derive cell level masks instead of storing them - #502
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boc.Cell.mask was only ever populated by the deserializer (from the d1 byte) and hand-set once in pruneCells. Nothing else maintained it: NewCell leaves it at 0 and AddRef never ORs a child's mask into the parent, so any tree built in memory around a nonzero-level cell - everything tlb.Marshal produces, e.g. via txemulator.tlbStructToBase64 - serialized as a level 0 parent over a level 1 child. ton rejects that with "level mask mismatch". The same stale mask made newImmutableCell compute the wrong number of hashes, so Hash256() of a freshly built tree disagreed with the identical wire-decoded one. Drop the field and derive the mask from a cell's type, content and refs the way ton's DataCell::create does: ordinary is the union of its refs, pruned branch takes its mask from the data, library is 0, and merkle cells shift right - a plain union would give a merkle proof root the wrong level. Both consumers go through the one rule, so serialization and hashing can no longer drift apart. Deriving a pruned branch's mask also validates its body length, which closes an out of range read in immutableCell.Hash/Depth reachable from any boc. Hash256() keeps returning the hash of the highest level, matching ton's Cell::get_hash(). For a tree with pruned branches that is no longer the representation hash, so HashAtLevel is added to get it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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boc.Cell.mask was only ever populated by the deserializer (from the d1 byte) and hand-set once in pruneCells. Nothing else maintained it: NewCell leaves it at 0 and AddRef never ORs a child's mask into the parent, so any tree built in memory around a nonzero-level cell - everything tlb.Marshal produces, e.g. via txemulator.tlbStructToBase64 - serialized as a level 0 parent over a level 1 child. ton rejects that with "level mask mismatch". The same stale mask made newImmutableCell compute the wrong number of hashes, so Hash256() of a freshly built tree disagreed with the identical wire-decoded one.
Drop the field and derive the mask from a cell's type, content and refs the way ton's DataCell::create does: ordinary is the union of its refs, pruned branch takes its mask from the data, library is 0, and merkle cells shift right - a plain union would give a merkle proof root the wrong level. Both consumers go through the one rule, so serialization and hashing can no longer drift apart.
Deriving a pruned branch's mask also validates its body length, which closes an out of range read in immutableCell.Hash/Depth reachable from any boc.
Hash256() keeps returning the hash of the highest level, matching ton's Cell::get_hash(). For a tree with pruned branches that is no longer the representation hash, so HashAtLevel is added to get it.