feat(metrics): new-clients KPI and scheduled reminder dispatch

The dashboard promised a new-clients card the API never produced; the
metric now counts distinct customer emails whose earliest-ever booking
lands in the window, joining the other four KPIs with the same trend
comparison. The card grid rebalances for five items.

Reminder dispatch also had no trigger — the endpoint existed but
nothing called it. A scheduled GitHub Actions workflow now posts to it
every 15 minutes using the job-runner key, so reminders actually fire
once the two secrets are configured.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/bookings/service.go

@@ -626,6 +626,7 @@ func (s *Service) DashboardSummary(ctx context.Context, principal domain.Princip
 			dashboardKPI("completed", "Completed", previousMetrics.CompletedCount, priorMetrics.CompletedCount, ""),
 			dashboardKPI("cancellations", "Cancellations", metrics.CancellationsCount, previousMetrics.CancellationsCount, ""),
 			dashboardKPI("utilization", "Utilization", metrics.UtilizationPercent, previousMetrics.UtilizationPercent, "%"),
+			dashboardKPI("new_clients", "New clients", metrics.NewClientsCount, previousMetrics.NewClientsCount, ""),
 		},
 		UpcomingBookings: upcoming,
 		AllBookings:      allBookings,

apps/backend/internal/bookings/service_test.go

@@ -463,38 +463,40 @@ func TestDashboardSummaryComputesKPIsWithTrends(t *testing.T) {
 	tenantID := membership.Tenant.ID
 
 	now := time.Now().UTC()
-	seed := func(offsetDays int, hours int, status string) {
+	seed := func(offsetDays int, hours int, status, email string) {
 		t.Helper()
 		starts := now.AddDate(0, 0, offsetDays).Add(time.Duration(hours) * time.Hour)
 		_, err := repo.CreateBooking(ctx, db.CreateBookingParams{
-			TenantID:    tenantID,
-			BookingMode: "appointment",
-			StartsAt:    starts,
-			EndsAt:      starts.Add(time.Hour),
-			Status:      status,
-			Reference:   "BK-T",
+			TenantID:      tenantID,
+			BookingMode:   "appointment",
+			CustomerEmail: email,
+			StartsAt:      starts,
+			EndsAt:        starts.Add(time.Hour),
+			Status:        status,
+			Reference:     "BK-T",
 		})
 		if err != nil {
 			t.Fatalf("seed booking: %v", err)
 		}
 	}
 
-	// Next 7 days: 3 bookings, one cancelled.
-	seed(1, 0, "confirmed")
-	seed(2, 0, "confirmed")
-	seed(3, 0, "cancelled")
-	// Last 7 days: 1 confirmed booking that already ended.
-	seed(-2, 0, "confirmed")
-	// 7-14 days ago: 2 completed bookings.
-	seed(-8, 0, "confirmed")
-	seed(-9, 0, "confirmed")
+	// Next 7 days: 3 bookings, one cancelled; two first-time clients
+	// (b@ returns, having booked 9 days ago).
+	seed(1, 0, "confirmed", "[email protected]")
+	seed(2, 0, "confirmed", "[email protected]")
+	seed(3, 0, "cancelled", "[email protected]")
+	// Last 7 days: 1 confirmed booking that already ended (returning client).
+	seed(-2, 0, "confirmed", "[email protected]")
+	// 7-14 days ago: 2 completed bookings; b@'s first visit plus a new client.
+	seed(-8, 0, "confirmed", "[email protected]")
+	seed(-9, 0, "confirmed", "[email protected]")
 
 	summary, err := service.DashboardSummary(ctx, domain.Principal{Subject: "demo-owner", Role: "owner"})
 	if err != nil {
 		t.Fatalf("dashboard summary: %v", err)
 	}
-	if len(summary.KPIs) != 4 {
-		t.Fatalf("expected 4 kpis, got %d", len(summary.KPIs))
+	if len(summary.KPIs) != 5 {
+		t.Fatalf("expected 5 kpis, got %d", len(summary.KPIs))
 	}
 	byCode := map[string]domain.DashboardKPI{}
 	for _, kpi := range summary.KPIs {
@@ -517,6 +519,12 @@ func TestDashboardSummaryComputesKPIsWithTrends(t *testing.T) {
 	if utilization.Value != "66%" || utilization.Trend != "down" {
 		t.Fatalf("utilization kpi = %+v", utilization)
 	}
+	// a@ and c@ have their first-ever booking next week (2); d@ was the
+	// only first-timer last week (1) — b@ first booked 8 days ago.
+	newClients := byCode["new_clients"]
+	if newClients.Value != "2" || newClients.Change != "+1" || newClients.Trend != "up" {
+		t.Fatalf("new clients kpi = %+v", newClients)
+	}
 }
 
 func bookAppointmentSlot(t *testing.T, repo db.Repository, service *Service) domain.CreateBookingResponse {

apps/backend/internal/db/bookings.go

@@ -181,7 +181,16 @@ func (r *PGRepository) GetDashboardMetrics(ctx context.Context, tenantID string,
 				),
 				0
 			)::integer AS utilization_percent,
-			COUNT(*) FILTER (WHERE starts_at >= $2 AND starts_at < $3 AND status = 'confirmed' AND ends_at < now()) AS completed_count
+			COUNT(*) FILTER (WHERE starts_at >= $2 AND starts_at < $3 AND status = 'confirmed' AND ends_at < now()) AS completed_count,
+			COUNT(DISTINCT customer_email) FILTER (
+				WHERE starts_at >= $2 AND starts_at < $3
+					AND NOT EXISTS (
+						SELECT 1 FROM bookings earlier
+						WHERE earlier.tenant_id = bookings.tenant_id
+							AND earlier.customer_email = bookings.customer_email
+							AND earlier.starts_at < $2
+					)
+			) AS new_clients_count
 		FROM bookings
 		WHERE tenant_id = $1
 	`, tenantID, startsAt, endsAt).Scan(
@@ -189,6 +198,7 @@ func (r *PGRepository) GetDashboardMetrics(ctx context.Context, tenantID string,
 		&metrics.CancellationsCount,
 		&metrics.UtilizationPercent,
 		&metrics.CompletedCount,
+		&metrics.NewClientsCount,
 	)
 	return metrics, err
 }

apps/backend/internal/db/repository.go

@@ -397,6 +397,7 @@ type DashboardMetrics struct {
 	CancellationsCount int
 	UtilizationPercent int
 	CompletedCount     int
+	NewClientsCount    int
 }
 
 type ReminderJobParams struct {
@@ -1488,6 +1489,21 @@ func (r *MemoryRepository) GetDashboardMetrics(_ context.Context, tenantID strin
 			}
 		}
 	}
+	firstSeen := map[string]time.Time{}
+	for _, booking := range r.bookings {
+		if booking.TenantID != tenantID {
+			continue
+		}
+		first, ok := firstSeen[booking.CustomerEmail]
+		if !ok || booking.StartsAt.Before(first) {
+			firstSeen[booking.CustomerEmail] = booking.StartsAt
+		}
+	}
+	for _, first := range firstSeen {
+		if !first.Before(startsAt) && first.Before(endsAt) {
+			metrics.NewClientsCount++
+		}
+	}
 	if metrics.BookingsCount == 0 {
 		metrics.UtilizationPercent = 0
 	} else {