Rewrite in Go: static binaries, zero runtime dependencies

Replace Node.js + Python codebase with three Go binaries:
- claude-statusline: CLI status bar for Claude Code
- claude-fetcher: standalone cron job for API usage
- claude-widget: system tray icon (fyne-io/systray + fogleman/gg)

All CGO-free for trivial cross-compilation. Add nfpm .deb packaging
with autostart and cron. CI pipeline produces Linux + Windows binaries,
.deb, .tar.gz, and .zip release assets.

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

internal/tray/tray.go

@@ -0,0 +1,215 @@
+package tray
+
+import (
+	"fmt"
+	"os/exec"
+	"runtime"
+	"sync"
+
+	"fyne.io/systray"
+	"git.davoryn.de/calic/claude-statusline/internal/config"
+	"git.davoryn.de/calic/claude-statusline/internal/fetcher"
+	"git.davoryn.de/calic/claude-statusline/internal/renderer"
+)
+
+type interval struct {
+	label   string
+	seconds int
+}
+
+var intervals = []interval{
+	{"1 min", 60},
+	{"5 min", 300},
+	{"15 min", 900},
+	{"30 min", 1800},
+}
+
+// App manages the tray icon, fetcher, and menu state.
+type App struct {
+	mu        sync.Mutex
+	usage     fetcher.ParsedUsage
+	bf        *fetcher.BackgroundFetcher
+	menuItems struct {
+		fiveHourText  *systray.MenuItem
+		fiveHourReset *systray.MenuItem
+		sevenDayText  *systray.MenuItem
+		sevenDayReset *systray.MenuItem
+		intervalRadio []*systray.MenuItem
+	}
+}
+
+// Run starts the tray application (blocking).
+func Run() {
+	app := &App{}
+	systray.Run(app.onReady, app.onExit)
+}
+
+func (a *App) onReady() {
+	systray.SetTitle("Claude Usage")
+	systray.SetTooltip("Claude Usage: loading...")
+
+	// Set initial icon (0%)
+	if iconData, err := renderer.RenderIconPNG(0); err == nil {
+		systray.SetIcon(iconData)
+	}
+
+	// Usage display items (non-clickable info)
+	a.menuItems.fiveHourText = systray.AddMenuItem("5h Usage: loading...", "")
+	a.menuItems.fiveHourText.Disable()
+	a.menuItems.fiveHourReset = systray.AddMenuItem("Resets in: —", "")
+	a.menuItems.fiveHourReset.Disable()
+
+	systray.AddSeparator()
+
+	a.menuItems.sevenDayText = systray.AddMenuItem("7d Usage: —", "")
+	a.menuItems.sevenDayText.Disable()
+	a.menuItems.sevenDayReset = systray.AddMenuItem("Resets in: —", "")
+	a.menuItems.sevenDayReset.Disable()
+
+	systray.AddSeparator()
+
+	// Refresh button
+	mRefresh := systray.AddMenuItem("Refresh Now", "Force refresh usage data")
+
+	// Interval submenu
+	mInterval := systray.AddMenuItem("Refresh Interval", "Change refresh interval")
+	currentInterval := a.getCurrentInterval()
+	for _, iv := range intervals {
+		item := mInterval.AddSubMenuItem(iv.label, fmt.Sprintf("Refresh every %s", iv.label))
+		if iv.seconds == currentInterval {
+			item.Check()
+		}
+		a.menuItems.intervalRadio = append(a.menuItems.intervalRadio, item)
+	}
+
+	// Session key
+	mSessionKey := systray.AddMenuItem("Session Key...", "Open session key config file")
+
+	systray.AddSeparator()
+	mQuit := systray.AddMenuItem("Quit", "Exit Claude Usage Widget")
+
+	// Start background fetcher
+	a.bf = fetcher.NewBackgroundFetcher(a.onUsageUpdate)
+	a.bf.Start()
+
+	// Handle menu clicks
+	go func() {
+		for {
+			select {
+			case <-mRefresh.ClickedCh:
+				a.bf.Refresh()
+			case <-mSessionKey.ClickedCh:
+				a.openSessionKeyFile()
+			case <-mQuit.ClickedCh:
+				systray.Quit()
+				return
+			}
+		}
+	}()
+
+	// Handle interval radio clicks
+	for i, item := range a.menuItems.intervalRadio {
+		go func(idx int, mi *systray.MenuItem) {
+			for range mi.ClickedCh {
+				a.setInterval(idx)
+			}
+		}(i, item)
+	}
+}
+
+func (a *App) onExit() {
+	if a.bf != nil {
+		a.bf.Stop()
+	}
+}
+
+func (a *App) onUsageUpdate(data fetcher.ParsedUsage) {
+	a.mu.Lock()
+	a.usage = data
+	a.mu.Unlock()
+
+	// Update icon
+	pct := 0
+	if data.Error == "" {
+		pct = data.FiveHourPct
+	}
+	if iconData, err := renderer.RenderIconPNG(pct); err == nil {
+		systray.SetIcon(iconData)
+	}
+
+	// Update tooltip
+	if data.Error != "" {
+		systray.SetTooltip(fmt.Sprintf("Claude Usage: %s", data.Error))
+	} else {
+		systray.SetTooltip(fmt.Sprintf("Claude Usage: %d%%", data.FiveHourPct))
+	}
+
+	// Update menu text
+	a.updateMenuText(data)
+}
+
+func (a *App) updateMenuText(data fetcher.ParsedUsage) {
+	if data.Error != "" {
+		a.menuItems.fiveHourText.SetTitle(fmt.Sprintf("5h Usage: %s", data.Error))
+		a.menuItems.fiveHourReset.SetTitle("Resets in: —")
+		a.menuItems.sevenDayText.SetTitle("7d Usage: —")
+		a.menuItems.sevenDayReset.SetTitle("Resets in: —")
+		return
+	}
+
+	if data.FiveHourPct > 0 {
+		a.menuItems.fiveHourText.SetTitle(fmt.Sprintf("5h Usage: %d%%", data.FiveHourPct))
+	} else {
+		a.menuItems.fiveHourText.SetTitle("5h Usage: 0%")
+	}
+	if data.FiveHourResetsIn != "" {
+		a.menuItems.fiveHourReset.SetTitle(fmt.Sprintf("Resets in: %s", data.FiveHourResetsIn))
+	} else {
+		a.menuItems.fiveHourReset.SetTitle("Resets in: —")
+	}
+
+	if data.SevenDayPct > 0 {
+		a.menuItems.sevenDayText.SetTitle(fmt.Sprintf("7d Usage: %d%%", data.SevenDayPct))
+	} else {
+		a.menuItems.sevenDayText.SetTitle("7d Usage: 0%")
+	}
+	if data.SevenDayResetsIn != "" {
+		a.menuItems.sevenDayReset.SetTitle(fmt.Sprintf("Resets in: %s", data.SevenDayResetsIn))
+	} else {
+		a.menuItems.sevenDayReset.SetTitle("Resets in: —")
+	}
+}
+
+func (a *App) getCurrentInterval() int {
+	cfg := config.Load()
+	return cfg.RefreshInterval
+}
+
+func (a *App) setInterval(idx int) {
+	if idx < 0 || idx >= len(intervals) {
+		return
+	}
+	// Update radio check marks
+	for i, item := range a.menuItems.intervalRadio {
+		if i == idx {
+			item.Check()
+		} else {
+			item.Uncheck()
+		}
+	}
+	a.bf.SetInterval(intervals[idx].seconds)
+}
+
+func (a *App) openSessionKeyFile() {
+	path := config.SessionKeyPath()
+	var cmd *exec.Cmd
+	switch runtime.GOOS {
+	case "windows":
+		cmd = exec.Command("notepad", path)
+	case "darwin":
+		cmd = exec.Command("open", "-t", path)
+	default:
+		cmd = exec.Command("xdg-open", path)
+	}
+	_ = cmd.Start()
+}