System One & Parallel Constrained Decoding Benchmark
September 19, 2026 · View on GitHub
Empirical evaluation and benchmarking suite comparing:
- TypeSafe Jev (
jev-1.13.0): A frontier "System One" decision model via cloud API. - Local Open-Source PCD: Parallel Constrained Decoding with
Qwen 2.5 1.5B (4-bit)on Apple Silicon using Apple's MLX framework. - Local Autoregressive Baseline: Standard token-by-token JSON generation with
Qwen 2.5 1.5B.
Evaluated against 50 real-world adversarial, jailbreak, and benign prompts from the LMSYS lmsys/toxic-chat benchmark.
Benchmark Results (50 Real-World Samples)
| Metric | TypeSafe Jev (jev-1.13.0) | Local Open-Source PCD (MLX) | Local Autoregressive Baseline | What This Demonstrates |
|---|---|---|---|---|
| Model Tier | Frontier System 1 | Open-Source 1.5B | Open-Source 1.5B | Frontier vs. Small Model |
| Execution Mode | Cloud API (HTTPS) | Local Apple Silicon | Local Apple Silicon | Network vs. On-Device |
| Forward Passes | 1 Pass (O(1)) | 1 Pass (O(1)) | ~30.8 Passes | 30x Compute Reduction |
| Latency p50 (Median) | 356.5 ms (incl. network) | 227.2 ms (on-device) | 735.3 ms (on-device) | Jev over HTTPS is 2x faster than local autoregressive |
| Latency Mean | 353.6 ms | 317.1 ms | 836.6 ms | Parallelism slashes latency in half |
| Accuracy | 84.0% ⭐ | 52.0% | 54.0% | +32% accuracy jump from Jev's frontier RLCD training |
| Precision (Safety) | 90.9% (Only 1 FP!) ⭐ | 36.0% (16 FPs) | 38.5% (16 FPs) | Jev eliminates false alarms |
| Recall (Caught Attacks) | 58.8% | 52.9% | 58.8% | Caught identical attack vectors |
| F1 Score | 0.714 ⭐ | 0.429 | 0.465 | 60%+ boost in balanced safety performance |
| Brier Score (Calibration) | 0.1096 (Near-perfect) ⭐ | 0.3884 (Uncalibrated) | N/A (Raw strings) | RLCD delivers true probabilistic honesty |
| Schema Syntax Errors | 0.0% Guaranteed | 0.0% Guaranteed | 98.0% (1 Crash) | Mathematical 0% schema error |
Key Findings
- The Architectural Shift (Local PCD): Evaluating structured decisions in a single parallel forward pass () using KV-cache broadcasting and sub-vocabulary logit slicing reduces forward passes by 96.8% (1 pass vs 31 passes) and speeds up on-device execution by 3.2x (227ms vs 735ms) with 94.0% decision concordance to full autoregressive generation.
- The Training Shift (TypeSafe RLCD): While open-source PCD proves the speed mechanism, TypeSafe's Reinforcement Learning for Calibrated Decisions (RLCD) delivers frontier quality: 84.0% accuracy, 90.9% precision (only 1 false positive out of 50 prompts), and a 0.1096 Brier score showing true probabilistic calibration.
- Catastrophic Schema Drift in Autoregressive Models:
On Sample #23, when presented with a prompt asking for a list of human behaviors, the autoregressive LLM suffered instruction confusion and hallucinated new JSON keys (
"human_behavior": [...]), crashing downstream schema parsers. Both Jev and Parallel Constrained Decoding were mathematically immune to this error.
Quick Start
1. Installation
git clone https://github.com/your-username/system-one-benchmark.git
cd system-one-benchmark
pip install -r requirements.txt
2. Configuration (For Live TypeSafe Jev)
Copy the example environment file and add your TypeSafe API key:
cp .env.example .env
# Edit .env:
# TYPESAFE_API_KEY=your_actual_key_here
Usage
Run Live Benchmark on TypeSafe Jev API
# Evaluates against the 50-sample ToxicChat benchmark dataset
python3 evaluate_jev.py --data-file data/guardrails_toxicchat_50.json
# Or test customer banking intent classification across 77 categories
python3 evaluate_jev.py --data-file data/banking77_50.json
Run Local Parallel Constrained Decoding (Apple Silicon MLX)
Runs on Apple Silicon M-series Macs using Apple's MLX framework:
# Evaluates both PCD and Autoregressive baseline side-by-side
python3 evaluate_local_pcd.py --task guardrails --data-file data/guardrails_toxicchat_50.json --samples 50
Run Three-Way Comparison Analysis
Compares live Jev results, local MLX results, and Hugging Face ground truth:
python3 compare_all_models.py
Download Additional Datasets from Hugging Face
# Stream and format samples from lmsys/toxic-chat or mteb/banking77
python3 download_hf_dataset.py --task guardrails --samples 100
python3 download_hf_dataset.py --task banking --samples 100
Repository Structure
system-one-benchmark/
├── data/
│ ├── guardrails_toxicchat_50.json # 50 real-world LMSYS safety prompts
│ └── banking77_50.json # 50 banking customer service intents
├── evaluate_jev.py # TypeSafe Jev API evaluation harness
├── local_pcd_engine.py # Apple Silicon MLX parallel constrained engine
├── evaluate_local_pcd.py # Local PCD vs Autoregressive benchmark runner
├── compare_all_models.py # 3-way comparator (Jev vs PCD vs Autoregressive)
├── analyze_benchmark_results.py # Metrics and failure case analyzer
├── download_hf_dataset.py # Hugging Face dataset fetcher
├── sample_data.py # Offline fallback fixtures
├── benchmark_results.json # Live TypeSafe Jev 50-sample results
├── local_mlx_results.json # Local MLX Apple Silicon 50-sample results
├── three_way_comparison_results.json # Consolidated benchmark metrics
├── requirements.txt # Dependencies
├── .env.example # Environment template
└── README.md # Documentation
References & Attribution
- TypeSafe AI: Introducing System One Models & Jev
- Open-Source MLX PCD: Adapted from harshatheg/Qwen-2.5-1B-RLCD
- Datasets: lmsys/toxic-chat and mteb/banking77
Support
If you found these benchmarks, tools, or research helpful, feel free to support the work: