JetBrains’ open-source ThinkRail IDE combines the pi coding agent with an editor, terminals, change review, and GitHub pull request workflows. A graph of SPEC.md files beside the code and reusable skills preserve project knowledge, while separate Git worktree branches and directories isolate parallel sessions. Its official architecture separates the host that owns agents and state, a versioned communication contract, and an independent UI. The desktop application and browser-based CLI share the same host. An authenticated model provider is required, and repository-defined MCP servers remain disabled until approved.