fix: anchor growth forecasts to real Tehran date

internal/growthreport/adapter.go

@@ -47,10 +47,13 @@ type Builder interface {
 	Build(ctx context.Context, merchantID int64, terminalID string) (Analysis, error)
 }
 
-type PostgreSQLBuilder struct{ pool *pgxpool.Pool }
+type PostgreSQLBuilder struct {
+	pool *pgxpool.Pool
+	now  func() time.Time
+}
 
 func NewPostgreSQLBuilder(pool *pgxpool.Pool) *PostgreSQLBuilder {
-	return &PostgreSQLBuilder{pool: pool}
+	return &PostgreSQLBuilder{pool: pool, now: time.Now}
 }
 
 func (b *PostgreSQLBuilder) Build(ctx context.Context, merchantID int64, terminalID string) (Analysis, error) {
@@ -88,7 +91,7 @@ func (b *PostgreSQLBuilder) Build(ctx context.Context, merchantID int64, termina
 	if err := b.pool.QueryRow(ctx, `SELECT max(created_at AT TIME ZONE 'Asia/Tehran')::date FROM payment_sessions`).Scan(&latest); err != nil {
 		return Analysis{}, fmt.Errorf("loading dataset watermark date: %w", err)
 	}
-	forecastStart := latest.AddDate(0, 0, 1)
+	forecastStart := tehranToday(b.now())
 	peer, err := b.loadPeer(ctx, merchantID, terminalID)
 	if err != nil {
 		return Analysis{}, err

internal/growthreport/orchestrator.go

@@ -46,10 +46,11 @@ func (s *Service) Create(ctx context.Context, userID, merchantID int64, request
 			return Record{}, false, err
 		}
 	}
-	watermark, start, err := s.repository.DatasetMetadata(ctx)
+	watermark, _, err := s.repository.DatasetMetadata(ctx)
 	if err != nil {
 		return Record{}, false, err
 	}
+	start := tehranToday(now)
 	fingerprint := s.fingerprint(merchantID, request.TerminalID, watermark, start)
 	var refreshDay *time.Time
 	if request.Refresh {
@@ -91,10 +92,11 @@ func (s *Service) Latest(ctx context.Context, merchantID int64, terminalID strin
 	record, err := s.repository.Latest(ctx, merchantID, terminalID, growth.AnalyticsVersion)
 	if err == nil {
 		record.Cached = true
-		watermark, start, metadataErr := s.repository.DatasetMetadata(ctx)
+		watermark, _, metadataErr := s.repository.DatasetMetadata(ctx)
 		if metadataErr != nil {
 			record.Stale = true
 		} else {
+			start := tehranToday(s.now())
 			record.Stale = record.Fingerprint != s.fingerprint(merchantID, terminalID, watermark, start)
 		}
 		record.NextRefreshAt, _ = s.repository.NextRefreshAt(ctx, merchantID, terminalID, growth.AnalyticsVersion, s.now())

internal/growthreport/repository.go

@@ -295,7 +295,7 @@ func (r *Repository) DatasetMetadata(ctx context.Context) (string, time.Time, er
 	if err != nil {
 		return "", time.Time{}, fmt.Errorf("loading growth dataset metadata: %w", err)
 	}
-	return sha + ":" + latest.Format(time.DateOnly), latest.AddDate(0, 0, 1), nil
+	return sha + ":" + latest.Format(time.DateOnly), latest, nil
 }
 
 func (r *Repository) CleanupSuperseded(ctx context.Context, cutoff time.Time) (int64, error) {

internal/growthreport/service_test.go

@@ -27,6 +27,16 @@ func TestNextTehranRefreshUsesCalendarBoundary(t *testing.T) {
 	}
 }
 
+func TestTehranTodayUsesClockInsteadOfDatasetWatermark(t *testing.T) {
+	t.Parallel()
+
+	now := time.Date(2026, time.August, 21, 8, 30, 0, 0, time.UTC)
+	got := tehranToday(now)
+	if got.Format(time.DateOnly) != "2026-08-21" {
+		t.Fatalf("tehranToday() = %s", got.Format(time.DateOnly))
+	}
+}
+
 func TestEstimatedTokenReservationCoversEveryRetryAndTurn(t *testing.T) {
 	t.Parallel()
 	small := EstimatedTokenReservation([]byte("{}"))

internal/growthreport/time.go

@@ -2,6 +2,15 @@ package growthreport
 
 import "time"
 
+func tehranToday(now time.Time) time.Time {
+	location, err := time.LoadLocation("Asia/Tehran")
+	if err != nil {
+		location = time.FixedZone("Asia/Tehran", 12600)
+	}
+	local := now.In(location)
+	return time.Date(local.Year(), local.Month(), local.Day(), 0, 0, 0, 0, location)
+}
+
 func NextTehranRefresh(now time.Time) time.Time {
 	location, err := time.LoadLocation("Asia/Tehran")
 	if err != nil {