diff --git a/src/components/Toolbar.test.tsx b/src/components/Toolbar.test.tsx
index aeaf6895..8300110a 100644
--- a/src/components/Toolbar.test.tsx
+++ b/src/components/Toolbar.test.tsx
@@ -112,7 +112,7 @@ describe('Toolbar', () => {
       const italic = screen.getByRole('button', { name: /Italic/ });
       const insertTable = screen.getByRole('button', { name: /^Insert table$/ });
       const insertImage = screen.getByRole('button', {
-        name: /Insert inline \(base64\) image/,
+        name: /Insert inline image/,
       });
       const enabledButtons = (
         screen.getAllByRole('button') as HTMLButtonElement[]
@@ -149,7 +149,7 @@ describe('Toolbar', () => {
 
       const bold = screen.getByRole('button', { name: /Bold/ });
       const insertImage = screen.getByRole('button', {
-        name: /Insert inline \(base64\) image/,
+        name: /Insert inline image/,
       });
       fireEvent.focus(insertImage);
       expect(insertImage).toHaveAttribute('tabindex', '0');
diff --git a/src/components/Toolbar.tsx b/src/components/Toolbar.tsx
index 55136e55..60da7703 100644
--- a/src/components/Toolbar.tsx
+++ b/src/components/Toolbar.tsx
@@ -8,7 +8,9 @@ import {
   type FocusEvent,
   type KeyboardEvent,
 } from 'react';
+import { Base64SizeError } from '../converter/base64.js';
 import { imageFileToInlineDataUri } from '../extensions/Base64Image.js';
+import { isSafeLinkHref } from '../extensions/SafeLink.js';
 import type { ImageConfig } from '../types.js';
 
 interface ToolbarProps {
@@ -30,6 +32,27 @@ interface ButtonProps {
 
 const TOOLBAR_ITEM_SELECTOR = 'button[data-cwl-toolbar-item="true"]';
 
+/** Read a genuine Blob's byte length without invoking caller-owned accessors. */
+function intrinsicBlobSize(blob: Blob): number {
+  const sizeGetter = Object.getOwnPropertyDescriptor(
+    globalThis.Blob.prototype,
+    'size',
+  )!.get!;
+  return Reflect.apply(sizeGetter, blob, []) as number;
+}
+
+/** Report an image failure without allowing host observer code to alter toolbar control flow. */
+function reportImageError(
+  onImageError: ((error: unknown) => void) | undefined,
+  error: unknown,
+): void {
+  try {
+    onImageError?.(error);
+  } catch {
+    // Host presentation or telemetry observers are best-effort only.
+  }
+}
+
 /** Return every toolbar button in visual and DOM navigation order. */
 function getToolbarButtons(toolbar: HTMLDivElement): HTMLButtonElement[] {
   return Array.from(
@@ -173,6 +196,7 @@ export function Toolbar({ editor, image, onImageError }: ToolbarProps) {
       editor.chain().focus().extendMarkRange('link').unsetLink().run();
       return;
     }
+    if (!isSafeLinkHref(url)) return;
     editor
       .chain()
       .focus()
@@ -203,18 +227,30 @@ export function Toolbar({ editor, image, onImageError }: ToolbarProps) {
       event.target.value = '';
       if (!file) return;
 
+      const maxSizeBytes = image?.maxSizeBytes ?? 10 * 1024 * 1024;
+      const sourceBytes = intrinsicBlobSize(file);
+      if (maxSizeBytes > 0 && sourceBytes > maxSizeBytes) {
+        reportImageError(
+          onImageError,
+          new Base64SizeError(sourceBytes, maxSizeBytes),
+        );
+        return;
+      }
+
       let src: string;
       try {
         src = await imageFileToInlineDataUri(file, {
-          maxSizeBytes: image?.maxSizeBytes ?? 10 * 1024 * 1024,
+          maxSizeBytes,
           maxDimension: image?.maxDimension ?? 1600,
           quality: image?.quality ?? 0.85,
         });
-      } catch (err) {
-        onImageError?.(err);
+      } catch {
+        reportImageError(onImageError, new Error('Image processing failed.'));
         return;
       }
 
+      if (editor.isDestroyed || !editor.isEditable) return;
+
       const alternativeText = window.prompt(
         'Image alternative text. Leave empty only if this image is decorative.',
         '',
@@ -368,7 +404,7 @@ export function Toolbar({ editor, image, onImageError }: ToolbarProps) {
           onClick={() => editor.chain().focus().deleteTable().run()}
         />
         <ToolbarButton
-          title="Insert inline (base64) image"
+          title="Insert inline image"
           label="🖼"
           onClick={() => fileInputRef.current?.click()}
         />
diff --git a/src/components/ToolbarCustomerCopy.test.tsx b/src/components/ToolbarCustomerCopy.test.tsx
new file mode 100644
index 00000000..4e56612b
--- /dev/null
+++ b/src/components/ToolbarCustomerCopy.test.tsx
@@ -0,0 +1,34 @@
+import { cleanup, render, screen } from '@testing-library/react';
+import { Editor } from '@tiptap/react';
+import { afterEach, describe, expect, it } from 'vitest';
+
+import { buildExtensions } from '../extensions/kit.js';
+import { Toolbar } from './Toolbar.js';
+
+let editor: Editor | undefined;
+
+afterEach(() => {
+  cleanup();
+  if (editor && !editor.isDestroyed) editor.destroy();
+  editor = undefined;
+});
+
+describe('Toolbar customer-facing image action copy', () => {
+  it('names the image action without exposing base64 implementation jargon', () => {
+    const element = document.createElement('div');
+    editor = new Editor({
+      element,
+      extensions: buildExtensions({ image: { maxDimension: 0 } }),
+      content: '<p>before</p>',
+    });
+
+    render(<Toolbar editor={editor} />);
+
+    expect(
+      screen.getByRole('button', { name: 'Insert inline image' }),
+    ).toBeInTheDocument();
+    expect(
+      screen.queryByRole('button', { name: /base64/i }),
+    ).not.toBeInTheDocument();
+  });
+});
diff --git a/src/components/ToolbarImageLifecycle.test.tsx b/src/components/ToolbarImageLifecycle.test.tsx
new file mode 100644
index 00000000..8f43f24c
--- /dev/null
+++ b/src/components/ToolbarImageLifecycle.test.tsx
@@ -0,0 +1,166 @@
+import { act, cleanup, fireEvent, render } from '@testing-library/react';
+import { Editor } from '@tiptap/react';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+
+import { buildExtensions } from '../extensions/kit.js';
+import { Toolbar } from './Toolbar.js';
+
+const PNG_BYTES = new Uint8Array([
+  0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a, 0x00, 0x00, 0x00, 0x0d,
+  0x49, 0x48, 0x44, 0x52, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01,
+  0x08, 0x06, 0x00, 0x00, 0x00, 0x1f, 0x15, 0xc4, 0x89,
+]);
+
+const openEditors: Array<{ editor: Editor; element: HTMLDivElement }> = [];
+
+function makeEditor(): Editor {
+  const element = document.createElement('div');
+  document.body.appendChild(element);
+  const editor = new Editor({
+    element,
+    extensions: buildExtensions({ image: { maxDimension: 0 } }),
+    content: '<p>before</p>',
+  });
+  openEditors.push({ editor, element });
+  return editor;
+}
+
+function delayedPngFile(delayMs = 25): File {
+  const file = new File([PNG_BYTES], 'slow.png', { type: 'image/png' });
+  Object.defineProperty(file, 'arrayBuffer', {
+    configurable: true,
+    value: () =>
+      new Promise<ArrayBuffer>((resolve) => {
+        setTimeout(() => resolve(PNG_BYTES.slice().buffer), delayMs);
+      }),
+  });
+  return file;
+}
+
+function fileInput(): HTMLInputElement {
+  return document.querySelector('input[type="file"]') as HTMLInputElement;
+}
+
+async function settleConversion(): Promise<void> {
+  await act(async () => {
+    await new Promise((resolve) => setTimeout(resolve, 45));
+  });
+}
+
+afterEach(() => {
+  cleanup();
+  for (const { editor, element } of openEditors.splice(0)) {
+    if (!editor.isDestroyed) editor.destroy();
+    element.remove();
+  }
+  vi.restoreAllMocks();
+});
+
+describe('Toolbar asynchronous image-upload lifecycle boundary', () => {
+  it('does not prompt or mutate after the editor becomes read-only', async () => {
+    const editor = makeEditor();
+    const before = editor.getHTML();
+    const prompt = vi.spyOn(window, 'prompt').mockReturnValue('stale image');
+    render(<Toolbar editor={editor} image={{ maxDimension: 0 }} />);
+
+    fireEvent.change(fileInput(), { target: { files: [delayedPngFile()] } });
+    editor.setEditable(false);
+    await settleConversion();
+
+    expect(prompt).not.toHaveBeenCalled();
+    expect(editor.getHTML()).toBe(before);
+    expect(editor.getHTML()).not.toContain('data:image/png;base64');
+  });
+
+  it('does not prompt after the editor is destroyed during conversion', async () => {
+    const editor = makeEditor();
+    const prompt = vi.spyOn(window, 'prompt').mockReturnValue('stale image');
+    render(<Toolbar editor={editor} image={{ maxDimension: 0 }} />);
+
+    fireEvent.change(fileInput(), { target: { files: [delayedPngFile()] } });
+    editor.destroy();
+    await settleConversion();
+
+    expect(prompt).not.toHaveBeenCalled();
+    expect(editor.isDestroyed).toBe(true);
+  });
+
+  it('does not expose hostile conversion throw values to the host error callback', async () => {
+    const editor = makeEditor();
+    const before = editor.getHTML();
+    const privateSentinel = new Error('private toolbar conversion sentinel');
+    const getPrototypeOf = vi.fn(() => {
+      throw privateSentinel;
+    });
+    const hostileThrownValue = new Proxy({}, { getPrototypeOf });
+    const hostileValues = new WeakSet<object>([hostileThrownValue]);
+    const file = new File([PNG_BYTES], 'hostile.png', { type: 'image/png' });
+    Object.defineProperty(file, 'arrayBuffer', {
+      configurable: true,
+      value: vi.fn().mockRejectedValue(hostileThrownValue),
+    });
+
+    let leakedHostileValue = false;
+    let observedError: unknown;
+    const onImageError = vi.fn((error: unknown) => {
+      observedError = error;
+      if (
+        typeof error === 'object' &&
+        error !== null &&
+        hostileValues.has(error)
+      ) {
+        leakedHostileValue = true;
+      }
+    });
+    const prompt = vi.spyOn(window, 'prompt').mockReturnValue('should not run');
+    render(
+      <Toolbar
+        editor={editor}
+        image={{ maxSizeBytes: 1024 * 1024, maxDimension: 0 }}
+        onImageError={onImageError}
+      />,
+    );
+
+    fireEvent.change(fileInput(), { target: { files: [file] } });
+    await settleConversion();
+
+    expect(onImageError).toHaveBeenCalledOnce();
+    expect(leakedHostileValue).toBe(false);
+    expect(getPrototypeOf).not.toHaveBeenCalled();
+    expect(observedError).toBeInstanceOf(Error);
+    expect((observedError as Error).message).toBe('Image processing failed.');
+    expect(prompt).not.toHaveBeenCalled();
+    expect(editor.getHTML()).toBe(before);
+    expect(editor.getHTML()).not.toContain('data:image');
+  });
+
+  it('contains host image-error observer failures after conversion rejection', async () => {
+    const editor = makeEditor();
+    const before = editor.getHTML();
+    const privateSentinel = new Error('private toolbar observer sentinel');
+    const failedFile = new File([PNG_BYTES], 'failed.png', { type: 'image/png' });
+    Object.defineProperty(failedFile, 'arrayBuffer', {
+      configurable: true,
+      value: vi.fn().mockRejectedValue(new Error('private conversion failure')),
+    });
+    const onImageError = vi.fn(() => {
+      throw privateSentinel;
+    });
+    const prompt = vi.spyOn(window, 'prompt').mockReturnValue('should not run');
+
+    render(
+      <Toolbar
+        editor={editor}
+        image={{ maxSizeBytes: 1024 * 1024, maxDimension: 0 }}
+        onImageError={onImageError}
+      />,
+    );
+
+    fireEvent.change(fileInput(), { target: { files: [failedFile] } });
+    await settleConversion();
+
+    expect(onImageError).toHaveBeenCalledOnce();
+    expect(prompt).not.toHaveBeenCalled();
+    expect(editor.getHTML()).toBe(before);
+  });
+});
diff --git a/src/components/ToolbarLinkPolicy.test.tsx b/src/components/ToolbarLinkPolicy.test.tsx
new file mode 100644
index 00000000..fee56eee
--- /dev/null
+++ b/src/components/ToolbarLinkPolicy.test.tsx
@@ -0,0 +1,50 @@
+import { cleanup, fireEvent, render, screen } from '@testing-library/react';
+import { Editor } from '@tiptap/react';
+import StarterKit from '@tiptap/starter-kit';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { Toolbar } from './Toolbar.js';
+
+const openEditors: Editor[] = [];
+
+function makeEditor(): Editor {
+  const element = document.createElement('div');
+  document.body.appendChild(element);
+  const editor = new Editor({
+    element,
+    extensions: [StarterKit],
+    content: '<p>link target</p>',
+  });
+  openEditors.push(editor);
+  return editor;
+}
+
+afterEach(() => {
+  cleanup();
+  for (const editor of openEditors.splice(0)) {
+    if (!editor.isDestroyed) editor.destroy();
+  }
+  vi.restoreAllMocks();
+});
+
+describe('Toolbar link policy boundary', () => {
+  it('rejects an executable URL before issuing an editor command', () => {
+    const editor = makeEditor();
+    const commandChain = {
+      focus: vi.fn(() => commandChain),
+      extendMarkRange: vi.fn(() => commandChain),
+      setLink: vi.fn(() => commandChain),
+      unsetLink: vi.fn(() => commandChain),
+      run: vi.fn(() => true),
+    };
+    vi.spyOn(editor, 'chain').mockReturnValue(
+      commandChain as unknown as ReturnType<Editor['chain']>,
+    );
+    vi.spyOn(window, 'prompt').mockReturnValue('javascript:alert(1)');
+
+    render(<Toolbar editor={editor} />);
+    fireEvent.click(screen.getByRole('button', { name: /Insert\/edit link/ }));
+
+    expect(commandChain.setLink).not.toHaveBeenCalled();
+    expect(commandChain.run).not.toHaveBeenCalled();
+  });
+});