Slot:Single confirmed as pure :List sugar (resolves the original
State<Frame?> offset-access motivation directly). Slot-in-Slot nesting
confirmed for component-composition uniformity: Dispatch.setLength/
setOffsetSource reused recursively keyed by the Slot object itself
(no new primitive), Slot.Length becomes a contribution-sum, teardown
is a flat destroySlotTree + explicit unbindLifetime instead of
recursive Clear(). Slot(initial?) constructor revived as pure :Add
sugar, with a new _crudUsed <-> _listed mutual-exclusion guard.
Also fixes a real off-by-one bug in the existing (pre-nesting)
Length/Offset recompute — offset was accumulating inclusive of its
own position instead of exclusive. A reentrancy guard was considered
and rejected: each Slot owns an independent bookkeeping table, so
nesting alone never re-enters the same one; genuine reentrancy is
now named UB under the same Source-to-State unidirectional-flow
principle already governing Source/State.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017ymPLYAQmEYnTrnrdAwxpU
qwreey
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