Remove the '\n' sentinel cell

The sentinel was appended to every \n-terminated line solely so that
draw()'s prevFgColor tracking would reset to default for the trailing
area; without it, an AttrReverse-styled last cell would carry its
rendered bg past the end of the line.

The same prevFgColor mechanism propagated AttrReverse past content on
*unterminated* lines too — which doesn't match real terminal behavior
(try `print '\x1b[7m\x1b[31mfoo'` in a shell: the reverse stops at
the last character) and isn't relied on by anything in lazygit, since
all our writers terminate lines with \n.

Drop the sentinel cell, drop prevFgColor, and just have draw() paint
trailing cells with the view's default fg/bg. The
TestUnterminatedReverseLineExtendsToEdge regression test inverts to
document the new (terminal-matching) behavior, renamed accordingly.
TestWriteString expectations also drop the trailing "" that came
from the sentinel.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pkg/gocui/view.go

@@ -806,14 +806,6 @@ func (v *View) write(p []byte) {
 
 	finishLine := func() {
 		v.autoRenderHyperlinksInCurrentLine()
-		if v.wx >= len(v.lines[v.wy].cells) {
-			v.writeCells([]cell{{
-				chr:     "",
-				width:   0,
-				fgColor: 0,
-				bgColor: 0,
-			}})
-		}
 	}
 
 	advanceToNextLine := func() {
@@ -1254,7 +1246,6 @@ func (v *View) draw() {
 	}
 
 	emptyCell := cell{chr: " ", width: 1, fgColor: ColorDefault, bgColor: ColorDefault}
-	var prevFgColor Attribute
 
 	for y, vline := range v.viewLines[start:] {
 		if y >= maxY {
@@ -1284,13 +1275,8 @@ func (v *View) draw() {
 			// if we're out of cells to write, we'll just print empty cells.
 			if cellIdx > len(vline.line)-1 {
 				c = emptyCell
-				c.fgColor = prevFgColor
 			} else {
 				c = vline.line[cellIdx]
-				// capturing previous foreground colour so that if we're using the reverse
-				// attribute we honour the final character's colour and don't awkwardly switch
-				// to a new background colour for the remainder of the line
-				prevFgColor = c.fgColor
 			}
 
 			fgColor := c.fgColor

pkg/gocui/view_test.go

@@ -44,17 +44,17 @@ func TestWriteString(t *testing.T) {
 		{
 			[]string{},
 			[]string{"1\n"},
-			[][]string{{"1", ""}},
+			[][]string{{"1"}},
 		},
 		{
 			[]string{},
 			[]string{"1\n", "2\n"},
-			[][]string{{"1", ""}, {"2", ""}},
+			[][]string{{"1"}, {"2"}},
 		},
 		{
 			[]string{"a"},
 			[]string{"1\n"},
-			[][]string{{"1", ""}},
+			[][]string{{"1"}},
 		},
 		{
 			[]string{"a\x00"},
@@ -74,12 +74,12 @@ func TestWriteString(t *testing.T) {
 		{
 			[]string{},
 			[]string{"1\r"},
-			[][]string{{"1", ""}},
+			[][]string{{"1"}},
 		},
 		{
 			[]string{"a"},
 			[]string{"1\r"},
-			[][]string{{"1", ""}},
+			[][]string{{"1"}},
 		},
 		{
 			[]string{"a\x00"},
@@ -462,29 +462,28 @@ func TestNewlineTerminatedLineClearsTrailingBg(t *testing.T) {
 	}
 }
 
-// TestUnterminatedReverseLineExtendsToEdge verifies that without a
-// terminating '\n' or '\x1b[K', the line's last cell's attributes
-// (including AttrReverse) propagate through the trailing area so a
-// reversed-bg line extends all the way to the right edge.
-func TestUnterminatedReverseLineExtendsToEdge(t *testing.T) {
+// TestUnterminatedReverseLineDoesNotExtend verifies that an unterminated
+// line ending with an AttrReverse cell does NOT propagate the reversed
+// background past the line's content — matching real terminal behavior
+// (try `print '\x1b[7m\x1b[31mfoo'` in a shell). The trailing area
+// is rendered as plain default.
+func TestUnterminatedReverseLineDoesNotExtend(t *testing.T) {
 	WithSimulationScreen(t, 14, 5)
 
 	v := NewView("name", 0, 0, 11, 4, OutputNormal)
 
-	// Reverse + red fg, "foo", no termination. Each "foo" cell renders
-	// with bg=red via reverse, and the trailing cells past "foo" must
-	// keep the reverse so the rendered bg extends to the right edge.
+	// Reverse + red fg, "foo", no termination. The trailing cells past
+	// "foo" should be plain default, NOT a continuation of the red bg.
 	v.writeString("\x1b[7m\x1b[31mfoo")
 	v.draw()
 
-	// Cells 1..3 are content; cells 4..10 are trailing. All ten should
-	// have reverse on with red fg (so they all render with bg=red).
-	for x := 1; x <= 10; x++ {
+	// Cells 4..10 are trailing and should be default with no reverse.
+	for x := 4; x <= 10; x++ {
 		_, style, _ := Screen.Get(x, 1)
-		assert.Equal(t, color.Maroon, style.GetForeground(),
-			"cell at (%d, 1) should have red fg under reverse", x)
-		assert.True(t, style.HasReverse(),
-			"cell at (%d, 1) should have reverse attribute", x)
+		assert.Equal(t, tcell.ColorDefault, style.GetForeground(),
+			"trailing cell at (%d, 1) should have default fg", x)
+		assert.False(t, style.HasReverse(),
+			"trailing cell at (%d, 1) should not have reverse attribute", x)
 	}
 }