feat(hooks): add setWidget API for multi-line status displays

- ctx.ui.setWidget(key, lines) for multi-line displays above editor
- Widgets appear below 'Working...' indicator, above editor
- Supports ANSI styling including strikethrough
- Added theme.strikethrough() method
- Plan-mode hook now shows todo list with checkboxes
- Completed items show checked box and strikethrough text

packages/coding-agent/src/core/custom-tools/loader.ts

@@ -92,6 +92,7 @@ function createNoOpUIContext(): HookUIContext {
 		input: async () => undefined,
 		notify: () => {},
 		setStatus: () => {},
+		setWidget: () => {},
 		custom: async () => undefined as never,
 		setEditorText: () => {},
 		getEditorText: () => "",

packages/coding-agent/src/core/hooks/runner.ts

@@ -49,6 +49,7 @@ const noOpUIContext: HookUIContext = {
 	input: async () => undefined,
 	notify: () => {},
 	setStatus: () => {},
+	setWidget: () => {},
 	custom: async () => undefined as never,
 	setEditorText: () => {},
 	getEditorText: () => "",

packages/coding-agent/src/core/hooks/types.ts

@@ -74,6 +74,28 @@ export interface HookUIContext {
 	 */
 	setStatus(key: string, text: string | undefined): void;
 
+	/**
+	 * Set a widget to display in the status area (above the editor, below "Working..." indicator).
+	 * Supports multi-line content. Pass undefined to clear.
+	 * Text can include ANSI escape codes for styling.
+	 *
+	 * @param key - Unique key to identify this widget (e.g., hook name)
+	 * @param lines - Array of lines to display, or undefined to clear
+	 *
+	 * @example
+	 * // Show a todo list
+	 * ctx.ui.setWidget("plan-todos", [
+	 *   theme.fg("accent", "Plan Progress:"),
+	 *   "☑ " + theme.fg("muted", theme.strikethrough("Step 1: Read files")),
+	 *   "☐ Step 2: Modify code",
+	 *   "☐ Step 3: Run tests",
+	 * ]);
+	 *
+	 * // Clear the widget
+	 * ctx.ui.setWidget("plan-todos", undefined);
+	 */
+	setWidget(key: string, lines: string[] | undefined): void;
+
 	/**
 	 * Show a custom component with keyboard focus.
 	 * The factory receives TUI, theme, and a done() callback to close the component.