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Levi Neuwirth 5b016f33b7 Two more glyph-members assumptions in the vertical-density axis (QMC 0.3.0) 
Review follow-up on 43215c7. Both findings were right, and the second falsified a
comment I wrote in that very commit.

1. Region staff bands were still identified by glyph `members`. vertical_raw
   measured content over all primitives but decided WHICH staff bands belong to a
   region by glyph membership -- reintroducing the assumption the change exists to
   shed. A staff band is allowed to own no glyphs: to_constrained emits one per
   staff of the region regardless, and a percussion-clef staff (no bundled glyph,
   so it engraves to a traced anchor stroke) with no notes owns only staff-line
   strokes. Membership now comes from content presence in one of the region's
   systems, which identifies the band exactly -- a staff band is per-(staff,
   region), so its content can land nowhere else.

2. Only the first realizing system was measured, justified by a comment claiming
   rigid system translation makes every realization agree. The inter-staff solve
   had just falsified that: it sizes each system's gaps from that system's own
   content. req:qmc:vertical now counts ONE UNIT PER REALIZATION, matching how
   realized inter-system gaps were already counted. That is a contributing-unit
   change, so unlike 43215c7's clarification the catalog moves: QMC 0.2.0 -> 0.3.0
   (the P12-I12 precedent). Raw formula, anchor, orientation, thresholds unchanged.

Two new fixtures, because an unexercised fix is what I criticised last round:
percussion_placeholder_staff (a valid, invariant-clean score whose lower band owns
zero glyphs and six strokes) and two_staff_wrapping_pressure (one region, two
systems, staff-line gap 15.93 where it collides and 7.87 where it is slack). Both
mutation-verified: the members filter scores 4.8e-7, first-system-only scores
1.3e-7 -- each ~0 where the corrected axis reports real deviation.

What the per-realization count exposes is not comfortable, and is recorded rather
than smoothed over: two_staff_wrapping_pressure now scores 0.739. Its pressured
system solves to the declared gap exactly; its slack system sits at ~5 staff
spaces against a preferred 2.0. The axis is symmetric -- a gap wider than
preferred is sprawl exactly as a narrower one is crowding -- and this solve only
expands, never compresses. The deferral "compressing an OVER-wide fixed gap toward
preferred ... rarely wanted" is promoted to measurably wrong. Named, not fixed:
compression is a layout change (golden churn, ENGRAVER_VERSION move), not a
measurement one.

Adjacent finding, parked: Staff::default_clef is never consulted -- to_constrained
takes the active clef from the instance's clef_sequence and falls back to
Clef::default() (treble), so a staff declaring its clef only on Staff engraves as
treble. Verified (no layout-ir consumer reads the field). Filed in layout-ir
DECISIONS with the ConstrainedLayoutIR listing gap, pending a >=3-candidate batch.

Measurement-only: no layout change, ENGRAVER_VERSION stays 11, zero golden churn.
Gate green; QMC PDF rebuilds clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
 		2026-07-09 11:39:28 -04:00
..
src Two more glyph-members assumptions in the vertical-density axis (QMC 0.3.0) 2026-07-09 11:39:28 -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 Two more glyph-members assumptions in the vertical-density axis (QMC 0.3.0) 2026-07-09 11:39:28 -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