Worked on the suzuki-shunsuke/tfaction repository to improve the reliability of Terraform automation workflows. Addressed a bug in Terraform plan handling by ensuring the plan output file, tfplan.binary, is always written to an explicit path in the current working directory. This adjustment resolved issues with relative path resolution that previously caused failures across different execution contexts, such as CI/CD runners and local scripts. The solution was implemented using Shell scripting and leveraged DevOps practices with Terraform. The fix was validated through targeted testing and code review, resulting in more deterministic automation and increased operational stability for infrastructure management tasks.