fixes

internal/features/spike.go

@@ -15,6 +15,12 @@ type SpikeConfig struct {
 	Multiple        float64       // a pattern must be novel or >= Multiple * its own baseline mean
 	MinExcess       int           // and excess errors must be >= MinExcess
 	TopPatterns     int
+	// DataSince is when data collection began (earliest row of any kind). When
+	// set, no alert fires until WarmupWindows windows of baseline exist,
+	// otherwise the first window after data begins reports everything as NEW.
+	// Zero disables the guard.
+	DataSince     time.Time
+	WarmupWindows int
 }
 
 func DefaultSpikeConfig() SpikeConfig {
@@ -64,6 +70,15 @@ func DetectSpikes(events []Event, at time.Time, cfg SpikeConfig) []Spike {
 	at = at.UTC()
 	start := at.Add(-cfg.Window)
 	baseStart := start.Add(-time.Duration(cfg.BaselineWindows) * cfg.Window)
+	if !cfg.DataSince.IsZero() {
+		warm := cfg.WarmupWindows
+		if warm <= 0 {
+			warm = min(cfg.BaselineWindows, 6)
+		}
+		if start.Sub(cfg.DataSince.UTC()) < time.Duration(warm)*cfg.Window {
+			return nil
+		}
+	}
 
 	type agg struct {
 		cur     int