Nunchaku FLUX.2 Klein Power LoRA Loader

Chaining three NunchakuKleinLoraLoader nodes to stack a realism LoRA, a skin LoRA, and something for anatomy is five minutes of wiring every time you want to test a different combination. This node is the "just give me a table" answer: one node, one widget, and an ordered list of Klein LoRAs you can add, reorder, toggle, and dial up or down without touching the graph. It's new (v1.2.0, August 2026), so if your install predates that, update.

Why you'd reach for it

Klein's one genuine workflow advantage over rivals like Z-Image is that it tolerates LoRA stacks - multiple LoRAs at strength 1.0 without the image burning to plastic. That's exactly the use case this node is built for. It's an aggregation UI over the ordinary loader contract: it preserves any LoRAs already inherited on the incoming model branch and publishes the same immutable ordered spec tuple you'd get from chaining individual loader nodes, so swapping between Power and ordinary loaders doesn't change behavior.

How it works

The rows input is technically a STRING containing serialized JSON, but you never type it. The node registers a custom widget (ComfyUI's Nodes 2.0 frontend, via getCustomWidgets/addDOMWidget) that edits the rows for you. Each row has a searchable LoRA picker (case-insensitive substring match on the full LoRA path), a signed strength value, and enable/disable. Zero-strength rows contribute nothing. + Add LoRA opens the picker and only inserts a new enabled row at strength 1.0 after you actually select something - escape or click-outside adds nothing, which is polite of it. Parsed LoRAs are cached in a small node-local LRU so repeated runs don't re-parse everything.

Inputs and outputs

Just two inputs: model (from NunchakuKleinModelLoader) and the rows widget. One output, MODEL, straight to your KSampler or next enhancer.

Installing it

Same pack as the rest of this family:

cd ComfyUI/custom_nodes
git clone https://github.com/tom-m-2020/ComfyUI-Nunchaku-Klein

Then the usual backend story: Vitoom Nunchaku wheel from huggingface.co/tonera/vitoom-nunchaku, tonera's Klein checkpoint into diffusion_models/. The author tested the widget with ComfyUI 0.29.0 and frontend package 1.47.10 - if your ComfyUI is older or heavily customized, the row editor may not render, so update ComfyUI first. rgthree is not a dependency, despite this feeling like an rgthree thing.

Common issues

• Rows widget doesn't appear - you're on an older frontend. Update ComfyUI, then refresh the browser page (hard refresh if the JS is cached).
• LoRA errors that vanish when you use the single loader - version sensitivity in Nunchaku LoRA support; the v1.2.1 changelog is full of LoRA compatibility fixes, so keep pack and backend current.
• "Only one active ... per MODEL branch" - you've stacked two enhancer nodes that can't coexist (Ref Latent Weight with Text/Ref Balance, for instance). Pick one; the error is explicit about which.