W21: a field the schema does not declare

[inhuman]

W14 stops one level short. It asks whether a NAME exists, and a name that
exists satisfies it — so pick.name passes while the step saving pick
declares only index. The engine resolves a missing field to an empty string
exactly as it does a missing name, so a condition on it is never true and the
branch is quietly never taken.

Found on a live catalogue: a bail-out branch keyed on pick.name had not run
once since it was written, while its author believed the behaviour was in
effect and had committed it as the important one of that change.

Scope, and what it deliberately does not do

Only variables with a declared schema are checked, and only the first level
of the path. A tool's result has no shape this package can know, and inventing
one would produce findings about fields that are really there — the fastest way
to teach an author to skip the report. The engine's own suffixes (mem,
skipped, failed) are legitimate on any variable and are not fields of the
answer.

Verified against a live catalogue

Zero findings on a clean catalogue, and — reintroducing the original defect for
one run — the rule fires with the difference spelled out:

[error] W21: step `#11` reads `pick.name`, but the schema of `pick` declares
no field `name` … Declared: index

Carries a fixture (schema-field.yaml) so it cannot stop firing unnoticed.

🤖 Generated with Claude Code