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Levi Neuwirth 9d28dd6615 Clear P12-I12: scope spacing_distortion to rhythmic columns (QMC 0.2.0) 
The Standard-tier spacing floor warned on short healthy scores: three
reference-suite entries measured spacing_distortion 0.36-0.41, above the
0.32 warning floor (0.8 x 0.40), a spurious diagnostic (every score still
passed Minimal). Root cause: the CV folded in the clef-to-first-note lead
advance, which is sized by notational-furniture width, not by rhythm.

Unlike P12-I11 (an engrave-side fix, no spec change), the defect here lived
in the metric's own normative definition, so the honest fix is a catalog
change - the mirror of I11: correct the measurement rather than relax the
threshold.

Quality Metric Catalog 0.1.0 -> 0.2.0: spacing_distortion is scoped to the
system's rhythmic columns (spring slots bearing a notehead or rest). The
clef / key-signature / time-signature lead and barlines contribute no
column, so a note-to-note advance spans them. quality::census now builds its
spacing columns only from a precomputed rhythmic-slot set (is_rhythmic: a
notehead*/rest* glyph anywhere in the slot); the CV and the >= 3-column
contributing-unit rule are otherwise unchanged.

Results: RS-3/5/6 drop to 0.2188 / 0.0819 / 0.0856 (all below the floor),
and the axis stays honest on real irregularity (RS-3 keeps 0.2188 from a
mid-line accidental). RS-2/RS-4 go vacuous-0.0 (their systems carry < 3
rhythmic columns - honestly "too little to measure," cleaner than the old
furniture noise). RS-1 0.1341 -> 0.1967 (cross-barline note advances).

The 1.0 anchor, orientation, range, tier thresholds, and the eight other
axes are unchanged. This is measurement-only: the resolved layout, canonical
bytes, render goldens, and ENGRAVER_VERSION are all untouched - only the
reported spacing_distortion value moves. The duration-aware optical-spacing
open question (deviation from duration-proportional spacing) stays open; it
needs the pipeline's deferred duration-aware preferred widths.

- catalog: spacing_distortion requirement (req:qmc:spacing) redefined over
  rhythmic columns, rationale + open-question note updated, version 0.2.0,
  revision-history row; PDF rebuilt clean (0 undefined refs).
- engrave: quality::census rhythmic-column filter + is_rhythmic; module and
  spacing_raw docs; the floor-column contrast test re-pointed from b-flat's
  spacing (no longer warns) to RS-1's casting-off (still between the Standard
  0.28 and Minimal 0.72 floors); new short_scores_do_not_trip_the_standard_
  spacing_floor locks the fix.
- QMC version breadcrumbs bumped to 0.2.0 (engrave + layout-ir quality.rs,
  both DECISIONS.md, testkit RS-1 comment); reference suite companion
  unchanged (cites the catalog by name, no pinned values).
- process trail: PASS12_BATCH I12 struck; PASS12_RATIFICATION_LOG I12
  section (Version movements: QMC 0.1.0 -> 0.2.0); engrave DECISIONS quality
  decision 8 + item 7 + candidate.

861 workspace tests pass; clippy -D warnings, fmt --check, rustdoc
-D warnings, and the catalog PDF build all clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NEs4aYiu8MXjdYdMxw8PTd
 		2026-07-05 13:57:10 -04:00
..
src Clear P12-I12: scope spacing_distortion to rhythmic columns (QMC 0.2.0) 2026-07-05 13:57:10 -04:00
Cargo.toml Phase 3 tranche 1: casting-off, K1 schema-fill, value-restoring undo 2026-07-02 21:55:26 -04:00
DECISIONS.md Clear P12-I12: scope spacing_distortion to rhythmic columns (QMC 0.2.0) 2026-07-05 13:57:10 -04:00
README.md Phase 3 tranche 1: casting-off, K1 schema-fill, value-restoring undo 2026-07-02 21:55:26 -04:00

README.md

epiphany-engrave

Agent I's engraving constraint solver (spec Chapter 9): turns a ConstrainedLayoutIR into a ResolvedLayoutIR with real geometry. It is the production-side replacement for epiphany-layout-ir's interface-only StubSolver; the two live in separate crates so the spec's core/product boundary stays sharp.

Status: Minimal tier, with casting-off

  • Engraver runs a deterministic horizontal spacing pass (the first axis of the two-pass spring layout): each spring slot is placed left-to-right by a collision-aware advance derived from real glyph bearings.
  • A casting-off pass (Phase 3's layout track) then breaks the spaced line into systems at measure boundaries (greedy first-fit against a PageGeometry — default A4 portrait at an 8 mm staff), stacks systems vertically at the vertical-band model's inter-system gap, assigns pages by content height, and populates the real ResolvedPage/ResolvedSystem tree. Every position is baked into a single y-up world frame (pages stacked vertically), so the SVG renderer and hit-testing consume the flat glyph/stroke lists unchanged.
  • The IR's declared constraints are evaluated — geometric families against the pre-casting spaced frame, break constraints against the final break structure (hard breaks are always honoured; a pathological soft break is skipped and recorded as an IrOverride decision). Chosen breaks are recorded as EngravingDecisions with SynthesisKind::EngravedBreak targets, attributed to the user override that requested them when one did.
  • It reports SolverTier::Minimal: hard constraints (break family included) satisfied, no optimality claim — the quality-metric vector stays the honest all-worst placeholder until the Quality Metric Catalog lands.

Deferred: the vertical soft-spring solve, per-system justification/stretch, optimal break search, widow/orphan control, and casting-off caching. See DECISIONS.md.

use epiphany_engrave::Engraver;
use epiphany_layout_ir::{ConstraintSolver, SolverConfig};

let report = Engraver::default().solve(&constrained_ir, &SolverConfig::default());
assert!(report.satisfied_hard_constraints);
let resolved = report.layout; // real pages/systems; hand to epiphany-render-svg