ScoreTuningContext gains `smufl` and `overrides` on the canonical wire.
`accidental_extensions` is deliberately STAGED to a later major: under
req:binfmt:frozen-layout a field addition is a major, so freezing a large
subtree whose consumer (the engraver) does not exist yet buys nothing and
risks a major-4 to fix a mis-shaped field. The three shapes 3a ratified
(Cents/CanonicalF64, AnchorPoint, SmuflVersion) stay reversible until
something exercises them.
Scope discovery: no operation payload embeds the tuning context, anywhere.
So the wire reached is the acceleration full-Score snapshot ONLY — the
canonical operation layer is untouched, no payload is born at v3, no frozen
v2 op-payload decoder is needed, and OperationEnvelopeBlock's accept-set
stays at 2 while Snapshot rises to 3. Major 3 is the first data-model bump
under which a chunk role's max does not move in lockstep. The canonical
base embeds no tuning context and stays major 0, byte-identical.
Migration: the live codec becomes v3; the 3-field form is frozen as
enc/dec_tuning_context_v2 and consumed by decode_v2_score (new, with its
byte-exact inverse encode_v2_score) and by the v0/v1 decoders — AND by
encode_v0_score/encode_v1_score, which the contract missed and which would
have silently corrupted the frozen forms through the strict-canonicality
re-encode check.
The frozen bytes are now pinned by a golden, because nothing else pinned
them. The cross-implementation decode corpus covers only the operation and
bundle surfaces — there is no epiphany-core vectors module — so every
existing test round-trips enc against dec and stays green under a
SELF-CONSISTENT reordering: swapping smufl and overrides in both halves
passed the entire workspace suite and 8/8 conformance, silently moving a
permanently frozen layout. schema_major_3_tuning_context_wire_bytes_are_frozen
asserts the exact encoding of the default (48 B) and a loaded (82 B)
context; it kills that swap. The S12 normalization is visible in the
literal: 1.4 stores minor_centi 40 (0x28), 1.12 stores 12.
Gate: fmt clean, clippy 0, 1282 passed / 0 failed, doc 0, conformance 8/8,
requirement labels 6/6 at 212/282/282 (unchanged — no new req: labels).
Mutations verified independently: breaking the v0 reroute kills 6 tests;
the wire-order swap kills the new golden.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
