From 786a326a7162f6865d2a6be2a5ff7fd77b9dd8cf Mon Sep 17 00:00:00 2001
From: robinwander <robinwander@users.noreply.github.com>
Date: Sun, 4 Jan 2026 22:15:25 -0600
Subject: [PATCH] fix(tui): trim trailing whitespace in wrapped lines to
 prevent width overflow

---
 packages/tui/src/utils.ts           |  5 +++--
 packages/tui/test/wrap-ansi.test.ts | 19 +++++++++++++++++--
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/packages/tui/src/utils.ts b/packages/tui/src/utils.ts
index 1a7b7767..2b2a4513 100644
--- a/packages/tui/src/utils.ts
+++ b/packages/tui/src/utils.ts
@@ -498,7 +498,7 @@ function wrapSingleLine(line: string, width: number): string[] {
 		const totalNeeded = currentVisibleLength + tokenVisibleLength;
 
 		if (totalNeeded > width && currentVisibleLength > 0) {
-			// Add specific reset for underline only (preserves background)
+			// Trim trailing whitespace, then add underline reset (not full reset, to preserve background)
 			let lineToWrap = currentLine.trimEnd();
 			const lineEndReset = tracker.getLineEndReset();
 			if (lineEndReset) {
@@ -527,7 +527,8 @@ function wrapSingleLine(line: string, width: number): string[] {
 		wrapped.push(currentLine);
 	}
 
-	return wrapped.length > 0 ? wrapped : [""];
+	// Trailing whitespace can cause lines to exceed the requested width
+	return wrapped.length > 0 ? wrapped.map((line) => line.trimEnd()) : [""];
 }
 
 const PUNCTUATION_REGEX = /[(){}[\]<>.,;:'"!?+\-=*/\\|&%^$#@~`]/;
diff --git a/packages/tui/test/wrap-ansi.test.ts b/packages/tui/test/wrap-ansi.test.ts
index d7acb47c..c747106e 100644
--- a/packages/tui/test/wrap-ansi.test.ts
+++ b/packages/tui/test/wrap-ansi.test.ts
@@ -12,14 +12,24 @@ describe("wrapTextWithAnsi", () => {
 
 			const wrapped = wrapTextWithAnsi(text, 40);
 
-			// First line should NOT contain underline code - it's just "read this thread "
-			assert.strictEqual(wrapped[0], "read this thread ");
+			// First line should NOT contain underline code - it's just "read this thread"
+			assert.strictEqual(wrapped[0], "read this thread");
 
 			// Second line should start with underline, have URL content
 			assert.strictEqual(wrapped[1].startsWith(underlineOn), true);
 			assert.ok(wrapped[1].includes("https://"));
 		});
 
+		it("should not have whitespace before underline reset code", () => {
+			const underlineOn = "\x1b[4m";
+			const underlineOff = "\x1b[24m";
+			const textWithUnderlinedTrailingSpace = `${underlineOn}underlined text here ${underlineOff}more`;
+
+			const wrapped = wrapTextWithAnsi(textWithUnderlinedTrailingSpace, 18);
+
+			assert.ok(!wrapped[0].includes(` ${underlineOff}`));
+		});
+
 		it("should not bleed underline to padding - each line should end with reset for underline only", () => {
 			const underlineOn = "\x1b[4m";
 			const underlineOff = "\x1b[24m";
@@ -101,6 +111,11 @@ describe("wrapTextWithAnsi", () => {
 			}
 		});
 
+		it("should truncate trailing whitespace that exceeds width", () => {
+			const twoSpacesWrappedToWidth1 = wrapTextWithAnsi("  ", 1);
+			assert.ok(visibleWidth(twoSpacesWrappedToWidth1[0]) <= 1);
+		});
+
 		it("should preserve color codes across wraps", () => {
 			const red = "\x1b[31m";
 			const reset = "\x1b[0m";