refactor: extract magic numbers to named constants

Replace inline numeric literals with named constants across 14 files:
server timeouts/rate limits, cluster thresholds/intervals, DB pool
sizes, alert/dial timeouts, TUI uptime thresholds, node status
thresholds, and state history limits.

internal/alert/alert.go

@@ -18,7 +18,9 @@ import (
 	"gitea.lerkolabs.com/lerkolabs/uptop/internal/models"
 )
 
-var alertClient = &http.Client{Timeout: 10 * time.Second}
+const alertHTTPTimeout = 10 * time.Second
+
+var alertClient = &http.Client{Timeout: alertHTTPTimeout}
 
 // sanitizeError strips the request URL from transport errors before they are
 // stored or displayed. *url.Error embeds the full URL, which for several

internal/cluster/cluster.go

@@ -38,14 +38,20 @@ func Start(ctx context.Context, cfg Config, eng *monitor.Engine) {
 	// "probe" mode is handled directly in main.go before cluster.Start is called
 }
 
+const (
+	followerTimeout        = 2 * time.Second
+	leaderFailureThreshold = 3
+	followerRetryInterval  = 5 * time.Second
+)
+
 func runFollowerLoop(ctx context.Context, cfg Config, eng *monitor.Engine) {
-	client := http.Client{Timeout: 2 * time.Second}
+	client := http.Client{Timeout: followerTimeout}
 	failures := 0
-	threshold := 3
+	threshold := leaderFailureThreshold
 
 	for {
 		select {
-		case <-time.After(5 * time.Second):
+		case <-time.After(followerRetryInterval):
 		case <-ctx.Done():
 			return
 		}
@@ -59,7 +65,7 @@ func runFollowerLoop(ctx context.Context, cfg Config, eng *monitor.Engine) {
 		isLeaderHealthy := false
 
 		if err == nil {
-			isLeaderHealthy = resp.StatusCode == 200
+			isLeaderHealthy = resp.StatusCode == http.StatusOK
 			_ = resp.Body.Close()
 		}
 

internal/cluster/probe.go

@@ -26,12 +26,18 @@ type ProbeConfig struct {
 	AllowPrivateTargets bool
 }
 
+const (
+	probeMinInterval     = 10
+	probeDefaultInterval = 30
+	probeAPITimeout      = 10 * time.Second
+)
+
 func RunProbe(ctx context.Context, cfg ProbeConfig) error {
-	if cfg.Interval < 10 {
-		cfg.Interval = 30
+	if cfg.Interval < probeMinInterval {
+		cfg.Interval = probeDefaultInterval
 	}
 
-	apiClient := &http.Client{Timeout: 10 * time.Second}
+	apiClient := &http.Client{Timeout: probeAPITimeout}
 	dial := monitor.SafeDialContext(cfg.AllowPrivateTargets)
 	strictClient := &http.Client{
 		Transport: &http.Transport{

internal/monitor/monitor.go

@@ -24,6 +24,7 @@ const (
 	maintPruneInterval    = 15 * time.Minute
 	defaultMaintRetention = 7 * 24 * time.Hour
 	dbWriteBuffer         = 4096
+	alertSendTimeout      = 30 * time.Second
 	dbPruneInterval       = 10 * time.Minute
 )
 
@@ -900,7 +901,7 @@ func (e *Engine) triggerAlert(alertID int, title, message string) {
 	provider := alert.GetProvider(cfg)
 	if provider != nil {
 		go func() {
-			ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+			ctx, cancel := context.WithTimeout(context.Background(), alertSendTimeout)
 			defer cancel()
 			if err := provider.Send(ctx, title, message); err != nil {
 				e.AddLog(fmt.Sprintf("Alert send failed (%s): %v", cfg.Name, err))
@@ -953,7 +954,7 @@ func (e *Engine) TestAlert(alertID int) error {
 	if provider == nil {
 		return fmt.Errorf("no provider for type %q", cfg.Type)
 	}
-	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	ctx, cancel := context.WithTimeout(context.Background(), alertSendTimeout)
 	defer cancel()
 	err = provider.Send(ctx, "🧪 Test Alert", fmt.Sprintf("Test notification from uptop for channel '%s'.", cfg.Name))
 	if err != nil {

internal/monitor/safedial.go

@@ -7,6 +7,8 @@ import (
 	"time"
 )
 
+const dialTimeout = 10 * time.Second
+
 var privateRanges []*net.IPNet
 
 func init() {
@@ -60,7 +62,7 @@ func SafeDialContext(allowPrivate bool) func(ctx context.Context, network, addr
 			}
 		}
 
-		dialer := &net.Dialer{Timeout: 10 * time.Second}
+		dialer := &net.Dialer{Timeout: dialTimeout}
 		for _, ip := range ips {
 			target := net.JoinHostPort(ip.IP.String(), port)
 			conn, err := dialer.DialContext(ctx, network, target)

internal/server/ratelimit.go

@@ -14,6 +14,11 @@ import (
 // guard.
 const maxVisitors = 10000
 
+const (
+	visitorCleanupInterval = 5 * time.Minute
+	visitorIdleCutoff      = 10 * time.Minute
+)
+
 type visitor struct {
 	tokens   float64
 	lastSeen time.Time
@@ -90,13 +95,13 @@ func (rl *RateLimiter) evictOldest() {
 }
 
 func (rl *RateLimiter) cleanup() {
-	ticker := time.NewTicker(5 * time.Minute)
+	ticker := time.NewTicker(visitorCleanupInterval)
 	defer ticker.Stop()
 	for {
 		select {
 		case <-ticker.C:
 			rl.mu.Lock()
-			cutoff := time.Now().Add(-10 * time.Minute)
+			cutoff := time.Now().Add(-visitorIdleCutoff)
 			for ip, v := range rl.visitors {
 				if v.lastSeen.Before(cutoff) {
 					delete(rl.visitors, ip)

internal/server/server.go

@@ -45,15 +45,27 @@ type Server struct {
 	statusRL *RateLimiter
 }
 
+const (
+	pushRateLimit   = 60
+	probeRateLimit  = 30
+	backupRateLimit = 10
+	statusRateLimit = 120
+
+	httpReadHeaderTimeout = 10 * time.Second
+	httpReadTimeout       = 30 * time.Second
+	httpWriteTimeout      = 60 * time.Second
+	httpIdleTimeout       = 120 * time.Second
+)
+
 func NewServer(cfg ServerConfig, s store.Store, eng *monitor.Engine) *Server {
 	return &Server{
 		cfg:      cfg,
 		store:    s,
 		eng:      eng,
-		pushRL:   NewRateLimiter(60, cfg.TrustedProxies),
-		probeRL:  NewRateLimiter(30, cfg.TrustedProxies),
-		backupRL: NewRateLimiter(10, cfg.TrustedProxies),
-		statusRL: NewRateLimiter(120, cfg.TrustedProxies),
+		pushRL:   NewRateLimiter(pushRateLimit, cfg.TrustedProxies),
+		probeRL:  NewRateLimiter(probeRateLimit, cfg.TrustedProxies),
+		backupRL: NewRateLimiter(backupRateLimit, cfg.TrustedProxies),
+		statusRL: NewRateLimiter(statusRateLimit, cfg.TrustedProxies),
 	}
 }
 
@@ -77,10 +89,10 @@ func (s *Server) Start() *http.Server {
 	httpSrv := &http.Server{
 		Addr:              addr,
 		Handler:           handler,
-		ReadHeaderTimeout: 10 * time.Second,
-		ReadTimeout:       30 * time.Second,
-		WriteTimeout:      60 * time.Second,
-		IdleTimeout:       120 * time.Second,
+		ReadHeaderTimeout: httpReadHeaderTimeout,
+		ReadTimeout:       httpReadTimeout,
+		WriteTimeout:      httpWriteTimeout,
+		IdleTimeout:       httpIdleTimeout,
 	}
 	go func() {
 		if s.cfg.TLSCert != "" && s.cfg.TLSKey != "" {

internal/store/sqlstore.go

@@ -18,6 +18,10 @@ const (
 	maxLogRows             = 200
 	maxStateChangesPerSite = 5000
 	maxMaintenanceExport   = 1000
+	maxOpenConns           = 25
+	maxIdleConns           = 5
+	connMaxLifetime        = 5 * time.Minute
+	tokenByteLen           = 16
 )
 
 type SQLStore struct {
@@ -32,9 +36,9 @@ func NewSQLStore(driverName, dsn string, dialect Dialect) (*SQLStore, error) {
 	if err != nil {
 		return nil, err
 	}
-	db.SetMaxOpenConns(25)
-	db.SetMaxIdleConns(5)
-	db.SetConnMaxLifetime(5 * time.Minute)
+	db.SetMaxOpenConns(maxOpenConns)
+	db.SetMaxIdleConns(maxIdleConns)
+	db.SetConnMaxLifetime(connMaxLifetime)
 	_, isDollar := dialect.(*PostgresDialect)
 	return &SQLStore{db: db, dialect: dialect, dollar: isDollar}, nil
 }
@@ -62,7 +66,7 @@ func (s *SQLStore) q(query string) string {
 }
 
 func generateToken() (string, error) {
-	b := make([]byte, 16)
+	b := make([]byte, tokenByteLen)
 	if _, err := rand.Read(b); err != nil {
 		return "", fmt.Errorf("crypto/rand failed: %w", err)
 	}

internal/tui/const.go

@@ -0,0 +1,20 @@
+package tui
+
+import "time"
+
+const (
+	nodeOnlineThreshold = 60 * time.Second
+	nodeStaleThreshold  = 5 * time.Minute
+
+	uptimeGoodPct      = 99.0
+	uptimeExcellentPct = 99.9
+	uptimeWarnPct      = 95.0
+	uptimePrecisionPct = 99.99
+
+	stateHistoryLookback = 30 * 24 * time.Hour
+	stateHistoryDays     = 30
+	stateHistoryLimit    = 100
+
+	httpErrorThreshold = 400
+	errorDetailMaxLen  = 30
+)

internal/tui/data.go

@@ -202,8 +202,8 @@ func (m *Model) loadDetailCmd(siteID int) tea.Cmd {
 	return func() tea.Msg {
 		changes := eng.GetStateChanges(siteID, 5)
 		now := time.Now()
-		allChanges := eng.GetStateChangesSince(siteID, now.Add(-30*24*time.Hour))
-		daily := monitor.ComputeDailyBreakdown(allChanges, currentStatus, 30, now)
+		allChanges := eng.GetStateChangesSince(siteID, now.Add(-stateHistoryLookback))
+		daily := monitor.ComputeDailyBreakdown(allChanges, currentStatus, stateHistoryDays, now)
 		return detailDataMsg{siteID: siteID, changes: changes, dailyDays: daily}
 	}
 }
@@ -213,7 +213,7 @@ func (m *Model) loadDetailCmd(siteID int) tea.Cmd {
 func (m *Model) loadHistoryCmd(siteID int) tea.Cmd {
 	eng := m.engine
 	return func() tea.Msg {
-		return historyDataMsg{siteID: siteID, changes: eng.GetStateChanges(siteID, 100)}
+		return historyDataMsg{siteID: siteID, changes: eng.GetStateChanges(siteID, stateHistoryLimit)}
 	}
 }
 

internal/tui/errclass.go

@@ -58,7 +58,7 @@ func classifyError(errorReason string, siteType string, statusCode int) ErrorCat
 	if strings.HasPrefix(lower, "http ") || strings.Contains(lower, "keyword not found") {
 		return ErrCatHTTP
 	}
-	if statusCode >= 400 {
+	if statusCode >= httpErrorThreshold {
 		return ErrCatHTTP
 	}
 
@@ -145,7 +145,7 @@ func extractDetail(errorReason string, cat ErrorCategory, statusCode int) string
 			}
 		}
 		if detail == "" {
-			detail = limitStr(errorReason, 30)
+			detail = limitStr(errorReason, errorDetailMaxLen)
 		}
 	case ErrCatTCP:
 		for _, keyword := range []string{"connection refused", "connection reset", "no route to host", "network unreachable"} {
@@ -155,7 +155,7 @@ func extractDetail(errorReason string, cat ErrorCategory, statusCode int) string
 			}
 		}
 		if detail == "" {
-			detail = limitStr(errorReason, 30)
+			detail = limitStr(errorReason, errorDetailMaxLen)
 		}
 	case ErrCatTLS:
 		for _, keyword := range []string{"certificate expired", "certificate has expired", "handshake failure", "unknown authority"} {
@@ -166,16 +166,16 @@ func extractDetail(errorReason string, cat ErrorCategory, statusCode int) string
 		}
 		if detail == "" && strings.Contains(lower, "x509:") {
 			idx := strings.Index(lower, "x509:")
-			detail = limitStr(errorReason[idx:], 30)
+			detail = limitStr(errorReason[idx:], errorDetailMaxLen)
 		}
 		if detail == "" {
-			detail = limitStr(errorReason, 30)
+			detail = limitStr(errorReason, errorDetailMaxLen)
 		}
 	case ErrCatHTTP:
 		if statusCode > 0 {
 			detail = fmt.Sprintf("HTTP %d", statusCode)
 		} else {
-			detail = limitStr(errorReason, 30)
+			detail = limitStr(errorReason, errorDetailMaxLen)
 		}
 	case ErrCatTimeout:
 		if strings.Contains(lower, "i/o timeout") {
@@ -187,12 +187,12 @@ func extractDetail(errorReason string, cat ErrorCategory, statusCode int) string
 		if strings.Contains(lower, "no icmp response") {
 			detail = "no response"
 		} else {
-			detail = limitStr(errorReason, 30)
+			detail = limitStr(errorReason, errorDetailMaxLen)
 		}
 	case ErrCatPrivate:
 		detail = "private IP blocked"
 	default:
-		detail = limitStr(errorReason, 30)
+		detail = limitStr(errorReason, errorDetailMaxLen)
 	}
 
 	return detail

internal/tui/tab_nodes.go

@@ -55,7 +55,7 @@ func (m Model) viewNodesTab() string {
 	regions := make(map[string]bool)
 	var leader string
 	for _, n := range m.nodes {
-		if time.Since(n.LastSeen) < 60*time.Second {
+		if time.Since(n.LastSeen) < nodeOnlineThreshold {
 			online++
 		}
 		if n.Region != "" {
@@ -81,10 +81,10 @@ func (m Model) fmtNodeStatus(lastSeen time.Time) string {
 		return m.st.subtleStyle.Render("UNKNOWN")
 	}
 	ago := time.Since(lastSeen)
-	if ago < 60*time.Second {
+	if ago < nodeOnlineThreshold {
 		return m.st.specialStyle.Render("ONLINE")
 	}
-	if ago < 5*time.Minute {
+	if ago < nodeStaleThreshold {
 		return m.st.warnStyle.Render("STALE")
 	}
 	return m.st.dangerStyle.Render("OFFLINE")

internal/tui/uptime_timeline.go

@@ -26,9 +26,9 @@ func (m Model) uptimeTimeline(days []monitor.DayReport, width int) string {
 	for _, d := range display {
 		ch := "█"
 		switch {
-		case d.UptimePct >= 99.0:
+		case d.UptimePct >= uptimeGoodPct:
 			sb.WriteString(m.st.specialStyle.Render(ch))
-		case d.UptimePct >= 95.0:
+		case d.UptimePct >= uptimeWarnPct:
 			sb.WriteString(m.st.warnStyle.Render(ch))
 		case d.UptimePct > 0:
 			sb.WriteString(m.st.dangerStyle.Render(ch))
@@ -39,9 +39,9 @@ func (m Model) uptimeTimeline(days []monitor.DayReport, width int) string {
 
 	pct := days[len(days)-1].UptimePct
 	pctStyle := m.st.specialStyle
-	if pct < 99.0 {
+	if pct < uptimeGoodPct {
 		pctStyle = m.st.dangerStyle
-	} else if pct < 99.9 {
+	} else if pct < uptimeExcellentPct {
 		pctStyle = m.st.warnStyle
 	}
 	sb.WriteString("  " + pctStyle.Render(fmt.Sprintf("%.2f%%", pct)))

internal/tui/view_dashboard.go

@@ -130,7 +130,7 @@ func (m Model) computeStats() dashboardStats {
 		}
 	}
 	for _, n := range m.nodes {
-		if !n.LastSeen.IsZero() && time.Since(n.LastSeen) > 5*time.Minute {
+		if !n.LastSeen.IsZero() && time.Since(n.LastSeen) > nodeStaleThreshold {
 			s.offlineNodes++
 		}
 	}
@@ -294,7 +294,7 @@ func (m Model) renderFooter(stats dashboardStats) string {
 	if len(m.nodes) > 0 {
 		online := 0
 		for _, n := range m.nodes {
-			if !n.LastSeen.IsZero() && time.Since(n.LastSeen) < 60*time.Second {
+			if !n.LastSeen.IsZero() && time.Since(n.LastSeen) < nodeOnlineThreshold {
 				online++
 			}
 		}

internal/tui/view_sla.go

@@ -40,10 +40,10 @@ func (m Model) viewSLAPanel() string {
 	}
 	bar := m.uptimeBar(r.UptimePct, barWidth)
 	uptimeColor := m.st.specialStyle
-	if r.UptimePct < 99.9 {
+	if r.UptimePct < uptimeExcellentPct {
 		uptimeColor = m.st.warnStyle
 	}
-	if r.UptimePct < 99.0 {
+	if r.UptimePct < uptimeGoodPct {
 		uptimeColor = m.st.dangerStyle
 	}
 	fmt.Fprintf(&b, "  %-16s %s  %s\n", m.st.subtleStyle.Render("Uptime"), uptimeColor.Render(fmt.Sprintf("%s%%", fmtPct(r.UptimePct))), bar)
@@ -94,10 +94,10 @@ func (m Model) buildSLADailyContent() string {
 		pctStr := fmtPct(day.UptimePct) + "%"
 
 		color := m.st.specialStyle
-		if day.UptimePct < 99.9 {
+		if day.UptimePct < uptimeExcellentPct {
 			color = m.st.warnStyle
 		}
-		if day.UptimePct < 99.0 {
+		if day.UptimePct < uptimeGoodPct {
 			color = m.st.dangerStyle
 		}
 
@@ -128,7 +128,7 @@ func fmtPct(pct float64) string {
 	if pct == 100 {
 		return "100.00"
 	}
-	if pct >= 99.99 {
+	if pct >= uptimePrecisionPct {
 		return fmt.Sprintf("%.3f", pct)
 	}
 	return fmt.Sprintf("%.2f", pct)