docs: reorder & testing

backend/internal/notification/deps.go

@@ -6,6 +6,7 @@ import (
 
 	"galaxy/backend/internal/config"
 	"galaxy/backend/internal/user"
+	"galaxy/backend/push"
 
 	"github.com/google/uuid"
 	"go.uber.org/zap"
@@ -13,9 +14,17 @@ import (
 
 // PushPublisher is the publisher contract notification uses to emit a
 // `client_event` push frame to gateway. The real implementation lives
-// in `backend/internal/push` ; NewNoopPushPublisher satisfies
+// in `backend/push` (`*push.Service`); NewNoopPushPublisher satisfies
 // the interface for tests that do not exercise push behaviour.
 //
+// `event` is a typed `push.Event`: the publisher invokes Marshal on
+// the event at publish time, so producers stay decoupled from the
+// wire encoding. Every catalog kind has a FlatBuffers schema in
+// `pkg/schema/fbs/notification.fbs` and is built by
+// `buildClientPushEvent`; an unknown kind falls back to
+// `push.JSONEvent` so a misconfigured producer keeps the pipeline
+// flowing.
+//
 // Implementations must be concurrency-safe. The deviceSessionID pointer
 // narrows the event to a single device session when non-nil; nil means
 // fan out to every active session of userID. eventID, requestID and
@@ -23,7 +32,7 @@ import (
 // into the signed client envelope; empty strings are forwarded
 // unchanged.
 type PushPublisher interface {
-	PublishClientEvent(ctx context.Context, userID uuid.UUID, deviceSessionID *uuid.UUID, kind string, payload map[string]any, eventID, requestID, traceID string) error
+	PublishClientEvent(ctx context.Context, userID uuid.UUID, deviceSessionID *uuid.UUID, event push.Event, eventID, requestID, traceID string) error
 }
 
 // Mailer is the email surface notification uses for outbound mail. The
@@ -76,11 +85,14 @@ type noopPushPublisher struct {
 	logger *zap.Logger
 }
 
-func (p *noopPushPublisher) PublishClientEvent(_ context.Context, userID uuid.UUID, deviceSessionID *uuid.UUID, kind string, payload map[string]any, eventID, requestID, traceID string) error {
+func (p *noopPushPublisher) PublishClientEvent(_ context.Context, userID uuid.UUID, deviceSessionID *uuid.UUID, event push.Event, eventID, requestID, traceID string) error {
+	kind := ""
+	if event != nil {
+		kind = event.Kind()
+	}
 	fields := []zap.Field{
 		zap.String("user_id", userID.String()),
 		zap.String("kind", kind),
-		zap.Int("payload_keys", len(payload)),
 	}
 	if deviceSessionID != nil {
 		fields = append(fields, zap.String("device_session_id", deviceSessionID.String()))