fix: improve custom input editor rendering

tests/render-helpers.test.ts

@@ -5,6 +5,7 @@ import { renderEditorBlock } from "../src/ui/render-helpers.ts";
 const ABC_PATTERN = /abc/;
 const BORDER_PATTERN = /┌|└/;
 const TYPE_YOUR_PATTERN = /Type your/;
+const SELECTED_BG_PATTERN = /\{selectedBg\}/;
 
 function mockTheme() {
 	return {
@@ -21,7 +22,7 @@ test("renderEditorBlock strips editor borders", () => {
 	const lines: string[] = [];
 	renderEditorBlock({
 		lines,
-		editorLines: ["┌──┐", "│abc│", "└──┘"],
+		editorLines: ["┌──┐", "abc", "└──┘"],
 		width: 40,
 		theme: mockTheme() as never,
 		indent: "   ",
@@ -30,6 +31,7 @@ test("renderEditorBlock strips editor borders", () => {
 
 	assert.equal(lines.length, 1);
 	assert.match(lines[0], ABC_PATTERN);
+	assert.match(lines[0], SELECTED_BG_PATTERN);
 	assert.doesNotMatch(lines[0], BORDER_PATTERN);
 });
 
@@ -37,7 +39,7 @@ test("renderEditorBlock shows a muted placeholder when empty", () => {
 	const lines: string[] = [];
 	renderEditorBlock({
 		lines,
-		editorLines: ["┌──┐", "│  │", "└──┘"],
+		editorLines: ["┌──┐", "  ", "└──┘"],
 		width: 40,
 		theme: mockTheme() as never,
 		indent: "   ",
@@ -48,5 +50,22 @@ test("renderEditorBlock shows a muted placeholder when empty", () => {
 
 	assert.equal(lines.length, 1);
 	assert.match(lines[0], TYPE_YOUR_PATTERN);
+	assert.match(lines[0], SELECTED_BG_PATTERN);
 	assert.doesNotMatch(lines[0], BORDER_PATTERN);
 });
+
+test("renderEditorBlock reapplies background after editor reset sequences", () => {
+	const lines: string[] = [];
+	renderEditorBlock({
+		lines,
+		editorLines: ["┌──┐", "abc\x1b[7m \x1b[0m", "└──┘"],
+		width: 40,
+		theme: mockTheme() as never,
+		indent: "   ",
+		availableWidth: 40,
+	});
+
+	assert.equal(lines.length, 1);
+	assert.match(lines[0], SELECTED_BG_PATTERN);
+	assert(lines[0].includes("\x1b[0m{selectedBg}"));
+});