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Levi Neuwirth e6308371d5 Push 3 slur review fix: measure slur_shape on whole slurs, not split fragments 
An adversarial review of the slur-quality tranche found a real interaction bug
between curve splitting (commit 5869691) and slur_shape measurement (7d61271):
slur_shape_raw iterated cast.curves — the per-system SUB-CUBICS of a
break-spanning slur — and measured each fragment as a unit. A slur that is
ideally shaped as a whole (ρ ≈ 0.16, in-band) splits into sub-arcs whose
diagonal chords each read flatter (ρ below 0.08), so the whole slur earned a
spurious "too flat" penalty (confirmed ~0.088) and was double-counted —
contradicting the catalog's "a tier that draws the ideal shallow arc measures 0"
property.

Fix: measure the WHOLE slur curves of the constrained input.curves (one unit per
drawn slur — the engraver's arc-proportion decision), not the cast fragments.
Casting's horizontal re-spacing and system-splitting are spacing/rendering
concerns, not shape ones. The Quality Metric Catalog contributing-units
definition is clarified: the unit is the whole slur, measured once even when
split across a break.

Regression: a break-spanning in-band slur splits (≥2 segments) yet measures 0.
Still measurement-only (no ENGRAVER_VERSION bump, no golden churn, RS suite
unaffected). 936 tests, conformance 8/8.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
 		2026-07-08 17:56:11 -04:00
..
src Push 3 slur review fix: measure slur_shape on whole slurs, not split fragments 2026-07-08 17:56:11 -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 Push 3 slur review fix: measure slur_shape on whole slurs, not split fragments 2026-07-08 17:56:11 -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