Release shardtree v0.7.1#198
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Release shardtree version 0.7.0
`LocatedPrunableTree::truncate_to_position` and its callers mishandle two situations in which the tree's pruned representation interacts badly with the truncation position: 1. The parent nodes reconstructed along the truncation path retain their cached root annotations. Such an annotation is a hash over the parent's complete subtree — including the data being truncated away — so a stale annotation later causes a spurious `Insert(Conflict(..))` (or a silently incorrect root) when the truncated region is refilled with different data, as happens when a wallet re-scans a divergent chain after a reorg. Annotations of this shape are routinely written by `insert_frontier`, which is invoked with the chain state at the start of every scanned batch. 2. When the truncation position falls in the interior of a pruned subtree (a merged hash node), `truncate_to_position` returns `None` — correctly, since truncating there would have to discard retained data along with the requested suffix — but `truncate_to_checkpoint` reacts to the refusal by silently skipping the truncation while still reporting success, leaving all post-checkpoint state in place. (Before the preceding cap-truncation fix, the cap had already been modified at that point, additionally leaving the store internally inconsistent.) The annotation tests and the `truncate_to_checkpoint` coherence test are RED at this commit; `truncate_to_position_fails_inside_pruned_subtree` passes, pinning the refusal contract that the fix must preserve. The fix follows in the next commit. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
`LocatedPrunableTree::truncate_to_position` now guarantees that nothing
derived from the discarded suffix of the tree survives a truncation
that it performs, and refuses truncation at any position the tree does
not individually represent:
- A subtree lying entirely at or below the truncation position is
retained unmodified (including any cached root annotation). This
check is now made once at the top of the recursion, generalizing the
check previously made only for pruned leaf nodes.
- Parent nodes whose subtrees lose data in the truncation are
reconstructed without their cached root annotations: such an
annotation is a hash over the parent's complete subtree, which by
construction of the truncation path includes discarded data.
- Truncation at a position in the interior of a pruned subtree (or at
which the tree holds no data) is refused, as before; it is the
caller's responsibility to select a position at which truncation is
possible.
`ShardTree::truncate_to_checkpoint{_depth}` now handle the refusal by
failing with `QueryError::CheckpointPruned`, leaving the store
unmodified, instead of silently skipping the truncation while still
reporting success.
The cap remains truncated with `truncate_cache_to_position`,
introduced by the preceding cap-truncation fix: the cap is a cache —
every node in it is a hash recomputable from the shards below — so a
cached entry spanning the truncation boundary is discarded rather
than making the position unusable. With refusal now handled up front,
the cap, shard, and checkpoint updates are performed unconditionally.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
shardtree: discard stale state when truncating
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