refactor(models): typed Status constants with IsBroken() predicate

Replace ~150 bare status string comparisons with typed models.Status
constants (StatusUp, StatusDown, StatusPending, StatusLate, StatusStale,
StatusSSLExp). Single IsBroken() method replaces the duplicated
isBroken lambda in monitor.go and isDown function in sla.go.

Adding a new status value (e.g. DEGRADED) now requires one constant
definition instead of grep-and-pray across 16 files.

CheckResult.Status stays string — the checker is the boundary between
raw protocol results and typed status. Cast happens at the edge in
handleStatusChange.

internal/cluster/probe.go

@@ -157,7 +157,7 @@ loop:
 			results = append(results, probeResultItem{
 				SiteID:      s.ID,
 				LatencyNs:   cr.LatencyNs,
-				IsUp:        cr.Status == "UP",
+				IsUp:        cr.Status == string(models.StatusUp),
 				ErrorReason: cr.ErrorReason,
 			})
 			mu.Unlock()

internal/metrics/prometheus.go

@@ -2,11 +2,12 @@ package metrics
 
 import (
 	"fmt"
-	"gitea.lerkolabs.com/lerkolabs/uptop/internal/models"
-	"gitea.lerkolabs.com/lerkolabs/uptop/internal/monitor"
 	"net/http"
 	"sort"
 	"strings"
+
+	"gitea.lerkolabs.com/lerkolabs/uptop/internal/models"
+	"gitea.lerkolabs.com/lerkolabs/uptop/internal/monitor"
 )
 
 func Handler(eng *monitor.Engine) http.HandlerFunc {
@@ -19,7 +20,7 @@ func Handler(eng *monitor.Engine) http.HandlerFunc {
 		writeHelp(&b, "uptop_monitor_up", "gauge", "Whether the monitor is up (1) or down (0).")
 		for _, s := range sites {
 			val := 0
-			if s.Status == "UP" {
+			if s.Status == models.StatusUp {
 				val = 1
 			}
 			writeGauge(&b, "uptop_monitor_up", labels(s), float64(val))

internal/models/models.go

@@ -28,7 +28,7 @@ type Site struct {
 	Regions        string
 
 	FailureCount    int
-	Status          string
+	Status          Status
 	StatusCode      int
 	Latency         time.Duration
 	CertExpiry      time.Time

internal/models/status.go

@@ -0,0 +1,18 @@
+package models
+
+type Status string
+
+const (
+	StatusUp      Status = "UP"
+	StatusDown    Status = "DOWN"
+	StatusPending Status = "PENDING"
+	StatusLate    Status = "LATE"
+	StatusStale   Status = "STALE"
+	StatusSSLExp  Status = "SSL EXP"
+)
+
+func (s Status) IsBroken() bool {
+	return s == StatusDown || s == StatusSSLExp
+}
+
+func (s Status) String() string { return string(s) }

internal/monitor/checker.go

@@ -47,7 +47,7 @@ func RunCheck(ctx context.Context, site models.Site, strict, insecure *http.Clie
 			if ips, err := net.LookupIP(host); err == nil {
 				for _, ip := range ips {
 					if isPrivateIP(ip) {
-						return CheckResult{SiteID: site.ID, Status: "DOWN", ErrorReason: "target resolves to private IP"}
+						return CheckResult{SiteID: site.ID, Status: string(models.StatusDown), ErrorReason: "target resolves to private IP"}
 					}
 				}
 			}
@@ -64,7 +64,7 @@ func RunCheck(ctx context.Context, site models.Site, strict, insecure *http.Clie
 	case "dns":
 		return runDNSCheck(ctx, site)
 	default:
-		return CheckResult{SiteID: site.ID, Status: "DOWN", ErrorReason: "unsupported monitor type: " + site.Type}
+		return CheckResult{SiteID: site.ID, Status: string(models.StatusDown), ErrorReason: "unsupported monitor type: " + site.Type}
 	}
 }
 
@@ -80,7 +80,7 @@ func runHTTPCheck(ctx context.Context, site models.Site, strict, insecure *http.
 
 	req, err := http.NewRequestWithContext(ctx, method, site.URL, nil)
 	if err != nil {
-		return CheckResult{SiteID: site.ID, Status: "DOWN", ErrorReason: "invalid request: " + err.Error()}
+		return CheckResult{SiteID: site.ID, Status: string(models.StatusDown), ErrorReason: "invalid request: " + err.Error()}
 	}
 
 	client := strict
@@ -94,12 +94,12 @@ func runHTTPCheck(ctx context.Context, site models.Site, strict, insecure *http.
 
 	result := CheckResult{
 		SiteID:    site.ID,
-		Status:    "UP",
+		Status:    string(models.StatusUp),
 		LatencyNs: latency.Nanoseconds(),
 	}
 
 	if err != nil {
-		result.Status = "DOWN"
+		result.Status = string(models.StatusDown)
 		result.ErrorReason = truncateError(err.Error(), maxErrorLength)
 		return result
 	}
@@ -107,7 +107,7 @@ func runHTTPCheck(ctx context.Context, site models.Site, strict, insecure *http.
 
 	result.StatusCode = resp.StatusCode
 	if !isCodeAccepted(resp.StatusCode, site.AcceptedCodes) {
-		result.Status = "DOWN"
+		result.Status = string(models.StatusDown)
 		expected := site.AcceptedCodes
 		if expected == "" {
 			expected = defaultAcceptedCodes
@@ -120,7 +120,7 @@ func runHTTPCheck(ctx context.Context, site models.Site, strict, insecure *http.
 		cert := resp.TLS.PeerCertificates[0]
 		result.CertExpiry = cert.NotAfter
 		if time.Now().After(cert.NotAfter) {
-			result.Status = "SSL EXP"
+			result.Status = string(models.StatusSSLExp)
 			result.ErrorReason = "SSL certificate expired"
 		}
 	}
@@ -136,7 +136,7 @@ func runPingCheck(_ context.Context, site models.Site) CheckResult {
 
 	pinger, err := probing.NewPinger(host)
 	if err != nil {
-		return CheckResult{SiteID: site.ID, Status: "DOWN", ErrorReason: "ping setup: " + err.Error()}
+		return CheckResult{SiteID: site.ID, Status: string(models.StatusDown), ErrorReason: "ping setup: " + err.Error()}
 	}
 	pinger.Count = 1
 	pinger.Timeout = siteTimeout(site)
@@ -147,14 +147,14 @@ func runPingCheck(_ context.Context, site models.Site) CheckResult {
 	latency := time.Since(start)
 
 	if err != nil {
-		return CheckResult{SiteID: site.ID, Status: "DOWN", LatencyNs: latency.Nanoseconds(), ErrorReason: "ping failed: " + err.Error()}
+		return CheckResult{SiteID: site.ID, Status: string(models.StatusDown), LatencyNs: latency.Nanoseconds(), ErrorReason: "ping failed: " + err.Error()}
 	}
 	if pinger.Statistics().PacketsRecv == 0 {
-		return CheckResult{SiteID: site.ID, Status: "DOWN", LatencyNs: latency.Nanoseconds(), ErrorReason: "no ICMP response"}
+		return CheckResult{SiteID: site.ID, Status: string(models.StatusDown), LatencyNs: latency.Nanoseconds(), ErrorReason: "no ICMP response"}
 	}
 
 	stats := pinger.Statistics()
-	return CheckResult{SiteID: site.ID, Status: "UP", LatencyNs: stats.AvgRtt.Nanoseconds()}
+	return CheckResult{SiteID: site.ID, Status: string(models.StatusUp), LatencyNs: stats.AvgRtt.Nanoseconds()}
 }
 
 func runPortCheck(_ context.Context, site models.Site) CheckResult {
@@ -170,10 +170,10 @@ func runPortCheck(_ context.Context, site models.Site) CheckResult {
 	latency := time.Since(start)
 
 	if err != nil {
-		return CheckResult{SiteID: site.ID, Status: "DOWN", LatencyNs: latency.Nanoseconds(), ErrorReason: truncateError(err.Error(), maxErrorLength)}
+		return CheckResult{SiteID: site.ID, Status: string(models.StatusDown), LatencyNs: latency.Nanoseconds(), ErrorReason: truncateError(err.Error(), maxErrorLength)}
 	}
 	_ = conn.Close()
-	return CheckResult{SiteID: site.ID, Status: "UP", LatencyNs: latency.Nanoseconds()}
+	return CheckResult{SiteID: site.ID, Status: string(models.StatusUp), LatencyNs: latency.Nanoseconds()}
 }
 
 func runDNSCheck(_ context.Context, site models.Site) CheckResult {
@@ -221,12 +221,12 @@ func runDNSCheck(_ context.Context, site models.Site) CheckResult {
 	latency := time.Since(start)
 
 	if err != nil {
-		return CheckResult{SiteID: site.ID, Status: "DOWN", LatencyNs: latency.Nanoseconds(), ErrorReason: "DNS query failed: " + err.Error()}
+		return CheckResult{SiteID: site.ID, Status: string(models.StatusDown), LatencyNs: latency.Nanoseconds(), ErrorReason: "DNS query failed: " + err.Error()}
 	}
 	if r.Rcode != dns.RcodeSuccess {
-		return CheckResult{SiteID: site.ID, Status: "DOWN", StatusCode: r.Rcode, LatencyNs: latency.Nanoseconds(), ErrorReason: "DNS RCODE: " + dns.RcodeToString[r.Rcode]}
+		return CheckResult{SiteID: site.ID, Status: string(models.StatusDown), StatusCode: r.Rcode, LatencyNs: latency.Nanoseconds(), ErrorReason: "DNS RCODE: " + dns.RcodeToString[r.Rcode]}
 	}
-	return CheckResult{SiteID: site.ID, Status: "UP", LatencyNs: latency.Nanoseconds()}
+	return CheckResult{SiteID: site.ID, Status: string(models.StatusUp), LatencyNs: latency.Nanoseconds()}
 }
 
 func siteTimeout(site models.Site) time.Duration {

internal/monitor/monitor.go

@@ -334,7 +334,7 @@ func (e *Engine) RecordHeartbeat(token string) bool {
 	}
 
 	var (
-		prevStatus string
+		prevStatus models.Status
 		name       string
 		alertID    int
 		downSince  time.Time
@@ -346,12 +346,12 @@ func (e *Engine) RecordHeartbeat(token string) bool {
 		downSince = s.StatusChangedAt // captured before mutation = when it went down
 
 		s.LastCheck = time.Now()
-		s.Status = "UP"
+		s.Status = models.StatusUp
 		s.FailureCount = 0
 		s.Latency = 0
 		s.LastError = ""
 		s.LastSuccessAt = time.Now()
-		if prevStatus != "UP" {
+		if prevStatus != models.StatusUp {
 			s.StatusChangedAt = time.Now()
 		}
 	})
@@ -360,13 +360,13 @@ func (e *Engine) RecordHeartbeat(token string) bool {
 	}
 
 	switch prevStatus {
-	case "PENDING":
+	case models.StatusPending:
 		e.AddLog(fmt.Sprintf("Push Monitor '%s' received first heartbeat", name))
-	case "LATE":
+	case models.StatusLate:
 		e.AddLog(fmt.Sprintf("Push Monitor '%s' heartbeat arrived (was late)", name))
-	case "STALE":
+	case models.StatusStale:
 		e.AddLog(fmt.Sprintf("Push Monitor '%s' heartbeat arrived (was stale)", name))
-	case "DOWN":
+	case models.StatusDown:
 		downDur := ""
 		if !downSince.IsZero() {
 			downDur = fmt.Sprintf(" (was down %s)", fmtDurationShort(time.Since(downSince)))
@@ -375,8 +375,8 @@ func (e *Engine) RecordHeartbeat(token string) bool {
 		go e.triggerAlert(alertID, "✅ RECOVERY", fmt.Sprintf("Push Monitor '%s' is receiving heartbeats.%s", name, downDur))
 	}
 
-	if prevStatus != "UP" && prevStatus != "PENDING" {
-		e.enqueueWrite(writeStateChange{siteID: targetID, fromStatus: prevStatus, toStatus: "UP"})
+	if prevStatus != models.StatusUp && prevStatus != models.StatusPending {
+		e.enqueueWrite(writeStateChange{siteID: targetID, fromStatus: string(prevStatus), toStatus: string(models.StatusUp)})
 	}
 
 	return true
@@ -434,12 +434,12 @@ func (e *Engine) Start(ctx context.Context) {
 				e.mu.RUnlock()
 				if !exists {
 					e.mu.Lock()
-					s.Status = "PENDING"
+					s.Status = models.StatusPending
 					if h, ok := e.GetHistory(s.ID); ok && len(h.Statuses) > 0 {
 						if h.Statuses[len(h.Statuses)-1] {
-							s.Status = "UP"
+							s.Status = models.StatusUp
 						} else {
-							s.Status = "DOWN"
+							s.Status = models.StatusDown
 						}
 						if len(h.Latencies) > 0 {
 							s.Latency = h.Latencies[len(h.Latencies)-1]
@@ -686,7 +686,7 @@ func (e *Engine) checkByID(ctx context.Context, id int) {
 }
 
 func (e *Engine) checkPush(_ context.Context, site models.Site) {
-	if site.Status == "PENDING" {
+	if site.Status == models.StatusPending {
 		return
 	}
 
@@ -702,16 +702,16 @@ func (e *Engine) checkPush(_ context.Context, site models.Site) {
 	now := time.Now()
 
 	if now.After(graceEnd) {
-		if site.Status != "DOWN" {
-			e.handleStatusChange(site, "DOWN", 0, 0, "heartbeat missed")
+		if site.Status != models.StatusDown {
+			e.handleStatusChange(site, string(models.StatusDown), 0, 0, "heartbeat missed")
 		}
 	} else if now.After(staleMark) {
-		if site.Status != "STALE" {
-			e.handleStatusChange(site, "STALE", 0, 0, "heartbeat stale")
+		if site.Status != models.StatusStale {
+			e.handleStatusChange(site, string(models.StatusStale), 0, 0, "heartbeat stale")
 		}
 	} else if now.After(overdue) {
-		if site.Status != "LATE" {
-			e.handleStatusChange(site, "LATE", 0, 0, "heartbeat overdue")
+		if site.Status != models.StatusLate {
+			e.handleStatusChange(site, string(models.StatusLate), 0, 0, "heartbeat overdue")
 		}
 	}
 }
@@ -727,9 +727,10 @@ func (e *Engine) handleStatusChange(snap models.Site, rawStatus string, code int
 	}
 
 	inMaint := e.isInMaintenance(snap.ID)
+	status := models.Status(rawStatus)
 
 	var (
-		prev, next            string
+		prev, next            models.Status
 		name, typ             string
 		alertID               int
 		failCount, maxRetries int
@@ -745,7 +746,7 @@ func (e *Engine) handleStatusChange(snap models.Site, rawStatus string, code int
 	_, exists := e.applyState(snap.ID, func(s *models.Site) {
 		// A non-UP result computed from a stale snapshot must not override a
 		// heartbeat (or newer check) that landed while we were evaluating.
-		if rawStatus != "UP" && s.LastCheck.After(snap.LastCheck) {
+		if status != models.StatusUp && s.LastCheck.After(snap.LastCheck) {
 			skipped = true
 			return
 		}
@@ -764,24 +765,24 @@ func (e *Engine) handleStatusChange(snap models.Site, rawStatus string, code int
 		s.HasSSL = snap.HasSSL
 		s.CertExpiry = snap.CertExpiry
 		s.LastError = errorReason
-		if rawStatus == "UP" {
+		if status == models.StatusUp {
 			s.LastSuccessAt = time.Now()
 			s.LastError = ""
 		}
 
 		// Status + failure-count transition, based on the CURRENT live status.
-		if rawStatus == "UP" {
+		if status == models.StatusUp {
 			s.FailureCount = 0
-			s.Status = "UP"
+			s.Status = models.StatusUp
 		} else {
 			if s.FailureCount <= s.MaxRetries {
 				s.FailureCount++
 			}
 			if s.FailureCount > s.MaxRetries {
-				if s.Status != rawStatus {
+				if s.Status != status {
 					confirmedDown = true
 				}
-				s.Status = rawStatus
+				s.Status = status
 				s.FailureCount = s.MaxRetries + 1
 			} else {
 				failedCheck = true
@@ -789,16 +790,16 @@ func (e *Engine) handleStatusChange(snap models.Site, rawStatus string, code int
 		}
 		failCount = s.FailureCount
 
-		if s.Status != prev && prev != "PENDING" {
+		if s.Status != prev && prev != models.StatusPending {
 			s.StatusChangedAt = time.Now()
-		} else if s.StatusChangedAt.IsZero() && s.Status != "PENDING" {
+		} else if s.StatusChangedAt.IsZero() && s.Status != models.StatusPending {
 			s.StatusChangedAt = time.Now()
 		}
 
 		// SSL expiry warning (fresh HasSSL/CertExpiry + config threshold).
 		if typ == "http" && s.CheckSSL && s.HasSSL {
 			days := int(time.Until(s.CertExpiry).Hours() / 24)
-			if days <= s.ExpiryThreshold && !s.SentSSLWarning && rawStatus != "SSL EXP" {
+			if days <= s.ExpiryThreshold && !s.SentSSLWarning && status != models.StatusSSLExp {
 				sslWarnFire = true
 				sslDays = days
 				s.SentSSLWarning = true
@@ -815,7 +816,7 @@ func (e *Engine) handleStatusChange(snap models.Site, rawStatus string, code int
 		return
 	}
 
-	e.recordCheck(snap.ID, latency, rawStatus == "UP")
+	e.recordCheck(snap.ID, latency, status == models.StatusUp)
 
 	if confirmedDown {
 		if errorReason != "" {
@@ -827,8 +828,8 @@ func (e *Engine) handleStatusChange(snap models.Site, rawStatus string, code int
 		e.AddLog(fmt.Sprintf("Monitor '%s' failed check %d/%d", name, failCount, maxRetries))
 	}
 
-	if changed && prev != "PENDING" {
-		e.enqueueWrite(writeStateChange{siteID: snap.ID, fromStatus: prev, toStatus: next, reason: errorReason})
+	if changed && prev != models.StatusPending {
+		e.enqueueWrite(writeStateChange{siteID: snap.ID, fromStatus: string(prev), toStatus: string(next), reason: errorReason})
 	}
 
 	if sslWarnFire {
@@ -839,13 +840,11 @@ func (e *Engine) handleStatusChange(snap models.Site, rawStatus string, code int
 		}
 	}
 
-	isBroken := func(s string) bool { return s == "DOWN" || s == "SSL EXP" }
-
-	if prev == "UP" && next == "LATE" {
+	if prev == models.StatusUp && next == models.StatusLate {
 		e.AddLog(fmt.Sprintf("Monitor '%s' heartbeat overdue", name))
 	}
 
-	if !isBroken(prev) && isBroken(next) && next != "PENDING" {
+	if !prev.IsBroken() && next.IsBroken() && next != models.StatusPending {
 		if inMaint {
 			e.AddLog(fmt.Sprintf("Monitor '%s' is DOWN (alerts suppressed — maintenance)", name))
 		} else {
@@ -859,7 +858,7 @@ func (e *Engine) handleStatusChange(snap models.Site, rawStatus string, code int
 			e.triggerAlert(alertID, "🚨 ALERT", msg)
 		}
 	}
-	if isBroken(prev) && next == "UP" {
+	if prev.IsBroken() && next == models.StatusUp {
 		downDur := ""
 		if !downSince.IsZero() {
 			downDur = fmt.Sprintf(" (was down %s)", fmtDurationShort(time.Since(downSince)))
@@ -869,7 +868,7 @@ func (e *Engine) handleStatusChange(snap models.Site, rawStatus string, code int
 			e.triggerAlert(alertID, "✅ RECOVERY", fmt.Sprintf("Monitor '%s' is UP%s", name, downDur))
 		}
 	}
-	if prev == "LATE" && next == "UP" && !isBroken(prev) {
+	if prev == models.StatusLate && next == models.StatusUp && !prev.IsBroken() {
 		e.AddLog(fmt.Sprintf("Monitor '%s' heartbeat arrived (was late)", name))
 	}
 }
@@ -991,12 +990,12 @@ func (e *Engine) GetDisplayStatus(site models.Site) string {
 	if e.isInMaintenance(site.ID) {
 		return "MAINT"
 	}
-	return site.Status
+	return string(site.Status)
 }
 
 func (e *Engine) checkGroup(_ context.Context, site models.Site) {
 	e.mu.RLock()
-	status := "UP"
+	status := models.StatusUp
 	hasChildren := false
 	for _, child := range e.liveState {
 		if child.ParentID != site.ID || child.Type == "group" {
@@ -1006,20 +1005,20 @@ func (e *Engine) checkGroup(_ context.Context, site models.Site) {
 		if child.Paused || e.isInMaintenance(child.ID) {
 			continue
 		}
-		if child.Status == "DOWN" || child.Status == "SSL EXP" {
-			status = "DOWN"
-		} else if child.Status == "STALE" && status != "DOWN" {
-			status = "STALE"
-		} else if child.Status == "LATE" && status != "DOWN" && status != "STALE" {
-			status = "LATE"
-		} else if child.Status == "PENDING" && status != "DOWN" && status != "STALE" && status != "LATE" {
-			status = "PENDING"
+		if child.Status == models.StatusDown || child.Status == models.StatusSSLExp {
+			status = models.StatusDown
+		} else if child.Status == models.StatusStale && status != models.StatusDown {
+			status = models.StatusStale
+		} else if child.Status == models.StatusLate && status != models.StatusDown && status != models.StatusStale {
+			status = models.StatusLate
+		} else if child.Status == models.StatusPending && status != models.StatusDown && status != models.StatusStale && status != models.StatusLate {
+			status = models.StatusPending
 		}
 	}
 	e.mu.RUnlock()
 
 	if !hasChildren {
-		status = "PENDING"
+		status = models.StatusPending
 	}
 
 	e.applyState(site.ID, func(s *models.Site) {
@@ -1072,15 +1071,15 @@ func (e *Engine) IngestProbeResult(nodeID string, siteID int, latencyNs int64, i
 
 	aggUp, avgLatency := AggregateStatus(results, e.aggStrategy)
 
-	rawStatus := "UP"
+	probeStatus := models.StatusUp
 	if !aggUp {
-		rawStatus = "DOWN"
+		probeStatus = models.StatusDown
 	}
 
 	updatedSite := site
 	updatedSite.Latency = time.Duration(avgLatency)
 	updatedSite.LastCheck = time.Now()
-	e.handleStatusChange(updatedSite, rawStatus, 0, time.Duration(avgLatency), errorReason)
+	e.handleStatusChange(updatedSite, string(probeStatus), 0, time.Duration(avgLatency), errorReason)
 }
 
 func (e *Engine) GetProbeResults(siteID int) map[string]NodeResult {

internal/monitor/sla.go

@@ -16,14 +16,14 @@ type SLAReport struct {
 	MTBF        time.Duration
 }
 
-func ComputeSLA(changes []models.StateChange, currentStatus string, window time.Duration) SLAReport {
+func ComputeSLA(changes []models.StateChange, currentStatus models.Status, window time.Duration) SLAReport {
 	now := time.Now()
 	windowStart := now.Add(-window)
 
 	report := SLAReport{Window: window}
 
 	if len(changes) == 0 {
-		if isDown(currentStatus) {
+		if models.Status(currentStatus).IsBroken() {
 			report.UptimePct = 0
 			report.Downtime = window
 		} else {
@@ -40,7 +40,7 @@ func ComputeSLA(changes []models.StateChange, currentStatus string, window time.
 	}
 
 	// Determine status at window start: last transition before or at windowStart.
-	statusAtStart := "UP"
+	statusAtStart := string(models.StatusUp)
 	for i := len(sorted) - 1; i >= 0; i-- {
 		if !sorted[i].ChangedAt.After(windowStart) {
 			statusAtStart = sorted[i].ToStatus
@@ -51,7 +51,7 @@ func ComputeSLA(changes []models.StateChange, currentStatus string, window time.
 	var upTime, downTime time.Duration
 	var outages []time.Duration
 	cursor := windowStart
-	wasDown := isDown(statusAtStart)
+	wasDown := models.Status(statusAtStart).IsBroken()
 
 	if wasDown {
 		report.OutageCount = 1
@@ -77,7 +77,7 @@ func ComputeSLA(changes []models.StateChange, currentStatus string, window time.
 			upTime += seg
 		}
 
-		newDown := isDown(sc.ToStatus)
+		newDown := models.Status(sc.ToStatus).IsBroken()
 		if !wasDown && newDown {
 			report.OutageCount++
 			outageStart = sc.ChangedAt
@@ -127,7 +127,7 @@ func ComputeSLA(changes []models.StateChange, currentStatus string, window time.
 	return report
 }
 
-func ComputeDailyBreakdown(changes []models.StateChange, currentStatus string, days int, now time.Time) []DayReport {
+func ComputeDailyBreakdown(changes []models.StateChange, currentStatus models.Status, days int, now time.Time) []DayReport {
 	reports := make([]DayReport, days)
 
 	for i := 0; i < days; i++ {
@@ -159,10 +159,6 @@ type DayReport struct {
 	UptimePct float64
 }
 
-func isDown(status string) bool {
-	return status == "DOWN" || status == "SSL EXP"
-}
-
 func filterChangesForWindow(changes []models.StateChange, start, end time.Time) []models.StateChange {
 	var filtered []models.StateChange
 	for _, sc := range changes {
@@ -180,7 +176,7 @@ func inferStatusAt(changes []models.StateChange, at time.Time) string {
 			return sc.ToStatus
 		}
 	}
-	return "UP"
+	return string(models.StatusUp)
 }
 
 func computeSLAForWindow(changes []models.StateChange, statusAtStart string, start, end time.Time) float64 {
@@ -193,7 +189,7 @@ func computeSLAForWindow(changes []models.StateChange, statusAtStart string, sta
 
 	var upTime, downTime time.Duration
 	cursor := start
-	wasDown := isDown(statusAtStart)
+	wasDown := models.Status(statusAtStart).IsBroken()
 
 	for _, sc := range sorted {
 		if sc.ChangedAt.Before(start) || !sc.ChangedAt.Before(end) {
@@ -205,7 +201,7 @@ func computeSLAForWindow(changes []models.StateChange, statusAtStart string, sta
 		} else {
 			upTime += seg
 		}
-		wasDown = isDown(sc.ToStatus)
+		wasDown = models.Status(sc.ToStatus).IsBroken()
 		cursor = sc.ChangedAt
 	}
 

internal/monitor/sla_test.go

@@ -137,24 +137,24 @@ func TestComputeDailyBreakdown(t *testing.T) {
 	}
 }
 
-func TestIsDown(t *testing.T) {
-	if !isDown("DOWN") {
-		t.Error("DOWN should be down")
+func TestIsBroken(t *testing.T) {
+	if !models.StatusDown.IsBroken() {
+		t.Error("DOWN should be broken")
 	}
-	if !isDown("SSL EXP") {
-		t.Error("SSL EXP should be down")
+	if !models.StatusSSLExp.IsBroken() {
+		t.Error("SSL EXP should be broken")
 	}
-	if isDown("UP") {
-		t.Error("UP should not be down")
+	if models.StatusUp.IsBroken() {
+		t.Error("UP should not be broken")
 	}
-	if isDown("LATE") {
-		t.Error("LATE should not be down")
+	if models.StatusLate.IsBroken() {
+		t.Error("LATE should not be broken")
 	}
-	if isDown("STALE") {
-		t.Error("STALE should not be down")
+	if models.StatusStale.IsBroken() {
+		t.Error("STALE should not be broken")
 	}
-	if isDown("PENDING") {
-		t.Error("PENDING should not be down")
+	if models.StatusPending.IsBroken() {
+		t.Error("PENDING should not be broken")
 	}
 }
 

internal/server/server.go

@@ -468,15 +468,15 @@ func Start(cfg ServerConfig, s store.Store, eng *monitor.Engine) *http.Server {
 			}
 			public := make(map[int]statusSite, len(state))
 			for id, site := range state {
-				status := site.Status
+				displayStatus := string(site.Status)
 				if allInMaint || maintSet[site.ID] || (site.ParentID > 0 && maintSet[site.ParentID]) {
-					status = "MAINT"
+					displayStatus = "MAINT"
 				}
 				public[id] = statusSite{
 					Name:      site.Name,
 					Type:      site.Type,
 					URL:       site.URL,
-					Status:    status,
+					Status:    displayStatus,
 					Paused:    site.Paused,
 					LastCheck: site.LastCheck,
 					Latency:   site.Latency,
@@ -569,10 +569,10 @@ func renderStatusPage(w http.ResponseWriter, title string, eng *monitor.Engine)
 
 	sort.Slice(sites, func(i, j int) bool {
 		if sites[i].Status != sites[j].Status {
-			if sites[i].Status == "DOWN" {
+			if sites[i].Status == models.StatusDown {
 				return true
 			}
-			if sites[j].Status == "DOWN" {
+			if sites[j].Status == models.StatusDown {
 				return false
 			}
 		}

internal/tui/format.go

@@ -143,16 +143,16 @@ func (m Model) fmtRetries(site models.Site) string {
 		dispCount = site.MaxRetries
 	}
 	s := fmt.Sprintf("%d/%d", dispCount, site.MaxRetries)
-	if site.Status == "DOWN" {
+	if site.Status == models.StatusDown {
 		return m.st.dangerStyle.Render(s)
 	}
-	if site.Status == "UP" && site.FailureCount > 0 {
+	if site.Status == models.StatusUp && site.FailureCount > 0 {
 		return m.st.warnStyle.Render(s)
 	}
 	return s
 }
 
-func (m Model) fmtStatus(status string, paused bool, inMaint bool) string {
+func (m Model) fmtStatus(status models.Status, paused bool, inMaint bool) string {
 	if paused {
 		return m.st.warnStyle.Render("◇ PAUSED")
 	}
@@ -160,18 +160,18 @@ func (m Model) fmtStatus(status string, paused bool, inMaint bool) string {
 		return m.st.maintStyle.Render("◼ MAINT")
 	}
 	switch status {
-	case "DOWN":
+	case models.StatusDown:
 		return m.st.dangerStyle.Render("▼ DOWN")
-	case "SSL EXP":
+	case models.StatusSSLExp:
 		return m.st.dangerStyle.Render("▼ SSL EXP")
-	case "LATE":
+	case models.StatusLate:
 		return m.st.warnStyle.Render("◆ LATE")
-	case "STALE":
+	case models.StatusStale:
 		return m.st.staleStyle.Render("◆ STALE")
-	case "PENDING":
+	case models.StatusPending:
 		return m.st.subtleStyle.Render("○ PENDING")
 	default:
-		return m.st.specialStyle.Render("▲ " + status)
+		return m.st.specialStyle.Render("▲ " + string(status))
 	}
 }
 

internal/tui/format_test.go

@@ -56,19 +56,19 @@ func TestSiteOrder(t *testing.T) {
 
 func TestFmtStatus(t *testing.T) {
 	tests := []struct {
-		status  string
+		status  models.Status
 		paused  bool
 		inMaint bool
 		wantSub string
 	}{
-		{"DOWN", false, false, "▼ DOWN"},
-		{"UP", false, false, "▲ UP"},
-		{"SSL EXP", false, false, "▼ SSL EXP"},
-		{"LATE", false, false, "◆ LATE"},
-		{"STALE", false, false, "◆ STALE"},
-		{"PENDING", false, false, "○ PENDING"},
-		{"DOWN", true, false, "◇ PAUSED"},
-		{"DOWN", false, true, "◼ MAINT"},
+		{models.StatusDown, false, false, "▼ DOWN"},
+		{models.StatusUp, false, false, "▲ UP"},
+		{models.StatusSSLExp, false, false, "▼ SSL EXP"},
+		{models.StatusLate, false, false, "◆ LATE"},
+		{models.StatusStale, false, false, "◆ STALE"},
+		{models.StatusPending, false, false, "○ PENDING"},
+		{models.StatusDown, true, false, "◇ PAUSED"},
+		{models.StatusDown, false, true, "◼ MAINT"},
 	}
 	for _, tt := range tests {
 		got := styledModel.fmtStatus(tt.status, tt.paused, tt.inMaint)

internal/tui/tab_sites.go

@@ -240,7 +240,7 @@ func (m Model) viewSitesTab() string {
 					name = limitStr(name, nameW-2)
 				}
 
-				if (site.Status == "DOWN" || site.Status == "SSL EXP" || site.Status == "LATE" || site.Status == "STALE") && site.LastError != "" {
+				if (site.Status == models.StatusDown || site.Status == models.StatusSSLExp || site.Status == models.StatusLate || site.Status == models.StatusStale) && site.LastError != "" {
 					nameLen := len([]rune(name))
 					errSpace := nameW - nameLen - 3
 					if errSpace > 10 {

internal/tui/update.go

@@ -455,7 +455,7 @@ func (m *Model) handleSLAData(msg slaDataMsg) (tea.Model, tea.Cmd) {
 	}
 	period := slaPeriods[msg.periodIdx]
 
-	var currentStatus string
+	var currentStatus models.Status
 	for _, s := range m.sites {
 		if s.ID == msg.siteID {
 			currentStatus = s.Status

internal/tui/view_dashboard.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 	"time"
 
+	"gitea.lerkolabs.com/lerkolabs/uptop/internal/models"
 	"github.com/charmbracelet/lipgloss"
 )
 
@@ -16,7 +17,7 @@ func sinApprox(x float64) float64 {
 func (m Model) pulseIndicator() string {
 	hasDown := false
 	for _, s := range m.sites {
-		if !s.Paused && !m.isMonitorInMaintenance(s.ID) && (s.Status == "DOWN" || s.Status == "SSL EXP") {
+		if !s.Paused && !m.isMonitorInMaintenance(s.ID) && (s.Status == models.StatusDown || s.Status == models.StatusSSLExp) {
 			hasDown = true
 			break
 		}
@@ -127,9 +128,9 @@ func (m Model) computeStats() dashboardStats {
 			continue
 		}
 		switch site.Status {
-		case "DOWN", "SSL EXP":
+		case models.StatusDown, models.StatusSSLExp:
 			s.downCount++
-		case "LATE":
+		case models.StatusLate:
 			s.lateCount++
 		}
 	}

internal/tui/view_detail.go

@@ -45,7 +45,7 @@ func (m Model) viewDetailPanel() string {
 
 	row("Status", m.fmtStatus(site.Status, site.Paused, m.isMonitorInMaintenance(site.ID)))
 
-	if (site.Status == "DOWN" || site.Status == "SSL EXP" || site.Status == "LATE" || site.Status == "STALE") && site.LastError != "" {
+	if (site.Status == models.StatusDown || site.Status == models.StatusSSLExp || site.Status == models.StatusLate || site.Status == models.StatusStale) && site.LastError != "" {
 		errWidth := m.termWidth - chromePadH - 19
 		if errWidth < 30 {
 			errWidth = 30
@@ -58,7 +58,7 @@ func (m Model) viewDetailPanel() string {
 		row("HTTP Code", strconv.Itoa(site.StatusCode))
 	}
 
-	if (site.Status == "DOWN" || site.Status == "SSL EXP") && site.LastError != "" {
+	if (site.Status == models.StatusDown || site.Status == models.StatusSSLExp) && site.LastError != "" {
 		chain := connectionChain(site.LastError, site.Type, site.StatusCode, strings.HasPrefix(site.URL, "https"))
 		if len(chain) > 0 {
 			b.WriteString("\n")
@@ -189,7 +189,7 @@ func (m Model) viewDetailPanel() string {
 		for i, sc := range stateChanges {
 			ago := fmtDuration(time.Since(sc.ChangedAt))
 			arrow := m.st.subtleStyle.Render(sc.FromStatus) + " → "
-			if sc.ToStatus == "UP" {
+			if sc.ToStatus == string(models.StatusUp) {
 				arrow += m.st.specialStyle.Render(sc.ToStatus)
 			} else {
 				arrow += m.st.dangerStyle.Render(sc.ToStatus)
@@ -198,7 +198,7 @@ func (m Model) viewDetailPanel() string {
 			if dur := computeOutageDuration(stateChanges, i); dur > 0 {
 				line += "  " + m.st.warnStyle.Render("outage "+fmtDuration(dur))
 			}
-			if sc.ErrorReason != "" && sc.ToStatus != "UP" {
+			if sc.ErrorReason != "" && sc.ToStatus != string(models.StatusUp) {
 				line += "  " + m.st.dangerStyle.Render(sc.ErrorReason)
 			}
 			b.WriteString(line + "\n")

internal/tui/view_history.go

@@ -17,14 +17,14 @@ type historyStats struct {
 
 func computeOutageDuration(changes []models.StateChange, idx int) time.Duration {
 	sc := changes[idx]
-	if sc.ToStatus != "UP" {
+	if sc.ToStatus != string(models.StatusUp) {
 		return 0
 	}
 	if idx+1 >= len(changes) {
 		return 0
 	}
 	prev := changes[idx+1]
-	if prev.ToStatus == "UP" {
+	if prev.ToStatus == string(models.StatusUp) {
 		return 0
 	}
 	dur := sc.ChangedAt.Sub(prev.ChangedAt)
@@ -122,11 +122,11 @@ func (m Model) buildHistoryContent() string {
 
 		arrow := m.st.subtleStyle.Render(sc.FromStatus) + " → "
 		switch sc.ToStatus {
-		case "UP":
+		case string(models.StatusUp):
 			arrow += m.st.specialStyle.Render(sc.ToStatus)
-		case "LATE":
+		case string(models.StatusLate):
 			arrow += m.st.warnStyle.Render(sc.ToStatus)
-		case "STALE":
+		case string(models.StatusStale):
 			arrow += m.st.staleStyle.Render(sc.ToStatus)
 		default:
 			arrow += m.st.dangerStyle.Render(sc.ToStatus)
@@ -138,7 +138,7 @@ func (m Model) buildHistoryContent() string {
 		}
 
 		reason := ""
-		if sc.ErrorReason != "" && sc.ToStatus != "UP" {
+		if sc.ErrorReason != "" && sc.ToStatus != string(models.StatusUp) {
 			reason = m.st.dangerStyle.Render(limitStr(sc.ErrorReason, reasonWidth))
 		}