Closes the two skipped null-preservation tests and the architectural
gap behind them. In CGA, null vectors represent Euclidean points;
under a conformal transformation a point must map to a point —
applying a versor sandwich to a null vector must preserve null
property. The previous implementation forced everything onto the
unit-versor shell, which is correct for field-state propagation but
wrong for geometric point input.
Implementation
- algebra/versor.py: new `_input_is_null(F)` checks `cga_inner(F,F) ≈ 0`;
`versor_apply` routes null inputs around `_close_applied_versor`
and returns the raw sandwich V·F·rev(V), which algebraically
preserves null property. Non-null inputs unchanged.
- core-rs/src/versor.rs: `versor_apply_closed_f64` gains the same
null-check branch via `input_is_null_f64`. ADR-0020 parity
preserved (8/8 versor_apply bit-identity tests still pass).
Test changes
- tests/test_architectural_invariants.py::TestINV06NullConePreservation::
test_versor_apply_preserves_null_property — un-skipped, passes.
- tests/test_rust_backend.py::test_rust_versor_apply_preserves_null_vectors
— un-skipped, passes.
- tests/test_versor_closure.py::test_versor_apply_closes_null_like_field_
results_for_runtime_contract — renamed to
test_versor_apply_preserves_null_property_for_null_inputs and
rewritten to assert the now-correct semantics (null in → null out).
The old contract over-specified closure for null inputs and
contradicted the architectural invariant; that's what kept the
invariant test skipped.
Stale gap docs updated
- inference_closure / cross_domain_transfer / multi_step_reasoning
gaps.md now lead with a resolution block: lanes pass at 100% on
both splits after the typed operators (transitive_walk,
multi_relation_walk, path_recall in generate/operators.py) +
pipeline wiring (_maybe_transitive_walk + _fold_walk_into_surface)
landed. The historic findings are preserved below for traceability.
- compositionality gaps.md: partial resolution — recall up from
6.25% to 68.75%; overall_pass True; residual ~30% miss requires
a relation-aware `compose_relations` operator (v2 follow-on).
Lane health unchanged: algebra 132, smoke 55, runtime 19, teaching 17,
packs 6, cognition 103. Cognition eval 100%. Four formerly-"blocked"
reasoning lanes confirmed 100% / overall_pass=True end-to-end.
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