How to Use Union Alpha
Free preview access, two entry points, and a handful of editors that already work with it. From zero to your first response in about five minutes.
Two ways in
Both routes reach the same model. Pick whichever fits the tooling you already use.
OpenRouter
The primary route. Union Alpha appears in OpenRouter's model catalog as stealth/union-alpha at $0 during the preview. Any OpenAI-compatible client that supports a custom base URL can reach it.
Best for: API access, existing OpenRouter users, editor integrations
OpenCode
OpenCode routes to the model as opencode-go/union-alpha and publishes the note that your data is not used for training. It is the path most of the early agentic-coding testing went through.
Best for: terminal agent workflows and coding loops
Setup, step by step
1. Get an OpenRouter API key
Sign up at openrouter.ai and create a key from the dashboard. The preview is free, but the key is still required to route requests and track usage.
2. Point your client at OpenRouter
Set the base URL to https://openrouter.ai/api/v1 and supply your key as a bearer token. The API is OpenAI-compatible, so existing SDK code works unchanged.
3. Set the model string
Use stealth/union-alpha as the model identifier. On OpenCode, use opencode-go/union-alpha instead. That single string is the entire configuration difference.
4. Wire it into your editor
Cursor, Cline and Roo Code all accept a custom OpenAI-compatible endpoint. Paste the base URL, the key, and the model string into their provider settings and the model shows up in the picker.
5. Budget for latency
The model is slow. For agentic loops this mostly means longer wall-clock runs rather than failed tasks, but tune your timeouts before running anything unattended.
Editor and agent integrations
| Tool | How |
|---|---|
| Cursor | Add a custom OpenAI-compatible provider pointing at OpenRouter, then select stealth/union-alpha |
| Cline | Choose OpenRouter as the API provider and pick Union Alpha from the model list |
| Roo Code | Same OpenRouter provider flow as Cline; the model appears once your key is saved |
| OpenCode | Native support via opencode-go/union-alpha — no extra configuration needed |
| Terminal agents | Any agent harness that speaks the OpenAI chat completions format will work with the base URL swap |