From the M2a review (no bug in the bookkeeping reduction; the gap was that the
Group-1 ops' *graph* materialization — reduce_onto — was unexercised by the
gates, which hid two invalid-graph edges). Fixes are graph-materialization only;
the bookkeeping projection, and therefore convergence/determinism, is unchanged.
- DeleteIdentifiedPitch of a single-pitch note's last pitch left an empty
(Chapter-5-invalid) PitchedEvent via EventArena::get_mut (which bypasses
insert's well-formedness guard). It now degrades the note to a Rest of the
same id/voice/position/duration; InsertIdentifiedPitch into a rest is the dual
(rest -> one-pitch note), keeping the graph consistent with the bookkeeping
that mints/tombstones the pitch object either way.
- ModifyEvent now skips placement-changing (move) and malformed-empty pitched
replacements in the graph rather than corrupting invariant 3
(VoiceEventsSortedNonOverlap) via get_mut; voice re-sort stays deferred and the
LWW bookkeeping still records the modify.
Coverage: graph_edit_session (criterion 1, reduce_onto + check_invariants) now
emits all five Group-1 kinds, so the real-Score gate exercises their graph
mutations at scale; plus two targeted reduce_onto regression tests (note->rest,
rest->note) in tests/graph_reduction.rs.
Docs: DECISIONS.md records the note<->rest equivalence and the ModifyEvent
placement deferral (catalog section prose routed to M2e); Transpose / P12-K2 note
the i8-saturation caveat; valuegen::pitch_value_nth no longer implies spelling()
is injective.
Gates: build/fmt/clippy -D warnings clean; cargo test --workspace green (ops
graph_reduction 13, ops lib 51); conformance_suite scale 1 passes. The unrelated
Agent-I working tree is left untouched; this commit stages only ops/testkit/spec.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Levi Neuwirth
c47f4b5cec