An audit reopened P12-K2, whose Pass-12 pin promised the repair would be "a
payload schema-major landing with the Chapter 4 tuning catalog". Both halves
were wrong, and the operation was more broken than the pin admitted.
Measured through EditorSession, not inferred. On a C4: +12 yields alteration
12 (six double-sharps, not C5); +128 clamps to 127 and still reports Applied;
targets [p, p] transposes twice; a non-Cmn position is silently untouched.
transpose(1000) then transpose(-1000) lands on -128, so the operation is not
invertible. Nothing downstream is at fault -- prepass::accidental_ids renders
alteration 12 faithfully. The defect is entirely in what Transpose means.
The false coupling is why this looked big. Pitch has orthogonal scale_position
and acoustic fields. Transposition adds an interval to a scale position;
tuning decides what frequency a scale position sounds at. Adding a fifth to C4
needs no tuning catalog. The same weld had spread: PitchSpaceMismatch was
"Reserved: requires the Chapter 4 tuning catalog" (it reads a discriminant),
and TranspositionInterval was "ADVISORY until the Chapter 4 tuning catalog
pins interval algebra". Push 4 splits: 4a is the algebra and needs no catalog;
4b is the catalog, which has its own blockers (cmn-24 is in the pitch-space
table but cannot exist while Cmn.alteration is i8 semitones).
Ratified by the user:
- New kind, freeze the old. An operation is history; a corrected reduction
rule would rewrite every score that used one. Transpose (disc 9) keeps its
exact semantics, now written as normative replay semantics rather than as
apologies. TransposeInterval takes disc 30. This is cheap: appending a kind
at >= 30 is a schema MINOR, and the payload's constituents are all major-0
layouts, so it stamps major 0. No major 3, no migration.
- Diatonic + chromatic interval, reusing TranspositionInterval -- which
already existed in graph.rs at major 2 for Instrument.transposition, already
codec'd, byte-for-byte the required pair. Minting an Interval beside it
would have been a second normative listing of one type, the drift P13-I1
just closed. Declared once now, in Chapter 2; Chapter 5 references it.
- Atomic refusal. Non-Cmn, AbsoluteHz, or an out-of-range result refuses the
whole operation. Never saturate, never partially apply. Tombstoned and
SYSTEM_DERIVED targets are still skipped: a deleted pitch is not an
untransposable pitch, it is one the operation has nothing to say about.
targets becomes CanonicalSet<PitchId> at the type level, not a Vec plus a
dedup() someone can forget (PitchId's Ord is its canonical byte order). This
was never a convergence bug -- every replica replaying [p, p] double-
transposes identically -- but a canonicalization one. It is free today because
no operation-payload decoder exists yet; once one lands in Push 5, dedup
normalization would change the meaning of stored operations. Push 4a blocks
Push 5, and that is why.
Spec: req:pitch:transposition (algebra + the three refusals), and four
req:opcat:transpose-* requirements. Operation Catalog 0.7.0 -> 0.8.0; Binary
Format 0.6.0 -> 0.7.0 (disc 30, and a seq-strictly-increasing notation whose
decoder must reject a duplicate rather than normalize it away).
This commit is the design gate: the spec now declares MUSTs the code does not
yet satisfy -- editor-core still authors Transpose, and TransposeInterval does
not exist. The implementation follows in this push.
Also recorded: the two existing transpose tests are false locks. Gutting
graph_transpose_pitch leaves both green -- they call base-free reduce(), where
graph is None and the function never runs, and assert only OperationEffect.
Only editor-core's undo_and_redo_a_transpose, three crates away, catches it.
Gate: clippy 0, 30 targets / 964 passed / 0 failed, docs 0 under -D warnings,
conformance 8/8, all three spec documents build with no undefined references.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Levi Neuwirth
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