EM reconstructs what was realized. Its whole apparatus — stratigraphic units, epochs, the reasoning chain from sources to assertions — is built to say how a thing came to be, and with what degree of confidence. It has no honest place for what was designed and never built.
That absence becomes visible as soon as a graph tries to speak the architectural view. The architectural-project reading studies the ancient design: shape and intent, without temporal depth. The stratigraphic reading studies the realization. A Functional Unit (DP-72) names a component — but a component of what? Of the fabric that stands, or of the project that was drawn? The two are different assertions, and the tools have no way to tell them apart.
Two cases force the question, and neither is exotic. An excavated construction site frozen mid-work is real fabric up to a point and pure intent beyond it; the interesting statement is precisely about the part that was never built. An unexecuted design — Michelangelo’s project for Porta Pia — has no fabric at all, yet is a fully-formed object of study, with its own sources, its own reasoning, its own reconstructive geometry.
Two homes are candidates. The project could enter as a category of Document: a source the reconstruction reasons from, reusing the existing Document → Extractor chain. It is cheap, and wrong in a specific way — it flattens a design into evidence, when a design that was never built is not documentation of a building but a proposition about one. The preferred route is a dedicated kind of Time Branch carrying a hypothetical period: had they realized it, it would have been like this. It sits beside the alternative chronological interpretations of DP-12 and the TimeBranch group node of DP-43, but it differs in kind — those branches are alternative readings of what did happen, this one is a period that never happened at all, and it must be marked so that no consumer downstream mistakes counterfactual geometry for realized fabric.
One guard travels with this from the start: EM studies the ancient project, it does not validate it. Simulation on the reconstructed model — solar, static, finite-element — comes after reconstruction and serves to understand, never to grade. The ancients did not build by our criteria.
1.7
Needed (Porta Pia, Rome — unexecuted Michelangelo design; plus an excavated construction site frozen mid-work)
Raised by E.D. 2026-08-01 while reviewing DP-72 (Functional Units). Verbatim: «dipende da cosa sto ricostruendo: il progetto antico o cosa è stato realizzato. Andrebbe evidenziato con un DP: necessità di formalizzare il progetto antico e usarlo come una particolare categoria di document o fare (meglio) prevedere un particolare tipo di temporal branch che mostra un periodo ipotetico dell'impossibilità (se lo avessero realizzato allora sarebbe stato cosi - nel caso di rinvenimenti trovati come cantieri in costruzione o progetti non realizzati di michelangelo - esempio di porta pia a roma).» Preference stated for the time-branch route over the document route. Blocks the field-shape decision for DP-72's geometry_type_ref.