SDXL is the first U-Net family in the diffusion backend: its denoiser is
pipe.unet (UNet2DConditionModel), not a DiT pipe.transformer, and a single-file
.safetensors is the whole pipeline rather than a transformer-only file. The
backend previously assumed a DiT transformer everywhere, so add the two hooks a
U-Net family needs and register SDXL.
DiffusionFamily gains denoiser_attr ("transformer" for DiT, "unet" for SDXL) and
single_file_is_pipeline (SDXL loads a single file via pipeline_class.from_single_file
with the base repo as config, instead of transformer_class.from_single_file plus a
companion assembly). _align_vae_dtype now reads the denoiser generically so img2img
and inpaint keep the VAE and U-Net dtypes aligned.
The non-GGUF trust gate is extended with a short, exact-match, safetensors-only
allowlist of official base repos (the SDXL base/refiner and sdxl-turbo), because
SDXL ships only as a full pipeline and has no unsloth-hosted GGUF. Local paths stay
trusted as before; a random repo, even one that detects as SDXL, is still rejected.
The image-conditioned and ControlNet workflows are the standard SDXL pipelines,
built around the resident modules via from_pipe like every other family, so SDXL
gets txt2img, img2img, inpaint, outpaint, upscale, LoRA and ControlNet. There is no
native sd.cpp mapping yet, so the no-GPU route falls back to diffusers.
Frontend catalog gains SDXL Base 1.0 and SDXL Turbo entries with SDXL step/guidance
defaults (Turbo: few steps, no CFG; base: ~30 steps, real CFG).
Tests: new test_diffusion_sdxl.py (family shape, detection, trust allowlist, model
kind, U-Net VAE-dtype alignment, LoRA gate) plus loader-branch tests in
test_diffusion_backend.py (pipeline-kind from_pretrained, single-file whole-pipeline
from_single_file, allowlist accept/reject). Verified live on GPU: sdxl-turbo loads
both as a pipeline and as a single file and generates coherent txt2img + img2img.
When a repo id resolves to no diffusion family the load raised 'Could not infer a
diffusion family... Pass family_override (z-image)', which points at an unrelated
family and doesn't say what is supported. Replace it with a message that lists the
supported families (from a new supported_family_names helper) and notes that video
models and image models whose diffusers transformer has no single-file loader are
not supported. Applies to both the diffusers and native sd.cpp load paths. Also
refreshes two stale family-registry comments that still called FLUX.2-dev omitted.
Loading unsloth/FLUX.2-dev-GGUF failed because detect_family knew only the
Qwen3-based FLUX.2-klein, so FLUX.2-dev (the full, Mistral-based Flux2Pipeline)
resolved to nothing and the load errored. Add a flux.2-dev family: Flux2Pipeline
+ Flux2Transformer2DModel over the black-forest-labs/FLUX.2-dev base repo (gated,
reachable with an HF token), with its FLUX.2 32-channel VAE and Mistral text
encoder wired for the sd-cli path from the open Comfy-Org/flux2-dev mirror.
text-to-image only: diffusers 0.38 ships no Flux2 img2img / inpaint pipeline for
dev. Frontend gets sensible dev defaults (28 steps, guidance 4), distinct from
klein's turbo defaults. Verified live: GGUF load resolves the family + gated base
repo and generates a real 1024x1024 image on GPU.
The chat picker treats a cached repo as an image model, and hides it, only
when it ships a diffusers model_index.json. Single-file, ComfyUI, and
ControlNet image checkpoints (an FP8 Qwen-Image, a z-image safetensors, a
Qwen-Image ControlNet) carry none, so they surfaced as loadable chat models.
Fall back to resolving the repo id against the known diffusion families, the
same resolver the Images backend loads from, so these checkpoints are tagged
text-to-image and stay in the Images picker only.
The Images picker's On Device tab hid every non-GGUF cached repo whenever a
task filter was active, so downloaded unsloth diffusion pipelines (bnb-4bit
and FP8 safetensors) never showed up there. List cached repos that pass the
task gate, limited under a filter to unsloth-hosted ones so base repos (which
fail the diffusion load trust gate) don't appear only to dead-end on click.
Chat behavior is unchanged: the task gate still drops image repos there.
