Levi Neuwirth
13c3d2fd46
Kind and tag 34, schema major 3, minor epoch 10. The last rung before G3, and the one that closes P13-S13: the tuning context becomes operation-authored, so it finally has a canonical carrier. The closure argument is the metadata precedent, not the canonical base - the base embeds no graph values for any field, and metadata has been durable purely through its operations since M2d. The payload carries epiphany_core::TuningContextSettings, a five-field subset of ScoreTuningContext, not the full graph type. ScoreTuningContext's codec deliberately drops accidental_extensions, so a full-value payload would have diverged between a live session, where accept stores the envelope as a value, and the same document reloaded, where the field decodes empty. canonical_value! could not have caught that: it compares bytes and never the originating value, so a field that never reached the bytes is structurally invisible to it. The subset makes the divergence unrepresentable instead of relying on a normalization step nothing can enforce, and it costs no wire design - the encoding is byte-identical to the existing five-field walk, which tuning_context_settings_canonical_bytes_match_score_tuning_context asserts directly. Reduction leaves accidental_extensions untouched. SetTuningContext is the sole genesis payload born at major 3, because minimal stamping is a function of each payload's value, so the accept-set raise is charged to this one surface: OperationEnvelopeBlock 2 to 3. The doc comment above it did not merely record the cap, it asserted that no operation payload embeds the tuning context - a sentence this rung falsifies - so it is rewritten rather than left beside a corrected constant. Undo restores the seeded base settings, default or not, and the never-authored versus authored-to-default distinction stays unobservable. An earlier draft of the contract had that backwards; PLAN_GENESIS_OPS section 5 trap 5 withdrew it, and SetMetadata is the disproof. Fixes two undefined references the interrupted run had not yet reached: operation_catalog.tex referenced sec:evolution:major3, a label defined in binary_format.tex, which LaTeX cannot resolve across documents. Replaced with the sectionsc convention already used for every other cross-companion citation in that file. Gate: 1409 tests, clippy 0, fmt clean, conformance 8/8 including [7f], both vector corpora regenerated, all four PDFs at 0 undefined references. The t5 and t7 mutations were re-run independently and observed to fail as specified; the remaining eight are not signed off, because the implementing run was stopped before it reported them. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01QjsEnYhm1gPpf6ii2iFxFV |
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| DECISIONS.md | ||
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README.md
epiphany-layout-ir
The Epiphany layout intermediate representation and constraint-solver
interface, implementing the normative requirements of Chapter 7 ("Layout
Intermediate Representation") and the interface of Chapter 9
("Constraint-Solver Interface") of the core specification
(spec/core_spec.pdf). This is Agent E's crate per spec/QUICKSTART.md — it
lands last among the implementation crates, building on Agent A's
epiphany-determinism and Agent B's epiphany-core (and on Agent C's
OperationKindTag for the edit-barrier types — see DECISIONS.md).
The IR sits between the score graph and two downstream consumers: the constraint solver, which resolves spacing and positioning, and the renderer, which produces final visual output. — Chapter 7
The score graph is the canonical truth about the music; this crate is a downstream projection of it. The transformation is a pipeline of four stages, each with its own type and a deterministic, provenance-preserving contract for the next.
What's here
| Area | Items | Spec |
|---|---|---|
| Stage 1 — logical | LogicalLayoutIR, LayoutRegion, composite LayoutObject, overrides/cross-region objects, to_logical |
Ch. 7 §"LogicalLayoutIR" |
| Stage 2 — constrained | ConstrainedLayoutIR, SpringSlot, LayoutConstraint, GlyphObject, to_constrained |
Ch. 7 §"ConstrainedLayoutIR" |
| Stage 3 — resolved | ResolvedLayoutIR, pages/systems/staves/measures, ResolvedGlyph |
Ch. 7 §"ResolvedLayoutIR" |
| Stage 4 — render (interface only) | RenderIR, RenderPrimitive, RenderIRProducer, to_render |
Ch. 7 §"RenderIR" |
| Time axis | canonical TimeAxisModel plus dynamic TimeAxis, including registered payload preservation |
Ch. 7 §"Layout Regions" |
| Provenance | Provenance, LayoutObjectId, SynthesisKind, stable_layout_id (a pure function of the source — stable across relayouts) |
Ch. 7 §"Provenance" |
| Engraving decisions | EngravingDecision/EngravingDecisionId/EngravingDecisionKind, DecisionSource |
Ch. 7 §"Engraving Decisions" |
| Vertical bands | VerticalBand/VerticalBandId/VerticalBandKind |
Ch. 7 §"Vertical Bands" |
| Incremental cache | LayoutCache, DependencyIndex, granular stage caches and invalidation |
Ch. 7 §"Incremental Layout and Caching" |
| Glyph catalog | GlyphCatalog (metric-lookup interface) + in-tree BravuraCatalog, GlyphCatalogIdentity, SmuflVersion, FontId, GlyphMetric/GlyphAnchor, BRAVURA_METRICS/BRAVURA_VERSION, metrics_hash_for (MUSCFNTM-tagged) |
Ch. 7 §"Glyph Catalog Interface" / §7.3.2 |
| Edit barriers | EditBarrier, BarrierScope, BarrierCondition, ObjectKind, EditContext (precise scope evaluation), keyed on Agent C's OperationKindTag |
Ch. 8 §"Edit Barriers" |
| Solver interface | ConstraintSolver (solve/solve_incremental, Send + Sync), SolverConfig/SolverBudget, SolverState, InvalidationSet, SolveReport, SolveStatus, SolverTier/SolverVersion, the v0 StubSolver |
Ch. 9 |
| Round-trip | round_trip, RoundTripReport, laid_out_object_ids |
Ch. 7 (v0 acceptance criterion 6) |
The stub solver
Per the QUICKSTART, the v0 constraint solver is a stub: StubSolver returns
SolveStatus::Solved with the input geometry verbatim (each glyph's resolved
position is exactly its constrained baseline), preserves provenance, and reports
all hard constraints satisfied. The real solver — Cassowary or otherwise — comes
later (Chapter 9 specifies the interface, not the algorithm); v0 only needs to
round-trip IR through the solver interface to prove the contracts hold. The one
stub validates the full Chapter 7 §7.3.2 catalog identity and all slot, band,
and geometry cross-references before reporting Solved. Explicit constraints
are rejected because this interface-only solver cannot honestly evaluate them.
The round-trip (v0 acceptance criterion 6)
round_trip runs graph → LogicalLayoutIR → ConstrainedLayoutIR →
stub-solved ResolvedLayoutIR → RenderIR and asserts the contract every stage
must satisfy:
- the stub solver reports
Solvedwith all hard constraints satisfied; - the complete
Provenanceof every object —source,synthesis,dependencies, andstable_id— survives every stage unchanged; - no two objects ever share a
stable_id, so manifestation multiplicity is preserved (a source manifested in two regions stays two layout objects); - the stub solver returns the input geometry verbatim;
- the set of score-graph sources recovered from the
RenderIRis exactly the set laid out — a surjection onto graph identity (one source may back several manifestations, each with its own stable id).
Agent F's testkit drives this same entry point (layout_stub::round_trip) on the
10-measure single-staff hand-off fixture and the rich multi-region generator.
Algorithmic scope
Per the QUICKSTART ("a prototype baseline, not the product"), this crate implements the Chapter 7 IR contracts and interface types, not a production engraving engine. The real spacing and casting-off algorithms, quality-metric computation, constraint solver, and renderer remain later implementations of these interfaces.
Determinism
IR coordinates are single-precision staff spaces (StaffSpace(f32),
Chapter 7 §7.2); the canonical ResolvedLayoutIR output quantizes them to
the 1/1024 grid at serialization time
(ResolvedLayoutIR::canonical_bytes), exactly as Appendix D §"Quantized Layout
Coordinates" prescribes — quantization absorbs all f32 variation below 1/2048
staff space, so the canonical output is independent of the floating-point
environment. The glyph-catalog identity hashes its consulted metrics (advance,
bounding box, named anchors) under the MUSCFNTM domain tag, and the
edit-barrier types carry a canonical encoding with set-valued fields emitted in
canonical byte order (sorted and de-duplicated). See DECISIONS.md.
Tests
cargo test -p epiphany-layout-ir covers each module plus the round-trip on
Agent B's valid_score / valid_score_rich generators. The end-to-end v0
acceptance gate (criterion 6) lives in the testkit.