Address the Codex review round on the video/quant work:
- Companion auto-quant now honors an explicit Speed=off. Both loaders already pin the DiT dense
under an explicit off (bit-exact reference), but the unset text-encoder / VAE quant still promoted
to auto and silently fp8/int8'd the companions, breaking the bit-exact request. An UNSET speed
still auto-quantises; an explicit companion scheme still forces it.
- The HunyuanVideo joint-attention trim is a speed lever (it swaps to the fused SDPA kernel), so gate
it on a non-off speed tier exactly like the adjacent attention-backend selection -- the off path
keeps the stock dense-mask attention.
- Explicit torchao text-encoder modes (int8 / fp8_dynamic / nvfp4) now run the same kernel smoke
test the auto ladder uses. They could clear the capability gate yet fail the real GEMM on a build
where quantize_ wraps the encoder but the kernel is broken; the caster's try/except only covers the
cast, not the first forward, so the load would report engaged then crash at generation. Now it
falls back to dense. Layerwise fp8 has no torchao GEMM, so the probe is a no-op for it.
- The trim pre-hook's fallback restores the caller's original kwargs (it may have emptied the image
stream / trimmed a text stream before failing), so the stock dense-mask path runs on exactly what
it expects, matching the empty-prompt guard.
- video_speedmem_bench mirrors the loader: installs the Hunyuan trim before the backend set (gated on
an active tier) and skips the auto int8 quant when it is the fp8-denied memory fallback and dense
fits resident, so the shipped/auto rows measure what the loader actually runs.
Tests: TE explicit-mode kernel probe (+ layerwise-fp8 bypass), trim mid-trim restore, and loader-level
speed=off companion suppression + trim skip for both backends. 262 backend tests pass; ruff clean.
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