Root fix for the SDXL 'compressed look': in VAE-space mode the
forward/reverse adapters previously applied noise_scaling directly to
VAE-space x with model-space eps, so for SDXL (scale_factor 0.13025)
the model saw noise 7.7x too small for the claimed timestep - the
input SNR never matched sigma and the refiner's prediction washed out.
Now forward_step converts x via process_latent_in, applies noise_scaling
in model space, and converts back via process_latent_out (reverse_step
mirrors it). predict_eps keeps returning model-space eps - principled
under the corrected theory since the slerp mixes it with std-1 random
noise. For pure-scaling formats the composition equals running the whole
algorithm in model space (exactness pinned by
process_latent_in(forward(x,e,s)) == s*x + s*e... i.e. noise at full
model-space scale).
The operate_in_vae_space flag is removed everywhere: the pipeline is
always VAE-space at the interfaces (ComfyUI LATENT convention); VAE
adapters no longer touch process_latent_out/in. Dominance guard gains
a lower bound (no-op detection) plus a refinement-changes-latent test.
Default injection is now the paper's slerp(eps_refined, eps_random,
noise_lambda) per pixelrush-correct.txt. The 2026-08-13 additive mode
(eps_pred + lambda*eps_rand) remains available via
noise_injection='additive' (node combo input) for workflows tuned
against it. Tests pin both formulas exactly via seeded randn streams
(lambda=0 -> pure eps, lambda=1 -> pure random, additive formula),
the slerp default, and invalid-mode rejection. The legacy-calibrated
HF tests are pinned to additive; a new slerp-mode HF guard holds the
provisional >=0.5 bound pending Step 11 calibration.
Per pixelrush-correct.txt the core must accept distinct epsilon
adapters: inversion_eps (base generator, drives the 0->K partial DDIM
inversion) and refiner_eps (distilled one-step refiner, drives the K->0
prediction). The node currently passes the same base-model predict_eps
for both - an intentional choice the corrected theory allows; a
separate refiner_model input is added in a later step. Tests pin the
call pattern (inversion at t=0, refiner at t=K) and that a distinct
refiner changes the output.
Per pixelrush-correct.txt: the mask is exp(-(xx^2+yy^2)/(2 sigma^2))
centered on the patch and peak-normalized to 1 - an explicit encoding of
the paper's Gaussian-filtered patch mask. Replaces the blurred-all-ones
approximation (sigma=8, kernel=41); gaussian_kernel_size is removed from
config, node schema and execute. Node sigma range widened to 1..128 so
the corrected default 24 is reachable from the UI.
alpha_k was only computed when sigma_at was None, so sigma_at +
DDIM fallback (either adapter missing) raised NameError. Compute it
whenever any fallback branch can execute; when both adapters are
provided alpha_bar_at is never called (pinned by test).
Add predict_x0_from_epsilon + ddim_deterministic_step (eta=0, source ->
dest schedule values, same epsilon) per pixelrush-correct.txt. The old
0->K / K->0 functions become thin wrappers over the generic form.
Tests pin the formula, wrapper equivalence, and eta=0 path-independence.
Per pixelrush-correct.txt: the 2026-08-12 unit-vector x linear-magnitude
form carried magnitudes separately; the paper convention is standard
vector slerp sin((1-t)w)/sin(w)*a + sin(tw)/sin(w)*b on raw flattened
vectors, with a lerp fallback when sin_omega < 1e-4. The conflicting
grep-tests (which forbade the corrected form) are rewritten to require it.
WildAi