Instructions to use tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF with libraries, inference providers, notebooks, and local apps. Follow these links to get started.

Notebooks
Google Colab
Kaggle
Local Apps Settings

How to use tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF with llama.cpp:

Install (macOS, Linux)

curl -LsSf https://llama.app/install.sh | sh
# Start a local OpenAI-compatible server with a web UI:
llama serve -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S
# Run inference directly in the terminal:
llama cli -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

Install from WinGet (Windows)

winget install llama.cpp
# Start a local OpenAI-compatible server with a web UI:
llama serve -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S
# Run inference directly in the terminal:
llama cli -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

Use pre-built binary

# Download pre-built binary from:
# https://github.com/ggerganov/llama.cpp/releases
# Start a local OpenAI-compatible server with a web UI:
./llama-server -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S
# Run inference directly in the terminal:
./llama-cli -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

Build from source code

git clone https://github.com/ggerganov/llama.cpp.git
cd llama.cpp
cmake -B build
cmake --build build -j --target llama-server llama-cli
# Start a local OpenAI-compatible server with a web UI:
./build/bin/llama-server -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S
# Run inference directly in the terminal:
./build/bin/llama-cli -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

Use Docker

docker model run hf.co/tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

LM Studio
Jan

vLLM

How to use tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF with vLLM:

Install from pip and serve model

# Install vLLM from pip:
pip install vllm
# Start the vLLM server:
vllm serve "tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF"
# Call the server using curl (OpenAI-compatible API):
curl -X POST "http://localhost:8000/v1/chat/completions" \
	-H "Content-Type: application/json" \
	--data '{
		"model": "tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF",
		"messages": [
			{
				"role": "user",
				"content": [
					{
						"type": "text",
						"text": "Describe this image in one sentence."
					},
					{
						"type": "image_url",
						"image_url": {
							"url": "https://cdn.britannica.com/61/93061-050-99147DCE/Statue-of-Liberty-Island-New-York-Bay.jpg"
						}
					}
				]
			}
		]
	}'

Use Docker

docker model run hf.co/tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

Ollama
How to use tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF with Ollama:
```
ollama run hf.co/tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S
```
Unsloth Desktop

How to use tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF with Pi:

Start the llama.cpp server

# Install llama.cpp:
brew install llama.cpp
# Start a local OpenAI-compatible server:
llama serve -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

Configure the model in Pi

# Install Pi:
npm install -g @earendil-works/pi-coding-agent
# Add to ~/.pi/agent/models.json:
{
  "providers": {
    "llama-cpp": {
      "baseUrl": "http://localhost:8080/v1",
      "api": "openai-completions",
      "apiKey": "none",
      "models": [
        {
          "id": "tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S"
        }
      ]
    }
  }
}

Run Pi

# Start Pi in your project directory:
pi

Docker Model Runner
How to use tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF with Docker Model Runner:
```
docker model run hf.co/tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S
```

Lemonade

How to use tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF with Lemonade:

Pull the model

# Download Lemonade from https://lemonade-server.ai/
lemonade pull tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

Run and chat with the model

lemonade run user.Swift1.5-Qwen3.8-Flash-Next-GGUF-IQ3_S

List all available models

lemonade list

Hermes Agent

How to use tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF with Hermes Agent:

Start the llama.cpp server

# Install llama.cpp:
brew install llama.cpp
# Start a local OpenAI-compatible server:
llama serve -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

Configure Hermes

# Install Hermes:
curl -fsSL https://hermes-agent.nousresearch.com/install.sh | bash
hermes setup
# Point Hermes at the local server:
hermes config set model.provider custom
hermes config set model.base_url http://127.0.0.1:8080/v1
hermes config set model.default tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

Run Hermes

hermes

Atomic Chat

OpenClaw

How to use tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF with OpenClaw:

Start the llama.cpp server

# Install llama.cpp:
brew install llama.cpp
# Start a local OpenAI-compatible server:
llama serve -hf tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S

Configure OpenClaw

# Install OpenClaw:
npm install -g openclaw@latest
# Register the local server and set it as the default model:
openclaw onboard --non-interactive --mode local \
  --auth-choice custom-api-key \
  --custom-base-url http://127.0.0.1:8080/v1 \
  --custom-model-id "tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF:IQ3_S" \
  --custom-provider-id llama-cpp \
  --custom-compatibility openai \
  --custom-text-input \
  --accept-risk \
  --skip-health

Run OpenClaw

openclaw agent --local --agent main --message "Hello from Hugging Face"

Swift 1.5 Qwen3.8-Flash-Next

Quantized version of ukisai/Swift1.5-Qwen3.8-Flash-Next using recipe from ISTA-DASLab/Qwen3.8-Flash-Next-GSQ-RCO-GGUF:IQ3_S and imatrix file from unsloth/Qwen3.8-Flash-Next-GGUF.

MTP is included, quantized to Q4_K_M using the same recipe from unsloth/Qwen3.8-Flash-Next-GGUF.

Small changes to the GSQ-RCO recipe:

Weight	Quant
`token_embd`	Q6_K
`blk.*.ffn_down_shexp`	Q8_0
`per_layer_token_embd`	BF16 (lazy load on disk, ~96GiB)

Website • Learn more • GGUF • GSQ-RCO GGUF • Evaluation • Enterprise licensing

Swift 1.5 Qwen3.8-Flash-Next

Swift 1.5 Qwen3.8-Flash-Next is UkisAI's reasoning-efficient derivative of Qwen3.8-Flash-Next. It uses 63.4% fewer thinking tokens, with a 1.8x speed up while keeping the accuracy loss <1% vs base on xhigh.

Demo

We gave base Qwen3.8-Flash-Next and Swift 1.5 Qwen3.8-Flash-Next the same prompt:

Create a 3D endless runner that has the fast, playful feel of Subway Surfers, but make the world and characters your own. I want to run through a lively place, dodge things, collect rewards, and feel the pace build the longer I survive. Make it fun to control and visually memorable. Use your judgment for the setting, mechanics, and little details that make it feel like a real game. Build it so I can launch and play it locally, then tell me how to run it.

Try the game yourself here: https://ukisai.com/swift-games/flash-next

Base Qwen3.8-Flash-Next took 8 minutes 52 seconds to build its game. Swift 1.5 took 4 minutes 56 seconds.

Training approach

We made Swift Flash Next efficient by figuring out which tokens were linked to pathological overthinking and penalizing them without "attacking" the reasoning length directly then regained the accuracy with RL and OPD, leading to "compressed" token usage while maintaining accuracy.

Swift 1.5 produces shorter reasoning traces. In our testing, we also observe fewer overthinking errors.

This release also features our previously mentioned post-training methods adapted specifically for coding and long-horizon agent work such as personal agents, terminal use and software engineering.

Our training data is viewable here: https://huggingface.co/datasets/ukisai/Qwen3.8-27B-multi-turn-agent-sft albeit it is not used out of the box, but rather re-sampled, turned into proper RL environments etc.

Evaluation

All scores compare the Qwen3.8-Flash-Next BF16 base with the Swift 1.5 BF16 checkpoint. Token columns report thinking tokens, except Terminal-Bench 2.1, which reports total generated output tokens.

Benchmark	Score		Mean tokens			Median tokens
Benchmark	Base	Swift 1.5	Base	Swift 1.5	Reduction	Reduction
General reasoning
GPQA-Diamond	89.80%	89.60%	17,683	7,823	↓ 55.8%	↓ 63.4%
MMLU-Pro	87.75%	87.20%	3,528	1,519	↓ 57.0%	↓ 24.0%
C-Eval	93.27%	93.60%	1,048	586	↓ 44.1%	↓ 7.1%
IFBench	73.20%	70.13%	8,310	4,411	↓ 46.9%	↓ 55.6%
Mathematics
AIME 2026	98.67%	96.67%	23,015	15,806	↓ 31.3%	↓ 51.1%
HMMT (Nov 2025)	98.00%	97.33%	25,487	16,530	↓ 35.1%	↓ 54.7%
Multimodal
ERQA	70.80%	69.30%	4,036	1,788	↓ 55.7%	↓ 47.7%
Coding
LiveCodeBench v6	88.40%	90.39%	17,833	9,849	↓ 44.8%	↓ 52.0%
Agentic coding
Terminal-Bench 2.1*	67.64%	69.66%	40,591	45,428	↑ 11.9%	↓ 17.9%

* Note: Terminal-Bench 2.1 results for Flash-Next are not an apples-to-apples comparison with Swift 1.5 27B. Flash-Next used default task timeouts, leading to lower scores for both the base model and Swift Flash-Next.

How to reproduce

Serving: BF16 · Qwen3 reasoning parser · context 262,144 · thinking xhigh · MTP disabled.
Sampling: temperature 1.0 · top_p 0.95 · top_k 20 · min_p 0 · presence_penalty 0 · repetition_penalty 1.
Benchmarks: five seeds (0–4) for the seeded question benchmarks; Terminal-Bench 2.1 uses five attempts per task. LiveCodeBench is full release v6 mean pass@1 over seeds.
Terminal-Bench 2.1: Harbor 0.20.0 / Terminus-2 2.0.0, pinned 89-task dataset, JSON parser, interleaved thinking, temperature 1, top_p 1, 131,072-token server context, 3,600-second LLM call timeout and native per-task limits. Swift used concurrency 8; its context-recovery fix was applied during the run.

Benchmark	Output cap
GPQA-Diamond	100,000
MMLU-Pro	100,000
C-Eval	16,384
IFBench	81,920
AIME 2026	250,000
HMMT Nov 2025	250,000
ERQA	100,000
LiveCodeBench v6	100,000

Efficiency across reasoning efforts

GPQA-Diamond at each reasoning_effort setting, Swift 1.5 against the base at the same setting:

Reasoning effort	Score		Mean tokens			Median tokens
Reasoning effort	Base	Swift 1.5	Base	Swift 1.5	Reduction	Reduction
Xhigh	89.80%	89.60%	17,683	7,823	↓ 55.8%	↓ 63.4%
Medium	86.36%	83.74%	4,157	2,483	↓ 40.3%	↓ 25.1%
Low	87.17%	84.75%	3,966	2,645	↓ 33.3%	↓ 19.7%

At xhigh, Swift 1.5 trails base by 0.20 percentage points while using 55.8% fewer mean and 63.4% fewer median thinking tokens. Medium and low save tokens but also lose 2.62 and 2.42 percentage points respectively.

Quantized models

Format	Repository	Runtime
AWQ INT4 (W4A16)	Swift-1.5-Qwen3.8-Flash-Next-W4A16-AWQ	vLLM (`compressed-tensors`)
AutoRound INT4 (W4A16)	Swift-1.5-Qwen3.8-Flash-Next-W4A16-AutoRound	vLLM (`auto-round`)
NVFP4	Swift-1.5-Qwen3.8-Flash-Next-NVFP4	NVIDIA Blackwell
GGUF	Swift-1.5-Qwen3.8-Flash-Next-GGUF	llama.cpp
GSQ-RCO GGUF (compact 2–3 bit)	Swift-1.5-Qwen3.8-Flash-Next-GSQ-RCO-GGUF	llama.cpp

How to use

The BF16 checkpoint is about 360 GB, so it needs a multi-GPU node. We evaluated it with tensor parallelism 8.

GGUF download

The GGUF version is available for compatible llama.cpp-based runtimes. For the smallest files, use the GSQ-RCO GGUF version: 66.5–76 GB mixed-precision quants refined for Swift 1.5 Flash-Next.

UkisAI API

Swift 1.5 Flash-Next is served through an OpenAI-compatible API at https://ukisai.com/api/flash-next/v1. It is free for research purposes and needs no API key. The model id is flash-next.

from openai import OpenAI

client = OpenAI(base_url="https://ukisai.com/api/flash-next/v1", api_key="none")
response = client.chat.completions.create(
    model="flash-next",
    messages=[{"role": "user", "content": "Explain speculative decoding in two sentences."}],
)
print(response.choices[0].message.content)

curl https://ukisai.com/api/flash-next/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{"model": "flash-next", "messages": [{"role": "user", "content": "Hello, Swift."}]}'

vLLM

Use a vLLM build with Qwen3.8-Flash-Next support:

vllm serve ukisai/Swift-Qwen3.8-Flash-Next \
  --dtype bfloat16 \
  --tensor-parallel-size 8 \
  --max-model-len 262144 \
  --reasoning-parser qwen3 \
  --enable-auto-tool-choice \
  --tool-call-parser qwen3_xml \
  --trust-remote-code \
  --port 8000

Reasoning effort is set per request through the chat template, for example "chat_template_kwargs": {"reasoning_effort": "low"}. xhigh is the default; medium and low are also supported.

SGLang

Alternatively, use an SGLang build with Qwen3.8-Flash-Next support, such as the lmsysorg/sglang:qwen38flashnext image:

sglang serve \
  --model-path ukisai/Swift-Qwen3.8-Flash-Next \
  --tp 8 \
  --context-length 262144 \
  --mem-fraction-static 0.85 \
  --reasoning-parser qwen3 \
  --tool-call-parser qwen3_coder \
  --port 8000

Adjust tensor parallelism and context length to your GPU memory. See the base model's vLLM recipe and SGLang cookbook for installation and hardware-specific settings.

Transformers

Use a Transformers release with Qwen3.8-Flash-Next support:

import torch
from transformers import AutoModelForImageTextToText, AutoProcessor

model_id = "ukisai/Swift-Qwen3.8-Flash-Next"
processor = AutoProcessor.from_pretrained(model_id)
model = AutoModelForImageTextToText.from_pretrained(
    model_id,
    torch_dtype=torch.bfloat16,
    device_map="auto",
)

To extend the context to 1,000,000 tokens, follow the YaRN settings on the Qwen3.8-Flash-Next model card.

Optional MTP decoding

The checkpoint includes the base model's one-layer MTP head. To enable self-speculative decoding, append the corresponding flags to the server command above:

# vLLM
--speculative-config '{"method":"mtp","num_speculative_tokens":1}'

# SGLang
--speculative-algorithm NEXTN --speculative-num-steps 3 \
  --speculative-eagle-topk 1 --speculative-num-draft-tokens 4

The benchmark scores above were measured without MTP.

License and access

Swift 1.5 Qwen3.8-Flash-Next is a derivative of Qwen3.8-Flash-Next (Copyright (c) 2026 Qwen, Qwen Community License 1.0). UkisAI's contribution, including the adapted weights, is licensed under the Swift Open License v1.0. See NOTICE for the change notice and attribution details.

Personal, research, educational, evaluation, and commercial use of the Swift contribution are free for individuals and organizations with gross annual revenue, including affiliates, of up to US$1,000,000. Above that threshold, commercial use requires a separate Swift Enterprise License. Contact UkisAI for terms.

The base model's terms still apply to it. Under the Qwen Community License 1.0, organizations that run a Model-as-a-Service or AI Work Assistant business need a separate license from Qwen before any commercial use, and products above 100 million monthly active users or US$20 million monthly revenue must prominently display the model name. Nothing in the Swift Open License limits your rights in Qwen3.8-Flash-Next itself under the Qwen Community License.

Citation

@misc{swift-qwen3.8-flash-next,
  title  = {Swift 1.5 Qwen3.8-Flash-Next},
  author = {UkisAI},
  year   = {2026},
  url    = {https://huggingface.co/ukisai/Swift-Qwen3.8-Flash-Next}
}

Acknowledgements

We acknowledge the NVIDIA Innovation Lab, Amazon Web Services, and Google Cloud for providing compute credits and infrastructure support for Swift's development, training, and evaluation.

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GGUF

Model size

180B params

Architecture

qwen4exp

Hardware compatibility

3-bit

Model tree for tomngdev/Swift1.5-Qwen3.8-Flash-Next-GGUF

Base model

Qwen/Qwen3.8-Flash-Next

Finetuned

ukisai/Swift1.5-Qwen3.8-Flash-Next

Quantized

(42)

this model