A layered transition graph (trellis) and solvers for the minimum-cost path.

Edges exist only between adjacent layers, and every node carries a weight (default 0) paid on entering it. Solvers find the minimum-cost path through all layers, treating layer 0 as a virtual start (every node reachable at its own node weight) and the last layer as a virtual end (best node wins).

The trellis stores only append-stable facts — structure and weights — and solving is a pure function of them: [Trellis::solve] consumes the building state and returns a [Solved] certificate pairing the trellis with its path. [Solved::append] hands back the building state to grow.

Solvers

• [ViterbiSolver]: Viterbi with SIMD acceleration. Stateless; usable with any trellis.
• [BruteForceSolver]: Correctness reference — never use in production.