Two changes in one PR (tightly coupled — the second wouldn't make
sense without the first):
1. Hoist the inspect-based snapshot helpers out of
test_adapter_base_signature.py into tests/_signature_snapshot.py
so future surfaces don't copy-paste introspection logic.
- build_class_signature_record(cls): walks public methods,
unwraps static/class/abstract methods, returns a stable
{class, methods: [...]} dict.
- build_dataclass_record(cls): walks dataclass fields via
dataclasses.fields(), returns {name, frozen, fields: [...]}.
- compare_against_snapshot(actual, path): writes-on-first-run +
diff-on-drift, with both expected and actual JSON in failure
message.
test_adapter_base_signature.py is rewritten to use the helpers;
the existing snapshot file is byte-identical (no behavior change).
2. New gate: tests/test_skill_loader_signature.py covers the
public dataclasses exported from skill_loader/loader.py:
- SkillMetadata: every adapter pattern-matches on .runtime for
skill-compat filtering. Renaming this field would silently
break per-adapter skill loading — the loader still returns
objects, but adapters' `if "*" in skill.metadata.runtime`
raises AttributeError at workspace boot.
- LoadedSkill: returned in SetupResult.loaded_skills.
Includes test_snapshot_has_required_skill_metadata_fields
defense-in-depth: ensures the runtime / id / name / description
fields stay even if both source and snapshot are updated together.
Verified: deliberately renaming SkillMetadata.runtime trips the
gate with full snapshot diff in the failure message.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
e336688278