The Custom File Viewer plugin adds the ability to open non-markdown files directly in external applications of your choice. You can map specific file extensions - like .py, .yaml, or .sh - to different programs, and even set a fallback app for anything that isn't explicitly mapped. An ignore list keeps certain file types, such as markdown, images, or videos, from triggering the feature, giving you fine control over what opens externally. Once configured, clicking a file in the explorer hands it off to the designated app without extra steps.