GitHub Copilot for JetBrains is moving to Copilot CLI as the default agent harness

Copilot CLI is becoming the default agent harness in GitHub Copilot for JetBrains, and our local harness will be deprecated.

This change provides greater consistency across all GitHub Copilot surfaces and is an important step toward faster feature parity and higher-quality results in GitHub Copilot for JetBrains.

Copilot CLI sessions run independently in the background on your machine and use the Copilot CLI agent harness, while the IDE starts, monitors, and steers them. This is the same architecture used across GitHub Copilot today and adopting it in JetBrains lets us ship the same capabilities to JetBrains developers at a faster pace.

Why we’re making this change

Copilot is not the same product it was a year ago. Agentic coding — long, multi-step sessions that plan, edit, and verify work autonomously — is now the core of the experience, and the harness that runs those sessions matters more than ever.

Until recently, JetBrains has used its own local harness. Maintaining a separate harness meant new capabilities landed in JetBrains later than in other surfaces, and it added a layer we had to keep in sync with the rest of Copilot.

Copilot CLI fixes that. Moving to it as the default harness delivers two concrete benefits:

• Better feature and model parity, faster. New capabilities and models built on Copilot CLI reach JetBrains developers on a similar timeline as our other surfaces, instead of waiting on a separate harness.
• Higher-quality results. Copilot CLI completes coding tasks at a higher quality, so the agent’s plans, edits, and fixes are more reliable.

What’s changing

We are gradually rolling out Copilot CLI as the default agent harness in GitHub Copilot for JetBrains. As this roll out reaches you, Copilot CLI will be selected by default in the agent provider. The local agent harness may be deprecated in a future release; we will share timing when it happens.

What this means for JetBrains developers

Your day-to-day workflow stays familiar — you start, monitor, and respond to agent sessions from the IDE just as you do today.

• Existing local sessions will be converted to Copilot CLI sessions. You do not lose your sessions; they move to the new harness.
• Sessions run in the background. Copilot CLI sessions continue running independently on your machine, which makes them well-suited for running tasks in parallel.
• You stay in control. When a session needs input or permission to act, you respond from within the IDE.

For step-by-step instructions on converting your existing local sessions to Copilot CLI sessions, see Migrate to Copilot CLI in JetBrains.

The bottom line

Your sessions aren’t going away, and your workflow stays familiar. By moving GitHub Copilot for JetBrains to use Copilot CLI as the default harness, you get new features faster and higher-quality results, while existing local sessions are converted automatically. If you have feedback, please open an issue in our Copilot IntelliJ feedback repo or fill out our survey.