Unscaled merged embeddings [1, L, hidden] — caller disposes.
bool [L] union multimodal soft-token mask (image | audio) for per-layer-input id zeroing (§3.3 Q2). Caller disposes.
OptionalprefixIncludes every media item and the exact token prefix through the last one.
bool [L] image-token mask for the bidirectional attention overlay. null when the prompt contains ANY audio (§3.3 Q1: mixed image+audio runs fully causal) or no images. Caller disposes when non-null.