diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 07b9770c..b5266050 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed IME hardware cursor positioning in the custom extension editor (`ctx.ui.editor()` / extension editor dialog) by propagating focus to the internal `Editor`, preventing the terminal cursor from getting stuck at the bottom-right during composition.
+
 ## [0.55.4] - 2026-03-02
 
 ### New Features
diff --git a/packages/coding-agent/src/modes/interactive/components/extension-editor.ts b/packages/coding-agent/src/modes/interactive/components/extension-editor.ts
index a9912f00..2b4d4814 100644
--- a/packages/coding-agent/src/modes/interactive/components/extension-editor.ts
+++ b/packages/coding-agent/src/modes/interactive/components/extension-editor.ts
@@ -11,6 +11,7 @@ import {
 	Container,
 	Editor,
 	type EditorOptions,
+	type Focusable,
 	getEditorKeybindings,
 	Spacer,
 	Text,
@@ -21,13 +22,22 @@ import { getEditorTheme, theme } from "../theme/theme.js";
 import { DynamicBorder } from "./dynamic-border.js";
 import { appKeyHint, keyHint } from "./keybinding-hints.js";
 
-export class ExtensionEditorComponent extends Container {
+export class ExtensionEditorComponent extends Container implements Focusable {
 	private editor: Editor;
 	private onSubmitCallback: (value: string) => void;
 	private onCancelCallback: () => void;
 	private tui: TUI;
 	private keybindings: KeybindingsManager;
 
+	private _focused = false;
+	get focused(): boolean {
+		return this._focused;
+	}
+	set focused(value: boolean) {
+		this._focused = value;
+		this.editor.focused = value;
+	}
+
 	constructor(
 		tui: TUI,
 		keybindings: KeybindingsManager,