Declare dtype on the VideoPositionEmb.generate_embeddings stub by Anai-Guo · Pull Request #15991 · Comfy-Org/ComfyUI

Anai-Guo · 2026-08-30T23:09:55Z

One line: add dtype=None to the VideoPositionEmb.generate_embeddings stub.

VideoPositionEmb.forward passes dtype to it:

# comfy/ldm/cosmos/position_embedding.py:49
embeddings = self.generate_embeddings(B_T_H_W_C, fps=fps, device=device, dtype=dtype)

# :53 — the stub in the same class
def generate_embeddings(self, B_T_H_W_C: torch.Size, fps=Optional[torch.Tensor], device=None):
    raise NotImplementedError

Both concrete subclasses in the file already declare dtype
(VideoRopePosition3DEmb at :100, LearnablePosEmbAxis at :192), so nothing
is broken at runtime today. The stub is the odd one out, and it is the thing a
new subclass gets written against — such an override raises
TypeError: generate_embeddings() got an unexpected keyword argument 'dtype'
on its first forward pass.

Checked by loading the module before and after, then generating an override that
copies whatever signature the stub advertises:

unpatched | stub: (self, B_T_H_W_C: torch.Size, fps=typing.Optional[torch.Tensor], device=None)
unpatched |   VideoRopePosition3DEmb: dtype declared = True
unpatched |   LearnablePosEmbAxis:   dtype declared = True
unpatched |   override copying the stub: (self, B_T_H_W_C, fps=None, device=None)
unpatched |   forward -> TypeError: NewEmb.generate_embeddings() got an unexpected keyword argument 'dtype'

patched   | stub: (self, B_T_H_W_C: torch.Size, fps=typing.Optional[torch.Tensor], device=None, dtype=None)
patched   |   override copying the stub: (self, B_T_H_W_C, fps=None, device=None, dtype=None)
patched   |   forward -> OK (1, 2, 3, 4, 5)

No behaviour change for either existing subclass.

🤖 Generated with Claude Code

VideoPositionEmb.forward calls self.generate_embeddings(..., dtype=dtype), but the abstract stub it sits next to does not accept dtype. Both subclasses in the file already do, so nothing breaks today; the stub is simply out of date, and an override written to the signature it advertises raises TypeError on first forward.

github-actions · 2026-08-30T23:10:08Z

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coderabbitai · 2026-08-30T23:11:48Z

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📝 Walkthrough

Walkthrough

VideoPositionEmb.generate_embeddings now accepts an optional dtype argument. The existing arguments and default behavior remain unchanged.

Merge Risk: ⚪ Minimal · up to 3a2ca

This localized signature fix enables compatible subclasses to receive the dtype argument without changing existing behavior. No actionable merge-blocking risk remains after normal checks and review.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: adding the dtype parameter to the VideoPositionEmb.generate_embeddings stub.
Description check	✅ Passed	The description accurately explains the signature mismatch, the caller and subclass context, the potential error for new overrides, and the validation performed.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Anai-Guo requested review from Kosinkadink, alexisrolland, comfyanonymous, guill, kijai and rattus128 as code owners August 30, 2026 23:09

coderabbitai Bot approved these changes Aug 30, 2026

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Declare dtype on the VideoPositionEmb.generate_embeddings stub - #15991

Declare dtype on the VideoPositionEmb.generate_embeddings stub#15991
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