D-258 invariant 2 says descending the ladder must reveal COMPOSITION — a cell
reading forest must be able to contain the clearings and rock the vote
suppressed. One assertion stood behind that, and it read:
assert!(tally.len() > 1 || share == 1.0, ...)
A single-class tally has a 100% share by definition, so both branches are always
satisfiable: the check could never fail, including in the exact case its own
message names, "or nothing was composed". The invariant had a test and no gate.
Split into the two bounds the invariant actually has, because it is two-sided:
conservation caps how much may be invented (majority > 50%, already asserted) and
composition sets a floor on how little (minority >= 0.1%). Verified by raising
the floor to 2% and watching it fail on the measured 1.07%, then restoring it —
the floor is a tripwire for "did anything happen", deliberately far below the
measurement rather than tuned to it.
Measured at the descent ladder's own anchor on Ferrath:
conservation: majority class 3 at 98.9% across 2 classes {1: 175, 3: 16209}
So composition IS working in the data and conservation holds. The map is flat
anyway, and tooling/atlas-flatness (added here) says why the eye was not enough:
rung distinct lum p1-p99
Global 1581 145.69
Region 2923 33.59
District 53 13.72
Quarter 46 11.01
Region carries almost TWICE Global's distinct-colour count while holding a
quarter of its structure — the dither pass adds colour noise, not information, so
a colour-count metric would have called the flattest rung the richest. Structure
falls ~92% from Global to Quarter.
The cause is a channel mismatch rather than a missing generator: composition
perturbs moisture_q/slope_q, and the base map draws morphology hue x elev_q
lightness. The ladder scenarios pass no overlays deliberately, so the composed
fields are never rendered in the very shots that judge this work. Recorded on
T-1213 with the three ways forward; the choice touches D-258 and is Jeroen's.
The gate is still #[ignore]d — noted on the ticket as worth moving into a harness
that runs, since believability and window-derivation already load real bodies in
the normal cargo test path.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
jpmschweitzerandClaude Opus 5
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