Implements the schema-minor MUST (binary_format.tex, Schema Versioning) that no
writer had ever honoured: a writer raises the chunk minor when it emits a
discriminant appended after the minor it otherwise declares, so an
unknown-discriminant decode failure is attributable to version skew rather than
corruption.
introduced_minor() lands on the five vocabularies with post-baseline variants -
OperationKind, OperationKindTag, OperationPayload, ReanchorReason, and
PreconditionFailureReason - each exhaustive with no wildcard arm, so a future
variant cannot compile without being assigned an epoch. The tag epochs live
inside operation_kind_tag_vocabulary! rather than beside it, because a sibling
match is the parallel list that macro exists to prevent. The sentinel is
Option<u16>, not 0, since 0 is a real baseline minor for V1-V3 and conflating
them would make the max read correctly only by accident.
An envelope's required minor is the max over every discriminant it actually
emits; a block's is the max over its envelopes; major and minor derive
independently. Baselines are not normalised - V0 keeps minor 1.
The manifest seam keeps epiphany-bundle opaque: no ops or layout-ir dependency,
and the aggregate version is supplied by the producer rather than derived, with
CommitContext carrying the previous one so unchanged barrier content preserves
it. The version rides the superblock slot that already exists; Manifest gains no
field, which would have been schema-major and would have defeated the rung.
bundle.rs's superblock check stays major-only - tightening it to full-version
equality is a conformance regression, and s11 locks that.
textproj carries the manifest SchemaVersion and never derives it, so
COMPANION_VERSION moves 0.9.0 to 0.10.0 with the corpus regenerated. Not because
of op-block stamping, which remains projection-invisible. A new normative
requirement records the carry-never-derive rule in the companion itself; its
rationale names layout-ir, which textproj genuinely lacks, rather than the
operation vocabulary, which it has.
Gate [7f] adds an independent oracle over decodable in-tree barrier fixtures,
requiring exact equality rather than >=. Equality is load-bearing: >= catches
under-stamping but not stale over-stamping after the sole maximum contributor is
removed. Undecodable blobs are reported not-checkable, never as a pass.
Also repairs binary_format.tex's stale claim that OperationKind and
OperationKindTag append at 30 with a history stopping at 29, while 30-33 are
taken and the normative tables already carry them.
Gate: 1399 tests, clippy 0, fmt clean, conformance 8/8 with [7f] at four
fixtures checked and one not-checkable, 102 decode vectors byte-identical
(verified, not assumed), 13 text-projection vectors.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QjsEnYhm1gPpf6ii2iFxFV
Levi Neuwirth
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