{"schema":"record/v1","id":"art_01M5MBVDDTG54VN2T9CMK5RF1P","type":"article","revision":1,"etag":"\"r1.s0\"","title":"If I re-run the same ComfyUI workflow with the same seed, which parts of the code and the docs decide whether I get the same image, and what should I write down so the run can be repeated or its drift explained?","summary":"At the pinned ComfyUI commit the KSampler path draws the initial latent noise on the CPU from torch.manual_seed(seed) and casts it to the latent dtype, and the project FAQ says this is why ComfyUI seeds are 'much more reproducible' across hardware than GPU-noise UIs. That covers only the starting noise: PyTorch's own notes say bit-identical results are not guaranteed across releases, commits, platforms or CPU/GPU, ComfyUI's --deterministic is a warn-only best effort whose help text says it may not make images deterministic, and later steps (ancestral noise, dtype, attention, batch) can still differ (see -02..-04). An agent should therefore log the software, device, launch-flag and graph facts listed in the method, and describe a rerun as 'same inputs and environment' rather than guaranteed identical.","status":"active","body":{"text":"At the pinned ComfyUI commit the KSampler path draws the initial latent noise on the CPU from torch.manual_seed(seed) and casts it to the latent dtype, and the project FAQ says this is why ComfyUI seeds are 'much more reproducible' across hardware than GPU-noise UIs. That covers only the starting noise: PyTorch's own notes say bit-identical results are not guaranteed across releases, commits, platforms or CPU/GPU, ComfyUI's --deterministic is a warn-only best effort whose help text says it may not make images deterministic, and later steps (ancestral noise, dtype, attention, batch) can still differ (see -02..-04). An agent should therefore log the software, device, launch-flag and graph facts listed in the method, and describe a rerun as 'same inputs and environment' rather than guaranteed identical.\n\nCurator qualifications: Curator located all evidence excerpts in the work copies (automated case-insensitive prefix match over decoded files). Code confirms CPU initial noise from torch.manual_seed(seed) cast to latent dtype; the FAQ reproducibility claim covers starting noise only (per-step noise: see C3R-0151 G23-03).\n\nEvidence status: curator/producer inference or synthesis from the cited sources (code read, not executed, where code is cited); correlated desk review (Claude); not independently reviewed.","citations":[{"url":"https://github.com/Comfy-Org/ComfyUI","note":"prepare_noise_inner; prepare_noise; FAQ"},{"url":"https://github.com/comfyanonymous/ComfyUI_examples/blob/f9431bb000ce792094ff345446e22cac1ea6cef3/faq/README.md","note":"prepare_noise_inner; prepare_noise; FAQ"},{"url":"https://github.com/pytorch/pytorch/blob/b40a4f2c025f42d1c2d4ece32daa39295b436f72/docs/source/notes/randomness.md","note":"prepare_noise_inner; prepare_noise; FAQ"},{"url":"https://github.com/huggingface/diffusers/blob/7e4383c0a2aeb384f3d3e0003b013a40c9b1e843/docs/source/en/using-diffusers/reusing_seeds.md","note":"prepare_noise_inner; prepare_noise; FAQ"}]},"categories":["T08","T09","T20"],"tags":[],"language":"en","visibility":"public","moderation":{"state":"visible","reason":null},"evidence":{"inspection":"source_inspected","execution":"not_run","review":"unreviewed","review_revision":null,"claims":[{"url":"https://github.com/Comfy-Org/ComfyUI","claim":"At the pinned ComfyUI commit the KSampler path draws the initial latent noise on the CPU from torch.manual_seed(seed) and casts it to the latent dtype, and the project FAQ says this is why ComfyUI seeds are 'much more reproducible' across hardware than GPU-noise UIs. That covers only the starting noise: PyTorch's own notes say bit-identical results are not guaranteed across releases, commits, platforms or CPU/GPU, ComfyUI's --deterministic is a warn-only best effort whose help text says it may not make images deterministic, and later steps (ancestral noise, dtype, attention, batch) can still differ (see -02..-04). 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That covers only the starting noise: PyTorch's own notes say bit-identical results are not guaranteed across releases, commits, platforms or CPU/GPU, ComfyUI's --deterministic is a warn-only best effort whose help text says it may not make images deterministic, and later steps (ancestral noise, dtype, attention, batch) can still differ (see -02..-04). An agent should therefore log the software, device, launch-flag and graph facts listed in the method, and describe a rerun as 'same inputs and environment' rather than guaranteed identical.\n\nCurator qualifications: Curator located all evidence excerpts in the work copies (automated case-insensitive prefix match over decoded files). Code confirms CPU initial noise from torch.manual_seed(seed) cast to latent dtype; the FAQ reproducibility claim covers starting noise only (per-step noise: see C3R-0151 G23-03).\n\nEvidence status: curator/producer inference or synthesis from the cited sources (code read, not executed, where code is cited); correlated desk review (Claude); not independently reviewed.","citations":[{"url":"https://github.com/Comfy-Org/ComfyUI","note":"prepare_noise_inner; prepare_noise; FAQ"},{"url":"https://github.com/comfyanonymous/ComfyUI_examples/blob/f9431bb000ce792094ff345446e22cac1ea6cef3/faq/README.md","note":"prepare_noise_inner; prepare_noise; FAQ"},{"url":"https://github.com/pytorch/pytorch/blob/b40a4f2c025f42d1c2d4ece32daa39295b436f72/docs/source/notes/randomness.md","note":"prepare_noise_inner; prepare_noise; FAQ"},{"url":"https://github.com/huggingface/diffusers/blob/7e4383c0a2aeb384f3d3e0003b013a40c9b1e843/docs/source/en/using-diffusers/reusing_seeds.md","note":"prepare_noise_inner; prepare_noise; FAQ"}]},"tags":[],"type":"article","links":[],"title":"If I re-run the same ComfyUI workflow with the same seed, which parts of the code and the docs decide whether I get the same image, and what should I write down so the run can be repeated or its drift explained?","rights":[{"notes":"Applies to this original summary only, not to the cited sources.","hosting":"permitted","component":"documentation","license_id":null,"modification":"unknown","evidence_urls":[],"model_training":"unknown","redistribution":"permitted"}],"summary":"At the pinned ComfyUI commit the KSampler path draws the initial latent noise on the CPU from torch.manual_seed(seed) and casts it to the latent dtype, and the project FAQ says this is why ComfyUI seeds are 'much more reproducible' across hardware than GPU-noise UIs. That covers only the starting noise: PyTorch's own notes say bit-identical results are not guaranteed across releases, commits, platforms or CPU/GPU, ComfyUI's --deterministic is a warn-only best effort whose help text says it may not make images deterministic, and later steps (ancestral noise, dtype, attention, batch) can still differ (see -02..-04). An agent should therefore log the software, device, launch-flag and graph facts listed in the method, and describe a rerun as 'same inputs and environment' rather than guaranteed identical.","evidence":{"claims":[{"url":"https://github.com/Comfy-Org/ComfyUI","claim":"At the pinned ComfyUI commit the KSampler path draws the initial latent noise on the CPU from torch.manual_seed(seed) and casts it to the latent dtype, and the project FAQ says this is why ComfyUI seeds are 'much more reproducible' across hardware than GPU-noise UIs. That covers only the starting noise: PyTorch's own notes say bit-identical results are not guaranteed across releases, commits, platforms or CPU/GPU, ComfyUI's --deterministic is a warn-only best effort whose help text says it may not make images deterministic, and later steps (ancestral noise, dtype, attention, batch) can still differ (see -02..-04). An agent should therefore log the software, device, launch-flag and graph facts listed in the method, and describe a rerun as 'same inputs and environment' rather than guaranteed identical.","locator":"prepare_noise_inner; prepare_noise; FAQ","classification":"inference"}],"review":"unreviewed","execution":"not_run","inspection":"source_inspected","execution_record_ids":[]},"language":"en","categories":["T08","T09","T20"],"extensions":{"curation/v1":{"curator":"CURATOR-A-20261021","revision":4,"topic_ids":["CAT:T06.AIC.06","CAT:T08.02","CAT:T08.07","CAT:T09.02"],"confidence":"Not stated; see limitations.","limitations":["Source pin hashes are native catalogue descriptor hashes, not upstream byte hashes. 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