ComfyUI-GGUF-FX

Complete GGUF model support for ComfyUI with local and Nexa SDK inference modes.

🌟 Features

Two Inference Modes

1. Text Generation (Local) - Direct GGUF model loading using llama-cpp-python
2. Nexa SDK - Managed models via Nexa SDK service

Key Features

• ✅ Simple configuration - Minimal parameters, maximum functionality
• ✅ Auto model detection - Nexa SDK automatically lists downloaded models
• ✅ Thinking mode support (DeepSeek-R1, Qwen3-Thinking)
• ✅ Stop sequences - Prevent over-generation
• ✅ Paragraph merging - Clean single-paragraph output
• ✅ Detailed logging - Debug-friendly console output
• ✅ Device optimization (CUDA, MPS, CPU)

📦 Installation

1. Install ComfyUI Custom Node

cd ComfyUI/custom_nodes
git clone https://github.com/weekii/ComfyUI-GGUF-FX.git
cd ComfyUI-GGUF-FX
pip install -r requirements.txt

2. For Nexa SDK Mode (Optional)

# Install Nexa SDK
pip install nexaai

# Start Nexa service
nexa serve

The service will be available at http://127.0.0.1:11434

🚀 Quick Start

Using Text Generation (Local GGUF)

Recommended for local GGUF files

[Text Model Loader]
├─ model: Select your GGUF file
└─ device: cuda/cpu/mps
    ↓
[Text Generation]
├─ max_tokens: 256  ← Recommended for single paragraph
├─ temperature: 0.7
├─ top_p: 0.8
├─ top_k: 40
├─ repetition_penalty: 1.1
├─ enable_thinking: False
└─ prompt: "Your prompt here"
    ↓
Output: context, thinking

Features:

• ✅ Direct file access
• ✅ No service required
• ✅ Fast and simple
• ✅ Stop sequences prevent over-generation
• ✅ Automatic paragraph merging

Using Nexa SDK Mode

Recommended for Nexa SDK ecosystem

Step 1: Download Model

# Download a model using Nexa CLI
nexa pull mradermacher/Huihui-Qwen3-4B-Instruct-2507-abliterated-GGUF:Q8_0 --model-type llm

# Check downloaded models
nexa list

Step 2: Use in ComfyUI

[Nexa Model Selector]
├─ base_url: http://127.0.0.1:11434
├─ refresh_models: ☐
└─ system_prompt: (optional)
    ↓
[Nexa SDK Text Generation]
├─ preset_model: Select from dropdown (auto-populated)
├─ max_tokens: 256
├─ temperature: 0.7
└─ prompt: "Your prompt here"
    ↓
Output: context, thinking

Features:

• ✅ Centralized model management
• ✅ Auto-populated model list
• ✅ Supports nexa pull workflow

📋 Available Nodes

Text Generation Nodes (Local GGUF)

🔷 Text Model Loader

Load GGUF models from /workspace/ComfyUI/models/LLM/GGUF/

Parameters:

• model: Select from available GGUF files
• device: cuda/cpu/mps
• n_ctx: Context window (default: 8192)
• n_gpu_layers: GPU layers (-1 for all)

Output:

• model: Model configuration

🔷 Text Generation

Generate text with loaded GGUF model

Parameters:

• model: From Text Model Loader
• max_tokens: Maximum tokens (1-8192, recommended: 256)
• temperature: Temperature (0.0-2.0)
• top_p: Top-p sampling (0.0-1.0)
• top_k: Top-k sampling (0-100)
• repetition_penalty: Repetition penalty (1.0-2.0)
• enable_thinking: Enable thinking mode
• prompt: Input prompt (at bottom for easy editing)

Outputs:

• context: Generated text
• thinking: Thinking process (if enabled)

Features:

• ✅ Stop sequences: ["User:", "System:", "\n\n\n", "\n\n##", "\n\nNote:", "\n\nThis "]
• ✅ Automatic paragraph merging for single-paragraph prompts
• ✅ Detailed console logging

Nexa SDK Nodes

🔷 Nexa Model Selector

Configure Nexa SDK service

Parameters:

• base_url: Service URL (default: http://127.0.0.1:11434)
• refresh_models: Refresh model list
• system_prompt: System prompt (optional)

Output:

• model_config: Configuration for Text Generation

🔷 Nexa SDK Text Generation

Generate text using Nexa SDK

Parameters:

• model_config: From Model Selector
• preset_model: Select from dropdown (auto-populated from nexa list)
• custom_model: Custom model ID (format: author/model:quant)
• auto_download: Auto-download if missing
• max_tokens: Maximum tokens (recommended: 256)
• temperature, top_p, top_k, repetition_penalty: Generation parameters
• enable_thinking: Enable thinking mode
• prompt: Input prompt (at bottom)

Outputs:

• context: Generated text
• thinking: Thinking process (if enabled)

Preset Models:

• DavidAU/Qwen3-8B-64k-Josiefied-Uncensored-HORROR-Max-GGUF:Q6_K
• mradermacher/Huihui-Qwen3-4B-Instruct-2507-abliterated-GGUF:Q8_0
• prithivMLmods/Qwen3-4B-2507-abliterated-GGUF:Q8_0

🔷 Nexa Service Status

Check Nexa SDK service status

Parameters:

• base_url: Service URL
• refresh: Refresh model list

Output:

• status: Service status and model list

🎯 Best Practices

For Single-Paragraph Output

System Prompt:

You are an expert prompt generator. Output ONLY in English.

**CRITICAL: Output EXACTLY ONE continuous paragraph. Maximum 400 words.**

Parameters:

max_tokens: 256  ← Key setting!
temperature: 0.7
top_p: 0.8
top_k: 20

Why max_tokens=256?

• ✅ Prevents over-generation
• ✅ Model completes task without extra commentary
• ✅ Reduces from ~2700 chars (11 paragraphs) to ~1300 chars (1 paragraph)

For Multi-Turn Conversations

Include history directly in prompt:

User: Hello
Assistant: Hi! How can I help?
User: Tell me a joke

No need for separate conversation history parameter.

💭 Thinking Mode

Automatically extracts thinking process from models like DeepSeek-R1 and Qwen3-Thinking.

Supported Tags:

• <think>...</think> (DeepSeek-R1, Qwen3)
• <thinking>...</thinking>
• [THINKING]...[/THINKING]

Usage:

[Text Generation]
├─ enable_thinking: True
└─ prompt: "Explain your reasoning"
    ↓
Outputs:
├─ context: Final answer (thinking tags removed)
└─ thinking: Extracted thinking process

Disable Thinking:

• Set enable_thinking: False
• Or add no_think to system prompt

📊 Mode Comparison

| Feature | Text Generation (Local) | Nexa SDK | |---------|------------------------|----------| | Setup | Copy GGUF file | nexa pull | | Service | Not required | Requires nexa serve | | Model Management | Manual | CLI (nexa list, nexa pull) | | Use Case | Local files, production | Nexa ecosystem, shared models | | Speed | Fast | Fast (via service) | | Flexibility | Any GGUF file | Only nexa pull models |

Recommendation:

• Use Text Generation for local GGUF files
• Use Nexa SDK if you're already using Nexa ecosystem

🐛 Troubleshooting

Output Too Long (Multiple Paragraphs)

Problem: Model generates 11 paragraphs instead of 1

Solution:

1. Reduce max_tokens from 512 to 256
2. Strengthen system prompt: Add "EXACTLY ONE paragraph"
3. Stop sequences are already configured

Nexa Service Not Available

Problem: ❌ Nexa SDK service is not available

Solution:

1. Start service: nexa serve
2. Check: curl http://127.0.0.1:11434/v1/models
3. Verify URL in node

Model Not in Dropdown

Problem: Downloaded model doesn't appear in Nexa SDK dropdown

Solution:

1. Check: nexa list
2. Click "refresh_models" in Nexa Model Selector
3. Restart ComfyUI

0B Entries in nexa list

Problem: nexa list shows 0B entries

Solution:

# Clean up invalid entries
rm -rf ~/.cache/nexa.ai/nexa_sdk/models/local
rm -rf ~/.cache/nexa.ai/nexa_sdk/models/workspace
find ~/.cache/nexa.ai/nexa_sdk/models -name "*.lock" -delete

# Verify
nexa list

📁 Directory Structure

ComfyUI-GGUF-FX/
├── README.md                       # This file
├── NEXA_SDK_GUIDE.md              # Detailed Nexa SDK guide
├── requirements.txt                # Dependencies
├── __init__.py                     # Node registration
├── config/
│   └── paths.py                    # Path configuration
├── core/
│   ├── inference_engine.py        # GGUF inference engine
│   ├── model_loader.py            # Model loader
│   └── inference/
│       ├── nexa_engine.py         # Nexa SDK engine
│       └── transformers_engine.py # Transformers engine
├── nodes/
│   ├── text_node.py               # Text Generation nodes
│   ├── nexa_text_node.py          # Nexa SDK nodes
│   ├── vision_node.py             # Vision nodes
│   └── system_prompt_node.py      # System prompt config
└── utils/
    ├── device_optimizer.py        # Device optimization
    └── system_prompts.py          # System prompt presets

🔄 Recent Updates

v2.2 (2025-10-29)

• ✅ Simplified Nexa Model Selector - Removed unused models_dir and model_source
• ✅ Removed unused outputs - Cleaner node interface
• ✅ Moved prompt to bottom - Better UX for long prompts
• ✅ Removed conversation_history - Use prompt directly
• ✅ Stop sequences - Prevent over-generation
• ✅ Paragraph merging - Clean single-paragraph output
• ✅ Dynamic model list - Auto-populated from Nexa SDK API
• ✅ Detailed logging - Debug-friendly console output

v2.1

• ✅ Nexa SDK integration
• ✅ Preset model list
• ✅ Thinking mode support

v2.0

• ✅ GGUF mode with llama-cpp-python
• ✅ ComfyUI /models/LLM integration

📝 Requirements

llama-cpp-python>=0.2.0
transformers>=4.30.0
torch>=2.0.0
Pillow>=9.0.0
requests>=2.25.0
nexaai  # Optional, for Nexa SDK mode

🤝 Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

📄 License

MIT License - see LICENSE file for details

🔗 Links

• GitHub: https://github.com/weekii/ComfyUI-GGUF-FX
• Nexa SDK: https://github.com/NexaAI/nexa-sdk
• Nexa SDK Guide: NEXA_SDK_GUIDE.md
• ComfyUI: https://github.com/comfyanonymous/ComfyUI

👤 Author

weekii weekii2024@gmail.com

🙏 Acknowledgments

• ComfyUI team for the amazing framework
• Nexa AI for the SDK
• HuggingFace for model hosting
• llama.cpp team for GGUF support

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Status: ✅ Production Ready
Version: 2.2
Last Updated: 2025-10-29