Turns the 'blocked design frontier' for ContentModelDeterminism.positionCap into
a ready-to-implement, FP-safe plan derived from the current engine. Documents the
root cause (group-ref inlining gives 2^K positions), why naive position
dedup/sharing is unsound (cross-context followpos merge = false positive), the
sound compositional algorithm (per-group memoized nullable/firstParticles/
lastParticles/followlast over particle identities, cross-boundary conflicts
computed per reference-site by the parent, the star condition for repetition,
bounded O(nodes x particles^2)), and the differential-gated rollout (build
alongside the inlining oracle, prove verdict-equality on XSTS + a group-ref fuzz,
only then switch and delete the cap) with acceptance criteria.
Mihaela Mihaljevic
ba69d716fa