hub v0.24.0: dispatcher routes critical severity (+ nil-prefs crash guard)

ProcessEvent routed only warning/error; a critical-severity event was silently dropped.
Now routes warning/error/critical, logs unrecognized severities, and guards a nil
GetNotificationPrefs (which would panic/crash the hub). host_disk_critical emits its
natural critical severity.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HxLA1mZurFq9kt8hneFeCs

hub/internal/notify/dispatcher.go

@@ -27,11 +27,15 @@ type Dispatcher struct {
 	mu            sync.Mutex
 	opCooldowns   map[string]time.Time // "customerID:eventType" → last operator notify
 	custCooldowns map[string]time.Time // "customerID:eventType" → last customer notify
+
+	// sendEmailFn is the email sender, seam-injected so tests exercise routing without real HTTP.
+	// Defaults to (*Dispatcher).sendEmail (Resend) in NewDispatcher.
+	sendEmailFn func(to, subject, textBody string) error
 }
 
 // NewDispatcher creates a new notification dispatcher.
 func NewDispatcher(s *store.Store, resendAPIKey, fromEmail, operatorEmail string, operatorOn bool, logger *log.Logger) *Dispatcher {
-	return &Dispatcher{
+	d := &Dispatcher{
 		store:         s,
 		resendAPIKey:  resendAPIKey,
 		fromEmail:     fromEmail,
@@ -42,6 +46,20 @@ func NewDispatcher(s *store.Store, resendAPIKey, fromEmail, operatorEmail string
 		opCooldowns:   make(map[string]time.Time),
 		custCooldowns: make(map[string]time.Time),
 	}
+	d.sendEmailFn = d.sendEmail
+	return d
+}
+
+// severityNotifies reports whether a severity triggers email notifications. warning / error / critical
+// notify; everything else (info, recovery/status, or an unrecognized value) does not. Pure → unit-tested.
+// (Before v0.24.0 a "critical" severity was silently dropped here — the host_disk-class bug.)
+func severityNotifies(severity string) bool {
+	switch severity {
+	case "warning", "error", "critical":
+		return true
+	default:
+		return false
+	}
 }
 
 // ProcessEvent evaluates an event and sends notifications as appropriate.
@@ -57,8 +75,13 @@ func (d *Dispatcher) ProcessEvent(customerID, eventType, severity, message, deta
 		return
 	}
 
-	// Only warning and error severity trigger notifications
-	if severity != "warning" && severity != "error" {
+	// warning / error / critical trigger notifications. "info" is an intentional non-notify (status/
+	// recovery events). Anything else is UNRECOGNIZED — log it (don't silently drop), so a bad severity
+	// surfaces instead of vanishing (the felhom-pve-class lesson: a critical event must never be lost).
+	if !severityNotifies(severity) {
+		if severity != "info" {
+			d.logger.Printf("[WARN] Dispatcher: unrecognized severity %q for %s/%s — not routing", severity, customerID, eventType)
+		}
 		return
 	}
 
@@ -79,7 +102,7 @@ func (d *Dispatcher) sendTestEmail(customerID string) {
 	subject := "[Felhom] Teszt értesítés"
 	body := "Kedves Ügyfél!\n\nEz egy teszt értesítés a Felhom monitoring rendszerből.\nAz értesítések megfelelően működnek.\n\nÜdvözlettel,\nFelhom.eu monitoring"
 
-	if err := d.sendEmail(prefs.Email, subject, body); err != nil {
+	if err := d.sendEmailFn(prefs.Email, subject, body); err != nil {
 		d.logger.Printf("[ERROR] Test email to %s failed: %v", prefs.Email, err)
 		d.store.LogNotification(customerID, "test", "info", "Teszt értesítés", "failed", err.Error(), "customer")
 		return
@@ -104,7 +127,7 @@ func (d *Dispatcher) processOperator(customerID, eventType, severity, message, d
 
 	subject, body := FormatOperatorEmail(customerID, eventType, severity, message, detailsJSON)
 
-	if err := d.sendEmail(d.operatorEmail, subject, body); err != nil {
+	if err := d.sendEmailFn(d.operatorEmail, subject, body); err != nil {
 		d.logger.Printf("[ERROR] Operator email failed for %s/%s: %v", customerID, eventType, err)
 		d.store.LogNotification(customerID, eventType, severity, message, "failed", err.Error(), "operator")
 		return
@@ -119,9 +142,11 @@ func (d *Dispatcher) processCustomer(customerID, eventType, severity, message, d
 		return
 	}
 
-	// Load preferences
+	// Load preferences. GetNotificationPrefs returns (nil, nil) for a customer with no notification row —
+	// guard the nil BEFORE dereferencing (else an event for such a customer panics the dispatcher
+	// goroutine and crashes the hub). No prefs / no email → no customer notification.
 	prefs, err := d.store.GetNotificationPrefs(customerID)
-	if err != nil || prefs.Email == "" {
+	if err != nil || prefs == nil || prefs.Email == "" {
 		return
 	}
 
@@ -148,7 +173,7 @@ func (d *Dispatcher) processCustomer(customerID, eventType, severity, message, d
 
 	subject, body := FormatCustomerEmail(customerID, eventType, severity, message, detailsJSON)
 
-	if err := d.sendEmail(prefs.Email, subject, body); err != nil {
+	if err := d.sendEmailFn(prefs.Email, subject, body); err != nil {
 		d.logger.Printf("[ERROR] Customer email failed for %s/%s: %v", customerID, eventType, err)
 		d.store.LogNotification(customerID, eventType, severity, message, "failed", err.Error(), "customer")
 		return