Plugin Management in Split Mode
A plugin can be installed on the backend, on the frontend, or on both sides. This article explains how the platform determines that and how plugin synchronization works.
A separate question is which modules of an installed plugin are actually loaded in each process. For split plugins, module loadability is controlled by content-module dependencies such as intellij.platform.backend and intellij.platform.frontend. See Modular Plugins and Split Mode for details.
Compatibility Check
A plugin may be:
compatible only with the backend
compatible only with the frontend
compatible with both sides
Compatibility is determined by the dependencies declared by the plugin and its content modules. By default, content modules are optional, which means that if a particular module's dependencies are not satisfied, that module is not loaded, but this does not affect the loading of other plugin modules. As a result, if the plugin dependencies are satisfied, the plugin is loaded. If a plugin consists of multiple modules and the dependencies of at least one module are satisfied, the plugin is loaded. For more details about modules and dependencies, see Modular Plugins.
When a plugin is installed from JetBrains Marketplace, the plugin manager checks its compatibility with both the frontend and the backend and installs it wherever its dependencies are satisfied.
Plugin Sync Flow
When a project is opened, the frontend and backend plugin sets are compared. If a difference is detected, the IDE shows a plugin synchronization notification, allowing the user to choose which plugins to install on each side.
Current Limitation
Plugin synchronization currently works only for plugins that are available on JetBrains Marketplace.
If a plugin is installed only from a local ZIP or JAR file, the synchronization flow cannot resolve it for the other side through Marketplace metadata. For a more convenient installation method than ad hoc local archives, consider publishing the plugin to JetBrains Marketplace or using a custom plugin repository.