standardagents/composer-api

OpenAI-compatible API proxy for Cursor Composer

What it solves

Cursor's first-party models, such as Composer 2.5 and Grok 4.6, are not natively exposed as raw OpenAI-compatible endpoints. This project provides a local server that bridges these models to an OpenAI-compatible API, allowing users to integrate Cursor's models into any OpenAI-compatible client.

How it works

It operates as a local macOS app that starts a localhost server (typically on port 8787) providing /v1/chat/completions and /v1/responses endpoints. The app stores the user's Cursor API key locally and forwards requests to Cursor's backend. It also supports text and image inputs, streaming and non-streaming outputs, and estimates token usage based on character counts and published pricing.

Who it’s for

Developers who want to use Cursor's specialized models (like Composer 2.5) in their own tools, scripts, or other AI agents and clients that support the OpenAI API standard.

Highlights

  • OpenAI Compatibility: Provides standard endpoints for chat completions and models list.
  • Local Security: Stores API keys locally within a macOS app to avoid exposing them in source control.
  • Multimodal Support: Handles text and image inputs (up to 1MB per image).
  • Model Access: Enables access to composer-2.5, composer-2.5-fast, grok-4.6, and grok-4.5 variants.
  • Integrated Agent Setup: Includes a tool to install a local OpenCode provider for agentic workflows.

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