Levi Neuwirth
567e8214a4
Two review findings after P4. Both real. The tag-omission failure could recur. After the P4 fix there were STILL four hand-maintained lists -- a test-local all_tags(), a barrier test spelling 0u8..=30, a fuzz corpus naming five tags, a vector corpus naming four -- plus a malformed-bytes test asserting that 31 rejects. A future tag 31 added to discriminant() and omitted from decode_canonical() would have left every one of them green, and the malformed test would have LOCKED it, exactly as the 30 version did two commits ago. operation_kind_tag_vocabulary! is now the single source. It generates discriminant, from_discriminant, and OperationKindTag::PAYLOAD_FREE from one list, and the generated discriminant match is exhaustive over the enum -- so a variant added to the enum and not to the macro fails to COMPILE. Everything downstream reads PAYLOAD_FREE: the decoder, the fuzz corpus (all 31 tags, not five), the conformance vectors (an accept vector per tag: 65 vectors, not 37), and the edit-barrier round-trip. Every "one past the vocabulary" constant is computed, never spelled; a spelled constant is the trap that springs on whoever appends the next tag. Verified end to end with a hypothetical tag 31. Added to the enum alone: compile error. Added to the enum and the macro: it compiles, decodes, and every derived check passes because they read PAYLOAD_FREE -- while the committed corpus's drift lock AND its now-stale "one past the vocabulary" reject vector both fail, forcing the new vectors into the diff. There is no path where a new tag leaves everything green. Second finding: the corpus called itself normative while the spec said it was deferred. Binary Format's "About This Companion" listed the cross-implementation decoder test among things the document does not cover, and the Golden Anchor Registry called it "the deferred conformance harness" whose literal-byte vectors a future test "should add". Both now ratify it. New req:binfmt:decode-vectors and a "The Decode Vector Corpus" section: a conforming decoder MUST accept every accept vector for a surface it implements, MUST reject every reject vector, and MUST re-encode an accepted value to exactly its bytes -- and accepting a reject vector and then normalizing it IS accepting it. Binary Format 0.8.0 -> 0.9.0. The wire-format fuzzer stays an implementation deliverable. The corpus header now cites the requirement instead of asserting one. Gate: fmt clean, clippy 0, 30 targets / 1024 passed / 0 failed, docs 0 under -D warnings, conformance 8/8 with [7d] at 65 vectors, zero golden churn, binary_format rebuilds with no undefined references. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> |
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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.