Add toggleable host separator lines (hotkey s)

Draw 1px yellow vertical lines between hosts when monitoring multiple
servers, making it easy to see where one host's bars end and the next
begins. Toggled with hotkey 's', persisted via 'w' to ~/.loadbarsrc.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index a8535be..630fa47 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -152,6 +152,43 @@ func TestConfig_showIOAvgLineRoundTrip(t *testing.T) {
 	}
 }
 
+func TestConfig_showSeparatorsRoundTrip(t *testing.T) {
+	// Write a config with showseparators=1, read it back, verify round-trip
+	c := Default()
+	c.ShowSeparators = true
+
+	dir := t.TempDir()
+	path := filepath.Join(dir, "rc")
+	f, err := os.Create(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := c.writeTo(f); err != nil {
+		f.Close()
+		t.Fatal(err)
+	}
+	f.Close()
+
+	data, _ := os.ReadFile(path)
+	if !bytes.Contains(data, []byte("showseparators=1")) {
+		t.Errorf("expected showseparators=1 in output, got:\n%s", data)
+	}
+
+	// Read it back
+	c2 := Default()
+	f2, err := os.Open(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer f2.Close()
+	if err := c2.parseReader(f2); err != nil {
+		t.Fatal(err)
+	}
+	if !c2.ShowSeparators {
+		t.Error("expected ShowSeparators=true after round-trip")
+	}
+}
+
 func TestGetClusterHostsFromFile(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "clusters")