The sequential text-encoder offload reported itself "not enabled" on a card
that plainly had `sequential_text_encoder = True`. Four defects, stacked so
each one hid the next; the first is much wider than the feature that exposed
it.

_resolve_config_key could not resolve ANY non-text model by alias. Typed
entries are keyed "<kind>:<name>", so the exact-id and alias-map lookups both
miss, and the basename fallback misses too: "video:LTX-2.3-PinkCherry" has no
slash, so basename() hands back the whole prefixed string. Every per-model
image / video / audio / tts / embedding setting was therefore replaced by the
global default, silently, for any model addressed by its alias -- which is the
only name that distinguishes two configs sharing one checkpoint path. The
resolver now tries the typed keys, ordered by the types the model is actually
registered as. images.py (6 sites) and tts.py looked their config up with a
raw config.get(model_key) and had the same bug; they resolve now, with a test
that fails if a raw one reappears.

The flag itself lived only in _raw_cfg, where a consumer reading
config['sequential_text_encoder'] never saw it. Promoted to a top-level
runtime kwarg, as gpu_split beside it already documents.

With the gate finally firing, the render failed: "Must provide
`prompt_attention_mask` when specifying `prompt_embeds`". encode_prompt's
return order had been guessed. Read off the installed sources, LTX-2 returns
(embeds, mask, neg_embeds, neg_mask) and Krea 2 returns (embeds, mask) --
the mask comes SECOND, and the old code read it third, filing negative
embeddings as the attention mask. Naming is now done by classifying the
values (a mask is an integer tensor, embeddings are floating) instead of by
position.

That rewrite then dropped Krea 2's negative prompt, which would have been
worse than the failure it replaced: Krea 2's __call__ encodes "" itself when
handed no negative, against an encoder this function has just moved to the
CPU. The negative is always encoded up front for those families now.

Hardened for families nobody has tried: an SDXL-shaped pipeline returns four
float tensors including the pooled pair, and naming only two does not degrade
quietly -- the pipeline rejects incomplete embeddings and the request fails.
If everything encode_prompt returned cannot be named, the optimisation is
abandoned for that request and says so.

Measured on LTX-2.3-PinkCherry (480x480, 25 frames, 8 steps, RTX 3090):

    without   369.4 s   peak 23718 MiB   91% util
    with      345.3 s   peak 24098 MiB   92% util   7.3 GiB freed

Read as headroom, not speed: the card is 24 GiB and the denoiser fills what
it is given, so peak sits at the ceiling either way and the 24 s is one
sample. The 7.3 GiB is what stops these renders being pushed to CPU offload,
where the same job took tens of minutes.

Also here: a clip-audio scene no longer needs an explicit duration (B1 said
the duration comes from the clip, and validation refused exactly the request
the feature exists for), and _free now reports per component whether it moved,
was already off the GPU, or REFUSED the move -- a bnb-quantized encoder can
refuse, and all three used to arrive as "nothing was freed".

test_sequential_text_encoder's fakes returned bare strings in the wrong tuple
order, which is why the bug shipped: the test encoded the mistaken belief
rather than the pipeline's contract. They carry dtypes and the real orders
now. test_compose's engine-selection test patches shutil.which as well,
because the production image ships wav2lip and sadtalker shims on PATH and the
test was asserting the absence of a binary the real deployment has.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014T3rZozi1Ehk96NG1WesgC