Working with Plugin Settings in FabrCore

Eric Brasher February 21, 2026 at 9:31 AM 4 min read

FabrCore uses a simple, convention-based approach to plugin settings through AgentConfiguration.Args. No schema system needed — just a naming convention and extension methods.

The Settings Convention

Plugin settings use a PluginAlias:Key naming convention stored as flat string values in the agent's Args dictionary. The PluginConfigExtensions class provides helper methods:

Reading Plugin Settings

// Read a single setting
var rootPath = config.GetPluginSetting("FileSystem", "RootPath");

// Read all settings for a plugin (returns Dictionary)
var settings = config.GetPluginSettings("FileSystem");

Configuration in JSON

Settings appear in the agent configuration's Args section:

Agent Configuration

{
    "Handle": "my-agent",
    "AgentType": "assistant",
    "Models": "default",
    "Args": {
        "FileSystem:RootPath": "/tmp/files",
        "FileSystem:MaxFileSize": "10485760",
        "WebBrowser:TimeoutMs": "30000",
        "WebBrowser:Headless": "true"
    }
}

Using Settings in a Plugin

FileSystemPlugin.cs

[PluginAlias("FileSystem")]
public class FileSystemPlugin : IFabrCorePlugin
{
    private string _rootPath = "/tmp/files";

    public Task InitializeAsync(
        AgentConfiguration config,
        IServiceProvider serviceProvider)
    {
        var rootPath = config.GetPluginSetting(
            "FileSystem", "RootPath");
        if (!string.IsNullOrEmpty(rootPath))
            _rootPath = rootPath;
        return Task.CompletedTask;
    }
}

Why Not a Framework Schema?

You might wonder why FabrCore doesn't include a [PluginSetting] attribute or a schema discovery API. The reason is simple: settings schema discovery is only valuable when there's a UI rendering settings forms, and that UI is your application's responsibility.

Different applications have different UI frameworks (Blazor, React, etc.) with different schema requirements. A 76-line settings registry mapping plugin aliases to their settings is reasonable application code — explicit, easy to maintain, and tailored to your specific UI.

Learn More

Check out the plugin settings documentation for the complete reference.

Tools Documentation FabrCore on GitHub

Eric Brasher

Builder of FabrCore and OpenCaddis.