sustn

sustn is a tool designed to automate codebase improvements by leveraging AI coding agents in a proactive manner. Unlike traditional AI coding tools that require manual prompting for each task, sustn continuously scans connected repositories to identify areas needing attention, such as dead code, missing tests, outdated documentation, security issues, and technical debt. It then ranks these findings by impact, creating a prioritized backlog of tasks for review.

Users can add their repositories to sustn, which conducts a deep scan using Claude Code or Codex. The resulting backlog is presented as a manageable task list, allowing users to reprioritize tasks, inspect the agent’s findings, and add notes or constraints before work begins. Once configured, sustn monitors the available Claude Code or Codex subscription budget and automatically works through the backlog when tokens are available, ensuring that no subscription resources go unused. Each completed task results in a new branch; users can review the changes and either create a pull request with one click or set sustn to open pull requests automatically. No changes are merged into the main branch without user approval, maintaining control and minimizing risk.

The tool is delivered as a downloadable application for Mac and integrates with existing developer workflows, requiring no additional infrastructure. It is intended for developers or teams who want to automate routine code maintenance and maximize the value of their AI coding agent subscriptions.