Window dashboard Money Saved to 30-day average

internal/db/dedup_test.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+	"time"
 
 	"veola/internal/crypto"
 	"veola/internal/models"
@@ -74,6 +75,51 @@ func TestDedupByItemAndURL(t *testing.T) {
 	}
 }
 
+func TestDashboardMoneySavedWindow(t *testing.T) {
+	if os.Getenv("CI_SKIP_SQLITE") != "" {
+		t.Skip()
+	}
+	s := newTestStore(t)
+	ctx := context.Background()
+
+	bp := 100.0
+	id, err := s.CreateItem(ctx, &models.Item{
+		Name: "Windowed", NtfyTopic: "veola", Active: true,
+		PollIntervalMinutes: 60, NtfyPriority: "default",
+		BestPrice: &bp,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	now := time.Now()
+	// A stale point well outside the 30-day window at a much higher price. If
+	// the average were computed over all history this would inflate "saved".
+	if err := s.InsertPricePoint(ctx, &models.PricePoint{
+		ItemID: id, Price: 500, PolledAt: now.AddDate(0, 0, -60),
+	}); err != nil {
+		t.Fatal(err)
+	}
+	// A recent point inside the window. Best price (100) is below it, so the
+	// only legitimate saving is 120 - 100 = 20.
+	if err := s.InsertPricePoint(ctx, &models.PricePoint{
+		ItemID: id, Price: 120, PolledAt: now.AddDate(0, 0, -5),
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	stats, err := s.GetDashboardStats(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if stats.SavedItemCount != 1 {
+		t.Fatalf("expected 1 saved item, got %d", stats.SavedItemCount)
+	}
+	if got := stats.MoneySaved; got < 19.99 || got > 20.01 {
+		t.Errorf("expected money saved ~20 (recent avg only), got %.2f", got)
+	}
+}
+
 func TestCJKRoundTrip(t *testing.T) {
 	s := newTestStore(t)
 	ctx := context.Background()

internal/db/queries.go

@@ -1040,11 +1040,16 @@ func (s *Store) GetDashboardStats(ctx context.Context) (*DashboardStats, error)
 	`).Scan(&d.UnpricedCount); err != nil {
 		return nil, err
 	}
+	// "Money saved" compares each item's current best price against its recent
+	// market average. The average is windowed to the last 30 days so stale
+	// historical prices don't anchor the baseline; items whose only price
+	// history predates the window simply don't contribute an estimate.
 	rows, err := s.DB.QueryContext(ctx, `
 		SELECT i.best_price, AVG(p.price) AS avg_price
 		FROM items i
 		JOIN price_history p ON p.item_id = i.id
 		WHERE i.active = 1 AND i.best_price IS NOT NULL
+		  AND p.polled_at >= datetime('now', '-30 day')
 		GROUP BY i.id
 	`)
 	if err != nil {