Module apm 

APM — Adaptive Probability Map for post-mixer refinement.

Phase 3: Two-stage APM cascade following V2 proven parameters.

APM maps (context, input_probability) → refined_probability using an interpolation table. The table adapts over time.

Stage 1: 512 contexts (bpos * byte_class), 50% blend with input. Stage 2: 16K contexts (c1 * c0_top4), 25% blend with input.

Structs

APMStage

An adaptive probability map stage.