Mainline

Mainline is a command line tool that lets coding agents save developer intent and decisions inside a Git repository, alongside the code. Records are stored as Git refs and notes, so they move through fetch, branch and merge like any other repository data. Mainline does not store code or AI chat transcripts. It keeps the goal of a task, the tradeoffs, abandoned approaches and no go areas that a future agent or reviewer would need. Agents operate it themselves through hooks, a skill and the CLI. At the start of a task an agent runs a preflight that reads the repository's history, decisions and risks, then records intent as it works and seals the record when finished. The stated benefits are that agents avoid repeating dead ends, can see another agent's recorded intent before a pull request exists and so spot logic conflicts early, read the constraints of risky modules before editing, and give reviewers the reasoning behind a change as well as the diff. It suits teams that use AI coding agents heavily and want that context to live in the repository rather than in a separate memory database or platform. The core, which covers the CLI, Git storage, agent context and the open protocol, is open source. A Team Cloud tier for reviewing agent generated pull requests and an Enterprise tier with self hosting and policy controls are described as planned, with no prices published. The vendor is seeking design partners.