ComfyUI Krea2 Merge is a standalone set of nodes for exactly combining two to four Krea 2 LoRAs without loading or modifying the base model. It supports the PEFT/Diffusers lora_A + lora_B keys used by Krea 2 LoRAs, while retaining support for Kohya lora_down + lora_up checkpoints.

This fork uses its own package name, extension name, node IDs, category, and output folder. It can therefore be installed alongside the original comfyui-merge extension without replacing its nodes.

Features

Merge two to four Krea 2 LoRAs without loading a base model.
Support PEFT/Diffusers lora_A + lora_B state dictionaries.
Retain Kohya lora_down + lora_up compatibility.
Infer missing alpha values from the LoRA rank.
Handle negative merge weights correctly for both lora_B and lora_up.
Exactly merge LoRAs with equal or different ranks without unwanted cross terms.
Enter positive or negative weights from -4.0 to 4.0.
Report unsupported files and incompatible tensor shapes clearly.
Save to ComfyUI/models/loras/krea2-merged-loras by default.
Keep merge results independent of input order for equal weights.

Installation

Download or clone this repository into:

ComfyUI/custom_nodes/comfyui-krea2-merge

Restart ComfyUI.

The extension requires PyTorch (provided by ComfyUI). The safetensors package is required for loading and saving .safetensors files and is included in normal ComfyUI installations.

Nodes

All nodes appear under Krea2 Merge / LoRA:

Krea2 Merge • Load LoRA — loads a LoRA as a state dictionary.
Krea2 Merge • Merge LoRAs — combines two to four LoRAs.
Krea2 Merge • Save LoRA — saves the merged state dictionary.
Krea2 Merge • Apply LoRA — loads and applies a LoRA to a connected model.

The internal node IDs are prefixed with Krea2Merge_, so workflows do not collide with the original extension.

Basic workflow

Add two Krea2 Merge • Load LoRA nodes and select your Krea 2 LoRAs.
Connect them to Krea2 Merge • Merge LoRAs.
Set weight1 and weight2. Optional third and fourth inputs use weight3 and weight4.
Keep the default exact_concat for a mathematically exact weighted merge. legacy_linear remains available only for compatibility with the original approximate factor-space behavior.
Select the output precision. fp16 is the practical default; use bf16 if that matches your Krea 2 setup.
Connect Krea2 Merge • Save LoRA and choose a filename ending in .safetensors.
Set allow_overwrite to yes when repeated runs should replace the same output file. Keep it on no to protect an existing merge.

On Windows, overwrite first moves the previous output to a temporary backup. If the new save fails, the original file is restored automatically. If Windows has the destination open or memory-mapped, use another filename or restart ComfyUI.

An example is included at workflow-examples/krea2-lora-merger.json.

The example includes Show Text from ComfyUI-Custom-Scripts to display the saved path. The Save node is also registered as an output node, so saving still works when Show Text is removed from a custom workflow.

Compatibility notes

exact_concat is the default. It concatenates complete A/B or down/up pairs, avoiding the cross terms produced when factors are added separately. It also supports different ranks: a rank-4 plus rank-16 module becomes rank 20.
Concatenation increases the output rank. Combining two rank-32 LoRAs produces rank 64; four produce rank 128. This increases file size and the temporary work needed while ComfyUI applies the LoRA.
legacy_linear preserves old saved workflows and factor-space results. It is approximate, introduces cross terms, and requires matching shapes and ranks.
exact_concat applies weights directly and ignores force_same_strength. For an even blend, start with weight1 = 0.5 and weight2 = 0.5.
Both modes operate only on the LoRA files; neither changes or saves the Krea 2 base model.
When a PEFT checkpoint has no embedded alpha tensors, the extension uses alpha = rank. This is the only value that can be recovered from a standalone .safetensors state dictionary without its training configuration.
DoRA magnitude vectors, LoCon lora_mid tensors, and other adapter methods are rejected instead of being silently omitted or merged incorrectly.
A connected third or fourth LoRA with a zero weight is ignored with a clear console warning.

Attribution

This project is derived from LingSss9/comfyui-merge and retains its MIT license. Krea 2 support, separate node IDs, validation, tests, and the release branding were added in this fork.

Krea 2 and its model names belong to their respective owners. This community extension is not an official Krea product.