Fix fan chart gaps and task durations

audit/internal/webui/server.go

@@ -84,6 +84,15 @@ func (r *metricsRing) snapshot() ([]float64, []string) {
 	return v, labels
 }
 
+func (r *metricsRing) latest() (float64, bool) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if len(r.vals) == 0 {
+		return 0, false
+	}
+	return r.vals[len(r.vals)-1], true
+}
+
 func timestampsSameLocalDay(times []time.Time) bool {
 	if len(times) == 0 {
 		return true
@@ -871,7 +880,7 @@ func namedFanDatasets(samples []platform.LiveMetricSample) ([][]float64, []strin
 				}
 			}
 		}
-		datasets = append(datasets, ds)
+		datasets = append(datasets, normalizeFanSeries(ds))
 	}
 	return datasets, names
 }
@@ -946,6 +955,27 @@ func normalizePowerSeries(ds []float64) []float64 {
 	return out
 }
 
+func normalizeFanSeries(ds []float64) []float64 {
+	if len(ds) == 0 {
+		return nil
+	}
+	out := make([]float64, len(ds))
+	var lastPositive float64
+	for i, v := range ds {
+		if v > 0 {
+			lastPositive = v
+			out[i] = v
+			continue
+		}
+		if lastPositive > 0 {
+			out[i] = lastPositive
+			continue
+		}
+		out[i] = 0
+	}
+	return out
+}
+
 // floatPtr returns a pointer to a float64 value.
 func floatPtr(v float64) *float64 { return &v }
 
@@ -1183,7 +1213,7 @@ func snapshotFanRings(rings []*metricsRing, fanNames []string) ([][]float64, []s
 			continue
 		}
 		vals, l := ring.snapshot()
-		datasets = append(datasets, vals)
+		datasets = append(datasets, normalizeFanSeries(vals))
 		name := "Fan"
 		if i < len(fanNames) {
 			name = fanNames[i]