Is there somewhere one can obtain more documentation on how to create an extension that uses the Git Extension API?
At https://github.com/microsoft/vscode/blob/maste
You can have a look at eamodio/vscode-gitlens, the main extension based on Git extension.
Its src/git/gitService.ts does call the GIt extension:
static async getBuiltInGitApi(): Promise {
try {
const extension = extensions.getExtension('vscode.git') as Extension;
if (extension !== undefined) {
const gitExtension = extension.isActive ? extension.exports : await extension.activate();
return gitExtension.getAPI(1);
}
} catch {}
return undefined;
}