Completes brainy's #35 side. When the at-gen vector gate serves a filtered
semantic read, Brainy now ships the historically-correct candidate vectors so the
native provider reranks against them with zero per-vector FFI crossing — the
provider need not duplicate the per-generation retention Brainy already does.
- New `AtGenerationVectors { ids: BigInt64Array; vectors: Float32Array; dim }` on
the VectorIndexProvider.search options bag (row-major: vectors[i*dim..] == ids[i];
invariant vectors.length === ids.length*dim; ids = the candidate set; dim must
match the index dim). The built-in JS index ignores it.
- buildAtGenerationVectors resolves each universe id's vector AS OF the generation
(the record before-image, or live getNoun when untouched since the pin — not
readNounRaw, whose canonical path is empty under lazy-vector eviction), interns
the id via the shared mapper, and packs row-major. Absent/vectorless/wrong-dim
ids are dropped (not vector-rankable). Bounded by the filtered universe.
Shape + the four clarifications (row-major, ids-are-the-candidate-set, dim-asserted,
filtered-path-only) confirmed with cor in the handoff #35 thread. Inert until cor's
native at-gen rerank advertises isGenerationVisible (honesty guard).
Tested: the mock versioned provider now asserts it receives atGenerationVectors with
the row-major invariant, correct dim, and ids resolving back to the at-gen universe.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>