Levi Neuwirth
7df5ca17ce
SetCanvasLayoutDefaults and SetSpellingPrecedence, kinds and tags 32/33, on the
SetMetadata LWW pattern: advisory last-writer-wins, no conflict, no idempotence
short-circuit, seeded from the base so a value-restoring undo of the first
operational write reaches the pre-operational value. Both carried types already
had Codec impls, so the packet designs no wire layout -- canonical_value!
delegation and one push_lp_bytes each, inheriting strict canonical-form
rejection rather than writing it.
Both stamp schema major 0 unconditionally, staying in the catch-all arm. The
op-block accept-set is untouched at 2; epiphany-bundle has an empty diff. The
raise to 3 belongs to G2b, and the chunk schema minor -- a MUST no writer has
ever honoured -- belongs to G-minor, filed as P13-S14 and deliberately not
fixed here.
Most of this commit is documentation the vocabulary had outgrown. G1 shipped
five normative falsehoods because its contract declared the wire surfaces out
of scope, and Push 4a left TransposeInterval out of both of core_spec's
normative listings. So binary_format's payload-layout and tag tables now reach
33 rather than 30, its snapshot-only bullet records that it is empty and why,
two spelled-out payload counts move from eight to nine, and core_spec's
listings gain all four missing kinds. The Pass-12 K8 doctrine is narrowed
rather than reversed: the root and canvas remain structural givens no operation
mints, and only the claim that the score's contents arrive outside the
operation set is superseded.
Two generators were stale by two tranches and fed corpora other suites treat as
exhaustive. layout_stub's is now derived from PAYLOAD_FREE with an explicit
Registered append instead of a hand-written match, so future built-ins follow
structurally; s10 asserts PAYLOAD_FREE union {Registered} so deleting that
append cannot pass.
Companion 0.8.0 -> 0.9.0, binary format 0.11.0 -> 0.12.0, catalog 0.9.0 ->
0.10.0 (covering G1 retroactively). 102 decode vectors, regenerated.
Coordinator verification: 1371 passed / 0 failed, clippy 0 warnings, fmt clean,
conformance 8/8 and 9/9, requirement_labels 6/6, four PDFs at 0 undefined
references, goldens byte-identical, accept-set confirmed still 2. Mutations
s3/s5/s7/s10 re-run independently and each observed to kill its test.
Two findings beyond the contract. max_supported_major is not reachable outside
epiphany-bundle -- mod bundle is private and the symbol is absent from its
pub use -- so the gate's "assert it in code" was unsatisfiable without touching
a crate the contract forbids; verified by reading the unedited source instead.
And core_spec carries two P12-K8 references, not one; the contract named only
the first, so the second is annotated here for consistency.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QjsEnYhm1gPpf6ii2iFxFV
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| .. | ||
| src | ||
| 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.