Which merge method does Agent Merge use to land a pull request?

[brentsmith721]

When Agent Merge is enabled in the GitHub Copilot app, which method does the app use for the final GitHub pull request merge: squash, merge commit, or rebase?

The Agent Merge menu exposes permissions for addressing reviews, fixing CI failures, resolving conflicts, and merging the pull request, but I do not see a merge-method selector. I could not find the final merge-method behavior documented in the public app documentation or changelog.

Could a maintainer clarify:

1. How is the final merge method selected: a fixed app default, repository configuration, or a per-project/per-PR preference?
2. What happens when the selected method is disabled by repository settings or restricted by branch rules? Is there a fallback, or does Agent Merge stop?
3. Is there a supported way to explicitly select or guarantee squash versus a regular merge commit before enabling automatic merging?

I am asking about the final PR merge into the base branch, not the branch-update strategy setting used to synchronize a session branch with its base. If behavior varies by app version or differs when a merge queue is involved, please clarify that as well.

A documentation link would be helpful. Thank you!