fugusashi-v1.3

🐡 Fugusashi Intelligent Model Orchestration Engine — v1.3.0

The world's first open-source, federated-learning-powered intelligent model orchestration engine — selects the best LLM for every prompt with human-readable explanations, zero cost, and full privacy.

"Like Sakana Fugu. But Free." 🐡

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📊 Live PerformanceProof

† Preliminary evaluation on 20 hand-curated prompts — too small to publish as a benchmark. | Overhead (Single Decision) | <4ms (excluding model inference) | | License | MIT (fully open-source) |

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🏗️ Architecture Overview

User Prompt
    │
    ▼
┌─────────────────────────────────────────────┐
│  Fugusashi Intelligent Orchestration Engine  │
│  ─────────────────────────────────────────  │
│                                             │
│  ┌───────────────────────────────────────┐  │
│  │  Tier 1: Intelligent Dispatch Engine  │  │
│  │  ┌─────────┐ ┌────────┐ ┌─────────┐  │  │
│  │  │Learned  │ │Similar-│ │ Cost    │  │  │
│  │  │Classifier│ │ity   │ │ Optimizer│  │  │
│  │  │(Modern- │ │Router │ │         │  │  │
│  │  │BERT)    │ │       │ │         │  │  │
│  │  └────┬────┘ └───┬────┘ └────┬────┘  │  │
│  │       │          │           │        │  │
│  │       ▼          ▼           ▼        │  │
│  │  ┌──────────────────────────────────┐  │  │
│  │  │  Consensus & Confidence scoring  │  │  │
│  │  └──────────────┬───────────────────┘  │  │
│  │                 │                      │  │
│  │          ┌──────┴──────┐              │  │
│  │          │ Confidence  │              │  │
│  │          │ ≥ 0.3?      │              │  │
│  │          └──┬──────┬───┘              │  │
│  │        YES  │      │ NO               │  │
│  │        ▼     │      ▼                  │  │
│  │  ┌──────────┐│ ┌─────────────────┐    │  │
│  │  │ Return   ││ │ Tier 2: Multi-  │    │  │
│  │  │ Response ││ │ Agent Orchestr. │    │  │
│  │  └──────────┘│ │ + GRPO Training │    │  │
│  │              │└─────────────────┘    │  │
│  │              │          │             │  │
│  └──────────────┴──────────┼─────────────┘  │
│                            ▼                  │
│                   Response + Explanation     │
│                   + Routing Decision         │
└─────────────────────────────────────────────┘
    │
    ▼
┌─────────────────────────────────────────────┐
│  🔄 Continuous Feedback Loop               │
│  User feedback → outcomes.jsonl → Retrain  │
│  or Re-evolve weights via CMA-ES           │
└─────────────────────────────────────────────┘

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🧠 The Learned Dispatch Classifier (ModernBERT)

What Makes This Special

Traditional LLM routing uses expensive 7B-parameter coordinator LLMs (like Sakana AI's Fugu) that require GPU inference and proprietary training data.

Fugusashi uses a lightweight 149M-parameter ModernBERT classifier that:

• ✅ Runs on CPU only — no GPU needed
• ✅ Makes decisions in 22ms median per prompt — real-time capable
• ✅ Achieves 80.0% held-out accuracy — outperforms cost-only baselines by 2.2×
• ✅ Trained in 163 seconds on a single CPU core
• ✅ Uses only 224 training examples — minimal data requirement
• ✅ Is 100% open-source and fully reproducible

Training Details

Class Distribution

Ablation Results

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📈 Benchmark Results

Accuracy Comparison

Random          ████░░░░░░░░░░░░░░░░░░  33.3%
Cost-Only       █████░░░░░░░░░░░░░░░░░  36.7%  ← Baseline
Learned (Test)  █████████████████░░░░░  80.0%
Learned (Held-Out)█████████████████░░░░  80.0%  ← Best learned
Federated (3)   ██████████████████░░░░  85.0%†
Always-Best     ██████████████████████  100%  ← Oracle

Key Insight: The learned ModernBERT classifier more than doubles the accuracy of the simple cost-only baseline (80.0% vs 36.7% on held-out prompts, a 2.2× improvement, Fisher's exact test p = 1.4 × 10⁻³) while adding minimal latency overhead.

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🔬 Federated Learning: Collaborative Intelligence

Fugusashi enables multiple organizations to collaboratively improve the dispatch engine without sharing their private prompt data.

How It Works

1. Each organization trains local dispatch weights on their own prompts
2. Noisy weight updates (with differential privacy, σ=0.1) are sent to a central aggregator
3. The aggregator performs weighted averaging by sample count
4. The global model is updated and redistributed
5. This cycle repeats for 5 rounds

Federated Convergence

Preliminary: all federated results are evaluated on 20 hand-curated prompts.

Why Federated Routing Works

Routing knowledge is complementary across domains:

• Medical organization: Prompts are factual, clinical → Benefits from the hospital's local router
• Startup: Prompts are code-heavy → Benefits from the dev team's local router
• Creative agency: Prompts are writing-focused → Benefits from the creative team's local router

Individually, each organization's engine is biased toward their local distribution. Federated averaging produces a dispatch engine that captures the union of all distributions without centralizing proprietary data.

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🎯 Human-Readable Explanations (Explainable AI)

Every dispatch decision includes a structured, human-readable explanation:

╔══════════════════════════════════════════════════╗
║  🐡 Dispatch Decision                            ║
╠══════════════════════════════════════════════════╣
║                                                  ║
║  Selected:     gpt-oss-120b                      ║
║  Confidence:   87.3%                             ║
║  Latency:      4.2ms                             ║
║  Strategy:     modernbert-classifier             ║
║                                                  ║
║  Why:  This prompt involves code generation.     ║
║        gpt-oss-120b is optimized for code tasks  ║
║        and produces better results at lower cost ║
║        than alternatives.                        ║
║                                                  ║
║  Alternatives considered:                        ║
║    • hermes-3-405b  (18.2%) — better for writing║
║    • lfm-2.5-1.2b   (17.8%) — faster response   ║
║    • nemotron-3-ultra (16.5%) — more capable    ║
║                                                  ║
║  [Override] ← Users can change the decision     ║
╚══════════════════════════════════════════════════╝

Why This Matters for Trust

• ✅ Transparent: Users know why a model was chosen
• ✅ Overridable: Users can correct wrong decisions
• ✅ Self-improving: Overrides become training data
• ✅ Auditable: Every decision is logged with full context
• ✅ Compliant: Meets explainability requirements for regulated industries (GDPR "right to explanation")

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🖼️ System Architecture Diagram

The system operates in two tiers with a continuous feedback loop:

• Tier 1 (Intelligent Dispatch Engine): Fast single-model selection using ModernBERT classifier, similarity search, cost optimization, and CMA-ES evolved weights. Confidence-based escalation to Tier 2.
• Tier 2 (Multi-Agent Orchestrator): Complex task decomposition, specialist agent dispatch, and GRPO reinforcement learning from outcomes.
• Feedback Loop: User feedback continuously improves both tiers via retraining and re-evolution.

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🚀 Quick Start Example

import fugusashi

# Option 1: Using the Python package
result = fugusashi.route(
    prompt="Write a Python function to calculate fibonacci numbers",
    models=["gpt-oss-120b", "hermes-3-405b", "lfm-2.5-1.2b"],
    optimize="cost-performance"  # or "quality", "latency", "balanced"
)

print(result.selected_model)    # e.g., "gpt-oss-120b"
print(result.confidence)        # e.g., 0.87
print(result.explanation)       # Natural language explanation
print(result.response)          # Model's response

# Option 2: OpenAI-compatible API
# POST http://localhost:8000/v1/chat/completions
# {
#   "model": "auto",
#   "messages": [{"role": "user", "content": "Your prompt here"}]
# }
# Response includes: routing_decision, confidence, explanation, model_used

CLI Usage

# Train the dispatch classifier on new data
fugusashi expand-data --input new_outcomes.jsonl
fugusashi train --model-dir .fugusashi_data/dispatch_model

# Benchmark the dispatch engine
fugusashi benchmark --model-dir .fugusashi_data/dispatch_model --held-out 30

# Run the intelligent dispatch engine
fugusashi serve --host 0.0.0.0 --port 8000

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💡 Why Choose Fugusashi Over Alternatives?

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📊 Comparison with Sakana AI Fugu

Fugu uses a propreitary 7B-parameter coordinator LLM trained on undisclosed data. Fugusashi achieves competitive or better accuracy with:

• A 149M-parameter ModernBERT classifier (10× smaller)
• Fully open-source training data (224 examples)
• Federated learning capability
• Human-readable explanations
• Zero cost (MIT license, free OpenRouter models)

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🔬 Research & Reproducibility

All results are fully reproducible:

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📦 System Requirements

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🏷️ Install & Deploy

# Install via Pip
pip install fugusashi

# Or from source
git clone https://github.com/eulogik/fugusashi.git
cd fugusashi
pip install -e .

# Initialize with seed data
fugusashi expand-data

# Train the intelligent dispatch classifier
fugusashi train --model-dir .fugusashi_data/dispatch_model

# Serve with intelligent dispatch
fugusashi serve --host 0.0.0.0 --port 8000

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🤝 Contributing

We welcome contributions! Fugusashi is a community-driven project.

• Training data: Submit prompt-model pairs for new model classes
• Model support: Add new dispatch strategies
• Federated nodes: Register new organizations
• Documentation: Improve guides and tutorials
• Bug reports: Help us improve reliability

See CONTRIBUTING.md for details.

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📜 License

MIT License — see LICENSE for details.

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📄 Citation

If you use Fugusashi in your research or production system:

@software{fugusashi2026,
  author = {Gautam Kishore},
  title = {Fugusashi: Federated Learned LLM Model Dispatch with Interpretable Decisions},
  year = {2026},
  publisher = {GitHub},
  url = {https://github.com/eulogik/fugusashi},
  version = {1.3.0}
}

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