Cursor

Cursor ships an "Override OpenAI Base URL" — one of the simplest tools to wire to PrimeRouter.

Get an API key first — see Common setup.

Setup (macOS / Windows / Linux — identical)

Cursor is a GUI app — same steps on every OS, only the settings shortcut differs.

1. Open Cursor → Settings:

   • macOS: Cmd + ,
   • Windows / Linux: Ctrl + ,

2. Left panel → Models

3. Disable all built-in models (Cursor Pro / GPT-4 / etc.)

4. In the Model Names input, type Claude Opus 4.7 and click Add

5. In OpenAI API Key, fill:

   OpenAI API Key:           sk-your-primerouter-key
   Override OpenAI Base URL: https://primerouter.ai/v1

6. Pick Claude Opus 4.7 from the top model selector

Once filled in, the screen should look like this:

Gotchas

WARNING

• Use the spaced, title-cased model name (e.g. Claude Opus 4.7). Cursor ships built-in entries for claude-opus-* / claude-sonnet-* — adding the same lower-cased, hyphenated string as a custom model collides with Cursor's built-in routing and shows up as garbled output or mid-stream cut-off.
• Cursor Tab completions use a proprietary model — they cannot be replaced this way. Only Chat / Composer / Agent route through your custom model.
• Agent mode: tick "Custom Model" next to the model so Cursor trusts it for tool use.

Recommended models

Pick any of the following names and add it to your Model Names list.

Scenario	Model Name
Daily Chat / Composer	Claude Sonnet 4.6
Stable Opus for complex tasks	Claude Opus 4.6
Agent / long tasks	Claude Opus 4.7