WanVideo Block List

This is a tiny helper node that does one boring-but-necessary thing: it turns a comma-separated list of block numbers into the list of integers that other WanVideoWrapper nodes want. Wan's diffusion transformer is a stack of blocks, and a few advanced features - block swap for VRAM, radial attention for speed - need you to say which blocks to act on. Typing "which blocks" as a clean list is what this node is for. Per its description, it feeds directly into the dense_blocks input of the WanVideoSetRadialAttention node, among others.

If you've never needed to point at specific transformer blocks, you can happily ignore this node forever. It shows up once you start pushing Wan onto hardware that doesn't quite fit it, or tuning the newer attention tricks.

How it works

You write a list like 0,2,5 or a range like 0-5, or a mix like 0,2,3-5. The node parses that string and emits it as a proper integer list. That list then tells a downstream node which blocks to swap to CPU (block swap), or which blocks to keep at full "dense" attention while the rest use the cheaper radial variant. It's pure plumbing - no model, no math, just turning human-friendly text into the format the real nodes consume.

The inputs and outputs that matter

• blocks (multiline string, default "1") - the list. Ranges are allowed (0-5), commas separate items (0,2,4), and you can combine them (0,2,3-5). This is the only thing you set.

Output:

• block_list (INT list) - the parsed integers. Wire it into whatever wants a block list: the dense_blocks input on WanVideoSetRadialAttention, a block-swap config, etc.

Why block selection matters on Wan

Block swap is the classic trick for fitting big Wan models into not-enough VRAM: you offload some transformer blocks to system RAM and stream them in as needed, trading speed for headroom. Community reports lean on it constantly - one user fitting VACE described swapping "24 Wan and 8 VACE blocks" to make an fp8 setup sit comfortably. Radial attention is the newer speed play, where most blocks run a sparse attention pattern and only the ones you name stay dense. Either way, which blocks is a real decision, and this node is how you express it cleanly instead of hand-formatting an integer array.

How to install it

Part of the WanVideoWrapper. ComfyUI Manager: search ComfyUI-WanVideoWrapper, install, restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/kijai/ComfyUI-WanVideoWrapper
pip install -r ComfyUI-WanVideoWrapper/requirements.txt

then restart. Nothing to download for this node itself - it's a string parser.

Common issues & troubleshooting

It connects to nothing useful on its own. This node only matters paired with a consumer - a block-swap node or WanVideoSetRadialAttention. If you dropped it in expecting it to do something visible, it won't; it's an input-shaper.

Range syntax bit you. Ranges are inclusive and use a hyphen: 0-5 means blocks 0 through 5. Don't use spaces around the commas if a node ever chokes; keep it tight like 0,2,3-5.

You listed blocks that don't exist. Wan models have a fixed block count; naming a block index past the end will error or silently do nothing in the downstream node. If block swap or radial attention isn't behaving, sanity-check that your highest number is within the model's block range.