Save First Frame Latent (Wan)

Narrow, useful, and easy to explain: this node takes a latent - specifically the first-frame latent you made with QwenToWanFirstFrameLatent - and writes it to a file on disk. That's the entire feature. You'd reach for it when you want to generate the starting frame inside ComfyUI but do the actual video generation somewhere else: a command-line Wan script, a separate rig, a batch job that reads latents off disk. It's the export hatch out of the graph.

Most people never need this, and that's fine. If your whole pipeline lives in one ComfyUI graph, you just wire the latent straight from the bridge node into your Wan sampler and never touch a file. But local video is a patchwork of tools, and Wan's frozen 2.1/2.2 weights get driven by all sorts of external harnesses. If yours expects a first-frame latent handed to it as a file, this is how you produce that file without leaving ComfyUI to author the frame.

How it works

You give it a latent and a filename, pick a format, and it serializes the tensor to disk, returning the path it wrote. No model runs. The three formats cover the obvious consumers: safetensors for the modern, safe-to-load standard; pt for anything expecting a raw PyTorch tensor; npz for NumPy-based tooling.

The inputs and outputs that matter

• latent - the first-frame latent to save, straight from QwenToWanFirstFrameLatent.
• filename_prefix (default qwen_first_frame) - the base name for the written file. Give each run a distinct prefix if you're batching so they don't collide.
• format (safetensors / pt / npz) - pick whatever your downstream tool reads. When in doubt, safetensors.

Output is a single file_path string - the location it wrote to, so you can log it or wire it into whatever comes next. It's an output node, so it does its work when the graph runs.

How to install it

ComfyUI Manager → ComfyUI-QwenImageWanBridge → install → restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/fblissjr/ComfyUI-QwenImageWanBridge

then restart. It's file I/O, so there's nothing heavy to download for the node itself.

Common issues & troubleshooting

The external tool won't load the file. Match the format to what it expects. A tool reading NumPy archives won't open a .pt, and vice versa. safetensors is the safest default but only if your consumer supports it.

I can't find where it saved. Check the returned file_path - that's the authoritative location. Files land under ComfyUI's output directory structure unless your setup redirects it; the prefix is a name, not a full path.

Is this the same as a normal latent save? Functionally similar, but this one is scoped to the Qwen-to-Wan first-frame use case and its formats. If you're staying entirely inside ComfyUI, you almost certainly don't need it - pass the latent node-to-node instead. Reach for this only when a frame has to leave the graph as a file.