MD-Chat

A lightweight, fast desktop client for experimenting with OpenAI-compatible APIs. Built with egui for native performance and CommonMark support.

Features

• Fast native performance with egui
• Full Markdown rendering support
• Light/Dark mode toggle
• Persistent window position
• Compatible with OpenAI and similar APIs (like Reservoir)
• Clean, minimal interface

Configuration

MD-Chat uses a TOML config file for settings such as your OpenAI API key and API URL. Environment variables are no longer required.

Config File Location

• macOS: ~/Library/Application Support/MD-Chat/config.toml
• Linux: ~/.config/MD-Chat/config.toml

The config file is created automatically on first run if it does not exist.

Example config.toml

Copyopenai_api_key = "sk-...yourkey..."
api_url = "https://api.openai.com/v1/chat/completions"

• If openai_api_key is missing or empty, requests will fail unless the API does not require a key.
• You can edit this file to change your API key or use a different API URL.

Building and Running

Copy# Build the application
cargo build --release

# Run the application
cargo run --release

Usage

1. Launch the application
2. Type your message in the input box
3. Press Enter or click Send to submit
4. View the markdown-formatted response

Modal Editing & Vim-like Navigation

MD-Chat supports modal editing inspired by vim, making keyboard navigation fast and efficient:

• Modes:

  • INSERT: Type and edit your message as usual. Press Esc to enter NORMAL mode.
  • NORMAL: Keyboard navigation and commands. Press i or click the input box to return to INSERT mode.

• Navigation in NORMAL mode:

  • j / k: Scroll down/up by a small amount
  • Shift+j / Shift+k: Scroll down/up by one window height
  • g: Jump to the top
  • G: Jump to the bottom
  • r: Refresh chat history

• Other:

  • The current mode is shown in the top right, styled like vim.
  • The input box is always interactive; clicking it in NORMAL mode returns you to INSERT mode.

This makes MD-Chat a joy to use for keyboard-centric users and fans of modal editing!

Development

The codebase is organized into two main components:

• src/main.rs: UI and application logic
• src/openai.rs: API client implementation

Dependencies

• eframe: Egui framework for native applications
• egui_commonmark: Markdown rendering support
• reqwest: HTTP client
• tokio: Async runtime
• serde: Serialization/deserialization

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this code except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.