New repositories created by Copilot use `master` instead of `main`

Start by reproducing the issue in the GitHub Copilot app and inspect the repository-creation flow that initializes the local Git repository. Trace how the initial branch name is selected, then verify with git branch --show-current that creation uses main or the applicable configured default branch.

Short summary

When the GitHub Copilot app creates a new repository from scratch, it initializes the repository with master as the default branch instead of main.

Affected version or release

Current GitHub Copilot desktop app as of 2026-09-18 (exact build not captured).

Installation context

GitHub Copilot desktop app on macOS, creating a new local repository through a Copilot session.

What happened?

I asked the GitHub Copilot app to create a new repository. The resulting repository used master as its initial/default branch.

GitHub-hosted repositories have defaulted to main since 2020 unless a user, organization, or enterprise explicitly configures another name. The app appears to be relying on a local git init fallback or otherwise hard-coding/allowing master, rather than using main or honoring the applicable configured default branch name.

Steps to reproduce

1. Open the GitHub Copilot app.
2. Start from an empty folder or ask Copilot to create a new repository.
3. Allow Copilot to initialize the Git repository.
4. Inspect the initial branch name with git branch --show-current.
5. Observe that the branch is named master.

Expected behavior

The initial branch should be named main, unless a different default branch name is explicitly configured for the user, organization, enterprise, or local Git environment. Ideally, repository creation should consistently honor the applicable configured default.

Additional context

GitHub's default-branch guidance states that new repositories created on GitHub use main: https://github.com/github/renaming#new-repositories-use-main-as-the-default-branch-name

Related but not duplicate reports:

• #511 describes the app assuming master when calculating changes.
• #786 describes collection projects not respecting per-repository default branches.