Remove the "halves" cover style again

Tried in macOS Terminal: it does not look good there either.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019reK4DUGYqDUjniWYJvwUW

internal/ui/cover.go

@@ -99,10 +99,6 @@ var (
 	// Coarse, but exact in terminals that draw block elements from the font
 	// with the halves off the cell's middle (macOS Terminal).
 	cellsStyle = coverStyle{"cells", 1, 1, func(int) rune { return ' ' }}
-	// halvesStyle (2×1 pixels): left and right half blocks only. Twice the
-	// detail of cells across, for terminals whose upper and lower halves do not
-	// meet at the middle but whose left and right ones do.
-	halvesStyle = coverStyle{"halves", 2, 1, func(mask int) rune { return [4]rune{' ', '▌', '▐', '█'}[mask] }}
 )
 
 // quadrants[mask] is the glyph that fills the quadrants set in mask
@@ -145,8 +141,6 @@ func coverStyleFor(setting string, env func(string) string) coverStyle {
 		return quadrantStyle
 	case "cells":
 		return cellsStyle
-	case "halves":
-		return halvesStyle
 	}
 	// Terminal.app draws block elements from the font, and their halves do
 	// not meet at the cell's middle: rows of a poster come out uneven.

internal/ui/cover_test.go

@@ -277,7 +277,6 @@ func TestCoverStyleFor(t *testing.T) {
 		{"sextant", nil, "sextant"},
 		{"auto", map[string]string{"TERM": "xterm-256color", "TERM_PROGRAM": "Apple_Terminal"}, "cells"},
 		{"cells", map[string]string{"TERM": "xterm-kitty"}, "cells"},
-		{"halves", map[string]string{"TERM_PROGRAM": "Apple_Terminal"}, "halves"},
 		{"quadrant", map[string]string{"TERM_PROGRAM": "Apple_Terminal"}, "quadrant"},
 	} {
 		if got := coverStyleFor(tc.setting, env(tc.env)).name; got != tc.want {
@@ -359,11 +358,3 @@ func TestCellsStyleIsFlat(t *testing.T) {
 		t.Errorf("got %q %v %v", ch, fg, bg)
 	}
 }
-
-func TestHalvesStyle(t *testing.T) {
-	dark, light := color.RGBA{0, 0, 0, 255}, color.RGBA{250, 250, 250, 255}
-	ch, fg, bg := halvesStyle.bestCell([]color.RGBA{light, dark})
-	if ch != '▌' || fg != light || bg != dark {
-		t.Errorf("light left half: %q %v %v", ch, fg, bg)
-	}
-}

internal/ui/settings.go

@@ -26,7 +26,7 @@ type settingsValues struct {
 	notify, bell                                      bool
 }
 
-var coverStyles = []string{"auto", "kitty", "sextant", "quadrant", "halves", "cells"}
+var coverStyles = []string{"auto", "kitty", "sextant", "quadrant", "cells"}
 
 // settingsFrom reads the settings in use.
 func settingsFrom(c *config.Config) settingsValues {