_paint moved only the paintable streams onto a device taken from the latent
the run started with, but the noise at an interior boundary is recovered from
a segment result on the sampler's device. On MiniMax H3's nested AV latent
that left the video stream on the CPU and the audio stream on CUDA, and
pack_latents refused the pair, so injection_stages and sequential_stages >= 2
crashed on every AV run. Single-stream latents only paid for a needless round
trip, which is why nothing caught it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>