Filed as a deferral -- pickups unmodelled -- it is closer to a live defect, and
the tree already held the proof. m35 placed a first measure at offset 0 and its
successor half a whole note later under a whole-note signature and asserted
invariant 20 fires. That is a pickup. The test has been labelled "wrong distance"
since packet 2. create_measure applies the same rule as a refusal, now observed
end to end rather than cited: the successor comes back NoOp with
MeasureMeterMismatch. Authoring a pickup does not leave it unmodelled; it makes
the rest of the instance unauthorable.
Both refusals carry the same reason code, so the fixture is the only thing
separating them. Pickup and successor both declare None, which keeps clause 2
from running on either side and makes the observed refusal provably clause 3's.
The pickup's own mint is asserted Applied before the successor's NoOp, because a
fixture whose operations never execute produces a non-Applied result
indistinguishable from a refusal.
The exemption is narrower than every document said. A first measure escapes only
the predecessor-dependent checks -- invariant 20's boundary clause, and
create_measure's clauses 1 and 3 -- plus agreement when it declares None or a
matching signature, and only when its other preconditions hold. It can still be
refused for a dead parent or an unresolving anchor referent, and invariant 10 can
still flag it. Seven surfaces carried the loose form; one had hardened into
falsehood, claiming all three clauses are vacuous for a first measure when
clause 2 has no predecessor dependency at all.
core/DECISIONS.md is deliberately untouched. It already said "never flagged by
the boundary clause" -- the one site that drew the distinction correctly -- and
an earlier contract draft listed it as defective by matching the phrase without
reading its qualifier. The corrected ops entry now quotes that qualifier, and a
positive gate check protects it.
A mid-score partial enters successfully and its successor fails, so the scope is
boundaries following any partial measure, not partial measures. The root cause is
a missing quantity rather than a missing exemption: both rules compare the
start-to-start distance against the governing signature's full measure_duration
when it actually equals the predecessor's own content duration. Introducing that
quantity is a semantic rung; this one stops at its edge, with both function
bodies byte-identical.
P13-S24 is filed for the Chapter 3 splitter deferral, which shares the missing
partial-duration concept and is otherwise independent.
Executed against spec/CONTRACT_P13S19_PARTIAL.md, four mutations.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QjsEnYhm1gPpf6ii2iFxFV
P13-S19 is filed as a deferral. It is closer to a live defect, and the tree
already contains the proof: m35_boundary_flags_wrong_distance places a first
measure at offset 0 and its successor half a whole note later, under a signature
whose measure_duration is a whole, and asserts invariant 20 fires. That is a
pickup, and the test has been labelled "wrong distance" since packet 2.
create_measure applies the same rule as a refusal. So authoring a pickup does
not merely leave it unmodelled -- it makes the rest of the instance unauthorable.
The rung corrects seven surfaces, three of them normative, one of them
outright false: ops/DECISIONS.md says all three CreateMeasure clauses are
vacuous for a first measure, and the agreement clause has no predecessor
dependency at all. It observes the reducer refusal rather than citing it, files
the Chapter 3 splitter deferral as its own candidate, and introduces no
partial-measure notion -- that is a semantic rung and pin 9 stops this one at
its edge.
Three over-readings committed while drafting are recorded inside the contract
rather than smoothed away, because text that is locally true and globally
misleading is the rung's own subject. It claimed a pickup is "neither refused
nor flagged" (the agreement clause runs on a first measure); it claimed that
again more weakly after the first fix (referential preconditions and invariant
10 still apply); and it listed core/DECISIONS.md as an understated surface by
matching "never flagged" without reading the qualifier that makes it correct.
That file is now explicitly out of bounds, with the reason, so a later reader
comparing it against the corrected ops entry does not "fix" the one site that
already draws the distinction.
The absence gate replaces a grep that could not fail. Two of its seven phrases
straddle a newline, so a line-oriented search would have returned nothing before
the correction as well as after; the gate normalizes whitespace, and all seven
anchors were confirmed present at 339269b so it fails today and can pass only
once the work lands.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QjsEnYhm1gPpf6ii2iFxFV
Levi Neuwirth