A CLIP text encoder reads 77 tokens, two of them markers. Handing a longer
prompt to a diffusers pipeline does not fail: the tokenizer truncates it and
the model renders what fits. The booru-tag fine-tune families (Pony,
Illustrious, NoobAI) open with a run of quality tags, so the part that got
dropped was the subject -- and the request answered 200 with an image, which
is why it was easy to miss.

Image prompts are now encoded here rather than by the pipeline, which is what
makes the rest possible:

  * as many 75-token windows as the prompt needs, concatenated -- no limit
  * the A1111 weight grammar: (tag:1.3), [tag], bare (tag) = 1.1, nesting
    multiplies, \( escapes. Per-token scaling with the window mean restored,
    so emphasis does not drag the brightness along with it
  * BREAK, which closes the current window instead of blending tags meant
    for different subjects
  * clip_skip, mapped to diffusers' own convention -- SDXL counts from the
    penultimate layer, SD 1.x from the final output and needs the layer norm
    applied by hand. Getting that backwards shifts every image

Three places were dropping the negative prompt outright. The sd.cpp path
hardcoded negative_prompt='', so for every GGUF image model whatever the
caller asked to avoid stopped at the API -- half the idiom, since the quality
tags have a negative half (score_4, score_5, score_6). /v1/images/edits and
/v1/images/inpaint had no field for one at all, so an edit could only ever be
steered positively. All three now pass it, and take clip_skip and
prompt_weighting with it.

clip_skip and prompt_weighting are also per-model and server-wide settings,
because a client speaking the plain OpenAI image API has no field to ask for
clip_skip and a model trained at 2 needs it on every request. Request beats
model beats global.

Weighting defaults on, so a literal '(' in prose now weighs 1.1 -- the
ecosystem's convention, with \( and prompt_weighting:false as the way out.
What that cannot be allowed to change is prompts that already worked: against
a real CLIPTextModel a short unweighted prompt encodes bit-identically to what
diffusers produced, because CLIP pads with its own end-of-text token, so
[bos]+toks+[eos]+pad... and [bos]+toks+pad...+[eos] are the same ids. The test
records that reasoning, so a tokenizer where it stops holding is caught.

Flux, SD3 and Z-Image carry a T5 with its own limit and conventions and keep
their pipeline's native text path.

49 tests; full suite 4410 passed with the same 15 pre-existing failures as
0.4.88 (diff empty).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S8LAP3ueNzQJtwzhgVbq66