FLUX.1 Kontext and Qwen-Image-Edit are a different kind of edit from img2img
and reach sd-server by a different path, and nothing in imagegen could
express it: EditRequest only had Init, which is noised and denoised back
under the prompt.
Measured against FLUX.1-Kontext on the netherstorm host 2026-07-30, on a
synthetic scene with a red rectangle, a blue rectangle and a flat background,
prompted "change the blue rectangle on the right to bright green, keep
everything else exactly the same":
via init_images (the only path that existed)
right rect (60,60,200) -> (47,82,228) still blue, instruction ignored
left rect (200,60,60) -> (229,43,50) drifted
background (150,200,240) -> (154,211,229) drifted
via extra_images (this change)
right rect (60,60,200) -> (70,254,4) green, as asked
left rect (200,60,60) -> (204,57,57) intact
background (150,200,240) -> (151,202,247) intact
No mask, no strength, no compositing — the model is handed the picture as
conditioning and the prompt as an instruction about it.
EditRequest.RefImages selects the path; when set, Init/Mask/Strength are
ignored rather than rejected, so a caller handing the same request to
whichever model is configured gets the better result on a Kontext-class model
instead of an error. The provider posts /sdapi/v1/txt2img with extra_images
(sd-server reads that field on both routes into gen_params.ref_images, where
the CLI's -r/--ref-image also lands); there is no init latent to denoise, so
sending one would only add noise to a pipeline that does not want any.
An all-empty reference set is refused: it would otherwise degrade into a
plain txt2img and render the prompt from scratch, which is not the request.
steve
2c70d32fd4