The gate refuses a schema that names both `timestamp` and `generated`,
because OKF §13.1 grants the legacy fallback only while `generated` is
ABSENT. `__post_init__` built the named set from `order | required |
allowed` and left `nullable` out, so
FrontmatterSchema(order=("timestamp", "title"),
nullable=frozenset({"generated"}))
constructed, and `violations()` on a document carrying both returned ().
The namespace is open by default, so a key named only by `nullable` is
admitted exactly as surely as an emitted one — the omission was a hole in
the gate, not a narrower gate.
Found by the proving consumer the same day the gate was written; their
construction is the red test case.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A2aKJxLejT9S8jYwoZ9fut
Kjell Tore Guttormsen
a00355533e