fix(LTXEulerAncestralRFScheduler): validate monotonicity of explicit sigma schedules#13466
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Anai-Guo wants to merge 1 commit intohuggingface:mainfrom
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fix(LTXEulerAncestralRFScheduler): validate monotonicity of explicit sigma schedules#13466Anai-Guo wants to merge 1 commit intohuggingface:mainfrom
Anai-Guo wants to merge 1 commit intohuggingface:mainfrom
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…plicit sigma schedules When sigmas are provided explicitly, validate that the schedule is monotonically non-increasing before accepting it. A non-monotone schedule causes alpha_down < 0 in step(), which silently corrupts denoising without raising an error. Fixes huggingface#13411
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What does this PR do?
Adds a monotonicity check to
LTXEulerAncestralRFScheduler.set_timesteps()when an explicit sigma schedule is provided.Bug: When
sigmasare supplied explicitly (ComfyUI-style),set_timesteps()accepts non-monotone schedules without complaint. Whenstep()is subsequently called on such a schedule, it computessigma_downfrom adjacent(sigma[i], sigma[i+1])pairs; a schedule increase at any step causesalpha_down < 0, which violates the CONST parametrization invariant and produces silently incorrect denoising output — no exception, no NaN, no warning.Fix: After the existing shape validation, raise a
ValueErrorif the provided sigmas are not monotonically non-increasing. This follows the philosophy stated inPHILOSOPHY.md("Raising concise error messages is preferred to silently correct erroneous input").Fixes #13411
Before submitting
set_timesteps; a test for non-monotone input can be added as a follow-up if requested.