Calibration is not singular acquisition

For event-code readout choose a regular laboratory event at $T=T_{\ast }$ and prepare $P_1\otimes {\rho }_S$ there. Its coordinate equals the incidence-time label, but its spatial position is not the apex. This is preinstalled calibration, not a signal arriving from $\mathcal{W}$. A history experiment may instead be read at $T=T_{\ast }+4\ell /c$, after all four labeled singular-intersection times.

A finite-duration reversible update performed afterward operates on metadata describing the prescribed zero germ. It does not physically cause an earlier singular incidence. The incidence was already part of the fixed classical family.