cadrumo.domain.calculations.registry.design_constant_bindings module¶

Selector model and build-time validator for the design_constant family.

A record-design constant is a byte run whose value is fixed by AEAT’s own diseño de registro rather than supplied by the taxpayer: the record-type marker, the modelo number, a sheet discriminator. The diseño states them in its own field text – “Constante número ‘1’.”, “Constante «720».” – and they are the same for every filing of that record.

Before this family such a run had no honest home. Routing it through manual_input asked the operator to type AEAT’s record format, and because that prompt is answerable-blank the run could emit blanks behind a valid digest, producing a file AEAT cannot parse. Routing it through an inline export literal was the other candidate and is refused for Modelo 720 by a deliberate contract: that layout represents every casilla through a binding and pins inline fields to carry neither a casilla id nor a literal.

So the constant stays a binding and carries its own value. The evidence for the value is NOT re-declared here: the binding’s existing source_refs already cites the diseño the constant is read from, which is what a reviewer follows.

What this family is NOT for, and the distinction is load-bearing. A run whose diseño text offers a blank alternative – Modelo 369’s [blanco | constante "C"] – is CONDITIONAL, and pinning one branch of it here would corrupt the record. A run whose constant IS blank – Modelo 714’s “Constante. Blanco” – is already correctly a filler and gains nothing from a value it does not have. Only an unconditional constant with a real value belongs here.