bif-coverage verified that every AST node field round-trips through the .bif
encoder/decoder, but the .bif interface-container types (TRoutineSig,
TUnitInterface, TMethodParam, TConstEntry, TVarEntry) were hand-serialised in
WriteMeta/EncodeMethodSig/etc. with no drift guard. Every cached-rebuild bug
just fixed was a serialised field on one of those types dropped from one side
of the round-trip — invisible to the tool, surfacing only as a runtime
miscompile.
Generalise the class scanner to ScanClassFile(path, names, objs, allowList);
add ScanInterfaceTypes() over an allow-list of the container types in
uUnitInterface.pas. Split uUnitInterfaceIO.pas into encoder-side and
decoder-side text and assert each serialised interface-type field's identifier
appears in both — the same looseness as the AST mechanism. Status file gains
the interface-type entries (serialise/safe); mutator-repopulated owning
collections are { no-bif }-exempt (their element data round-trips through the
per-entry encoders).
Negative test confirmed: dropping ImplUsedUnits/HasInitialization/VTableSlot
from either side is now reported as a gap with exit 1. Clean tree exits 0.
74da3eadcc