SemanticCompute v1.18.0

SemanticCompute v1.18.0 — reachable, consistent, and honest about its own confidence

A minor shaped entirely by one consumer's verification discipline. Their standing test for done-ness —
merged, on a released main, discoverable by the normal route, AND consistent with the paths that
already existed — is this release's changelog in four clauses.

Fixed

precision is now in sc_check_parity's declared JSON schema. The v1.17.0 runtime accepted it,
validated it, and refused unknowns helpfully — and tools/list never mentioned it, so a client
discovering the tool by schema introspection (the normal MCP route) would report the feature missing
from a build that has it. The consumer's third instance of "a fix that exists but is not reachable by
the normal route", and the argument that has moved every change in this thread.

A passing float64 check now reports the OBSERVED maximum error. The first float64 path reported
maxAbsoluteError: 0 on a pass whose true maximum was 3.55e-15 — and the finding was worse than the
report: the float32 doctor had always reported the observed maximum over ALL elements, so the two
precisions carried differently-scoped numbers under the same field name. Not a convention; a
divergence, introduced by testing the new path in isolation. Now mirrored to float32 exactly,
including the relative-error denominator, pinned by a passing-check-reports-true-max test.

Added

The suggestion abstention floor. sc_suggest_families labels its own confidence regime: top
coverage below 40% returns confidence: "low" with an abstention-grade note — because a consumer
left a resampler unmapped for a week on a top-ranked nonsense hit, and "a confident wrong answer is
indistinguishable from a confident right one, so a detector that guesses costs more than one that
abstains". The floor is honest about its limits: the same 28–36 band has held both nonsense and
CORRECT top hits in the evidence, so below the floor the claim is "rank carries little signal here",
never "this is wrong". The pinned below-floor case is the consumer's own: a windowed-sinc FIR
DESIGNER, for which the honest answer is that no family covers it (SC ships FIR apply, not design).

The landing page's code-knowable numbers are gated (LandingNumbersSyncTests) — family counts and
the full kind-distribution bars are checked against the catalogue, closing the drift class found at
the v1.15.0 cut the way the README table gate closed its sibling.

Verification surface: 1,201 tests in 260 suites; the kernel-compile sweep covers 365 programs across
224 lowerings, 0 failed.