The ruling names nine surfaces. Each op touches roughly thirteen places -- the
kind variant, four hand-written matches, the decode arm and its validation, the
reduction arm, both text-projection arms, validate, vectors, the fuzz
generators, and the catalog. Nine at thirteen is not one dispatch, so this plans
a ladder rather than a contract.
The load-bearing finding is that G1 is one operation. Score::empty gives
Canvas::default() and empty vectors, and the chain to a note is
CreateInstrument -> CreateStaff -> CreateRegion -> CreateStaffInstance ->
CreateVoice -> InsertEvent, of which only the first is missing. Every later
arrow already exists with graph-aware preconditions. So a single new kind
satisfies the ruling's acceptance criteria 1 and 3 and unblocks T1b.
It is also cheap. Instrument's major-2 appends are mandatory rather than
Option-hidden, so CreateInstrument is unconditionally born at major 2 -- exactly
where CreateStaff already sits, and the op-block accept-set is already 2. No
raise, no wire change. Checked every carried type's fields for the same
property: eight of the nine are major 0 or 2, and SetTuningContext alone drags
OperationEnvelopeBlock to 3, so the raise is spent once in G2, where S13 closes.
The tranche also designs no wire layouts. All nine carried types already have
Codec impls and already ship inside Score; CanonicalValue delegates to them
without introducing a layout, and its generated decode_canonical already
rejects non-canonical encodings, so each payload inherits strict-form
enforcement on the same seam the decode-vector corpus uses.
Traps recorded, including one that would bite quietly: OperationKind's
discriminant match is hand-written and is a DIFFERENT space from the
macro-guarded tag space -- they are not aligned, and Push 4a's four-green-lists
failure is why the tag half is a macro now. Also that bundle.rs documents the
accept-set cap with the tuning-context rationale in prose, so the comment must
move with the number.
Four questions need ratification before a G1 contract: delete/modify coverage
per family, the decomposition_attachments derived-not-authored call, the
measure/meter invariant, and the ladder shape itself.
All fifteen line citations verified against the working tree.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QjsEnYhm1gPpf6ii2iFxFV
Levi Neuwirth
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