diff --git a/internal/config/config.go b/internal/config/config.go
index 5913425..db0fca7 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -107,7 +107,7 @@ func Save(cfg Config) error {
 		return fmt.Errorf("creating config dir: %w", err)
 	}
 
-	f, err := os.Create(ConfigPath())
+	f, err := os.OpenFile(ConfigPath(), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o600)
 	if err != nil {
 		return fmt.Errorf("creating config file: %w", err)
 	}
diff --git a/internal/pipeline/aggregator.go b/internal/pipeline/aggregator.go
index 906d6a1..39f191b 100644
--- a/internal/pipeline/aggregator.go
+++ b/internal/pipeline/aggregator.go
@@ -97,6 +97,17 @@ func AggregateDays(sessions []model.SessionStats, since, until time.Time) []mode
 		ds.EstimatedCost += s.EstimatedCost
 	}
 
+	// Fill in every day in the range so the chart shows gaps as zeros
+	day := since.Local().Truncate(24 * time.Hour)
+	end := until.Local().Truncate(24 * time.Hour)
+	for !day.After(end) {
+		dayKey := day.Format("2006-01-02")
+		if _, ok := dayMap[dayKey]; !ok {
+			dayMap[dayKey] = &model.DailyStats{Date: day}
+		}
+		day = day.AddDate(0, 0, 1)
+	}
+
 	// Convert to sorted slice (most recent first)
 	days := make([]model.DailyStats, 0, len(dayMap))
 	for _, ds := range dayMap {