Add ControlNet conditioning, the #2 most-used diffusion workflow after
LoRA, on the diffusers backend for the families with ControlNet pipelines
(FLUX.1 and Qwen-Image), with Union models as the default picks.
Backend
- New core/inference/diffusion_controlnet.py: family-gated discovery
(curated Union models + local dirs + bare owner/name repos), resolution
to a loadable repo/dir, control-image preprocessing (passthrough +
a dependency-free canny edge map), and a supports_controlnet gate.
- diffusion.py: a ControlNet manager parallel to the LoRA one. Loads the
(small) ControlNet model once via from_pretrained (cached by id) and
builds the family's ControlNet pipeline via Pipeline.from_pipe(base,
controlnet=model), reusing the resident base modules at their loaded
dtype (no reload, no recast). Passes the control image + conditioning
scale + guidance start/end at generate time; cleared on unload.
- Families: FLUX.1 -> FluxControlNetPipeline/Model, Qwen-Image ->
QwenImageControlNetPipeline/Model. Others declare none (gated off).
- Gated off for the native engine, GGUF-via-diffusers, and torchao
fp8/int8 dense (same rule as LoRA). v1 conditions txt2img only.
- Request contract: optional controlnet on DiffusionGenerateRequest;
supports_controlnet in status; the choice persisted in gallery meta.
- New GET /api/models/diffusion-controlnets for the picker.
Frontend
- A ControlNet control in the Images rail (model select + control-image
upload + control-type select + strength slider), gated by the loaded
model's supports_controlnet + family, shown for text-to-image.
Tests
- New test_diffusion_controlnet.py (10): discovery/resolve/preprocess/gate
helpers, request validation, family wiring, and the diffusers pipe
manager (loads once, caches, from_pipe with controlnet, rejects
unsupported families).
