New load_dimension(str | Path) in dimension.py: is_file() -> FileNotFoundError,
then Dimension.model_validate_json -> pydantic.ValidationError on malformed shape.
Fail-fast because dimension config is authoritative startup input (contrast the
tolerant verdict-inbox RAW layer). Stdlib + pydantic only — stays MAF-free
(test_okf_is_maf_free AST guard green). Exported from __init__.py in both the
import block and __all__. RED-first: 3 loader tests failed on the missing import,
green after. tests/test_dimension.py + test_okf.py: 29 passed.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KNNiJRk1sSwxgVLS5AobT1
