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>

2 files changed, 45 insertions, 3 deletions

diff --git a/internal/config/config.go b/internal/config/config.go
index d53fd7f..1b4c9e1 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -28,8 +28,9 @@ type Config struct {
 	ShowIOAvgLine bool
 	ShowCores     bool
 	ShowMem     bool
-	ShowNet     bool
-	SSHOpts    string
+	ShowNet        bool
+	ShowSeparators bool
+	SSHOpts        string
 	Cluster    string
 }
 
@@ -106,7 +107,8 @@ func (c *Config) parseReader(f *os.File) error {
 		"title": true, "barwidth": true, "cpuaverage": true, "extended": true,
 		"hasagent": true, "height": true, "maxwidth": true, "netaverage": true,
 		"netlink": true, "showcores": true, "showmem": true,
-		"showavgline": true, "showioavgline": true, "shownet": true, "sshopts": true, "cluster": true,
+		"showavgline": true, "showioavgline": true, "shownet": true, "showseparators": true,
+		"sshopts": true, "cluster": true,
 	}
 	scanner := bufio.NewScanner(f)
 	for scanner.Scan() {
@@ -171,6 +173,8 @@ func (c *Config) set(key, val string) {
 		c.ShowMem = parseBool(val)
 	case "shownet":
 		c.ShowNet = parseBool(val)
+	case "showseparators":
+		c.ShowSeparators = parseBool(val)
 	case "sshopts":
 		c.SSHOpts = val
 	case "cluster":
@@ -207,6 +211,7 @@ func (c *Config) writeTo(f *os.File) error {
 	writeBool("showcores", c.ShowCores)
 	writeBool("showmem", c.ShowMem)
 	writeBool("shownet", c.ShowNet)
+	writeBool("showseparators", c.ShowSeparators)
 	writeStr("sshopts", c.SSHOpts)
 	writeStr("cluster", c.Cluster)
 	return w.Flush()
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")