From 950045bf5d4229b0d2b38eb1c705171bdff3acde Mon Sep 17 00:00:00 2001
From: wuyangfan <1102042793@qq.com>
Date: Sun, 17 May 2026 20:07:39 +0800
Subject: [PATCH] fix(textarea): cursor navigation and wrap at exact line width

When soft-wrapped content exactly filled the textarea width, wrap() used
>= and created a phantom blank line, and vertical cursor movement stopped
one column early (offset >= CharWidth-1) (#887).

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 textarea/textarea.go      |  4 +--
 textarea/textarea_test.go | 66 ++++++++++++++++++++++++++++-----------
 2 files changed, 50 insertions(+), 20 deletions(-)

diff --git a/textarea/textarea.go b/textarea/textarea.go
index f0c0ca54..f9fa58a1 100644
--- a/textarea/textarea.go
+++ b/textarea/textarea.go
@@ -699,7 +699,7 @@ func (m *Model) setCursorLineRelative(delta int) {
 
 	offset := 0
 	for offset < charOffset {
-		if m.row >= len(m.value) || m.col >= len(m.value[m.row]) || offset >= nli.CharWidth-1 {
+		if m.row >= len(m.value) || m.col >= len(m.value[m.row]) || offset >= nli.CharWidth {
 			break
 		}
 		offset += rw.RuneWidth(m.value[m.row][m.col])
@@ -1849,7 +1849,7 @@ func wrap(runes []rune, width int) [][]rune {
 		}
 	}
 
-	if uniseg.StringWidth(string(lines[row]))+uniseg.StringWidth(string(word))+spaces >= width {
+	if uniseg.StringWidth(string(lines[row]))+uniseg.StringWidth(string(word))+spaces > width {
 		lines = append(lines, []rune{})
 		lines[row+1] = append(lines[row+1], word...)
 		// We add an extra space at the end of the line to account for the
diff --git a/textarea/textarea_test.go b/textarea/textarea_test.go
index 41d51f74..55c81635 100644
--- a/textarea/textarea_test.go
+++ b/textarea/textarea_test.go
@@ -743,8 +743,8 @@ func TestView(t *testing.T) {
 					>
 					>
 				`),
-				cursorRow: 1,
-				cursorCol: 0,
+				cursorRow: 0,
+				cursorCol: 4,
 			},
 		},
 		{
@@ -814,8 +814,8 @@ func TestView(t *testing.T) {
 					>
 					>
 				`),
-				cursorRow: 1,
-				cursorCol: 0,
+				cursorRow: 0,
+				cursorCol: 4,
 			},
 		},
 		{
@@ -861,8 +861,8 @@ func TestView(t *testing.T) {
 					>
 					>
 				`),
-				cursorRow: 3,
-				cursorCol: 0,
+				cursorRow: 2,
+				cursorCol: 1,
 			},
 		},
 		{
@@ -884,8 +884,8 @@ func TestView(t *testing.T) {
 					>
 					>
 				`),
-				cursorRow: 3,
-				cursorCol: 0,
+				cursorRow: 2,
+				cursorCol: 1,
 			},
 		},
 		{
@@ -908,8 +908,8 @@ func TestView(t *testing.T) {
 					>
 					>
 				`),
-				cursorRow: 3,
-				cursorCol: 0,
+				cursorRow: 2,
+				cursorCol: 1,
 			},
 		},
 		{
@@ -933,8 +933,8 @@ func TestView(t *testing.T) {
 
 
 				`),
-				cursorRow: 3,
-				cursorCol: 0,
+				cursorRow: 2,
+				cursorCol: 1,
 			},
 		},
 		{
@@ -1004,8 +1004,8 @@ func TestView(t *testing.T) {
 					>
 					>
 				`),
-				cursorRow: 1,
-				cursorCol: 0,
+				cursorRow: 0,
+				cursorCol: 4,
 			},
 		},
 		{
@@ -1118,8 +1118,8 @@ func TestView(t *testing.T) {
 					│>         │
 					└──────────┘
 				`),
-				cursorRow: 1,
-				cursorCol: 0,
+				cursorRow: 0,
+				cursorCol: 4,
 			},
 		},
 		{
@@ -1241,8 +1241,8 @@ func TestView(t *testing.T) {
 					│>         │
 					└──────────┘
 				`),
-				cursorRow: 1,
-				cursorCol: 0,
+				cursorRow: 0,
+				cursorCol: 8,
 			},
 		},
 		{
@@ -2403,6 +2403,36 @@ func newTextArea() Model {
 	return textarea
 }
 
+func TestWrapExactWidthNoPhantomLine(t *testing.T) {
+	const width = 10
+	input := []rune("0123456789")
+
+	lines := wrap(input, width)
+	if len(lines) > 1 {
+		for i, line := range lines {
+			if i > 0 && len(strings.TrimSpace(string(line))) == 0 {
+				t.Fatalf("phantom wrap line at index %d: %#v", i, lines)
+			}
+		}
+	}
+}
+
+func TestCursorDownPastExactWidthLine(t *testing.T) {
+	textarea := newTextArea()
+	textarea.SetWidth(20)
+
+	line1 := strings.Repeat("x", 20)
+	textarea.SetValue(line1 + "\nsecond")
+	textarea.row = 0
+	textarea.col = len(line1)
+	textarea.lastCharOffset = textarea.LineInfo().CharOffset
+
+	textarea.CursorDown()
+	if textarea.row != 1 {
+		t.Fatalf("row %d want 1 after moving down from a full-width line", textarea.row)
+	}
+}
+
 func keyPress(key rune) tea.Msg {
 	return tea.KeyPressMsg{Code: key, Text: string(key)}
 }