Scoping disposition A found two things that move the rung's size in
opposite directions.
Cheaper: the refusal needs no new PreconditionFailureReason and no
schema-minor epoch. reduce.rs:1236's container_not_empty() helper
already covers "a create carrying children" by its own doc, and three
creates already call it for exactly this shape. create_staff_group is
the sole outlier.
More expensive: this is a canonical reduction-semantics change, not
merely a behaviour change. The same operation set now reduces to a
different Score, so core_spec.tex:11614 applies — canonical bases
materialized beforehand cannot be reused without rebuilding. That
requirement is currently unenforceable, so the contract is complete and
ratifiable as a plan but explicitly not dispatchable.
S27 is why. The version machinery is self-referential:
reduction_version_for sources a new superblock's value from the
canonical base's own self-report, and open compares it only against the
superblock that value seeded. The check is not vacuous — it catches a
corrupt base disagreeing with its superblock — but it necessarily
passes for a conformingly propagated stale base, which is the case the
requirement exists to prevent.
An earlier draft of pin 0 claimed no writer path existed at all. That
was false, and the way it was false is recorded in both the contract and
the S27 row: the search behind it looked for constructor calls, which
cannot find a path that propagates an existing value without
constructing one. The instrument could not observe the thing it was used
to rule out.
Docs only. No code, no spec sources, no implementation authorized.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QjsEnYhm1gPpf6ii2iFxFV
