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Levi Neuwirth 81b7f42f0a Schema major 2 Phase E2: slur curves + cubic-bézier primitive 
The third pipeline primitive kind, review-hardened (5 verified findings fixed
pre-commit). A `Curve` (four control points, mirroring `Stroke`) threads
through all three IR stages, the canonical-encode fingerprint (a 5th u32 count
prefix; width-lock 4→5), the round-trip provenance chains and count identity,
`to_render`, the stub solver, engrave remap + casting, SVG path emission, and
hit-testing.

Slurs draw as one cubic bézier per slur carrying the slur's exact provenance
(no synthesis). LayoutContent::Slur resolves each endpoint event to a Note
column at to_logical (SlurEndpoint At/Unresolved — E1's honest-placement
discipline); a symmetric arc whose apex sits `height` from the endpoint line;
curvature_override direction+height honored, style.line (dashed) deferred to
Push 3. Honest non-drawing (traced anchor kept) for an unresolved endpoint, a
non-left-to-right span, or a cross-staff slur (no single staff — would float
at yo=0). Authored height/thickness sanitized to defaults when non-positive
(a negative thickness would else fail validation and blank the layout).

Hit-test: HitShape::Curve (Copy) flattens the cubic to a 16-segment capsule
inside contains/intersects (one region per curve); a slur click resolves to
Slur generically (no editor arm; edit ops refuse it). render-svg: stroked
unfilled <path C> after strokes/before glyphs + curve_count + content-hull
bounds. engrave: HorizontalRemap::curves; casting curve_system = Rigid-to-
start-system (no de Casteljau split — deferred; break-spanning slur draws
whole in its start system, kept for the source surjection); ENGRAVER_VERSION
4→5; slur_shape_penalty now 0.0 by construction (Minimal draws the ideal arc).

Existing SVG goldens changed only in the provenance-note comment (curves now
enumerated) — geometry byte-identical; 6 snapshots gained curve_count; new
ten_measure_with_slurs goldens. 929 tests, conformance 8/8.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
 		2026-07-08 15:33:00 -04:00
..
src Schema major 2 Phase E2: slur curves + cubic-bézier primitive 2026-07-08 15:33:00 -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 Schema major 2 Phase E2: slur curves + cubic-bézier primitive 2026-07-08 15:33:00 -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