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Levi Neuwirth 6d37f39826 Text-projection parity: smufl and overrides project, and a persistence gap surfaces 
Schema major 3 put `smufl` and `overrides` on the binary wire and left the text
surface alone. This closes that: `TextValue for ScoreTuningContext` projects
five fields in `fn enc` order, with four new leaf impls (SmuflVersion,
SmuflVersionRequirement, TuningScope, TuningOverride) mirroring the four Codec
impls 3b-i froze.

The rule that moved them is the one this projection always followed — the text
projection is the same canonical surface the binary codec is. What changed was
not the rule but a premise: the old doc comment excluded all three fields
because "no schema major 3 has been opened", and 3b-i opened it.
`accidental_extensions` was staged out of that major and stays in-memory only,
so it is still correctly absent — the staging line now falls in the same place
on both surfaces, which is what the inverted tests assert.

No header-version bump and no document vector moved. This is a value-projection
change, not a document-format one: epiphany-textproj has no reference to a
tuning context anywhere, and the canonical base projects as a single opaque
byte atom (req:textproj:base-snapshot-inline), not structurally. So
req:textproj:header-version's sole accepted version (0 7 0) is untouched, all
13 document vectors are unchanged, and req:textproj:roundtrip was never
violated — the tuning context is not part of the projected document.

Both tests were renamed and inverted, following 3b-i's treatment of the binary
pair rather than rewriting the tranche-2/3a decision entries. Mutation-verified:
making `overrides` project as an always-empty vector — the exact regression this
fixes — fails both.

Two stale-pointer classes fixed, both of the kind this pass was hunting: the
comment in codec.rs naming the old text-test names and claiming the text
surface was unchanged; and ScoreTuningContext's per-field docs in graph.rs,
which still read "In memory only this tranche" for `smufl` and `overrides` —
stale since 3b-i, and contradicting the struct-level wire note they point at.
The struct-level doc was already correct.

Filed P13-S13, found while scoping and deliberately not fixed here: the tuning
context has NO canonical persistence path. Its only *persisted* carrier is the
acceleration snapshot, which Chapter 8 makes non-canonical and regenerable; no
canonical carrier embeds it at all. No operation authors it (the ops
vocabulary's only `tuning` references are the per-pitch TuningReference::Inherit)
and MaterializedState does not carry it. So a per-voice tuning override survives
a snapshot round-trip but cannot be authored, replicated, or merged, which makes
req:tuning:tuning-resolution-order's scopes 2-4 unreachable from any exchangeable
document. Not a regression — nothing ever worked; major 3 made the gap visible
by giving the value a wire form and no way to reach it.

The candidate prices both routes. Ratification is about the carrier, not the
encoding — the layouts are frozen and correct either way — but the operation
route is not quite the free schema-minor it first looks: blocks stamp minimally,
and bundle.rs caps OperationEnvelopeBlock at major 2 precisely because no
operation payload embeds the tuning context. An authoring operation carrying a
TuningOverride would stamp v3, dragging a role accept-set raise along with the
kind append.

Gate: fmt clean, clippy 0, 1336 passed / 0 failed, doc 0, conformance 8/8,
requirement labels 6/6 at 212/282/282.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QjsEnYhm1gPpf6ii2iFxFV
 		2026-07-24 14:02:31 -04:00
..
src Text-projection parity: smufl and overrides project, and a persistence gap surfaces 2026-07-24 14:02:31 -04:00
tests Text Projection: the Chapter-5 value layer, from one field list 2026-07-21 12:17:49 -04:00
Cargo.toml A B C D F 2026-06-19 12:42:31 -04:00
DECISIONS.md Text-projection parity: smufl and overrides project, and a persistence gap surfaces 2026-07-24 14:02:31 -04:00
README.md Phase 2: spelling + decomposition pre-passes (Agent H) with F merge gate 2026-06-23 16:33:39 -04:00

README.md

epiphany-core

The Epiphany score graph: the in-memory representation of all musical content in a score, implementing the normative requirements of Chapters 2–5 of the core specification (spec/core_spec.pdf). This is Agent B's crate per spec/QUICKSTART.md — the largest scope — building only on Agent A's epiphany-determinism.

The graph is the canonical truth about the music; layout, serialization, and editing operations are downstream projections and consumers of it. — Chapter 5, Design Principles

What's here

Area Items Spec
Identifiers ReplicaId (+ SYSTEM_DERIVED), OperationId, the typed 128-bit family (EventId, PitchId, VoiceId, …), TypedObjectId, IdentityContext, derive_system_id Ch. 5 §"Identifiers"; Ch. 6 §"Operation Identity"
Time RationalTime (inline-or-promoted), MusicalPosition/MusicalDuration (typed algebra), WallClockTime/WallClockDuration, TimeAnchor/AnchorOffset, EventPosition/EventDuration/ConcreteDuration, TimeSignature/BeatGroup, NotatedComponent/NoteValue Ch. 3
Tempo TempoMap, Tempo, TempoSegment, TempoShape with closed-form musical_to_wallclock/wallclock_to_musical over constant/linear/exponential segments (curve deferred → TempoError) Ch. 3 §"Tempo Map"
Pitch Pitch, ScalePosition, IdentifiedPitch, PitchSpelling, the spelling-attachment subsystem, ReferencePitch, spell (single-pitch simplest spelling), all three equivalences (scale_position_equivalent, enharmonic_equivalent, sounding_equivalent) Ch. 2; Ch. 4 registry ids
Pre-passes derive_annotations: the real spelling pre-pass (Temperley line-of-fifths) + notational-decomposition pre-pass (metric greedy-aligned splitting) as canonical derived annotations (not stored), the eligibility TaxonomyReport, and resolve_spelling (authored-override precedence) Ch. 2 §"Spelling Pre-Pass"; Ch. 3 §"Notational Decomposition"
Events the Event taxonomy (7 variants) and the slotmap-backed EventArena Ch. 5 §"The Event Arena"
Graph Canvas, Region, Staff vs StaffInstance, Voice/VoiceOrigin, Measure, BarlineAlignmentGroup, aleatoric EventOrderingDAG (acyclic by construction), the full cross-cutting registry, the full top-level Score Ch. 5
Indexes ScoreIndexes: the four mandatory indexes (event-time, cross-cutting-reference, measure, spelling-attachment) Ch. 5 §"Indexes"
Invariants check_invariants over all 19 enumerated graph invariants, with a typed InvariantViolation witness per check Ch. 5 §"Graph Invariants"
Generators generators::valid_score/valid_score_rich (positive), violating_score (negative, per invariant), shrink (witness minimizer) QUICKSTART, Agent B hand-off

The identity discipline this crate enforces

  1. Replica + counter, big-endian canonical bytes. Every typed identifier is (replica << 64) | counter; its canonical 16-byte form is to_be_bytes() (8-byte replica, 8-byte counter) and the numeric Ord is the Appendix-D lexicographic byte order. Identity is exact, never tolerant.
  2. A reserved system namespace. ReplicaId::SYSTEM_DERIVED is rejected by ReplicaId::generate/from_entropy; system-derived ids (derive_system_id, derive_promoted_voice_id) live only in that namespace, with counters trunc64(BLAKE3(domain_tag || canonical_inputs)) via epiphany-determinism.
  3. Cross-kind confusion is a compile error. Each object kind has its own newtype; TypedObjectId tags them apart with a discriminant that is part of canonical content.

Graph invariants as property tests

The Chapter 5 invariants are property tests in CI, not runtime assertions in release builds (QUICKSTART). check_invariants returns every violation with a small witness. For each invariant generators provides:

  • a positive generator (valid_score / arbitrary_graph_corpus) whose output passes every check, and
  • a negative generator (violating_score) plus a shrinker (shrink) that minimizes a violating graph to a small witness while retaining only the structure the violation needs.

Generation is deterministic (a vendored SplitMix64), so a failing case reproduces from its seed — no platform entropy enters generation (Appendix D §"Randomness").

Implementation decisions

Per QUICKSTART "Decisions you'll need to make" (full rationale in DECISIONS.md):

  • Replica entropy: getrandom (decision 1). ReplicaId::generate re-draws until the value is not the reserved namespace.
  • Event-arena storage: slotmap (decision 2) plus a hash index for the required O(1) EventId lookup and generation-checked stale handles.
  • Sync only (decision 4): no async anywhere.
  • Current stable Rust (decision 5); MSRV pinned at the workspace's 1.77.
  • RationalTime's promoted arm uses num-rational's BigRational, the spec's reference design (Ch. 3 §"Recommended Implementation").
  • unsafe is forbidden crate-wide (#![forbid(unsafe_code)]).

Hand-off criteria (QUICKSTART, Agent B)

  • Every invariant has both a generator and a shrinker (generators::{valid_score, violating_score, shrink}; one per invariant, property-tested), plus targeted tests for the cross-cutting/anchor/tie sub-rules.
  • The arbitrary-graph corpus runs clean (generators::tests::positive_corpus_runs_clean, 500 graphs), and a breadth corpus (valid_score_rich: concurrent metric/proportional/ aleatoric regions, measures, triplet, tie, spanner, marker, chord symbol, decomposition, tombstones) runs clean over 200 seeds.
  • cargo test -p epiphany-core clean (69 unit + 5 integration).
  • cargo clippy --all-targets -- -D warnings clean; cargo doc clean under RUSTDOCFLAGS="-D warnings".

Depth of the invariant checks

The checks are not surface-level. In particular: invariant 3 computes per-clock event intervals and detects both disorder and overlap; invariant 7 resolves region extents to absolute wall-clock coordinates (wall-clock leaves, plus event/region/measure-start anchors — an event anchor is its region origin plus its region-relative position) and only skips pairs that can't be placed without the deferred tempo map; invariant 9 sweeps every reachable anchor (region extents, meter changes, measure starts, clef/key changes, user breaks, spanners, spelling ranges); invariant 10 resolves all graph references — cross-cutting anchor targets, annotation layers, tuplet parents, graphic objects, and event-internal references (indeterminate alternatives, trajectory event-pitches, graphic-event objects, cue sources); invariant 11 covers every id kind, plus tombstone/live collisions, SYSTEM_DERIVED misuse (including the score's own identity context), and arena index/well-formedness integrity (catching post-get_mut corruption); invariant 17 validates explicit and implicit (pitch-id-ascending) tie pairings, per-class adjacency, and the cross-voice position rule; invariant 18 recomputes the deterministic promoted-voice derivation. Enharmonic equivalence is a sounding notion (octave matters: C4 ≠ C5). Empty pitched events are rejected at the arena boundary and re-checked; IdentityContext::try_new rejects the reserved replica and counters use checked_add so a counter is never silently reused.

Known bounded limitations (deferred dependencies)

  • Tempo conversion integrates the piecewise map in closed form for Constant/Linear/Exponential segments (Chapter 3 §"Conversion"); only TempoShape::Curve is deferred to the open numerical algorithm (TempoError::CurveIntegrationUnsupported). Segment boundaries that cannot be placed without the score graph, and malformed segment sequences, return a TempoError, never a wrong answer. The inverse round-trips ordinary rhythms via a documented continued-fraction approximation (DECISIONS P11-7).
  • Region time-overlap (invariant 7) resolves extents to absolute wall-clock, now including musical event positions placed through the region's effective tempo map (its local_tempo_map, else the score map). Extents that still cannot be placed (no tempo defined, or a deferred curve) are skipped rather than rejected. Sound (no false positives), incomplete (DECISIONS P11-4).
  • System-promoted voice derivation (invariant 18) retains the winning and losing operation ids on VoiceOrigin::SystemPromoted; the checker recomputes the exact four-input derivation used by epiphany-ops.
  • The Chapter 4 tuning catalog — PitchSpace/TuningSystem/ AccidentalRegistry definitions, the built-in catalog, the hierarchical resolver, and the position→frequency resolution function — is not an Agent B deliverable (the QUICKSTART lists those as referenced-by-id). This crate models the identifiers and the score-level ScoreTuningContext; Pitch::sounding_equivalent takes a caller-supplied frequency resolver. See DECISIONS P11-5.

Scope boundaries

The full Chapter 5 top-level Score shape is modeled (metadata, instruments, staff groups, parts, tuning context, tempo map, analysis layers, views) along with the complete CrossCuttingRegistry (slurs, ties, beams, tuplets, spanners, markers, repeats, analytical annotations, comments, graphic gestures, lyrics, chord symbols). The reference- and identity-bearing fields are modeled in depth; deeper bodies (tuning resolution, tempo-curve integration, part layout, view recipes, glyph/engraving detail) are Chapters 3/4/7 and later companions.

Engraving-display detail (StemConfiguration, ClefChange, KeySignatureChange, articulations, dynamics, line styles, spanner/marker visual kinds) is introduced informally here and fully defined in Chapter 7 — it belongs to Agent E (epiphany-layout-ir), and this crate carries minimal, clearly-marked placeholders for it. Operation envelopes, stamps (HLC), causal contexts, the canonical reduction, tombstone tracking, and conflict records are Chapter 6 / Agent C (epiphany-ops); epiphany-core defines only the OperationId they hang off and the tombstone-aware invariants.

Ambiguities discovered while building are not resolved in code — they are batched as Pass 11 candidates in DECISIONS.md (QUICKSTART, Process notes).