diff --git a/android/app/src/main/java/com/example/gutenbergkit/EditorActivity.kt b/android/app/src/main/java/com/example/gutenbergkit/EditorActivity.kt
index ab173102..fb2c2e6b 100644
--- a/android/app/src/main/java/com/example/gutenbergkit/EditorActivity.kt
+++ b/android/app/src/main/java/com/example/gutenbergkit/EditorActivity.kt
@@ -1,5 +1,6 @@
 package com.example.gutenbergkit
 
+import android.app.AlertDialog
 import android.content.Context
 import android.content.Intent
 import android.content.pm.ApplicationInfo
@@ -311,6 +312,22 @@ fun EditorScreen(
                             }
                         }
                     })
+                    setAutocompleterTriggeredListener(object : GutenbergView.AutocompleterTriggeredListener {
+                        override fun onAutocompleterTriggered(type: String) {
+                            val suggestions = when (type) {
+                                "at-symbol" -> arrayOf("alice", "bob", "charlie")
+                                "plus-symbol" -> arrayOf("photoblog", "traveldiaries", "dailydev")
+                                else -> return
+                            }
+                            AlertDialog.Builder(context)
+                                .setTitle("Select a suggestion")
+                                .setItems(suggestions) { _, which ->
+                                    appendTextAtCursor(suggestions[which] + " ")
+                                }
+                                .setNegativeButton("Cancel", null)
+                                .show()
+                        }
+                    })
                     // Demo app has no persistence layer, so return null.
                     // In a real app, return the persisted title and content from autosave.
                     setLatestContentProvider(object : GutenbergView.LatestContentProvider {
diff --git a/ios/Demo-iOS/Sources/Views/EditorView.swift b/ios/Demo-iOS/Sources/Views/EditorView.swift
index 23dcf736..ca1aaed8 100644
--- a/ios/Demo-iOS/Sources/Views/EditorView.swift
+++ b/ios/Demo-iOS/Sources/Views/EditorView.swift
@@ -216,7 +216,24 @@ private struct _EditorView: UIViewControllerRepresentable {
         }
 
         func editor(_ viewController: EditorViewController, didTriggerAutocompleter type: String) {
-            // No-op for demo
+            let suggestions: [String]
+            switch type {
+            case "at-symbol":
+                suggestions = ["alice", "bob", "charlie"]
+            case "plus-symbol":
+                suggestions = ["photoblog", "traveldiaries", "dailydev"]
+            default:
+                return
+            }
+
+            let alert = UIAlertController(title: "Select a suggestion", message: nil, preferredStyle: .actionSheet)
+            for suggestion in suggestions {
+                alert.addAction(UIAlertAction(title: suggestion, style: .default) { _ in
+                    viewController.appendTextAtCursor(suggestion + " ")
+                })
+            }
+            alert.addAction(UIAlertAction(title: "Cancel", style: .cancel))
+            viewController.present(alert, animated: true)
         }
 
         func editor(_ viewController: EditorViewController, didOpenModalDialog dialogType: String) {
diff --git a/src/components/editor/test/use-host-bridge.test.jsx b/src/components/editor/test/use-host-bridge.test.jsx
index cd6ee49b..33d29a79 100644
--- a/src/components/editor/test/use-host-bridge.test.jsx
+++ b/src/components/editor/test/use-host-bridge.test.jsx
@@ -332,6 +332,49 @@ describe( 'useHostBridge', () => {
 		} );
 	} );
 
+	it( 'appendTextAtCursor preserves existing content when block attribute is a RichTextData object', () => {
+		const existingContent = 'Existing block content @';
+		const richTextData = {
+			toString: () => existingContent,
+			valueOf: () => existingContent,
+			toHTMLString: () => existingContent,
+		};
+
+		mockGetSelectedBlockClientId.mockReturnValue( 'block-1' );
+		mockGetBlock.mockReturnValue( {
+			name: 'core/paragraph',
+			clientId: 'block-1',
+			attributes: { content: richTextData },
+		} );
+		getBlockType.mockReturnValue( {
+			attributes: { content: { type: 'string' } },
+		} );
+		mockGetSelectionStart.mockReturnValue( {
+			clientId: 'block-1',
+			attributeKey: 'content',
+			offset: existingContent.length,
+		} );
+		mockGetSelectionEnd.mockReturnValue( {
+			clientId: 'block-1',
+			attributeKey: 'content',
+			offset: existingContent.length,
+		} );
+
+		renderHook( () =>
+			useHostBridge( defaultPost, editorRef, markBridgeReady )
+		);
+
+		window.editor.appendTextAtCursor( 'username ' );
+
+		// The block should contain the original content plus the
+		// appended text — not just the appended text alone.
+		expect( mockUpdateBlock ).toHaveBeenCalledWith( 'block-1', {
+			attributes: expect.objectContaining( {
+				content: 'Existing block content @username ',
+			} ),
+		} );
+	} );
+
 	it( 'appendTextAtCursor returns false when no block is selected', () => {
 		mockGetSelectedBlockClientId.mockReturnValue( null );
 
diff --git a/src/components/editor/use-host-bridge.js b/src/components/editor/use-host-bridge.js
index 073aec4f..f91392f2 100644
--- a/src/components/editor/use-host-bridge.js
+++ b/src/components/editor/use-host-bridge.js
@@ -150,9 +150,7 @@ export function useHostBridge( post, editorRef, markBridgeReady ) {
 				return false;
 			}
 
-			const blockContent = normalizeAttribute(
-				block.attributes?.content
-			);
+			const blockContent = block.attributes?.content || '';
 			const currentValue = create( { html: blockContent } );
 			const selectionStart = getSelectionStart();
 			const selectionEnd = getSelectionEnd();