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/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)