api/notifications: register preview endpoint in main.go

The GET /api/notifications/preview endpoint was already implemented
in internal/api/notifications.go but was never registered in main.go.
This commit wires up the NotificationsHandler to enable the test
thumbnail endpoint for UI development and QA.

The endpoint accepts query parameters:
- type: notification type (fall, anomaly, zone_enter, sleep)
- person: person name (optional, defaults to "Alice")

It calls the appropriate Generate*Thumbnail function from the
render package and returns PNG bytes with Content-Type: image/png.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

mothership/cmd/mothership/main.go

@@ -527,6 +527,16 @@ func main() {
 	notificationSettingsHandler.RegisterRoutes(r)
 	log.Printf("[INFO] Notification settings API registered at /api/settings/notifications")
 
+	// Phase 6: Notifications REST API (channels, preview, test)
+	notificationsHandler, err := api.NewNotificationsHandler(filepath.Join(cfg.DataDir, "notifications.db"))
+	if err != nil {
+		log.Printf("[WARN] Failed to create notifications handler: %v", err)
+	} else {
+		defer notificationsHandler.Close()
+		notificationsHandler.RegisterRoutes(r)
+		log.Printf("[INFO] Notifications API registered at /api/notifications/*")
+	}
+
 	// Phase 6: Feature discovery notifications
 	// Notifier manages one-time feature discovery notifications with quiet hours support
 	featureNotifier, err := featurehelp.NewNotifier(mainDB)

mothership/internal/api/notifications.go

@@ -13,6 +13,8 @@ import (
 
 	"github.com/go-chi/chi/v5"
 	_ "modernc.org/sqlite"
+
+	"github.com/spaxel/mothership/internal/render"
 )
 
 // NotificationsHandler manages notification delivery channels.
@@ -312,6 +314,7 @@ func (n *NotificationsHandler) RegisterRoutes(r chi.Router) {
 	r.Get("/api/notifications/config", n.handleGetConfig)
 	r.Post("/api/notifications/config", n.handleSetConfig)
 	r.Post("/api/notifications/test", n.handleSendTest)
+	r.Get("/api/notifications/preview", n.handlePreview)
 }
 
 // notificationConfigResponse is the response for channel configuration requests.
@@ -435,6 +438,73 @@ func (n *NotificationsHandler) handleSendTest(w http.ResponseWriter, r *http.Req
 	})
 }
 
+// handlePreview handles GET /api/notifications/preview
+// Returns a rendered test image for UI development and QA.
+// Query params:
+//   - type: notification type (fall, anomaly, zone_enter, sleep)
+//   - person: person name (optional, defaults to "Alice")
+func (n *NotificationsHandler) handlePreview(w http.ResponseWriter, r *http.Request) {
+	// Parse query parameters
+	notifType := r.URL.Query().Get("type")
+	personName := r.URL.Query().Get("person")
+
+	// Set defaults
+	if personName == "" {
+		personName = "Alice"
+	}
+
+	// Define test zones
+	zones := []render.Zone{
+		{ID: "kitchen", Name: "Kitchen", X: 0, Y: 0, W: 4, D: 3, Color: "#4fc3f7"},
+		{ID: "living", Name: "Living", X: 4, Y: 0, W: 5, D: 4, Color: "#81c784"},
+		{ID: "hallway", Name: "Hallway", X: 4, Y: 4, W: 2, D: 2, Color: "#ffb74d"},
+		{ID: "bedroom", Name: "Bedroom", X: 6, Y: 4, W: 3, D: 3, Color: "#ba68c8"},
+	}
+
+	// Define test person
+	person := render.Person{
+		Name:      personName,
+		X:         2.0,
+		Y:         1.5,
+		Z:         1.0,
+		Color:     "#4488ff",
+		Confidence: 0.85,
+		IsFall:    false,
+	}
+
+	var pngData []byte
+	var err error
+
+	// Generate thumbnail based on notification type
+	switch notifType {
+	case "fall":
+		pngData, err = render.GenerateFallDetectedThumbnail(10.0, 8.0, zones, person, "Kitchen")
+	case "anomaly":
+		pngData, err = render.GenerateAnomalyAlertThumbnail(10.0, 8.0, zones, "Living")
+	case "zone_enter":
+		pngData, err = render.GenerateZoneEnterThumbnail(10.0, 8.0, zones, person, "Kitchen")
+	case "sleep":
+		person.Z = 0.5 // Sleeping position
+		pngData, err = render.GenerateSleepSummaryThumbnail(10.0, 8.0, zones, person, "7h 23m")
+	default:
+		// Default to fall detection preview
+		pngData, err = render.GenerateFallDetectedThumbnail(10.0, 8.0, zones, person, "Kitchen")
+	}
+
+	if err != nil {
+		log.Printf("[ERROR] Failed to generate preview thumbnail: %v", err)
+		http.Error(w, "failed to generate preview", http.StatusInternalServerError)
+		return
+	}
+
+	// Set headers and write PNG data
+	w.Header().Set("Content-Type", "image/png")
+	w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
+	if _, err := w.Write(pngData); err != nil {
+		log.Printf("[ERROR] Failed to write preview response: %v", err)
+	}
+}
+
 // ── Notification sending (called by automation engine) ────────────────────────────
 
 // SendNotification sends a notification via all enabled channels.

mothership/internal/api/notifications_test.go

@@ -304,6 +304,107 @@ func TestNotificationsHandler(t *testing.T) {
 			t.Errorf("Expected body 'Custom Body', got '%s'", mockSender.body)
 		}
 	})
+
+	t.Run("GET /api/notifications/preview - fall detection", func(t *testing.T) {
+		req := httptest.NewRequest("GET", "/api/notifications/preview?type=fall&person=Bob", nil)
+		w := httptest.NewRecorder()
+		router.ServeHTTP(w, req)
+
+		if w.Code != http.StatusOK {
+			t.Errorf("Expected status 200, got %d: %s", w.Code, w.Body.String())
+		}
+
+		ct := w.Header().Get("Content-Type")
+		if ct != "image/png" {
+			t.Errorf("Expected Content-Type 'image/png', got '%s'", ct)
+		}
+
+		// Verify PNG data was returned (PNG magic bytes)
+		body := w.Body.Bytes()
+		if len(body) < 8 {
+			t.Fatalf("Expected PNG data, got %d bytes", len(body))
+		}
+		// PNG magic bytes: 137 80 78 71 13 10 26 10
+		if body[0] != 0x89 || body[1] != 0x50 || body[2] != 0x4e || body[3] != 0x47 {
+			t.Errorf("Expected PNG magic bytes, got %x %x %x %x", body[0], body[1], body[2], body[3])
+		}
+	})
+
+	t.Run("GET /api/notifications/preview - zone_enter", func(t *testing.T) {
+		req := httptest.NewRequest("GET", "/api/notifications/preview?type=zone_enter&person=Alice", nil)
+		w := httptest.NewRecorder()
+		router.ServeHTTP(w, req)
+
+		if w.Code != http.StatusOK {
+			t.Errorf("Expected status 200, got %d: %s", w.Code, w.Body.String())
+		}
+
+		ct := w.Header().Get("Content-Type")
+		if ct != "image/png" {
+			t.Errorf("Expected Content-Type 'image/png', got '%s'", ct)
+		}
+	})
+
+	t.Run("GET /api/notifications/preview - anomaly", func(t *testing.T) {
+		req := httptest.NewRequest("GET", "/api/notifications/preview?type=anomaly", nil)
+		w := httptest.NewRecorder()
+		router.ServeHTTP(w, req)
+
+		if w.Code != http.StatusOK {
+			t.Errorf("Expected status 200, got %d: %s", w.Code, w.Body.String())
+		}
+
+		ct := w.Header().Get("Content-Type")
+		if ct != "image/png" {
+			t.Errorf("Expected Content-Type 'image/png', got '%s'", ct)
+		}
+	})
+
+	t.Run("GET /api/notifications/preview - sleep", func(t *testing.T) {
+		req := httptest.NewRequest("GET", "/api/notifications/preview?type=sleep", nil)
+		w := httptest.NewRecorder()
+		router.ServeHTTP(w, req)
+
+		if w.Code != http.StatusOK {
+			t.Errorf("Expected status 200, got %d: %s", w.Code, w.Body.String())
+		}
+
+		ct := w.Header().Get("Content-Type")
+		if ct != "image/png" {
+			t.Errorf("Expected Content-Type 'image/png', got '%s'", ct)
+		}
+	})
+
+	t.Run("GET /api/notifications/preview - default (no type)", func(t *testing.T) {
+		req := httptest.NewRequest("GET", "/api/notifications/preview", nil)
+		w := httptest.NewRecorder()
+		router.ServeHTTP(w, req)
+
+		if w.Code != http.StatusOK {
+			t.Errorf("Expected status 200, got %d: %s", w.Code, w.Body.String())
+		}
+
+		// Default should return fall detection preview
+		body := w.Body.Bytes()
+		if len(body) < 8 {
+			t.Fatalf("Expected PNG data, got %d bytes", len(body))
+		}
+		// Verify PNG magic bytes
+		if body[0] != 0x89 || body[1] != 0x50 || body[2] != 0x4e || body[3] != 0x47 {
+			t.Errorf("Expected PNG magic bytes, got %x %x %x %x", body[0], body[1], body[2], body[3])
+		}
+	})
+
+	t.Run("GET /api/notifications/preview - cache control", func(t *testing.T) {
+		req := httptest.NewRequest("GET", "/api/notifications/preview?type=fall", nil)
+		w := httptest.NewRecorder()
+		router.ServeHTTP(w, req)
+
+		cc := w.Header().Get("Cache-Control")
+		if cc != "no-cache, no-store, must-revalidate" {
+			t.Errorf("Expected Cache-Control 'no-cache, no-store, must-revalidate', got '%s'", cc)
+		}
+	})
 }
 
 // mockNotifySender is a test implementation of NotifySender.