Add MiniMax H3 AV latent builder

[Goldlionren]

Summary

• add a native MiniMax H3 AV Latent node for assembling separately encoded video and audio latents into the official H3 NestedTensor format
• validate MiniMax H3 stream shapes, matching batch sizes, and video/audio temporal compatibility using the existing H3 timing constants
• register the node next to Empty MiniMax H3 AV Latent and add focused CPU-only tests

Testing

• 9 passed — focused AV latent tests
• 224 passed, 0 skipped, 0 failed — tests-unit/comfy_extras_test
• Ruff passed for touched files
• target compileall passed
• git diff --check passed
• import, schema, execution, and extension registration validation passed

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• comfy_extras/nodes_minimax_h3.py
• tests-unit/comfy_extras_test/test_minimax_h3_av_latent.py

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📓 Path-based instructions (6)

**/*

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**/*: Keep changes small, direct, and limited to the narrowest necessary code path and smallest number of files.
Prefer practical fixes, minimal dependencies, and existing repository patterns; remove obsolete, dead, unreachable, or unused code.
Preserve existing APIs, node names, model-loading behavior, file layout, and workflow compatibility unless replacement is explicitly intended.
Core ComfyUI must not add outbound internet requests, telemetry, tracking, reporting, remote configuration, or background network activity. User-authorized model downloads are limited to the requested artifact and must exclude telemetry and unrelated metadata.

Files:

• comfy_extras/nodes_minimax_h3.py
• tests-unit/comfy_extras_test/test_minimax_h3_av_latent.py

**/*.py

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Do not add torch.no_grad, torch.inference_mode, or inference-mode wrappers. Do not add model freeze/unfreeze toggles; only disable globally enabled inference mode when a training path requires gradients.
Remove inference-only training behavior such as dropout while preserving checkpoint and state-dict compatibility; use nn.Identity when deleting a module would alter keys or ordering.
Keep imports at module scope except established optional-backend probes or imports required to avoid cycles; avoid unnecessary try/except blocks and use specific exceptions with useful fallbacks.
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Prefer existing ComfyUI and Comfy Kitchen operations, quantization helpers, cast/offload helpe...

Files:

• comfy_extras/nodes_minimax_h3.py
• tests-unit/comfy_extras_test/test_minimax_h3_av_latent.py

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• comfy_extras/nodes_minimax_h3.py
• tests-unit/comfy_extras_test/test_minimax_h3_av_latent.py

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Files:

• comfy_extras/nodes_minimax_h3.py
• tests-unit/comfy_extras_test/test_minimax_h3_av_latent.py

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Treat AGENTS.md as mandatory repository policy, not optional style guidance.
Flag PR changes that violate AGENTS.md even when the code is otherwise functional.
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Files:

• comfy_extras/nodes_minimax_h3.py
• tests-unit/comfy_extras_test/test_minimax_h3_av_latent.py

comfy_extras/**

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comfy_extras/**: Community-contributed extra nodes. Focus on:

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Files:

• comfy_extras/nodes_minimax_h3.py

🧠 Learnings (7)

📚 Learning: 2026-02-21T14:01:41.482Z

Learnt from: pythongosssss
Repo: Comfy-Org/ComfyUI PR: 12555
File: comfy_extras/nodes_glsl.py:719-724
Timestamp: 2026-02-21T14:01:41.482Z
Learning: In PyOpenGL, bare Python scalars can be accepted for 1-element array parameters by NumberHandler. This means you can pass an int/float directly to OpenGL texture deletion (e.g., glDeleteTextures(tex)) without wrapping in a list. Verify function-specific expectations and ensure types match what the OpenGL call expects; use explicit lists only when the API requires an array.

Applied to files:

• comfy_extras/nodes_minimax_h3.py
• tests-unit/comfy_extras_test/test_minimax_h3_av_latent.py

📚 Learning: 2026-03-04T14:05:31.426Z

Learnt from: jtydhr88
Repo: Comfy-Org/ComfyUI PR: 12757
File: comfy_extras/nodes_custom_sampler.py:1069-1089
Timestamp: 2026-03-04T14:05:31.426Z
Learning: In the ComfyUI sampling pipeline, treat percent_to_sigma(0.0) as a sentinel value (999999999.9) that means starting from pure noise. This is consistent with BasicScheduler via calculate_sigmas. The SamplingPercentToSigma node’s return_actual_sigma flag differentiates this sentinel from sigma_max. Reviewers should not flag CurveToSigmas or similar nodes that rely on percent_to_sigma as bugs; downstream samplers are expected to handle the sentinel correctly. When reviewing related sampling-related code, assume this sentinel semantics unless there is explicit handling for a real sigma_max.

Applied to files:

• comfy_extras/nodes_minimax_h3.py

📚 Learning: 2026-04-04T13:29:15.653Z

Learnt from: kijai
Repo: Comfy-Org/ComfyUI PR: 13258
File: comfy_extras/nodes_frame_interpolation.py:151-189
Timestamp: 2026-04-04T13:29:15.653Z
Learning: In this ComfyUI codebase, node `execute()` inference is already run under a global `torch.inference_mode()` context established in the execution engine (e.g., `execution.py` around line ~732). During review, avoid recommending changes that wrap node inference loops in `torch.inference_mode()`—it is already applied, so such suggestions are likely redundant.

Applied to files:

• comfy_extras/nodes_minimax_h3.py

📚 Learning: 2026-05-09T18:40:40.199Z

Learnt from: kijai
Repo: Comfy-Org/ComfyUI PR: 13813
File: comfy_extras/nodes_wandancer.py:868-872
Timestamp: 2026-05-09T18:40:40.199Z
Learning: When building video/temporal decoding nodes that call ComfyUI’s VAE.decode (comfy/sd.py), leverage VAE.decode’s existing VRAM-aware chunking along dim 0. Reshape or transpose the latent so the temporal dimension T is folded into dim 0 (e.g., transform a latent of shape [B, T, C, H, W] into [B*T, C, H, W] before calling vae.decode). This lets VAE.decode do chunked decoding without needing an explicit per-frame loop inside the node itself.

Applied to files:

• comfy_extras/nodes_minimax_h3.py

📚 Learning: 2026-05-20T00:10:14.673Z

Learnt from: Pauan
Repo: Comfy-Org/ComfyUI PR: 13997
File: comfy_extras/nodes_string.py:12-25
Timestamp: 2026-05-20T00:10:14.673Z
Learning: In the ComfyUI `comfy_extras/` codebase, some nodes intentionally ship with a default input string that references parameters that may not yet be connected. If the default would raise a `KeyError` (e.g., examples like `MathExpression` default `a + b`, or `StringFormat` default `{a}` with `min=0` and autogrow inputs), treat it as an intentional “hint default” UX pattern, not a bug. During review, do not flag this behavior or recommend changing `min` to `1` or altering the default to an empty string solely to avoid the `KeyError`.

Applied to files:

• comfy_extras/nodes_minimax_h3.py

📚 Learning: 2026-07-26T18:37:44.213Z

Learnt from: jtydhr88
Repo: Comfy-Org/ComfyUI PR: 15090
File: comfy_extras/nodes_video.py:230-235
Timestamp: 2026-07-26T18:37:44.213Z
Learning: In ComfyUI node implementations under `comfy_extras`, do not add regular widget/prompt inputs to `fingerprint_inputs` if they are already included in the node cache signature via `comfy_execution/caching.py:get_immediate_node_signature` (it records every non-link prompt input as `(key, inputs[key])`). Reserve `fingerprint_inputs` only for out-of-band state that can change without changing the prompt inputs (e.g., the selected source file’s modification time). For example, inputs like `LoadVideo.edit` should not be redundantly added to `fingerprint_inputs`; use it only for things not represented in prompt inputs.

Applied to files:

• comfy_extras/nodes_minimax_h3.py

📚 Learning: 2026-07-13T17:26:10.852Z

Learnt from: silveroxides
Repo: Comfy-Org/ComfyUI PR: 14922
File: tests-unit/comfy_extras_test/test_qwen_visual_fusion.py:3-7
Timestamp: 2026-07-13T17:26:10.852Z
Learning: In Comfy unit tests that import CUDA-dependent modules (e.g., tests that need `comfy_extras/nodes_qwen.py`), set the global `cli_args.cpu = True` at module load time *before* importing `comfy_extras/nodes_qwen.py` when CUDA is unavailable. Do not rely on `pytest` fixtures or `monkeypatch` for this kind of import-time behavior, because fixtures run after the test module is imported/collected and the CUDA code would already execute. The goal is to prevent import-time CUDA initialization and keep the tests runnable in CPU-only environments.

Applied to files:

• tests-unit/comfy_extras_test/test_minimax_h3_av_latent.py

🔇 Additional comments (2)

comfy_extras/nodes_minimax_h3.py (1)

112-154: LGTM!

Also applies to: 449-449

tests-unit/comfy_extras_test/test_minimax_h3_av_latent.py (1)

1-62: LGTM!

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📝 Walkthrough

Walkthrough

Adds MiniMaxH3AVLatent, which combines video and audio latent tensors into a nested MiniMax H3 AV latent. The node validates tensor ranks, dimensions, channel counts, batch sizes, and compatible timelines. The node is registered in the MiniMax H3 extension. Unit tests cover construction, validation failures, timeline tolerance, and registration order.

Merge Risk: ⚪ Minimal · up to 0958c

This localized node addition includes validation and focused tests, with the reported checks passing; no actionable merge-blocking risk remains beyond normal review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely identifies the main change: adding a MiniMax H3 AV latent builder.
Description check	✅ Passed	The description directly explains the new node, its validation behavior, registration, and test coverage.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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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