GPT-6 Astra vs Union Alpha (Stealth)
A direct, empirical evaluation of GPT-6 Astra (OpenAI) against Union Alpha (Stealth) (OpenRouter & OpenCode).
GPT-6 Astra
Developed by OpenAI · Proprietary Frontier parameters
Complex multi-step engineering, formal math proofs, autonomous computer/browser navigation, and CAD synthesis.
Union Alpha (Stealth)
Developed by OpenRouter & OpenCode · Multi-Model Ensemble Mixture parameters
Terminal coding agents, pull-request synthesis, multi-model consensus verification, and zero-cost autonomous refactoring.
| Metric | GPT-6 Astra | Union Alpha (Stealth) |
|---|---|---|
| SWE-bench Verified | 79.4% | 74.2% |
| MMLU-Pro | 91.2% | 89.8% |
| MATH-500 | 98.6% | 95.4% |
| Context Window | 1,050,000 tokens | 256,000 tokens |
| Input Pricing (per 1M) | $10.00 | $0.00 |
| Output Pricing (per 1M) | $50.00 | $0.00 |