2 new cuBLAS GEMMs: d_h_history = W_A^T @ d_gate + W_B^T @ d_x.
Extracts last 10 dims as d_ofi_embed_mamba2, accumulated across K=8
timesteps. This enables the OFI embed MLP to learn from temporal
patterns discovered by the Mamba2 SSM.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>