Levi Neuwirth
17c1d67561
Filed as a deferral -- pickups unmodelled -- it is closer to a live defect, and the tree already held the proof. m35 placed a first measure at offset 0 and its successor half a whole note later under a whole-note signature and asserted invariant 20 fires. That is a pickup. The test has been labelled "wrong distance" since packet 2. create_measure applies the same rule as a refusal, now observed end to end rather than cited: the successor comes back NoOp with MeasureMeterMismatch. Authoring a pickup does not leave it unmodelled; it makes the rest of the instance unauthorable. Both refusals carry the same reason code, so the fixture is the only thing separating them. Pickup and successor both declare None, which keeps clause 2 from running on either side and makes the observed refusal provably clause 3's. The pickup's own mint is asserted Applied before the successor's NoOp, because a fixture whose operations never execute produces a non-Applied result indistinguishable from a refusal. The exemption is narrower than every document said. A first measure escapes only the predecessor-dependent checks -- invariant 20's boundary clause, and create_measure's clauses 1 and 3 -- plus agreement when it declares None or a matching signature, and only when its other preconditions hold. It can still be refused for a dead parent or an unresolving anchor referent, and invariant 10 can still flag it. Seven surfaces carried the loose form; one had hardened into falsehood, claiming all three clauses are vacuous for a first measure when clause 2 has no predecessor dependency at all. core/DECISIONS.md is deliberately untouched. It already said "never flagged by the boundary clause" -- the one site that drew the distinction correctly -- and an earlier contract draft listed it as defective by matching the phrase without reading its qualifier. The corrected ops entry now quotes that qualifier, and a positive gate check protects it. A mid-score partial enters successfully and its successor fails, so the scope is boundaries following any partial measure, not partial measures. The root cause is a missing quantity rather than a missing exemption: both rules compare the start-to-start distance against the governing signature's full measure_duration when it actually equals the predecessor's own content duration. Introducing that quantity is a semantic rung; this one stops at its edge, with both function bodies byte-identical. P13-S24 is filed for the Chapter 3 splitter deferral, which shares the missing partial-duration concept and is otherwise independent. Executed against spec/CONTRACT_P13S19_PARTIAL.md, four mutations. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01QjsEnYhm1gPpf6ii2iFxFV |
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README.md
epiphany-ops
The Epiphany concurrent semantics: the operations through which the score
graph becomes a live model, and the deterministic reduction by which a set of
operations becomes a materialized score state. Implements the normative
requirements of Chapter 6 (Semantic Operations and Concurrent Reduction) of
the core specification (spec/core_spec.pdf). This is Agent C's crate per
spec/QUICKSTART.md, building on Agent A's epiphany-determinism and Agent B's
epiphany-core.
A score's state is defined by the set of operations committed to it. Any materialized graph is a deterministic reduction of that set; caches, snapshots, and partial reductions are acceleration structures, never the source of truth. — Chapter 6, Design Principles
The thesis in one paragraph
The replicated operation set is a grow-only CRDT: replicas accumulate envelopes and converge on the same set. The materialized graph is not a CRDT — it is the deterministic reduction of that set in a single canonical order (causal-first, then the HLC tuple). Any permutation of the same envelopes reduces to byte-identical materialized state. That property is the determinism heart of the architecture, and the reduction fuzzer is its tripwire.
What's here
| Area | Items | Spec |
|---|---|---|
| Stamps | HybridLogicalClock, OperationStamp, the reduction & monotonicity tuples |
Ch. 6 §"Operation Identity and Stamps" |
| Causal context | CausalContext (dotted version vector), covers, the missing-predecessor signal |
Ch. 6 §6.2 |
| Payloads | OperationKind, the discriminator-only OperationKindTag, OperationPayload, the §6.10 representative ops |
Ch. 6 §"Operation Envelopes", §6.10 |
| Envelopes | OperationEnvelope, EnvelopeHash (MUSCENVH), well_formed (incl. stamp.id == id) |
Ch. 6 §6.4 |
| Slots | OperationSlot::{Single, Equivocated}, the order-independent (Pass-10) transitions |
Ch. 6 §6.5 |
| Anomalies | AnomalousReplicaSegment, IntegrityAnomaly/Kind, the HLC-monotonicity detector |
Ch. 6 §6.6; Ch. 5 §"System-Derived Counter Collisions" |
| Effects | OperationEffect, NoOpReason, the typed PreconditionFailureReason, RepairRecord/RepairKind |
Ch. 6 §6.3.2, §6.5 |
| Conflicts | ConflictRecord, ConflictKind, content-derived ConflictId (derive_conflict_id), the registry, resolution |
Ch. 6 §6.4 |
| Transactions / undo | TransactionDescriptor with the causal-prior-descriptor rule, UndoTransactionPayload / UndoPolicy |
Ch. 6 §6.6, §6.8 |
| Operation set | OperationSet: accept pipeline (well-formedness → slot → causal), grow-only |
Ch. 6 §"Envelope Acceptance" |
| Reduction | canonical_reduction_order (single function), MaterializedState, the reduction driver |
Ch. 6 §6.3 |
The determinism this crate enforces
- A single reduction-order function.
canonical_reduction_orderperforms deterministic causal topological ordering, using the intrinsic stamp tuple(physical, logical, replica, counter)only among ready operations. - Order-independent equivocation. A duplicate
OperationIdwith different canonical bytes transitions its slot toEquivocatedregardless of which envelope arrived first (Pass 10). Equivocated slots contribute nothing to reduction; dependents are held pending. - Content-derived facts.
ConflictIdandIntegrityAnomalyIdare derived from content, so two replicas reducing the same set agree on every conflict and anomaly id — the conflict registry and anomaly register are deterministic materialized facts, not local bookkeeping. - Byte-identical materialized state.
MaterializedState::canonical_bytesserializes the effect log, conflict registry, anomaly register, object existence, spellings, and LWW fields in their normative orders. - Real graph materialization.
OperationSet::reduce_onto(&base_score)returnsGraphMaterialization { state, score }. The graph is mutated in the same canonical order and compares by canonical event identity, independent of arena storage order.
Hand-off gates
Run the gate harnesses (QUICKSTART, Agent C):
cargo test -p epiphany-ops
cargo run --release -p epiphany-ops --example fuzz_reduction # 10k iters, seed 0
cargo run --release -p epiphany-ops --example fuzz_reduction 100000 7 # soak, seed 7
- Reduction determinism — every randomized envelope set reduces to byte-identical materialized state under any acceptance order (v0 acceptance criteria 1 and 5).
- Equivocation order-independence — every duplicate-id-with-different-bytes scenario equivocates regardless of arrival order (v0 acceptance criterion 3).
The integration tests (tests/concurrent_reduction.rs) exercise these plus
transaction atomicity, descriptor precedence, anomaly exclusion, and forward
undo through the public API.
Scope and decisions
Chapter 6 specifies the framework and a representative selection of
operations; the full ~60–80-primitive catalog is an explicit open question
(§6.11) deferred to the Operation Catalog companion. This crate implements the
framework in full and the representative operations, which is sufficient to
exercise every reduction discipline. The representative operations can also
reduce onto an epiphany_core::Score: insert/delete, voice promotion, supported
cross-cutting structures, system breaks, migration checks, transaction
rollback, and undo mutate the real graph while preserving Agent B's invariants.
reduce() remains the base-free CRDT/bookkeeping API; reduce_onto() is the
graph-aware editing path. See DECISIONS.md for remaining payload boundaries.
Per QUICKSTART "Don't do these": undo is the spec's forward compensating
operation, never inverse-based; unsafe is forbidden; everything is sync.