Compose Multiplatform 1.12 adds experimental MCP server

A code change—and the running app can display the modified interface without being restarted. This is exactly where JetBrains is focusing with Compose Multiplatform 1.12.0: The framework is gaining an experimental MCP server for hot-reload operations that connects AI coding agents to an open application.

MCP stands for Model Context Protocol. Through this integration, an agent can trigger reloads, take screenshots and inspect the semantic tree of the interface—that is, the structure that describes its elements and their meaning. It can also simulate clicks and text input and read application logs. According to JetBrains, this makes it possible to determine, for example, whether a change was loaded successfully or whether it caused a runtime error.

This shifts part of the verification process closer to the moment when the code is changed. An agent can therefore observe and interact with the running interface. However, the MCP server remains an experimental tool.

Also experimental is API version 2 for WindowState and DialogState in the androidx.compose.ui.window.v2 package. It is intended to enable finer control: Minimum and maximum sizes can be set for windows, while dialogs can be positioned relative to the main window. Among other examples, JetBrains shows a centered window with a fixed size of 400.dp × 200.dp.

For developers, the version offers two new experimental capabilities: AI agents can inspect a running app more directly, while windows and dialogs can be controlled more precisely. Compose Multiplatform remains open source; web support is still designated as Beta. In addition, the web version loads Noto fonts on demand when an application cannot display characters because the required fonts are missing.