MiniMax H3 TAEH3 Preview Capability / 快速预览能力 (Advanced EXP/T8)

If you've run MiniMax H3 in ComfyUI and stared at a progress preview that only shows a single video frame per step while it renders, this node is the "is that just how it is?" answer. The TAEH3 Preview Capability node is a read-only probe that checks whether ComfyUI's native TAEH3 progress-preview path is available on your install and whether the matching models/vae_approx asset is actually in place. No inputs, no side effects, no sampling changes - you drag it in, run it, and read the verdict.

What TAEH3 is and why you care

TAEH3 is the tiny latent decoder for H3 (part of the taehv family, the same idea as TAESD for SD checkpoints): a cheap approximate VAE that decodes a latent into a watchable image during sampling, without paying for a full VAE decode every step. For video models that means a progress preview that isn't just noise. Without the asset, ComfyUI falls back to previewing only the first video frame at each step - which is the exact behavior most people hit and assume is broken.

The node inspects the installed vae_approx asset structurally (it checks the 24-channel temporal decoder) without loading it, and reports:

• available - is the TAEH3 asset present and structurally right?
• active - is the native preview path actually engaged?
• status - a human-readable explanation.
• report_json - the detail, including the caveat that current native behavior previews only the first frame per step.

So a available=true, active=false combo tells you the asset is there but the preview setting isn't switched on, which is a different fix than a missing download.

Fixing it when it's not available

Two things have to be true. First, the model:

# from https://github.com/madebyollin/taehv
# put taeh3.safetensors into:
ComfyUI/models/vae_approx/

Then enable the preview: launch ComfyUI with the TAESD/TAEH3 preview option selected in the startup settings. If you're on a one-click/整合包 install, that toggle lives in the launcher, not in a workflow. Note the pack's own framing: TAEH3 preview is for monitoring, and the final video always comes from the real H3 video VAE - the tiny decoder is not what you ship.

Where people get burned

The most common miss is having the file in the wrong folder. It must be taeh3.safetensors in ComfyUI/models/vae_approx/, not models/vae. Second, expecting this node to enable anything - it's deliberately inspection-only, so if available is true and active is false, the fix is in your launcher's preview setting, and no node in this pack will change it for you. That's a stated design decision: the author refuses to silently modify preview configuration.

Installing it

It ships with the comfyui-minimax-h3-audio-T8 pack - ComfyUI Manager search "MiniMax H3 Audio T8", or clone https://github.com/T8mars/comfyui-minimax-h3-audio-T8.git into custom_nodes, then update ComfyUI core first and restart. This node specifically is part of the 21-community-advanced "System Cache and Diagnostics" workflow, which is a good landing spot if you want the risk diagnostic, residency strategy, and this preview check in one pass.