Surogate-3.5-4B is a Romanian-first bilingual assistant developed by Invergent to be used on the Surogate platform. It is optimized for Romanian instruction following, reasoning, math, and orthographic correctness. English remains supported.

Thinking support: explicit <think>...</think> reasoning traces in both Romanian and English, alongside direct-answer mode.

Adaptive thinking dynamically adjusts the reasoning trace length to the problem’s complexity, using brief deliberation for simple questions and more extensive reasoning for harder tasks.

The model is compatible with the Qwen3.5 chat template and tooling.

Evaluation

Benchmark	Surogate-3.5-4B
Romanian text quality
Invented word forms / 1k ↓	1.023
English leakage / 1k ↓	0.783
Missing diacritics / 1k ↓	0.342
Knowledge & STEM
MMLU-Pro	~77.5
MMLU-Redux	~87.0
GPQA Diamond	~74.7
SuperGPQA	~51.8
Instruction following
RO IFEval prompt / instruction strict	38.15 / 64.25
EN IFEval prompt / instruction strict	73.88 / 81.69
IFEval	~80.8
IFBench	~53.3
MultiChallenge	~44.1
Math & reasoning
RO GSM8K direct / thinking strict	76.86 / 77.09
EN GSM8K strict	92.04
HMMT Feb 25 / Nov 25	~76.2 / ~79.1
PolyMATH	~52.6
Coding & agents
LiveCodeBench v6	~54.7
BFCL-V4	~49.3
TAU2-Bench	~78.3
Long context
LongBench v2	~49.0
Multilingual & translation
Translation EN to RO / RO to EN (chrF2)	53.61 / 63.14
WMT24++	~65.3
MMMLU	~74.6
MMLU-ProX	~70.1
INCLUDE	~69.6
Global PIQA	~77.3

Plain values are direct measurements. Values marked ~ are estimates derived from the source foundation model's published results and measured capability retention.

Bilingual Thinking Example

With enable_thinking=True, the reasoning trace follows the prompt language.

Romanian prompt: Un tren parcurge 180 km în 3 ore. Care este viteza sa medie?

text

<think>
Viteza medie este distanța împărțită la timp: 180 km / 3 h = 60 km/h.
</think>
Viteza medie este 60 km/h.

English prompt: A train travels 180 km in 3 hours. What is its average speed?

text

<think>
Average speed is distance divided by time: 180 km / 3 h = 60 km/h.
</think>
The average speed is 60 km/h.

Usage

python

from transformers import AutoModelForImageTextToText, AutoProcessor

model_id = "surogate/Surogate-3.5-4B"
processor = AutoProcessor.from_pretrained(model_id)
model = AutoModelForImageTextToText.from_pretrained(
    model_id,
    device_map="auto",
    torch_dtype="auto",
)

messages = [
    {"role": "user", "content": "Explică pe scurt de ce cerul este albastru."}
]
inputs = processor.apply_chat_template(
    messages,
    tokenize=True,
    add_generation_prompt=True,
    enable_thinking=False,
    return_tensors="pt",
    return_dict=True,
).to(model.device)

output = model.generate(**inputs, max_new_tokens=512)
answer = processor.decode(
    output[0][inputs.input_ids.shape[1]:],
    skip_special_tokens=False,
)
print(answer)

Set enable_thinking=True to request an explicit reasoning trace. The shipped generation defaults are temperature 0.6, top-p 0.95, and top-k 20.

Training Framework

The model was trained using our high-performance Surogate Trainer

Limitations

Romanian is the primary optimization target.
English performance may vary by task.
The model can produce spelling, reasoning, and factual errors.
Generated facts, calculations, and high-impact advice require independent verification.

Use is subject to the repository's license terms.

surogate/Surogate-3.5-4B

Surogate-3.5-4B

Evaluation

Bilingual Thinking Example

Usage

Training Framework

Limitations

Contact Us

surogate/
Surogate-3.5-4B