RS-1 honestly failed the Minimal casting_off_quality threshold under the
reference engraver: greedy first-fit left a two-measure stub last system
(width CV 0.6145 -> clamped 1.0 > 0.90). Cleared the honest way — an
engrave-side balance pass, no Quality Metric Catalog or core-spec change.
Casting-off gains a second phase, a widow rebalance
(casting::rebalance_widows, run between the greedy walk and vertical
stacking): it moves whole trailing measures from a region's penultimate
system into its final one, choosing the shift that minimizes the larger of
the two distribution penalties the catalog defines for the break family —
the width imbalance (casting_off_quality, the CV of the region's system
widths) and the non-final break penalty (system_break_penalty, the mean of
|W-w|/W over non-final systems). distribution_cost computes each raw by the
same formula as quality.rs's casting_off_raw / system_break_raw (mean not
worst, abs not clamp), so the rebalance optimizes the values the metric
census will report. The two axes pull against each other, so their min-max
lands on a 6/4 split for RS-1 (casting_off 1.0 -> 0.4463, system_break
0.254 -> 0.677, every axis <= 0.90) — with comfortable margin, over the
fragile full-balance 5/5 (system_break 0.889, a hair under 0.90).
Scope is tight: only a region's last boundary moves, and only when greedy
placed it (an Automatic boundary with no break requirement or page force
pinned to its slot); a user/IR-anchored or page-forced boundary is never
disturbed, the penultimate system keeps >= 1 measure, the final never grows
past its predecessor, and the system count is unchanged — so every
break-count and page-assignment invariant (and all break-constraint tests)
hold untouched.
The casting_off 0.5 anchor and the 0.90 Minimal column were vindicated, not
relaxed: the engraver improved, no anchor rescale / threshold loosening /
RS-1 override. Core spec Chapter 9's "Minimal makes no optimality claim"
already permits the heuristic, so nothing normative changed (no .tex/PDF
rebuild). P12-I12 (the Standard-tier spacing floor on short scores) stays
open.
- engrave: rebalance_widows + distribution_cost + two-phase module docs;
ENGRAVER_VERSION 2 -> 3 (a wrapping score's baked geometry differs from
pure greedy); three new casting tests (even-split preference, the
mean-not-worst break penalty for 3+ systems, and the resolved final
system); the_wrapping_fixture_is_measured_honestly re-pinned to the 6/4
values (both axes floor-warn under Standard, status untouched).
- testkit: RS-1 minimal_xfail row removed (promoted to a plain Pass); the
suite ships no xfail rows.
- render-svg: ten_measure.engrave.{svg,snapshot} goldens regenerated
(view_box width 83.99 -> 64.95; still two systems).
- process trail: PASS12_BATCH I11 struck; PASS12_RATIFICATION_LOG
"no spec change" section; engrave DECISIONS casting-off decision 9 +
quality item 7 + candidate promoted.
860 workspace tests pass; clippy -D warnings, fmt --check, rustdoc
-D warnings all clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NEs4aYiu8MXjdYdMxw8PTd
Levi Neuwirth
bc9fb27d36