fix: push notification

internal/repository/push_repo.go

@@ -52,6 +52,28 @@ func (r *PushRepo) ListByUser(ctx context.Context, userID string) ([]model.PushS
 	return out, rows.Err()
 }
 
+// PruneToMostRecent keeps only the `keep` most-recently-used subscriptions for
+// a user, deleting older ones — a soft per-user device cap.
+func (r *PushRepo) PruneToMostRecent(ctx context.Context, userID string, keep int) error {
+	if keep < 1 {
+		keep = 1
+	}
+	_, err := r.pg.Pool.Exec(ctx, `
+		DELETE FROM push_subscriptions
+		WHERE user_id = $1 AND id NOT IN (
+			SELECT id FROM push_subscriptions
+			WHERE user_id = $1
+			ORDER BY last_used_at DESC NULLS LAST
+			LIMIT $2
+		)`,
+		userID, keep,
+	)
+	if err != nil {
+		return fmt.Errorf("prune push subscriptions: %w", err)
+	}
+	return nil
+}
+
 // DeleteByEndpoint removes a subscription (on unsubscribe or when the push
 // service reports it gone).
 func (r *PushRepo) DeleteByEndpoint(ctx context.Context, endpoint string) error {