# Composer

Composer is an AI model released by Cursor (now part of SpaceXSI) on Oct 29 2025.

## Facts

| Field | Value |
| --- | --- |
| Model | Composer |
| Developer | Cursor (now part of SpaceXSI) |
| Release date | Wednesday, Oct 29 2025 |
| Licensing | Closed |

## About Composer

Composer was released by Cursor on October 29, 2025 as an agent model for software engineering. It used a mixture-of-experts architecture and reinforcement learning in development environments equipped with search, editing and terminal tools. Cursor designed it for interactive use, where repeated reasoning and tool calls needed to feel fast enough for a programmer to stay involved.

The training emphasized solving problems inside large codebases, including respecting existing abstractions rather than merely producing code that passed a narrow test. Cursor's own evaluation measured real requests from its engineers and researchers. The model was developed for use inside Cursor, with the surrounding editor and agent tools supplying repository access and executing the model's requested actions.

## Questions and answers

### When was Composer released?

Composer was released by Cursor (now part of SpaceXSI) on Wednesday, Oct 29 2025.

### Who made Composer?

Composer was built by Cursor (now part of SpaceXSI). Elon Musk's AI company building the Grok series of models. Founded in 2023 as xAI, merged into SpaceX as SpaceXAI in 2026 and renamed SpaceXSI (SpaceX Super Intelligence) that October. Cursor (Anysphere) and its Composer coding models were acquired in 2026 and are tracked here.

### Is Composer open source?

No. Composer is a closed model. The weights are not published — it is available only through the provider's own API, apps, or partner platforms.

### What came before and after Composer?

SpaceXSI's previous tracked release was Grok 4 Fast on Sep 19 2025, 40 days earlier. It was followed by Grok 4.1 on Nov 17 2025.


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Canonical page: https://aireleasetracker.com/model/xai/composer
Site index: https://aireleasetracker.com/llms.txt
Source: AI Release Tracker (https://aireleasetracker.com). Most benchmark scores come from lab launch material; gathered results identify the leaderboard that published them.