Create a CodeCommit repository in the secondary Region. Implement an AWS CodeBuild project to perform a Git mirror operation of the primary Region's CodeCommit repository to the secondary Region's CodeCommit repository. Develop an AWS Lambda function that triggers the CodeBuild project. Set up an Amazon EventBridge rule to respond to merge events in the primary Region's CodeCommit repository and configure it to invoke the Lambda function.

Create an Amazon S3 bucket in the secondary Region. Establish an AWS Fargate task to perform a Git mirror operation of the primary Region's CodeCommit repository and store the result in the S3 bucket. Create an AWS Lambda function to initiate the Fargate task. Configure an Amazon EventBridge rule to react to merge events in the CodeCommit repository and set it to invoke the Lambda function.

Create an AWS CodeArtifact repository in the secondary Region. Design an AWS CodePipeline pipeline that incorporates the primary Region’s CodeCommit repository as the source action. Include a cross-Region stage in the pipeline that packages the CodeCommit repository contents and deposits them into the CodeArtifact repository upon merging a pull request into the CodeCommit repository.

Create an AWS Cloud9 environment and a CodeCommit repository in the secondary Region. Set up the primary Region's CodeCommit repository as a remote repository within the AWS Cloud9 environment. Link the secondary Region's CodeCommit repository to the AWS Cloud9 environment.