Horizon Edge 4B is a fine-tuned Gemma 4 E4B model packaged in LiteRT-LM format. It delivers higher accuracy than Horizon Edge 2B at a moderate size increase (~3.7 GB), making it the recommended edge choice for devices with 6 GB+ RAM.

⚠️ License: SafeCircle Research License (SRL-1.0). Commercial use prohibited without written permission. Contact legal@safecircle.tech.

Available Variants

File	Target	Optimized For
`horizon-edge-e4b.litertlm`	General	CPU/GPU cross-platform
`horizon-edge-e4b_Google_Tensor_G5.litertlm`	Google Tensor G5	Pixel 10
`horizon-edge-e4b_intel_LNL.litertlm`	Intel Lunar Lake	Ultra 200V laptops
`horizon-edge-e4b_intel_PTL.litertlm`	Intel Panther Lake	Core Ultra 300
`horizon-edge-e4b_qualcomm_qcs8275.litertlm`	Qualcomm QCS8275	Dragonwing IQ8 (NPU)
`horizon-edge-e4b_qualcomm_sm8750.litertlm`	Qualcomm SM8750	Snapdragon 8 Elite
`horizon-edge-e4b-web.litertlm`	Web	WebGPU browsers

All variants share the same fine-tuned weights; they differ only in hardware-specific compilation.

Model Details

Property	Value
Base model	google/gemma-4-E4B-it
Fine-tuning	QLoRA — rank 128, alpha 256, all projection layers
Training data	1.6M synthetic conversations across 8 categories
Dataset	safecircleai/horizon-training-data
Hardware	NVIDIA H100 NVL (94 GB)
Training steps	15,000
Format	LiteRT-LM (.litertlm)
Model size	~3.7 GB

Risk Categories

Category	Description
`grooming`	Trust building, boundary testing, secrecy requests
`bullying`	Harassment, threats, cyberbullying
`sexual_content`	Explicit messages, inappropriate requests
`isolation`	Controlling behavior, network isolation
`personal_info`	Requests for identifying information
`platform_migration`	Moving to less monitored platforms
`threats`	Violent threats, dangerous challenges
`benign`	Safe, normal conversation

Usage

LiteRT-LM CLI

bash

uv tool install litert-lm

litert-lm run horizon-edge-e4b.litertlm \
    --prompt "Analyze this conversation: Child: hey, want to meet up? Don't tell your parents."

Android / iOS — LiteRT-LM SDK

Load the .litertlm file with the LiteRT-LM SDK. The model includes the tokenizer, system prompt, and chat template — no additional configuration required.

Python

python

from litert_lm import LiteRTLM

model = LiteRTLM("horizon-edge-e4b.litertlm")
result = model.generate(
    "Analyze this conversation:\nChild: hey\nOther: how old are you? where do you live?"
)
print(result)

Deployment Pattern

Incoming message
      │
      ▼
Horizon Edge 4B (on-device, LiteRT-LM)
      │
      ├── safe ──► No action
      │
      └── risk ──► Horizon Full (cloud API, full severity assessment)
                        │
                        ▼
                  Human moderator review

For the full server-side model, see safecircleai/horizon-full. For the smaller 2B variant, see safecircleai/horizon-edge-2b.

Citation

bibtex

@misc{horizon2026,
  title={Horizon: Child Safety Risk Detection via Fine-tuned LLMs},
  author={SafeCircle},
  year={2026},
  url={https://huggingface.co/safecircleai/horizon-edge-4b}
}