Platform projects consist of ordinary Git repositories, so you can work on them with IntelliJ IDEA and other JetBrains IDEs. MainPath integration is leaner here than in Cursor, VS Code and Antigravity: there is no extension with a welcome page and start buttons, and you set up project configuration in the IDE yourself.
What MainPath provides
The MainPath Toolbox can install IntelliJ IDEA during developer setup and open projects in it with one click if you choose it as the default tool there. The project folder contains an .idea directory, symlinked from local-configuration, which serves as the shared place for team settings. In JetBrains, open the parent project folder under ~/Documents/MainPath/<organization-slug>/<project-slug> with all repositories, so backend, app and configuration sit in one window.
What you set up yourself
Run configurations, SDK assignment and module structure are created in the IDE; MainPath does not generate them. You start applications in the IDE terminal inside the respective repository with the mp CLI:
mp run-local
Runtime versions come from the repository’s .tool-versions; when the IDE asks for an SDK, pick the version listed there so that local builds and the pipeline match.
AI assistant in JetBrains
MainPath rules for Cursor, Claude Code and Codex come from the agent plugin (mp agent install), not from files in the project folder. If you use the JetBrains AI Assistant, point it in your prompt or in its settings to the same conventions (start via mp run-local, no changes to .gitlab-ci.yml and env/*.generated.env). You can start Claude Code and Codex independently of the IDE in the terminal of the project folder. How to add project-specific instructions is described in Your own rules for AI agents.