Bite-sized, TDD-style task breakdown for the second tier of the engine
redesign: introduce VarStore, Factor trait, BuiltinFactor enum, and
EpsilonOrMax schedule, then re-implement Game::likelihoods on top of
the new machinery. Internal-only refactor; public Game/History API
unchanged.
Acceptance: existing tests pass within ULP, iteration counts match T0,
no Batch::iteration regression vs T0 (~21.5 µs).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Bite-sized, TDD-style task breakdown for the first tier of the engine
redesign: Gaussian to natural-parameter storage, dense Vec storage
replacing HashMap, ScratchArena to eliminate per-event allocs,
Result-ifying the lone panic. No top-level public API change.
Acceptance gate: ≥3x speedup on Batch::iteration vs. baseline.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Comprehensive design for a multi-tier rewrite covering performance,
factor-graph extensibility, convergence scheduling, and API surface.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
