Door B takes a profile (keyword-only, DEFAULT) and, under a profile carrying
facets, derives each dropped document's title, number, hierarchy and
cross-references, writes them into the concept's own frontmatter, and projects
them into the index entry.
The additive requirement is answered by one decision rather than by an
algorithm: the index is a PROJECTION of the concept files, recomputed from the
whole bundle each round. Nothing is diffed, so the three invariants hold by
construction -- rebuild-from-scratch equals incremental byte for byte,
re-dropping a document replaces its entry instead of doubling it, and a
relation formed in round 3 UPDATES the round-1 entry it is about, which an
append-only index could never do.
An unresolved pointer is marked '?' in the entry rather than omitted: during
build-up, pointing at something not dropped yet is normal, and the dangerous
version is the one that leaves no trace. Facet values are validated per file
BEFORE the write, so a producer value that breaks the grammar fails that file
and not the run.
DEFAULT is byte-identical with and without the new parameter, and is asserted
so. Door B keeps writing the literal 'generated: true' rather than the
profile's ownership stamp -- routing it through the profile would move
DEFAULT's bytes and orphan every bundle this door has already written; that is
a separate question and answering it here would have answered it silently.
18 new tests; suite 677 -> 695.
