fix: prune start checkpoint on eviction#8
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A checkpoint taken at position 0 anchors to the START sentinel, which pruneCheckpoints skipped unconditionally — so limit eviction left it alive even though the state it named was no longer reachable, and revertTo silently landed on a different state instead of throwing. Prune START-anchored checkpoints whenever entries are evicted from the front. A dropped redo branch still leaves them intact: position 0 remains reachable there. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
pruneCheckpoints takes a plain readonly Anchor[] instead of a ReadonlySet: the redo-drop call site returns to its original shape, the eviction site is one spread, and the types check by ordinary array covariance rather than method bivariance. Reword the pruning docs to state the real rule — pruning is by anchor identity, not state reachability, which differ for a checkpoint anchored to the newest evicted entry — and note in revertTo the invariant that keeps indexOf from returning -1. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Summary by cubic
Fixes incorrect handling of position-0 checkpoints during eviction. Eviction now prunes
START-anchored checkpoints sorevertTocan’t land on an unreachable state; redo-branch drops still keep them.Bug Fixes
STARTwhen front eviction occurs;revertToon a pruned name throws.Refactors
pruneCheckpointsto acceptreadonly Anchor[]and updated call sites.Written for commit 1f551d6. Summary will update on new commits.