex!]];
     }
 
-    if (index.compositeSegments !== undefined) {
-      return index.compositeSegments.map((segment) => {
+    if (currentSelectionIndex.compositeSegments !== undefined) {
+      return currentSelectionIndex.compositeSegments.map((segment) => {
         const { blockIndex } = segment;
 
         return this.#model.serialized.blocks[blockIndex!];

From 2681e5bde79970a4f3778d84b78dbfb94232c21a Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Wed, 8 Jul 2026 18:57:14 +0100
Subject: [PATCH 10/15] feat(clipboard-plugin): describe clipboard object

---
 packages/core/src/plugins/ClipboardPlugin.ts | 43 +++++++++++++++++++-
 1 file changed, 41 insertions(+), 2 deletions(-)

diff --git a/packages/core/src/plugins/ClipboardPlugin.ts b/packages/core/src/plugins/ClipboardPlugin.ts
index 02acf39a..95417bcb 100644
--- a/packages/core/src/plugins/ClipboardPlugin.ts
+++ b/packages/core/src/plugins/ClipboardPlugin.ts
@@ -1,4 +1,4 @@
-import type { CopyUIEvent, EditorAPI, EditorjsPlugin, EditorjsPluginParams, EventBus } from '@editorjs/sdk';
+import type { BlockData, CopyUIEvent, EditorAPI, EditorjsPlugin, EditorjsPluginParams, EventBus } from '@editorjs/sdk';
 import { CopyUIEventName } from '@editorjs/sdk';
 import { PluginType } from '@editorjs/sdk';
 
@@ -46,12 +46,13 @@ export class ClipboardPlugin implements EditorjsPlugin {
 
       const selectionAsPlainText = currentDOMSelection.toString();
       const selectionAsHTML = this.#parseDOMSelectionToHTML(currentDOMSelection);
+      const clipboardEditorJSObject = this.#createClipboardObject(selectedBlocks);
 
       nativeEvent.preventDefault();
 
       nativeEvent.clipboardData?.setData('text/plain', selectionAsPlainText);
       nativeEvent.clipboardData?.setData('text/html', selectionAsHTML);
-      nativeEvent.clipboardData?.setData('application/x-editor-js', JSON.stringify(selectedBlocks));
+      nativeEvent.clipboardData?.setData('application/x-editor-js', JSON.stringify(clipboardEditorJSObject));
     };
 
     eventBus.addEventListener(`ui:${CopyUIEventName}`, this.#copyEventListener);
@@ -96,4 +97,42 @@ export class ClipboardPlugin implements EditorjsPlugin {
 
     return template.innerHTML;
   }
+
+  /**
+   *
+   * @param blocks - content to create a clipboard object
+   */
+  #createClipboardObject(blocks: BlockData[] = []): ClipboardEditorJSObject {
+    return {
+      blocks,
+      meta: {
+        version: '3.0.0',
+      },
+    };
+  }
+}
+
+/**
+ *
+ */
+interface ClipboardEditorJSObject {
+  /**
+   *
+   */
+  blocks: BlockData[];
+
+  /**
+   *
+   */
+  meta: Meta;
+}
+
+/**
+ *
+ */
+interface Meta {
+  /**
+   *
+   */
+  version: string;
 }

From 2b288dc5b1bfbd069abcb307134a9fafa0cf479c Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Wed, 8 Jul 2026 20:07:27 +0100
Subject: [PATCH 11/15] refactor(selection-api): return empty array instead of
 null

---
 packages/core/src/components/SelectionManager.ts | 6 +++---
 packages/core/src/plugins/ClipboardPlugin.ts     | 2 +-
 packages/sdk/src/api/SelectionAPI.ts             | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/packages/core/src/components/SelectionManager.ts b/packages/core/src/components/SelectionManager.ts
index ca19b4e5..5a75b05b 100644
--- a/packages/core/src/components/SelectionManager.ts
+++ b/packages/core/src/components/SelectionManager.ts
@@ -230,11 +230,11 @@ export class SelectionManager {
   /**
    *
    */
-  public selectedBlocks(): BlockNodeSerialized[] | null {
+  public selectedBlocks(): BlockNodeSerialized[] {
     const currentSelectionIndex = this.currentSelection;
 
     if (currentSelectionIndex === null) {
-      return null;
+      return [];
     }
 
     if (currentSelectionIndex.isBlockIndex) {
@@ -251,6 +251,6 @@ export class SelectionManager {
       });
     }
 
-    return null;
+    return [];
   }
 }
diff --git a/packages/core/src/plugins/ClipboardPlugin.ts b/packages/core/src/plugins/ClipboardPlugin.ts
index 95417bcb..8a111aac 100644
--- a/packages/core/src/plugins/ClipboardPlugin.ts
+++ b/packages/core/src/plugins/ClipboardPlugin.ts
@@ -34,7 +34,7 @@ export class ClipboardPlugin implements EditorjsPlugin {
       /**
        * Don't override native event if there are no blocks selected
        */
-      if (selectedBlocks === null || selectedBlocks.length === 0) {
+      if (selectedBlocks.length === 0) {
         return;
       }
 
diff --git a/packages/sdk/src/api/SelectionAPI.ts b/packages/sdk/src/api/SelectionAPI.ts
index f7daecfe..d22b5754 100644
--- a/packages/sdk/src/api/SelectionAPI.ts
+++ b/packages/sdk/src/api/SelectionAPI.ts
@@ -67,5 +67,5 @@ export interface SelectionAPI {
   /**
    *
    */
-  get selectedBlocks(): BlockNodeSerialized[] | null;
+  get selectedBlocks(): BlockNodeSerialized[];
 }

From f2a60679c05e66a490384308ed3f24119251b9fb Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Wed, 8 Jul 2026 20:15:19 +0100
Subject: [PATCH 12/15] chore: add docs

---
 packages/core/src/api/SelectionAPI.ts            |  4 ++--
 packages/core/src/components/SelectionManager.ts |  2 +-
 packages/core/src/plugins/ClipboardPlugin.ts     | 14 ++++++++------
 packages/sdk/src/api/SelectionAPI.ts             |  2 +-
 4 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/packages/core/src/api/SelectionAPI.ts b/packages/core/src/api/SelectionAPI.ts
index 32be09f9..5e2b323a 100644
--- a/packages/core/src/api/SelectionAPI.ts
+++ b/packages/core/src/api/SelectionAPI.ts
@@ -90,9 +90,9 @@ export class SelectionAPI implements SelectionApiInterface {
   }
 
   /**
-   *
+   * Returns array of selected blocks
    */
-  public get selectedBlocks(): BlockNodeSerialized[] | null {
+  public get selectedBlocks(): BlockNodeSerialized[] {
     return this.#selectionManager.selectedBlocks();
   }
 }
diff --git a/packages/core/src/components/SelectionManager.ts b/packages/core/src/components/SelectionManager.ts
index 5a75b05b..4c11f87b 100644
--- a/packages/core/src/components/SelectionManager.ts
+++ b/packages/core/src/components/SelectionManager.ts
@@ -228,7 +228,7 @@ export class SelectionManager {
   };
 
   /**
-   *
+   * Returns an array of selected blocks using the current selection index
    */
   public selectedBlocks(): BlockNodeSerialized[] {
     const currentSelectionIndex = this.currentSelection;
diff --git a/packages/core/src/plugins/ClipboardPlugin.ts b/packages/core/src/plugins/ClipboardPlugin.ts
index 8a111aac..a51be293 100644
--- a/packages/core/src/plugins/ClipboardPlugin.ts
+++ b/packages/core/src/plugins/ClipboardPlugin.ts
@@ -99,13 +99,15 @@ export class ClipboardPlugin implements EditorjsPlugin {
   }
 
   /**
-   *
+   * Creates representation of copied from EditorJS data as an object with metadata
+   * @internal
    * @param blocks - content to create a clipboard object
    */
   #createClipboardObject(blocks: BlockData[] = []): ClipboardEditorJSObject {
     return {
       blocks,
       meta: {
+        // @todo get version info from Core
         version: '3.0.0',
       },
     };
@@ -113,26 +115,26 @@ export class ClipboardPlugin implements EditorjsPlugin {
 }
 
 /**
- *
+ * Custom EditorJS data-type object for clipboard events
  */
 interface ClipboardEditorJSObject {
   /**
-   *
+   * Array of copied blocks data
    */
   blocks: BlockData[];
 
   /**
-   *
+   * Metadata from EditorJS
    */
   meta: Meta;
 }
 
 /**
- *
+ * Metadata from EditorJS
  */
 interface Meta {
   /**
-   *
+   * Version of EditorJS Core
    */
   version: string;
 }
diff --git a/packages/sdk/src/api/SelectionAPI.ts b/packages/sdk/src/api/SelectionAPI.ts
index d22b5754..6585d2dc 100644
--- a/packages/sdk/src/api/SelectionAPI.ts
+++ b/packages/sdk/src/api/SelectionAPI.ts
@@ -65,7 +65,7 @@ export interface SelectionAPI {
   caretIndex: Index | null;
 
   /**
-   *
+   * Returns array of selected blocks
    */
   get selectedBlocks(): BlockNodeSerialized[];
 }

From 264f721669a93b4c731acfbc69c8af7e080596ed Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Wed, 8 Jul 2026 21:04:23 +0100
Subject: [PATCH 13/15] chore: update docs

---
 .../src/entities/EventBus/events/ui/CopyUIEvent.ts  |  5 +++--
 packages/ui/src/Blocks/Blocks.ts                    | 13 ++++---------
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts b/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts
index f9b65746..abf86fdf 100644
--- a/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts
+++ b/packages/sdk/src/entities/EventBus/events/ui/CopyUIEvent.ts
@@ -6,7 +6,8 @@ import { UIEventBase } from './UIEventBase.js';
 export const CopyUIEventName = 'copy';
 
 /**
- * Payload @todo update doc
+ * Payload of CopyUIEvent
+ * Contains a native clipboard event
  */
 export interface CopyUIEventPayload {
   /**
@@ -17,7 +18,7 @@ export interface CopyUIEventPayload {
 }
 
 /**
- * Delegated copy event from the editor @todo update doc
+ * Delegated copy event from the editor block holder
  */
 export class CopyUIEvent extends UIEventBase<CopyUIEventPayload> {
   /**
diff --git a/packages/ui/src/Blocks/Blocks.ts b/packages/ui/src/Blocks/Blocks.ts
index e61cf222..66f3037d 100644
--- a/packages/ui/src/Blocks/Blocks.ts
+++ b/packages/ui/src/Blocks/Blocks.ts
@@ -1,19 +1,14 @@
-import type {
+import type { EventBus,
   BlockAddedCoreEvent,
-  BlockRemovedCoreEvent, CopyUIEvent, EditorAPI,
+  BlockRemovedCoreEvent, CopyUIEventPayload,
   EditorjsPlugin,
-  EditorjsPluginParams
-} from '@editorjs/sdk';
+  EditorjsPluginParams, EditorAPI } from '@editorjs/sdk';
 import {
   CoreEventType,
+  CopyUIEvent,
   UiComponentType,
   BeforeInputUIEvent
 } from '@editorjs/sdk';
-import type { EventBus,
-  BlockAddedCoreEvent,
-  BlockRemovedCoreEvent, CopyUIEventPayload,
-  EditorjsPlugin,
-  EditorjsPluginParams } from '@editorjs/sdk';
 import Style from './Blocks.module.pcss';
 import { isNativeInput, make } from '@editorjs/dom';
 import { BlocksHolderRenderedUIEvent, BlockSelectedUIEvent } from './events/index.js';

From f4601a6d56fd3ef0cca46a8690819dd3e4259130 Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Wed, 8 Jul 2026 21:07:55 +0100
Subject: [PATCH 14/15] fix: make removeEventListener js-private

---
 packages/core/src/plugins/ClipboardPlugin.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/core/src/plugins/ClipboardPlugin.ts b/packages/core/src/plugins/ClipboardPlugin.ts
index a51be293..075bf79f 100644
--- a/packages/core/src/plugins/ClipboardPlugin.ts
+++ b/packages/core/src/plugins/ClipboardPlugin.ts
@@ -62,14 +62,14 @@ export class ClipboardPlugin implements EditorjsPlugin {
    * Destroys the plugin and removes all event listeners
    */
   public destroy(): void {
-    this.removeEventListener();
+    this.#removeEventListener();
   }
 
   /**
    * Removes the event listener for copy events
    * @internal
    */
-  private removeEventListener(): void {
+  #removeEventListener(): void {
     if (this.#copyEventListener !== undefined) {
       this.#eventBus.removeEventListener(`ui:${CopyUIEventName}`, this.#copyEventListener);
     }

From ec4aca5108782f66020bd58f344682658935e4dd Mon Sep 17 00:00:00 2001
From: Ilya Maroz <37909603+ilyamore88@users.noreply.github.com>
Date: Thu, 9 Jul 2026 20:30:33 +0100
Subject: [PATCH 15/15] chore(clipboard-plugin): add unit-tests

---
 .../core/src/plugins/ClipboardPlugin.spec.ts  | 321 ++++++++++++++++++
 1 file changed, 321 insertions(+)
 create mode 100644 packages/core/src/plugins/ClipboardPlugin.spec.ts

diff --git a/packages/core/src/plugins/ClipboardPlugin.spec.ts b/packages/core/src/plugins/ClipboardPlugin.spec.ts
new file mode 100644
index 00000000..01ae63c0
--- /dev/null
+++ b/packages/core/src/plugins/ClipboardPlugin.spec.ts
@@ -0,0 +1,321 @@
+/* eslint-disable @typescript-eslint/naming-convention */
+import { jest } from '@jest/globals';
+import { ClipboardPlugin } from './ClipboardPlugin';
+import type { CoreConfigValidated, EditorjsPluginParams } from '@editorjs/sdk';
+import { EventBus } from '@editorjs/sdk';
+import { CopyUIEventName } from '@editorjs/sdk';
+import { EditorAPI } from '../api';
+
+jest.mock('@editorjs/sdk', () => {
+  const originalModule = jest.requireActual('@editorjs/sdk');
+
+  return {
+    // @ts-expect-error - jest.requireActual returns object
+    ...originalModule,
+    EventBus: jest.fn().mockImplementation(() => {
+      const listeners = new Map<string, EventListener>();
+
+      return {
+        addEventListener: jest.fn((event: string, fn: EventListener) => {
+          listeners.set(event, fn);
+        }),
+        removeEventListener: jest.fn((event: string) => {
+          listeners.delete(event);
+        }),
+        /**
+         * Test helper: dispatch a previously-registered event
+         * @param event - event name to fire
+         * @param evt - event payload
+         */
+        __fire: (event: string, evt: Event) => listeners.get(event)?.(evt),
+      };
+    }),
+  };
+});
+
+jest.mock('../api', () => {
+  return {
+    EditorAPI: jest.fn().mockImplementation(() => ({
+      selection: {
+        selectedBlocks: [] as unknown[],
+      },
+    })),
+  };
+});
+
+describe('ClipboardPlugin', () => {
+  let pluginParamsMock: EditorjsPluginParams;
+
+  beforeEach(() => {
+    pluginParamsMock = {
+      eventBus: new EventBus(),
+      api: new EditorAPI(),
+      config: {} as CoreConfigValidated,
+    };
+  });
+
+  describe('constructor()', () => {
+    it('should add CopyUIEvent listener', () => {
+      const { eventBus } = pluginParamsMock;
+
+      new ClipboardPlugin(pluginParamsMock);
+
+      expect(eventBus.addEventListener).toHaveBeenCalled();
+    });
+  });
+
+  describe('.destroy()', () => {
+    it('should remove CopyUIEvent listener', () => {
+      const { eventBus } = pluginParamsMock;
+      const cp = new ClipboardPlugin(pluginParamsMock);
+
+      cp.destroy();
+
+      expect(eventBus.removeEventListener).toHaveBeenCalled();
+    });
+  });
+
+  describe('CopyUIEvent listener', () => {
+    /**
+     * Shape of `document` exposed to the plugin under test.
+     */
+    interface DocumentStub {
+      /**
+       * Creates a fake element; only `'template'` is exercised by the plugin.
+       */
+      createElement: (tag: string) => unknown;
+    }
+
+    /**
+     * Shape of `window` exposed to the plugin under test.
+     */
+    interface WindowStub {
+      /**
+       * Returns a fake `Selection` matching the `MockDOMSelectionOptions` shape.
+       */
+      getSelection: () => unknown;
+    }
+
+    /**
+     * `globalThis` augmented with the DOM globals the plugin reads at runtime.
+     * Used to stub `window.getSelection` / `document.createElement` under the
+     * `node` Jest test environment.
+     */
+    interface GlobalThisWithDOM {
+      /**
+       * `document` global; only present under DOM-capable test environments.
+       */
+      document?: DocumentStub;
+      /**
+       * `window` global; only present under DOM-capable test environments.
+       */
+      window?: WindowStub;
+    }
+
+    // eslint-disable-next-line jsdoc/require-jsdoc
+    type FireableEventBus = EventBus & { __fire: (event: string, evt: Event) => void };
+
+    /**
+     * Spies returned by `dispatchCopyEvent` for assertions on the native event.
+     */
+    interface DispatchedEventSpies {
+      /**
+       * Spy on the native event's `preventDefault` method.
+       */
+      preventDefault: jest.Mock;
+      /**
+       * Spy on the native event's `clipboardData.setData` method.
+       */
+      setData: jest.Mock;
+    }
+
+    /**
+     * Builds a stub `CopyUIEvent`-shaped object with a `preventDefault` spy and a
+     * `clipboardData.setData` spy, then dispatches it through the EventBus mock.
+     * @returns spies for `preventDefault` and `clipboardData.setData`
+     */
+    function dispatchCopyEvent(): DispatchedEventSpies {
+      const eventBus = pluginParamsMock.eventBus as unknown as FireableEventBus;
+      const preventDefault = jest.fn();
+      const setData = jest.fn();
+
+      const nativeEvent = {
+        preventDefault,
+        clipboardData: { setData },
+      } as unknown as ClipboardEvent;
+      const uiEvent = { detail: { nativeEvent } } as unknown as Event;
+
+      eventBus.__fire(`ui:${CopyUIEventName}`, uiEvent);
+
+      return {
+        preventDefault,
+        setData,
+      };
+    }
+
+    // eslint-disable-next-line jsdoc/require-jsdoc
+    function setSelectedBlocks(blocks: unknown[]): void {
+      const { api } = pluginParamsMock;
+
+      // eslint-disable-next-line jsdoc/require-jsdoc
+      (api.selection as { selectedBlocks: unknown[] }).selectedBlocks = blocks;
+    }
+
+    /**
+     * Describes a stubbed DOM selection for the duration of a single test.
+     */
+    interface MockDOMSelectionOptions {
+      /**
+       * Value returned by `selection.toString()`.
+       */
+      plainText: string;
+      /**
+       * Inner HTML of the resulting `HTMLTemplateElement`.
+       */
+      html: string;
+      /**
+       * Number of ranges in the selection. Defaults to `1`.
+       */
+      rangeCount?: number;
+    }
+
+    /**
+     * Stubs the DOM globals (`window.getSelection`, `document.createElement`) so the
+     * plugin's DOM-dependent code paths can be exercised under the `node` test env.
+     * Returns a `restore` callback to undo the mocks in `afterEach`.
+     * @param options - plain text and HTML the selection should expose
+     * @returns restore function that reinstates the original globals
+     */
+    function mockDOMSelection(options: MockDOMSelectionOptions): () => void {
+      const { plainText, html, rangeCount = 1 } = options;
+
+      const cloneContents = jest.fn(() => ({}));
+      const range = { cloneContents };
+      const selection = {
+        rangeCount,
+        toString: jest.fn(() => plainText),
+        getRangeAt: jest.fn(() => range),
+      };
+      const templateContent = {
+        appendChild: jest.fn(),
+      };
+      const template = {
+        content: templateContent,
+        get innerHTML(): string {
+          return html;
+        },
+      };
+      const documentStub = {
+        createElement: jest.fn((tag: string) => {
+          if (tag === 'template') {
+            return template;
+          }
+
+          return undefined;
+        }),
+      };
+      const windowStub = {
+        getSelection: jest.fn(() => selection),
+      };
+      const hadDocument = Object.prototype.hasOwnProperty.call(globalThis, 'document');
+      const hadWindow = Object.prototype.hasOwnProperty.call(globalThis, 'window');
+      const g = globalThis as GlobalThisWithDOM;
+      const originalDocument = g.document;
+      const originalWindow = g.window;
+
+      g.document = documentStub;
+      g.window = windowStub;
+
+      return (): void => {
+        if (hadDocument) {
+          g.document = originalDocument;
+        } else {
+          delete g.document;
+        }
+        if (hadWindow) {
+          g.window = originalWindow;
+        } else {
+          delete g.window;
+        }
+      };
+    }
+
+    describe('when no blocks are selected', () => {
+      beforeEach(() => {
+        setSelectedBlocks([]);
+      });
+
+      it('should not prevent native event', () => {
+        new ClipboardPlugin(pluginParamsMock);
+
+        const { preventDefault } = dispatchCopyEvent();
+
+        expect(preventDefault).not.toHaveBeenCalled();
+      });
+    });
+
+    describe('when blocks are selected', () => {
+      let restoreDOMMocks: () => void;
+
+      beforeEach(() => {
+        setSelectedBlocks([
+          { id: 'b1',
+            type: 'paragraph' },
+          { id: 'b2',
+            type: 'header' },
+        ]);
+      });
+
+      afterEach(() => {
+        if (restoreDOMMocks !== undefined) {
+          restoreDOMMocks();
+          restoreDOMMocks = (): void => undefined;
+        }
+      });
+
+      it('should add current selection as text to native event', () => {
+        restoreDOMMocks = mockDOMSelection({ plainText: 'hello',
+          html: '<p>hello</p>' });
+
+        new ClipboardPlugin(pluginParamsMock);
+
+        const { setData } = dispatchCopyEvent();
+
+        expect(setData).toHaveBeenCalledWith('text/plain', 'hello');
+      });
+
+      it('should add current selection as html to native event', () => {
+        restoreDOMMocks = mockDOMSelection({ plainText: 'hello',
+          html: '<p>hello</p>' });
+
+        new ClipboardPlugin(pluginParamsMock);
+
+        const { setData } = dispatchCopyEvent();
+
+        expect(setData).toHaveBeenCalledWith('text/html', '<p>hello</p>');
+      });
+
+      it('should add custom editorjs data-type to native event', () => {
+        restoreDOMMocks = mockDOMSelection({ plainText: 'hello',
+          html: '<p>hello</p>' });
+
+        new ClipboardPlugin(pluginParamsMock);
+
+        const { setData } = dispatchCopyEvent();
+
+        expect(setData).toHaveBeenCalledWith(
+          'application/x-editor-js',
+          JSON.stringify({
+            blocks: [
+              { id: 'b1',
+                type: 'paragraph' },
+              { id: 'b2',
+                type: 'header' },
+            ],
+            meta: { version: '3.0.0' },
+          })
+        );
+      });
+    });
+  });
+});