metrics(power): export UPS nominal watts for real draw calculations

internal/metrics/exporter.go

@@ -17,6 +17,7 @@ type Sample struct {
 	RuntimeSecond int
 	BatteryCharge float64
 	LoadPercent   float64
+	PowerNominalW float64
 	ThresholdSec  int
 	Trigger       bool
 	BreachCount   int
@@ -106,6 +107,8 @@ func (e *Exporter) serveMetrics(w http.ResponseWriter, _ *http.Request) {
 	b.WriteString("# TYPE hecate_ups_battery_charge_percent gauge\n")
 	b.WriteString("# HELP hecate_ups_load_percent UPS output load percentage.\n")
 	b.WriteString("# TYPE hecate_ups_load_percent gauge\n")
+	b.WriteString("# HELP hecate_ups_power_nominal_watts UPS nominal power rating in watts.\n")
+	b.WriteString("# TYPE hecate_ups_power_nominal_watts gauge\n")
 	b.WriteString("# HELP hecate_ups_threshold_seconds Red-line threshold for runtime-based shutdown.\n")
 	b.WriteString("# TYPE hecate_ups_threshold_seconds gauge\n")
 	b.WriteString("# HELP hecate_ups_trigger_active Whether this UPS source currently breaches shutdown trigger conditions.\n")
@@ -131,6 +134,7 @@ func (e *Exporter) serveMetrics(w http.ResponseWriter, _ *http.Request) {
 		b.WriteString(fmt.Sprintf("hecate_ups_runtime_seconds%s %d\n", labels, s.RuntimeSecond))
 		b.WriteString(fmt.Sprintf("hecate_ups_battery_charge_percent%s %.2f\n", labels, s.BatteryCharge))
 		b.WriteString(fmt.Sprintf("hecate_ups_load_percent%s %.2f\n", labels, s.LoadPercent))
+		b.WriteString(fmt.Sprintf("hecate_ups_power_nominal_watts%s %.2f\n", labels, s.PowerNominalW))
 		b.WriteString(fmt.Sprintf("hecate_ups_threshold_seconds%s %d\n", labels, s.ThresholdSec))
 		b.WriteString(fmt.Sprintf("hecate_ups_trigger_active%s %d\n", labels, boolNum(s.Trigger)))
 		b.WriteString(fmt.Sprintf("hecate_ups_breach_count%s %d\n", labels, s.BreachCount))

internal/metrics/exporter_test.go

@@ -18,6 +18,7 @@ func TestExporterEmitsCoreMetrics(t *testing.T) {
 		RuntimeSecond: 412,
 		BatteryCharge: 81.5,
 		LoadPercent:   27.4,
+		PowerNominalW: 510,
 		ThresholdSec:  354,
 		Trigger:       true,
 		BreachCount:   2,
@@ -38,6 +39,7 @@ func TestExporterEmitsCoreMetrics(t *testing.T) {
 		"hecate_ups_runtime_seconds{source=\"db-ups\",target=\"atlasups@localhost\"",
 		"hecate_ups_battery_charge_percent{source=\"db-ups\",target=\"atlasups@localhost\"",
 		"hecate_ups_load_percent{source=\"db-ups\",target=\"atlasups@localhost\"",
+		"hecate_ups_power_nominal_watts{source=\"db-ups\",target=\"atlasups@localhost\"",
 		"hecate_ups_threshold_seconds{source=\"db-ups\",target=\"atlasups@localhost\"",
 	}
 	for _, m := range mustContain {

internal/service/daemon.go

@@ -131,6 +131,7 @@ func (d *Daemon) Run(ctx context.Context) error {
 					RuntimeSecond: sample.RuntimeSeconds,
 					BatteryCharge: sample.BatteryCharge,
 					LoadPercent:   sample.LoadPercent,
+					PowerNominalW: sample.NominalPowerW,
 					ThresholdSec:  threshold,
 					Trigger:       trigger,
 					BreachCount:   breachCount[target.Name],

internal/ups/nut.go

@@ -16,6 +16,7 @@ type Sample struct {
 	RuntimeSeconds int
 	BatteryCharge  float64
 	LoadPercent    float64
+	NominalPowerW  float64
 	RawStatus      string
 }
 
@@ -95,6 +96,11 @@ func parseNUT(raw string) (Sample, error) {
 			out.LoadPercent = load
 		}
 	}
+	if nominalRaw := kv["ups.realpower.nominal"]; nominalRaw != "" {
+		if nominal, ok := parseNumber(nominalRaw); ok {
+			out.NominalPowerW = nominal
+		}
+	}
 	return out, nil
 }
 

internal/ups/nut_test.go

@@ -3,9 +3,10 @@ package ups
 import "testing"
 
 func TestParseNUT(t *testing.T) {
-	raw := `battery.runtime: 384
+raw := `battery.runtime: 384
 battery.charge: 72
 ups.load: 19
+ups.realpower.nominal: 510
 ups.status: OB LB
 `
 	s, err := parseNUT(raw)
@@ -27,4 +28,7 @@ ups.status: OB LB
 	if s.LoadPercent != 19 {
 		t.Fatalf("expected load 19, got %.2f", s.LoadPercent)
 	}
+	if s.NominalPowerW != 510 {
+		t.Fatalf("expected nominal power 510, got %.2f", s.NominalPowerW)
+	}
 }