Add safe BSSN-EScalar kernel and transfer toggles

AMSS_NCKU_source/makefile.inc

@@ -48,6 +48,17 @@ endif
 ##   0           : fall back to original Fortran kernels
 USE_CXX_KERNELS ?= 1
 
+## BSSN-EScalar RHS switch
+##   1           : use BSSN-EScalar C wrapper on the normal patch path
+##   0 (default) : keep the original Fortran BSSN-EScalar RHS for precision-safe runs
+## Note: this requires USE_CXX_KERNELS=1 because the wrapper reuses the C BSSN kernel.
+USE_CXX_ESCALAR_KERNEL ?= 0
+
+## Cached transfer switch
+##   1           : enable cached Sync/Restrict/OutBd transfer on evolution hot paths
+##   0 (default) : keep the original uncached transfer path for precision-safe runs
+USE_TRANSFER_CACHE ?= 0
+
 ## RK4 kernel implementation switch
 ##   1 (default) : use C/C++ rewrite of rungekutta4_rout (for optimization experiments)
 ##   0           : use original Fortran rungekutta4_rout.o