Wendi 2B

Fast, instruction-aware decisions from a compact 2B model.

Wendi is a System One decision model fine-tuned from Qwen3.5-2B. Given evidence, a decision criterion and a small set of alternatives, it selects an answer through a single next-token prediction.

Use cases include workflow routing, next-action selection, instruction-sensitive classification, evidence checks, tool-use analysis and email classification.

This repository contains the standalone merged BF16 checkpoint for wendi-2b.

Usage

Deploy with a recent SGLang or vLLM build supporting Qwen3.5. Install the engine for your GPU platform using its linked installation guide, then run one of the commands below from the downloaded model directory. Replace . with wenzani/Wendi-2B to load from Hugging Face instead.

SGLang

Installation guide

python -m sglang.launch_server \
  --model-path . \
  --served-model-name wendi-2b \
  --dtype bfloat16 \
  --tp-size 1 \
  --host 127.0.0.1 \
  --port 8000

vLLM

Installation guide · Qwen3.5 serving guide

vllm serve . \
  --served-model-name wendi-2b \
  --dtype bfloat16 \
  --tensor-parallel-size 1 \
  --language-model-only \
  --host 127.0.0.1 \
  --port 8000

Both expose an OpenAI-compatible API at http://127.0.0.1:8000/v1, with model name wendi-2b. For decision requests, set chat_template_kwargs to {"enable_thinking": false}, use uppercase option letters, and score the next token over the allowed alternatives. The configured context is 262,144 tokens; adjust SGLang's --context-length or vLLM's --max-model-len to fit your available memory.

Benchmarks

Internal held-out evaluations of Wendi 2B in BF16, using Transformers and restricted next-token option scoring on an AMD Radeon Pro W7900. All values below are accuracy; counts show correct answers out of evaluated examples. These measurements use the evaluation harness, not the serving engines above.

General decisions

Category Correct / examples Accuracy
Banking intent 131 / 160 81.88%
Contract evidence 101 / 160 63.12%
Emotion classification 122 / 160 76.25%
Multilingual intent 123 / 180 68.33%
Numeric reasoning 48 / 100 48.00%
Qualitative reasoning 94 / 100 94.00%
State tracking 93 / 100 93.00%
Temporal and numeric reasoning 33 / 60 55.00%
Workflow rules 70 / 100 70.00%
Overall 815 / 1,120 72.77%

Behavior analysis

Category Correct / examples Accuracy
Event order 57 / 60 95.00%
Latency checks 57 / 60 95.00%
Token-count metadata 53 / 60 88.33%
Tool-call detection 79 / 102 77.45%
Tool-call counting 74 / 99 74.75%
Exact user quotations 73 / 99 73.74%
Overall 393 / 480 81.88%

Email classification

Category Correct / examples Accuracy
Natural-email phishing 135 / 160 84.38%
Synthetic phishing contrasts 115 / 120 95.83%
Spam classification 76 / 80 95.00%

Instruction following

Two internal holdouts: the established suite has 120 examples per category; the additional scenario suite has 40 per category.

Category Established suite Additional scenarios
Constraint selection 66.67% 77.50%
Evidence scope 93.33% 92.50%
Exception policies 86.67% 90.00%
Numeric policies 62.50% 57.50%
Rule precedence 74.17% 87.50%
Untrusted-content handling 99.17% 100.00%
Overall 80.42% (579 / 720) 84.17% (202 / 240)

Training

Wendi was trained with supervised fine-tuning followed by hybrid GRPO, combining decision rewards, supervised loss and KL regularization. Language-only rank-16 LoRA adapters were merged into the BF16 checkpoint.

The final training stage used 4,000 examples over 1,000 optimizer updates:

Component Examples
General-decision replay 1,600
Behavior analysis 800
Email classification 800
Instruction following 800

Data combines published datasets, synthetic tool-use conversations and original procedural tasks. Sources include:

License

Apache-2.0. Wendi is a modified derivative of Qwen3.5-2B, incorporating supervised and hybrid-RL language-model updates. The upstream license is included in LICENSE. Training sources retain their original licenses and attribution.

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