feat: triple-toggle CPU display mode via 1 key; add tooltip, font, hit-test

CPU display now cycles through three states with each press of 1:
  0 = CPUModeAverage  – aggregate bar only (default)
  1 = CPUModeCores    – individual core bars + aggregate
  2 = CPUModeOff      – all CPU bars hidden

Config file stores cpumode=N (integer); old showcores=0/1 is read for
backward compatibility. CLI flag --showcores replaced by --cpumode.

Other improvements landed in this commit:
- internal/display: add font.go (text rendering), hittest.go (bar hit
  testing), tooltip.go (mouse-over tooltip), tooltip_test.go
- internal/display: mouse tracking and drawOverlay hook in display.go
- internal/display: update build tags to //go:build form
- internal/collector: embed remote script via script_embed.go /
  scriptdata/loadbars-remote.sh
- internal/collector: CPULine.Total() changed to value receiver
- internal/collector: table test improvements (name field, t.Run)
- internal/constants: BytesPerSec consts promoted from var to const
- Magefile.go: fix error formatting and install path

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

17 files changed, 1332 insertions, 112 deletions

diff --git a/Magefile.go b/Magefile.go
index 46dd2ef..17c40ae 100644
--- a/Magefile.go
+++ b/Magefile.go
@@ -40,7 +40,7 @@ func Install() error {
 	}
 	bin := filepath.Join(gopath, "bin")
 	if err := os.MkdirAll(bin, 0o755); err != nil {
-		return err
+		return fmt.Errorf("mkdir %s: %w", bin, err)
 	}
-	return sh.RunV("cp", "-v", binaryName, bin+"/")
+	return sh.RunV("cp", "-v", binaryName, filepath.Join(bin, binaryName))
 }
diff --git a/cmd/loadbars/main.go b/cmd/loadbars/main.go
index 555812c..0ee8071 100644
--- a/cmd/loadbars/main.go
+++ b/cmd/loadbars/main.go
@@ -27,7 +27,7 @@ func main() {
 	flag.IntVar(&cfg.CPUAverage, "cpuaverage", cfg.CPUAverage, "Num of CPU samples for avg")
 	flag.IntVar(&cfg.NetAverage, "netaverage", cfg.NetAverage, "Num of net samples for avg")
 	flag.StringVar(&cfg.NetLink, "netlink", cfg.NetLink, "Link speed (mbit, 10mbit, 100mbit, gbit, 10gbit or number)")
-	flag.BoolVar(&cfg.ShowCores, "showcores", cfg.ShowCores, "Toggle core display")
+	flag.IntVar(&cfg.CPUMode, "cpumode", cfg.CPUMode, "CPU display mode (0=average, 1=cores, 2=off)")
 	flag.BoolVar(&cfg.ShowMem, "showmem", cfg.ShowMem, "Toggle mem display")
 	flag.BoolVar(&cfg.ShowNet, "shownet", cfg.ShowNet, "Toggle net display")
 	flag.BoolVar(&cfg.Extended, "extended", cfg.Extended, "Toggle extended display")
diff --git a/internal/collector/parse_test.go b/internal/collector/parse_test.go
index ec77067..fe7a73c 100644
--- a/internal/collector/parse_test.go
+++ b/internal/collector/parse_test.go
@@ -44,29 +44,31 @@ func TestParseCPULine(t *testing.T) {
 
 func TestParseMemLine(t *testing.T) {
 	tests := []struct {
+		name      string
 		line      string
 		wantKey   string
 		wantValue int64
 		wantOK    bool
 	}{
-		{"MemTotal:       123456 kB", "MemTotal", 123456, true},
-		{"MemFree:         99999 kB", "MemFree", 99999, true},
-		{"Buffers:             0 kB", "Buffers", 0, true},
-		{"not a mem line", "", 0, false},
-		{"", "", 0, false},
+		{"MemTotal", "MemTotal:       123456 kB", "MemTotal", 123456, true},
+		{"MemFree", "MemFree:         99999 kB", "MemFree", 99999, true},
+		{"Buffers_zero", "Buffers:             0 kB", "Buffers", 0, true},
+		{"not_a_mem_line", "not a mem line", "", 0, false},
+		{"empty_string", "", "", 0, false},
 	}
 	for _, tt := range tests {
-		got, ok := ParseMemLine(tt.line)
-		if ok != tt.wantOK {
-			t.Errorf("ParseMemLine(%q) ok = %v, want %v", tt.line, ok, tt.wantOK)
-			continue
-		}
-		if !tt.wantOK {
-			continue
-		}
-		if got.Key != tt.wantKey || got.Value != tt.wantValue {
-			t.Errorf("ParseMemLine(%q) = %+v, want key=%q value=%d", tt.line, got, tt.wantKey, tt.wantValue)
-		}
+		t.Run(tt.name, func(t *testing.T) {
+			got, ok := ParseMemLine(tt.line)
+			if ok != tt.wantOK {
+				t.Fatalf("ParseMemLine(%q) ok = %v, want %v", tt.line, ok, tt.wantOK)
+			}
+			if !tt.wantOK {
+				return
+			}
+			if got.Key != tt.wantKey || got.Value != tt.wantValue {
+				t.Errorf("ParseMemLine(%q) = %+v, want key=%q value=%d", tt.line, got, tt.wantKey, tt.wantValue)
+			}
+		})
 	}
 }
 
diff --git a/internal/collector/script_embed.go b/internal/collector/script_embed.go
new file mode 100644
index 0000000..168ca37
--- /dev/null
+++ b/internal/collector/script_embed.go
@@ -0,0 +1,9 @@
+package collector
+
+import _ "embed"
+
+// RemoteScript is the loadbars-remote.sh script embedded for local and SSH execution.
+// Path is relative to this file's directory (internal/collector).
+//
+//go:embed scriptdata/loadbars-remote.sh
+var RemoteScript []byte
diff --git a/internal/collector/scriptdata/loadbars-remote.sh b/internal/collector/scriptdata/loadbars-remote.sh
new file mode 100644
index 0000000..9037ad8
--- /dev/null
+++ b/internal/collector/scriptdata/loadbars-remote.sh
@@ -0,0 +1,35 @@
+#!/bin/bash
+# loadbars-remote.sh - Emits loadbars protocol (M LOADAVG, M MEMSTATS, M NETSTATS, M CPUSTATS)
+# for local or remote execution. No Perl required.
+# Usage: bash loadbars-remote.sh
+# Interval for CPU sampling (seconds)
+INTERVAL=0.14
+
+while true; do
+  # Load average: first 3 fields of /proc/loadavg joined by ;
+  echo "M LOADAVG"
+  read -r l1 l5 l15 _ < /proc/loadavg 2>/dev/null || true
+  echo "${l1:-0};${l5:-0};${l15:-0}"
+
+  # Memory: full /proc/meminfo
+  echo "M MEMSTATS"
+  cat /proc/meminfo 2>/dev/null || true
+
+  # Network: /proc/net/dev, skip 2 header lines, then "iface: rx... tx..."
+  echo "M NETSTATS"
+  while IFS= read -r line; do
+    line="${line/:/ }"
+    set -- $line
+    # $1=iface, $2=rx_bytes $3=rx_packets $4=rx_errs $5=rx_drop ... $10=tx_bytes $11=tx_packets $12=tx_errs $13=tx_drop
+    if [ -n "$2" ] || [ -n "${10:-}" ]; then
+      echo "$1:b=${2:-0};tb=${10:-0};p=${3:-0};tp=${11:-0} e=${4:-0};te=${12:-0};d=${5:-0};td=${13:-0}"
+    fi
+  done < <(tail -n +3 /proc/net/dev 2>/dev/null)
+
+  # CPU: /proc/stat, 20 times with INTERVAL sleep
+  echo "M CPUSTATS"
+  for _ in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
+    cat /proc/stat 2>/dev/null || true
+    sleep "$INTERVAL" 2>/dev/null || true
+  done
+done
diff --git a/internal/collector/types.go b/internal/collector/types.go
index b0db600..13bcb1f 100644
--- a/internal/collector/types.go
+++ b/internal/collector/types.go
@@ -7,7 +7,7 @@ type CPULine struct {
 }
 
 // Total returns sum of all CPU counters.
-func (c *CPULine) Total() int64 {
+func (c CPULine) Total() int64 {
 	return c.User + c.Nice + c.System + c.Idle + c.Iowait + c.IRQ + c.SoftIRQ + c.Steal + c.Guest + c.GuestNice
 }
 
diff --git a/internal/config/config.go b/internal/config/config.go
index ba7886e..90b8192 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -26,7 +26,7 @@ type Config struct {
 	NetLink    string
 	ShowAvgLine    bool
 	ShowIOAvgLine  bool
-	ShowCores      bool
+	CPUMode        int // constants.CPUModeAverage / CPUModeCores / CPUModeOff
 	ShowMem        bool
 	ShowNet        bool
 	ShowSeparators bool
@@ -46,7 +46,7 @@ func Default() Config {
 		MaxWidth:   1900,
 		NetAverage: 15,
 		NetLink:    "gbit",
-		ShowCores:     false,
+		CPUMode:       constants.CPUModeAverage, // start with aggregate bar only
 		ShowMem:       false,
 		ShowNet:       false,
 		MaxBarsPerRow: 0,
@@ -108,7 +108,7 @@ func (c *Config) parseReader(f *os.File) error {
 	validKeys := map[string]bool{
 		"title": true, "barwidth": true, "cpuaverage": true, "extended": true,
 		"hasagent": true, "height": true, "maxwidth": true, "netaverage": true,
-		"netlink": true, "showcores": true, "showmem": true,
+		"netlink": true, "cpumode": true, "showcores": true, "showmem": true,
 		"showavgline": true, "showioavgline": true, "shownet": true, "showseparators": true,
 		"maxbarsperrow": true, "sshopts": true, "cluster": true,
 	}
@@ -169,8 +169,18 @@ func (c *Config) set(key, val string) {
 		c.ShowAvgLine = parseBool(val)
 	case "showioavgline":
 		c.ShowIOAvgLine = parseBool(val)
+	case "cpumode":
+		// 0=average, 1=cores, 2=off — clamp to valid range
+		if n, err := strconv.Atoi(val); err == nil && n >= 0 && n < constants.CPUModeCount {
+			c.CPUMode = n
+		}
 	case "showcores":
-		c.ShowCores = parseBool(val)
+		// Backward-compatible: old boolean showcores maps to CPUMode
+		if parseBool(val) {
+			c.CPUMode = constants.CPUModeCores
+		} else {
+			c.CPUMode = constants.CPUModeAverage
+		}
 	case "showmem":
 		c.ShowMem = parseBool(val)
 	case "shownet":
@@ -209,7 +219,7 @@ func (c *Config) writeTo(f *os.File) error {
 	writeStr("netlink", c.NetLink)
 	writeBool("showavgline", c.ShowAvgLine)
 	writeBool("showioavgline", c.ShowIOAvgLine)
-	writeBool("showcores", c.ShowCores)
+	writeInt("cpumode", c.CPUMode)
 	writeBool("showmem", c.ShowMem)
 	writeBool("shownet", c.ShowNet)
 	writeBool("showseparators", c.ShowSeparators)
diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index 630fa47..7b0bb37 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -25,9 +25,6 @@ func TestConfig_parseReader(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			c := Default()
-			f, _ := os.Open(os.DevNull)
-			defer f.Close()
-			// Use a temp file with the content since parseReader takes *os.File
 			dir := t.TempDir()
 			path := filepath.Join(dir, "rc")
 			if err := os.WriteFile(path, []byte(tt.input), 0600); err != nil {
@@ -54,7 +51,7 @@ func TestConfig_parseReader(t *testing.T) {
 func TestConfig_writeTo(t *testing.T) {
 	c := Default()
 	c.BarWidth = 25
-	c.ShowCores = true
+	c.CPUMode = 1 // CPUModeCores
 	dir := t.TempDir()
 	path := filepath.Join(dir, "out")
 	f, err := os.Create(path)
@@ -73,8 +70,8 @@ func TestConfig_writeTo(t *testing.T) {
 	if !bytes.Contains(data, []byte("barwidth=25")) {
 		t.Errorf("expected barwidth=25 in %s", data)
 	}
-	if !bytes.Contains(data, []byte("showcores=1")) {
-		t.Errorf("expected showcores=1 in %s", data)
+	if !bytes.Contains(data, []byte("cpumode=1")) {
+		t.Errorf("expected cpumode=1 in %s", data)
 	}
 }
 
diff --git a/internal/constants/constants.go b/internal/constants/constants.go
index 0022621..e2a4fcb 100644
--- a/internal/constants/constants.go
+++ b/internal/constants/constants.go
@@ -16,6 +16,14 @@ const (
 	UserYellowThreshold = 50   // CPU user % for dark yellow
 )
 
+// CPUMode controls which CPU bars are displayed (cycles with the 1 key).
+const (
+	CPUModeAverage = 0 // Show only the aggregate CPU bar (default)
+	CPUModeCores   = 1 // Show individual core bars plus the aggregate
+	CPUModeOff     = 2 // Hide all CPU bars entirely
+	CPUModeCount   = 3 // Total number of CPU modes for cycling
+)
+
 // Exit codes
 const (
 	Success  = 0
@@ -52,7 +60,7 @@ var (
 )
 
 // BytesPerSec for link speed reference (bytes per second at given mbit)
-var (
+const (
 	BytesMbit    = 125000
 	Bytes10Mbit  = 1250000
 	Bytes100Mbit = 12500000
diff --git a/internal/display/activate.go b/internal/display/activate.go
index b9040d7..ac9b340 100644
--- a/internal/display/activate.go
+++ b/internal/display/activate.go
@@ -1,4 +1,4 @@
-// +build !darwin
+//go:build !darwin
 
 package display
 
diff --git a/internal/display/activate_darwin.go b/internal/display/activate_darwin.go
index 54c6b94..478d558 100644
--- a/internal/display/activate_darwin.go
+++ b/internal/display/activate_darwin.go
@@ -1,4 +1,4 @@
-// +build darwin
+//go:build darwin
 
 package display
 
diff --git a/internal/display/display.go b/internal/display/display.go
index 749c26c..47f8f10 100644
--- a/internal/display/display.go
+++ b/internal/display/display.go
@@ -17,7 +17,9 @@ import (
 	"github.com/veandco/go-sdl2/sdl"
 )
 
-const smoothFactor = 0.12 // blend toward target each frame; lower = smoother
+// smoothFactor controls how quickly bars blend toward their target values each frame.
+// Lower values produce smoother animations.
+const smoothFactor = 0.12
 
 // linkScales lists the supported network link speeds in ascending order,
 // used by the f/v hotkeys to cycle through link scale values.
@@ -27,7 +29,7 @@ var linkScales = []string{"mbit", "10mbit", "100mbit", "gbit", "10gbit"}
 type runState struct {
 	showAvgLine    bool
 	showIOAvgLine  bool
-	showCores      bool
+	cpuMode        int // constants.CPUModeAverage / CPUModeCores / CPUModeOff
 	showMem        bool
 	showNet        bool
 	showSeparators bool
@@ -40,27 +42,9 @@ type runState struct {
 	smoothedNet    map[string]*struct{ rxPct, txPct float64 }
 	prevNet        map[string]stats.NetStamp // aggregated (summed) previous net stamp per host
 	peakHistory    map[string][]float64
-}
-
-// newRunState builds initial run state from config.
-func newRunState(cfg *config.Config, winW, winH int32) *runState {
-	return &runState{
-		showAvgLine:    cfg.ShowAvgLine,
-		showIOAvgLine:  cfg.ShowIOAvgLine,
-		showCores:      cfg.ShowCores,
-		showMem:        cfg.ShowMem,
-		showNet:        cfg.ShowNet,
-		showSeparators: cfg.ShowSeparators,
-		extended:       cfg.Extended,
-		winW:           winW,
-		winH:           winH,
-		prevCPU:        make(map[string]collector.CPULine),
-		smoothedCPU:    make(map[string]*[10]float64),
-		smoothedMem:    make(map[string]*struct{ ramUsed, swapUsed float64 }),
-		smoothedNet:    make(map[string]*struct{ rxPct, txPct float64 }),
-		prevNet:        make(map[string]stats.NetStamp),
-		peakHistory:    make(map[string][]float64),
-	}
+	mouseX         int32     // last known mouse X position (for tooltip hit testing)
+	mouseY         int32     // last known mouse Y position (for tooltip hit testing)
+	mouseLastMove  time.Time // timestamp of last mouse movement; tooltip hidden after 3s idle
 }
 
 // Run runs the SDL display loop until ctx is cancelled or user presses 'q'.
@@ -111,6 +95,29 @@ func Run(ctx context.Context, cfg *config.Config, src stats.Source) error {
 	}
 }
 
+// newRunState builds initial run state from config.
+func newRunState(cfg *config.Config, winW, winH int32) *runState {
+	return &runState{
+		showAvgLine:    cfg.ShowAvgLine,
+		showIOAvgLine:  cfg.ShowIOAvgLine,
+		cpuMode:        cfg.CPUMode,
+		showMem:        cfg.ShowMem,
+		showNet:        cfg.ShowNet,
+		showSeparators: cfg.ShowSeparators,
+		extended:       cfg.Extended,
+		winW:           winW,
+		winH:           winH,
+		prevCPU:        make(map[string]collector.CPULine),
+		smoothedCPU:    make(map[string]*[10]float64),
+		smoothedMem:    make(map[string]*struct{ ramUsed, swapUsed float64 }),
+		smoothedNet:    make(map[string]*struct{ rxPct, txPct float64 }),
+		prevNet:        make(map[string]stats.NetStamp),
+		peakHistory:    make(map[string][]float64),
+		mouseX:         -1, // off-screen until first mouse move
+		mouseY:         -1,
+	}
+}
+
 func clampInt(v, min, max int) int {
 	if v < min {
 		return min
@@ -134,6 +141,9 @@ func handleEvents(window *sdl.Window, cfg *config.Config, state *runState) bool
 			if handleKey(ev.Keysym.Sym, window, cfg, state) {
 				return true
 			}
+		case *sdl.MouseMotionEvent:
+			state.mouseX, state.mouseY = ev.X, ev.Y
+			state.mouseLastMove = time.Now()
 		case *sdl.WindowEvent:
 			if ev.Event == sdl.WINDOWEVENT_RESIZED {
 				state.winW, state.winH = ev.Data1, ev.Data2
@@ -149,8 +159,16 @@ func handleKey(sym sdl.Keycode, window *sdl.Window, cfg *config.Config, state *r
 	case sdl.K_q:
 		return true
 	case sdl.K_1:
-		state.showCores = !state.showCores
-		fmt.Println("==> Toggled show cores:", state.showCores)
+		// Cycle through three CPU display modes: average → all cores → off → average
+		state.cpuMode = (state.cpuMode + 1) % constants.CPUModeCount
+		switch state.cpuMode {
+		case constants.CPUModeAverage:
+			fmt.Println("==> CPU: average bar only")
+		case constants.CPUModeCores:
+			fmt.Println("==> CPU: individual cores")
+		case constants.CPUModeOff:
+			fmt.Println("==> CPU: off")
+		}
 	case sdl.K_2, sdl.K_m:
 		state.showMem = !state.showMem
 		fmt.Println("==> Toggled show mem:", state.showMem)
@@ -194,7 +212,7 @@ func handleKey(sym sdl.Keycode, window *sdl.Window, cfg *config.Config, state *r
 	case sdl.K_w:
 		cfg.ShowAvgLine = state.showAvgLine
 		cfg.ShowIOAvgLine = state.showIOAvgLine
-		cfg.ShowCores = state.showCores
+		cfg.CPUMode = state.cpuMode
 		cfg.ShowMem = state.showMem
 		cfg.ShowNet = state.showNet
 		cfg.ShowSeparators = state.showSeparators
@@ -270,7 +288,7 @@ func barRect(winW, winH int32, numBars, maxPerRow, barIndex int) (x, y, w, h int
 // When showAvgLine/showIOAvgLine are enabled, global average lines are drawn on top.
 func drawFrame(renderer *sdl.Renderer, src stats.Source, cfg *config.Config, state *runState) {
 	snap := src.Snapshot()
-	numBars := countBars(snap, state.showCores, state.showMem, state.showNet)
+	numBars := countBars(snap, state.cpuMode, state.showMem, state.showNet)
 	// Always clear the entire window before drawing. SDL2 uses double-buffering,
 	// so skipping clear leaves stale content in the back buffer.
 	renderer.SetDrawColor(0, 0, 0, 255)
@@ -282,13 +300,15 @@ func drawFrame(renderer *sdl.Renderer, src stats.Source, cfg *config.Config, sta
 	if state.showIOAvgLine {
 		drawGlobalIOAvgLine(renderer, snap, state, numBars, cfg.MaxBarsPerRow)
 	}
+	// Draw mouse-over tooltip and host highlight inversion on top of all bars
+	drawOverlay(renderer, snap, cfg, state)
 }
 
-func countBars(snap map[string]*stats.HostStats, showCores, showMem, showNet bool) int {
+func countBars(snap map[string]*stats.HostStats, cpuMode int, showMem, showNet bool) int {
 	n := 0
 	for _, host := range sortedHosts(snap) {
 		if h := snap[host]; h != nil {
-			n += len(sortedCPUNames(h.CPU, showCores))
+			n += len(sortedCPUNames(h.CPU, cpuMode))
 			if showMem {
 				n++
 			}
@@ -430,7 +450,7 @@ func drawGlobalIOAvgLine(renderer *sdl.Renderer, snap map[string]*stats.HostStat
 // drawHostBars draws CPU, mem, and net bars for one host and advances barIndex.
 // maxPerRow controls multi-row wrapping (0 = single row).
 func drawHostBars(renderer *sdl.Renderer, h *stats.HostStats, host string, cfg *config.Config, state *runState, numBars, maxPerRow int, barIndex *int) {
-	cpuNames := sortedCPUNames(h.CPU, state.showCores)
+	cpuNames := sortedCPUNames(h.CPU, state.cpuMode)
 	for _, name := range cpuNames {
 		key := host + ";" + name
 		cur := h.CPU[name]
@@ -506,14 +526,20 @@ func sortedHosts(snap map[string]*stats.HostStats) []string {
 	return out
 }
 
-func sortedCPUNames(cpu map[string]collector.CPULine, showCores bool) []string {
+func sortedCPUNames(cpu map[string]collector.CPULine, cpuMode int) []string {
+	// CPUModeOff: hide all CPU bars
+	if cpuMode == constants.CPUModeOff {
+		return nil
+	}
 	var names []string
 	for name := range cpu {
 		if name == "cpu" {
+			// Aggregate bar always shown unless CPUModeOff
 			names = append(names, "cpu")
 			continue
 		}
-		if showCores {
+		// Individual core bars only shown in CPUModeCores
+		if cpuMode == constants.CPUModeCores {
 			names = append(names, name)
 		}
 	}
diff --git a/internal/display/display_test.go b/internal/display/display_test.go
index 332fe32..b51e6d1 100644
--- a/internal/display/display_test.go
+++ b/internal/display/display_test.go
@@ -141,7 +141,7 @@ func renderOneCPUBar(t *testing.T, systemPct, userPct, idlePct float64, extended
 
 	prev, cur := makeCPUPair(systemPct, userPct, idlePct)
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = false
 	cfg.ShowNet = false
 	cfg.Extended = extended
@@ -212,7 +212,7 @@ func TestMemBar_RamAndSwap(t *testing.T) {
 	defer surface.Free()
 
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = true
 	cfg.ShowNet = false
 
@@ -266,7 +266,7 @@ func TestNetBar_RxTx(t *testing.T) {
 	defer surface.Free()
 
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = false
 	cfg.ShowNet = true
 	cfg.NetLink = "gbit"
@@ -318,7 +318,7 @@ func TestNetBar_AggregatesAllInterfaces(t *testing.T) {
 	defer surface.Free()
 
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = false
 	cfg.ShowNet = true
 	cfg.NetLink = "gbit"
@@ -372,7 +372,7 @@ func TestMultiHost_BarCount(t *testing.T) {
 	defer surface.Free()
 
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = true
 	cfg.ShowNet = true
 
@@ -397,7 +397,7 @@ func TestMultiHost_BarCount(t *testing.T) {
 	}
 
 	snap := src.Snapshot()
-	numBars := countBars(snap, false, true, true)
+	numBars := countBars(snap, constants.CPUModeAverage, true, true)
 	if numBars != 6 {
 		t.Fatalf("expected 6 bars (2 hosts × 3), got %d", numBars)
 	}
@@ -418,7 +418,7 @@ func TestMultiHost_BarCount(t *testing.T) {
 }
 
 func TestCores_Toggle(t *testing.T) {
-	// With showCores=true and 2 cores, we get cpu + cpu0 + cpu1 = 3 CPU bars
+	// Three CPU mode states: average (1 bar), cores (3 bars), off (0 → floor 1)
 	hostStats := &stats.HostStats{
 		CPU: map[string]collector.CPULine{
 			"cpu":  {System: 500, User: 0, Idle: 500},
@@ -429,16 +429,22 @@ func TestCores_Toggle(t *testing.T) {
 
 	snap := map[string]*stats.HostStats{"host1": hostStats}
 
-	// showCores=true: should count 3 CPU bars
-	nWith := countBars(snap, true, false, false)
-	if nWith != 3 {
-		t.Errorf("showCores=true: expected 3 bars, got %d", nWith)
+	// CPUModeAverage: aggregate bar only (1 bar)
+	nAverage := countBars(snap, constants.CPUModeAverage, false, false)
+	if nAverage != 1 {
+		t.Errorf("CPUModeAverage: expected 1 bar, got %d", nAverage)
 	}
 
-	// showCores=false: should count 1 CPU bar (aggregate only)
-	nWithout := countBars(snap, false, false, false)
-	if nWithout != 1 {
-		t.Errorf("showCores=false: expected 1 bar, got %d", nWithout)
+	// CPUModeCores: aggregate + individual cores = cpu + cpu0 + cpu1 (3 bars)
+	nCores := countBars(snap, constants.CPUModeCores, false, false)
+	if nCores != 3 {
+		t.Errorf("CPUModeCores: expected 3 bars, got %d", nCores)
+	}
+
+	// CPUModeOff: no CPU bars → countBars floors to 1 (window always shows something)
+	nOff := countBars(snap, constants.CPUModeOff, false, false)
+	if nOff != 1 {
+		t.Errorf("CPUModeOff: expected 1 (floor), got %d", nOff)
 	}
 }
 
@@ -486,7 +492,7 @@ func TestNetBar_NoInterface(t *testing.T) {
 	defer surface.Free()
 
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = false
 	cfg.ShowNet = true
 
@@ -548,7 +554,7 @@ func TestRemainderPixels_AfterToggleMem(t *testing.T) {
 	src := &mockSource{data: hosts}
 
 	cfg := defaultTestConfig()
-	cfg.ShowCores = true
+	cfg.CPUMode = constants.CPUModeCores
 	cfg.ShowMem = true
 	cfg.ShowNet = false
 
@@ -589,7 +595,7 @@ func TestRemainderPixels_AfterToggleMem(t *testing.T) {
 // newHotkeyTestEnv creates a test environment with 1 host, 2 CPU cores, memory,
 // and 2 net interfaces. Returns all components needed for handleKey + drawFrame
 // pixel inspection tests.
-func newHotkeyTestEnv(t *testing.T, showCores, showMem, showNet bool) (
+func newHotkeyTestEnv(t *testing.T, cpuMode int, showMem, showNet bool) (
 	renderer *sdl.Renderer, surface *sdl.Surface,
 	cfg *config.Config, state *runState, src *mockSource,
 ) {
@@ -602,7 +608,7 @@ func newHotkeyTestEnv(t *testing.T, showCores, showMem, showNet bool) (
 	}
 
 	cfg = defaultTestConfig()
-	cfg.ShowCores = showCores
+	cfg.CPUMode = cpuMode
 	cfg.ShowMem = showMem
 	cfg.ShowNet = showNet
 
@@ -662,36 +668,52 @@ func TestHandleKey_UnknownKey(t *testing.T) {
 		t.Error("expected handleKey(x) to return false")
 	}
 	// State should be unchanged
-	if state.showCores != cfg.ShowCores || state.showMem != cfg.ShowMem || state.showNet != cfg.ShowNet {
+	if state.cpuMode != cfg.CPUMode || state.showMem != cfg.ShowMem || state.showNet != cfg.ShowNet {
 		t.Error("unknown key should not change state")
 	}
 }
 
 func TestHandleKey_ToggleCores(t *testing.T) {
-	renderer, surface, cfg, state, src := newHotkeyTestEnv(t, false, false, false)
+	renderer, surface, cfg, state, src := newHotkeyTestEnv(t, constants.CPUModeAverage, false, false)
 	defer renderer.Destroy()
 	defer surface.Free()
 
-	// Before: showCores=false → 1 CPU bar (aggregate)
+	// State 0 (CPUModeAverage): single aggregate bar spans full width
 	drawFrame(renderer, src, cfg, state)
-	// The single bar spans full width; check it has color at x=100
-	assertPixelColor(t, surface, 100, 95, constants.Blue, 5, "aggregate CPU bar before toggle")
+	assertPixelColor(t, surface, 100, 95, constants.Blue, 5, "aggregate CPU bar in average mode")
 
-	// Press '1' to toggle cores on
+	// Press '1': CPUModeAverage → CPUModeCores
 	handleKey(sdl.K_1, nil, cfg, state)
-	if !state.showCores {
-		t.Fatal("expected showCores=true after pressing 1")
+	if state.cpuMode != constants.CPUModeCores {
+		t.Fatalf("expected cpuMode=CPUModeCores after first press, got %d", state.cpuMode)
 	}
 
-	// After: showCores=true → 3 CPU bars (cpu + cpu0 + cpu1)
+	// State 1 (CPUModeCores): 3 CPU bars (cpu + cpu0 + cpu1), each ~66px wide at 200px window
 	drawFrame(renderer, src, cfg, state)
-	// With 3 bars at width 200: barWidth=66, bars at x=0, x=66, x=132
-	// Third bar (cpu1) should have color
-	assertPixelColor(t, surface, 140, 95, constants.Blue, 5, "cpu1 bar after toggle")
+	// Third bar (cpu1) starts at x=133; check it has color at x=140
+	assertPixelColor(t, surface, 140, 95, constants.Blue, 5, "cpu1 bar visible in cores mode")
+
+	// Press '1': CPUModeCores → CPUModeOff
+	handleKey(sdl.K_1, nil, cfg, state)
+	if state.cpuMode != constants.CPUModeOff {
+		t.Fatalf("expected cpuMode=CPUModeOff after second press, got %d", state.cpuMode)
+	}
+
+	// State 2 (CPUModeOff): no CPU bars; countBars returns 1 (floor) so window is still drawn
+	nOff := countBars(src.Snapshot(), constants.CPUModeOff, false, false)
+	if nOff != 1 {
+		t.Errorf("CPUModeOff: expected countBars=1 (floor), got %d", nOff)
+	}
+
+	// Press '1': CPUModeOff → CPUModeAverage (wraps around)
+	handleKey(sdl.K_1, nil, cfg, state)
+	if state.cpuMode != constants.CPUModeAverage {
+		t.Fatalf("expected cpuMode=CPUModeAverage after third press, got %d", state.cpuMode)
+	}
 }
 
 func TestHandleKey_ToggleMem(t *testing.T) {
-	renderer, surface, cfg, state, src := newHotkeyTestEnv(t, false, false, false)
+	renderer, surface, cfg, state, src := newHotkeyTestEnv(t, constants.CPUModeAverage, false, false)
 	defer renderer.Destroy()
 	defer surface.Free()
 
@@ -728,7 +750,7 @@ func TestHandleKey_ToggleMemAlias(t *testing.T) {
 }
 
 func TestHandleKey_ToggleNet(t *testing.T) {
-	renderer, surface, cfg, state, src := newHotkeyTestEnv(t, false, false, false)
+	renderer, surface, cfg, state, src := newHotkeyTestEnv(t, constants.CPUModeAverage, false, false)
 	defer renderer.Destroy()
 	defer surface.Free()
 
@@ -764,7 +786,7 @@ func TestHandleKey_ToggleNetAlias(t *testing.T) {
 }
 
 func TestHandleKey_ToggleExtended(t *testing.T) {
-	renderer, surface, cfg, state, src := newHotkeyTestEnv(t, false, false, false)
+	renderer, surface, cfg, state, src := newHotkeyTestEnv(t, constants.CPUModeAverage, false, false)
 	defer renderer.Destroy()
 	defer surface.Free()
 
@@ -852,7 +874,7 @@ func TestHandleKey_WriteConfig(t *testing.T) {
 	state := newRunState(cfg, 200, 100)
 	// Modify state values that should be copied to config
 	state.showAvgLine = true
-	state.showCores = true
+	state.cpuMode = constants.CPUModeCores
 	state.showMem = true
 	state.showNet = true
 	state.extended = true
@@ -862,8 +884,8 @@ func TestHandleKey_WriteConfig(t *testing.T) {
 	if !cfg.ShowAvgLine {
 		t.Error("expected ShowAvgLine=true in config after 'w'")
 	}
-	if !cfg.ShowCores {
-		t.Error("expected ShowCores=true in config after 'w'")
+	if cfg.CPUMode != constants.CPUModeCores {
+		t.Errorf("expected CPUMode=CPUModeCores in config after 'w', got %d", cfg.CPUMode)
 	}
 	if !cfg.ShowMem {
 		t.Error("expected ShowMem=true in config after 'w'")
@@ -877,7 +899,7 @@ func TestHandleKey_WriteConfig(t *testing.T) {
 }
 
 func TestHandleKey_LinkScaleUp(t *testing.T) {
-	renderer, surface, cfg, state, src := newHotkeyTestEnv(t, false, false, true)
+	renderer, surface, cfg, state, src := newHotkeyTestEnv(t, constants.CPUModeAverage, false, true)
 	defer renderer.Destroy()
 	defer surface.Free()
 
@@ -950,7 +972,7 @@ func TestGlobalAvgLine_SingleHost(t *testing.T) {
 
 	prev, cur := makeCPUPair(40, 40, 20) // 80% used (40 sys + 40 user)
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = false
 	cfg.ShowNet = false
 
@@ -988,7 +1010,7 @@ func TestGlobalAvgLine_MultiHost(t *testing.T) {
 	prev2, cur2 := makeCPUPair(20, 20, 60) // 40% used
 
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = false
 	cfg.ShowNet = false
 
@@ -1023,7 +1045,7 @@ func TestGlobalAvgLine_Disabled(t *testing.T) {
 
 	prev, cur := makeCPUPair(40, 40, 20) // 80% used
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = false
 	cfg.ShowNet = false
 
@@ -1284,7 +1306,7 @@ func TestHandleKey_ToggleSeparators(t *testing.T) {
 }
 
 func TestSeparator_TwoHosts_Enabled(t *testing.T) {
-	// Two hosts (100% system = blue) with separators enabled: yellow pixel at boundary
+	// Two hosts (100% system = blue) with separators enabled: red pixel at boundary
 	const w, h int32 = 200, 100
 
 	renderer, surface, err := createTestRenderer(w, h)
@@ -1298,7 +1320,7 @@ func TestSeparator_TwoHosts_Enabled(t *testing.T) {
 	prev2, cur2 := makeCPUPair(100, 0, 0)
 
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = false
 	cfg.ShowNet = false
 	cfg.ShowSeparators = true
@@ -1321,7 +1343,7 @@ func TestSeparator_TwoHosts_Enabled(t *testing.T) {
 }
 
 func TestSeparator_TwoHosts_Disabled(t *testing.T) {
-	// Two hosts (100% system = blue) with separators disabled: no yellow at boundary
+	// Two hosts (100% system = blue) with separators disabled: no red at boundary
 	const w, h int32 = 200, 100
 
 	renderer, surface, err := createTestRenderer(w, h)
@@ -1335,7 +1357,7 @@ func TestSeparator_TwoHosts_Disabled(t *testing.T) {
 	prev2, cur2 := makeCPUPair(100, 0, 0)
 
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = false
 	cfg.ShowNet = false
 	cfg.ShowSeparators = false
@@ -1370,7 +1392,7 @@ func TestSeparator_SingleHost(t *testing.T) {
 
 	prev, cur := makeCPUPair(50, 30, 20)
 	cfg := defaultTestConfig()
-	cfg.ShowCores = false
+	cfg.CPUMode = constants.CPUModeAverage
 	cfg.ShowMem = false
 	cfg.ShowNet = false
 	cfg.ShowSeparators = true
diff --git a/internal/display/font.go b/internal/display/font.go
new file mode 100644
index 0000000..d6dae18
--- /dev/null
+++ b/internal/display/font.go
@@ -0,0 +1,248 @@
+package display
+
+import "github.com/veandco/go-sdl2/sdl"
+
+// Bitmap font: 5x7 pixel glyphs for ASCII 32–126, rendered via FillRect.
+// Each glyph is 7 rows of 5 bits (MSB = leftmost pixel).
+
+const (
+	glyphW = 5 // pixels per character width
+	glyphH = 7 // pixels per character height
+	charGap = 1 // horizontal gap between characters
+)
+
+// font5x7 maps ASCII 32–126 to 7-byte bitmaps (one byte per row, top 5 bits used).
+// Index 0 = space (0x20), index 94 = tilde (0x7E).
+var font5x7 = [95][7]byte{
+	// space (0x20)
+	{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
+	// ! (0x21)
+	{0x20, 0x20, 0x20, 0x20, 0x20, 0x00, 0x20},
+	// " (0x22)
+	{0x50, 0x50, 0x00, 0x00, 0x00, 0x00, 0x00},
+	// # (0x23)
+	{0x50, 0xF8, 0x50, 0x50, 0x50, 0xF8, 0x50},
+	// $ (0x24)
+	{0x20, 0x70, 0xA0, 0x70, 0x28, 0x70, 0x20},
+	// % (0x25)
+	{0xC8, 0xC8, 0x10, 0x20, 0x40, 0x98, 0x98},
+	// & (0x26)
+	{0x40, 0xA0, 0xA0, 0x40, 0xA8, 0x90, 0x68},
+	// ' (0x27)
+	{0x20, 0x20, 0x00, 0x00, 0x00, 0x00, 0x00},
+	// ( (0x28)
+	{0x10, 0x20, 0x40, 0x40, 0x40, 0x20, 0x10},
+	// ) (0x29)
+	{0x40, 0x20, 0x10, 0x10, 0x10, 0x20, 0x40},
+	// * (0x2A)
+	{0x00, 0x20, 0xA8, 0x70, 0xA8, 0x20, 0x00},
+	// + (0x2B)
+	{0x00, 0x20, 0x20, 0xF8, 0x20, 0x20, 0x00},
+