The coverage manifest claimed Tagged.Mapping and Tagged.Node validate key
uniqueness, but the tagged validator's only default check was the built-in
tag check: the claim was false. Tagged.Mapping keeps every parsed pair, so a
duplicate key survives into the tree and is as invalid as in the plain model.
Add Tagged.BuiltinCheck.mappingKeysAreUnique, a Check<Mapping, Node> on the
one validation framework, to the tagged validator's defaults; the traversal
now offers each mapping to the checks. It reports each duplicate at its key
path, with failing, near-miss, and nested fixtures, and the two default
tagged checks are pinned by description.
Correct the Model.Value coverage reason: merges and aliases resolve at parse
time, so they are not a validation-phase invariant. Every validated manifest
entry now names an invariant a check actually enforces. 403 tests pass.
Mihaela M
47960a85c8