Stage 2: fixed-data and region-wise readings

Gate V is unchanged. The imported fixed external data are those of the XVI-L Scope box: the preparation ${\sigma }_{\epsilon }$ is the fixed time-only ramp of XII-C (Section sec:freeze), never varied and with no $\epsilon \to 0$; the interaction switch ${\chi }_{\mathrm{I}}\in {C_c}^{\infty }(M)$ is independent and compact. The closed form of ${\sigma }_{\epsilon }$ is the XII-C profile recalled in Lemma lem:to-indep, with $\epsilon$ fixed but not numerically specified; the predecessors give no closed form of ${\chi }_{\mathrm{I}}$, and none is selected inside XVI-M.