fix(coding-agent): stabilize interactive status indicators

Closes #6026

packages/coding-agent/test/status-indicator.test.ts

@@ -0,0 +1,32 @@
+import type { TUI } from "@earendil-works/pi-tui";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { IdleStatus, RetryStatusIndicator } from "../src/modes/interactive/components/status-indicator.ts";
+import { initTheme } from "../src/modes/interactive/theme/theme.ts";
+
+describe("status indicators", () => {
+	afterEach(() => {
+		vi.useRealTimers();
+	});
+
+	it("keeps idle status at the same height as status indicators", () => {
+		const idleStatus = new IdleStatus();
+
+		const lines = idleStatus.render(20);
+		expect(lines).toHaveLength(2);
+		expect(lines).toEqual([" ".repeat(20), " ".repeat(20)]);
+	});
+
+	it("disposes retry countdown updates", () => {
+		initTheme("dark");
+		vi.useFakeTimers();
+		const requestRender = vi.fn();
+		const tui = { requestRender } as unknown as TUI;
+		const indicator = new RetryStatusIndicator(tui, 1, 3, 1000);
+		const callsBeforeDispose = requestRender.mock.calls.length;
+
+		indicator.dispose();
+		vi.advanceTimersByTime(2000);
+
+		expect(requestRender).toHaveBeenCalledTimes(callsBeforeDispose);
+	});
+});