Levi Neuwirth
ff9bd0fd06
Implements the schema-minor MUST (binary_format.tex, Schema Versioning) that no writer had ever honoured: a writer raises the chunk minor when it emits a discriminant appended after the minor it otherwise declares, so an unknown-discriminant decode failure is attributable to version skew rather than corruption. introduced_minor() lands on the five vocabularies with post-baseline variants - OperationKind, OperationKindTag, OperationPayload, ReanchorReason, and PreconditionFailureReason - each exhaustive with no wildcard arm, so a future variant cannot compile without being assigned an epoch. The tag epochs live inside operation_kind_tag_vocabulary! rather than beside it, because a sibling match is the parallel list that macro exists to prevent. The sentinel is Option<u16>, not 0, since 0 is a real baseline minor for V1-V3 and conflating them would make the max read correctly only by accident. An envelope's required minor is the max over every discriminant it actually emits; a block's is the max over its envelopes; major and minor derive independently. Baselines are not normalised - V0 keeps minor 1. The manifest seam keeps epiphany-bundle opaque: no ops or layout-ir dependency, and the aggregate version is supplied by the producer rather than derived, with CommitContext carrying the previous one so unchanged barrier content preserves it. The version rides the superblock slot that already exists; Manifest gains no field, which would have been schema-major and would have defeated the rung. bundle.rs's superblock check stays major-only - tightening it to full-version equality is a conformance regression, and s11 locks that. textproj carries the manifest SchemaVersion and never derives it, so COMPANION_VERSION moves 0.9.0 to 0.10.0 with the corpus regenerated. Not because of op-block stamping, which remains projection-invisible. A new normative requirement records the carry-never-derive rule in the companion itself; its rationale names layout-ir, which textproj genuinely lacks, rather than the operation vocabulary, which it has. Gate [7f] adds an independent oracle over decodable in-tree barrier fixtures, requiring exact equality rather than >=. Equality is load-bearing: >= catches under-stamping but not stale over-stamping after the sole maximum contributor is removed. Undecodable blobs are reported not-checkable, never as a pass. Also repairs binary_format.tex's stale claim that OperationKind and OperationKindTag append at 30 with a history stopping at 29, while 30-33 are taken and the normative tables already carry them. Gate: 1399 tests, clippy 0, fmt clean, conformance 8/8 with [7f] at four fixtures checked and one not-checkable, 102 decode vectors byte-identical (verified, not assumed), 13 text-projection vectors. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01QjsEnYhm1gPpf6ii2iFxFV |
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| Cargo.toml | ||
| DECISIONS.md | ||
| README.md | ||
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.