Modian is a modern, decoupled, cross-platform Chinese Input Method Editor (IME) framework.

It explores how system-level software such as IMEs can be designed using Clean Architecture and Multi-Process Design, addressing common issues in traditional IME implementations:

• Tight coupling between OS APIs and core logic
• Poor cross-platform reuse
• Crash propagation to host applications
• Hard-to-extend engine architecture

Inspired by the “Four Treasures of the Study” (文房四宝), Modian separates responsibilities into independent components while keeping the core logic portable.

👉 See Architecture Evolution.

(Modian V1.0 Clean Architecture)

Modian decouples the IME into four independent cooperating components:

OS Driver / Adapter

Role Handles OS-specific events, intercepts keystrokes, and commits text to the host application.

Design OS-specific thin client designed for minimal logic and crash isolation.

Stack C++23, Windows TSF (planned macOS IMK)

Core Logic Server

Role Central process responsible for state management, candidate generation, and engine coordination.

Design Single source of truth. Runs as background service to isolate failures from host apps.

Stack C++23, IPC (Named Pipes)

Engine Plugins (Planned)

Role Defines input conversion logic (Pinyin, Wubi, etc.)

Design Pluggable architecture enabling independent engine development.

Stack C ABI plugin interface (planned)

Stateless UI Renderer

Role Displays candidate window and interaction UI.

Design Stateless UI process communicating with core via IPC.

Stack Rust, Tauri, Svelte

• Multi-process architecture for crash isolation
• Clean architecture layering for testability
• IPC-based communication instead of shared memory
• Pluggable engine architecture
• Cross-platform core logic
• Modular CMake project structure
• Incremental architecture evolution

Core C++23

UI Rust + Tauri + Svelte

Build CMake

IPC Named Pipes (Windows)

Testing Unit tests + Integration tests + Benchmarks

• Multi-process IME architecture
• TSF thin client + C++ core server
• IPC-based state synchronization
• Clean architecture layering
• Modular build system
• Iterative architecture evolution
• Designed for cross-platform support