GitHub Copilot Agent Merge Enters Preview: Let an Agent Drive Your PR to Mergeable, and Exactly How to Turn It On (Checked Sept 2026)

GitHub’s Copilot changelog on 2026-09-04 shipped something with immediate practical value: Agent Merge, currently in public preview.

It targets the least interesting part of shipping code: the branch is written, the PR is open, and now it is stuck on unanswered review comments, one red CI check, and a merge conflict. None of it is hard. All of it eats an afternoon.

1. What Agent Merge actually does

The VS Code 1.136 release notes put it plainly: Agent Merge helps you take a pull request across the finish line. It asks an agent to address review feedback, fix failed checks and merge conflicts, and rerun workflows. The loop repeats until the PR is ready to merge.

Four jobs, in plain terms:

1. Read review feedback and apply the changes
2. Fix the CI checks that went red
3. Resolve merge conflicts
4. Rerun the workflows, then look at the results again

The key word is the loop — it does not patch once and hand back; it keeps going until things are green.

2. How to turn it on

From the official release notes:

• Setting: chat.agentMerge.enabled
• Where: only inside the Agents view, enabled per session
• How: run the command Enable Agent Merge for Active Session, or click the Agent Merge button in the title bar

So it is not a global always-on feature — you opt in for a specific session. That design is sensible: letting an agent rewrite a PR that is already under review should be an explicit, one-at-a-time grant, not something running quietly in the background.

The release notes do not state specific limitations, so we mark that as not documented rather than guessing.

3. What else shipped in the same release

From the same 2026-09-04 changelog:

• Claude Fable 5.1 is available to Copilot Pro+, Max, Business and Enterprise users
• Gemini 3.8 Flash is rolling out to Copilot Pro, Pro+, Max, Business and Enterprise users
• Copilot app and CLI now honor content exclusions (generally available), keeping sensitive code out of context across agentic workflows
• The GitHub Copilot harness is generally available in Copilot for JetBrains
• Multi-root workspaces are now experimental, bringing Copilot and Claude agent sessions to every folder

One caveat on multi-root worth remembering: agent hooks remain scoped to a single workspace folder. If hooks are detected in several folders, VS Code prompts you to pick a primary one. The experimental settings are chat.agentHost.copilotAgent.multiRootEnabled and chat.agentHost.claudeAgent.multiRootEnabled.

4. Should you use it yet?

Three things to weigh:

• It is a preview. Preview features change behaviour, get renamed, and break. Do not wire it into anything that auto-merges to your main branch.
• It touches your PR for real. It edits the branch and reruns workflows — these are not suggestions. Make sure you can roll the branch back.
• What it saves is fragmented time. Its value is not writing features, it is finishing them. If your team’s PRs routinely sit for days behind one red check, this will feel more useful than any new model.

Our suggestion: run it once on an old PR nobody is waiting on, read what it changed, and only then decide whether it belongs in your normal flow.

5. Three-line summary

1. Agent Merge (preview) loops over review feedback, failed checks and merge conflicts until the PR is mergeable.
2. The setting is chat.agentMerge.enabled, and it is enabled per session in the Agents view, not globally.
3. Shipping alongside it: Fable 5.1 (Pro+ and up), Gemini 3.8 Flash (Pro and up), and content exclusions in the app and CLI.

Official links

• GitHub Copilot changelog: https://github.blog/changelog/2026-09-04-github-copilot-weekly-releases-august-31/
• VS Code 1.136 release notes: https://code.visualstudio.com/updates/v1_136

More on this site

• GitHub Copilot tool page
• Copilot free vs paid
• Setting up content exclusion for the Copilot app and CLI
• Gemini 3.8 Flash in GitHub Copilot
• Setting up Copilot code review to approve PRs

Read directly from the official changelog and release notes on 2026-09-05. Preview features can change at any time.