Mainline

Mainline is an open-source, Git-native intent recording system for coding agents. It lets AI agents automatically save developer intent, tradeoffs, and key decisions directly into the Git repository using refs and notes. Unlike chat logs or PR descriptions, Mainline compresses engineering judgment into compact intent records that future agents can retrieve before editing code. The system integrates into existing Git workflows—fetch, branch, merge, and fork all carry intent alongside code. Mainline is designed for teams who want repo-owned memory without locking into a new database or platform. It helps avoid repeated dead ends, detect logic conflicts early, and understand high-risk code constraints before making changes. It works via a CLI, agent hooks, and skills, and can be used with any Git-based coding workflow. Key features include live conflict detection for logic conflicts before Git conflicts, high-risk code trap annotations per module, and review-behind-intent to see original goals and reasoning. The local hub lets you browse historical decisions and work in progress. The project self-dogfoods with its own live intent Hub on GitHub, showing real usage. Mainline is currently in public alpha with an open-source core. Team and enterprise features (hosted collaboration, review guardrails) are planned. It competes with chat-log-based memory or external databases by staying inside Git, with no platform lock-in.