u/Wreit

https://preview.redd.it/2sl156mq4c2h1.png?width=3440&format=png&auto=webp&s=cf3adcc4275065ad06267b4f4a4413625451f3eb

Hey r/dotnet,

I wanted to share a project I’ve been building for a while
It started from a small frustration I kept having with desktop/workspace apps

I use a mix of tools every day: editor, terminal, AI chats, scripts, dashboards, notes, local services, and random utilities. Most of them are good on their own, but I often wished I had one desktop workspace that I could shape around my workflow instead of constantly jumping between apps.

So I started building Sunder.

The idea is simple:
Start with a desktop shell, then add capabilities through installable packages.

It’s built with .NET and Avalonia, and the core repo includes:

- Desktop app
- Local runtime host
- CLI
- Package SDK
- Package templates
- MSBuild package tooling
- `.sunderpkg` package format
- Package validation/install/update flow

The part I spent the most time thinking about was the package system.

I didn’t want packages to reference the app internals directly, so packages use a public SDK layer. They can contribute UI views, settings pages, background services, extensions, configuration, secrets, storage, logging, and other runtime capabilities.

Package metadata is declared in C# with assembly attributes, and the build tooling generates the manifest/dev output/archive.

The first package family I built is AI-agent oriented, because that was the workflow I personally needed first. It has local agent sessions, profiles, model providers, file/shell/web tools, local and Docker execution, MCP, memory, skills, and subagents.

But Sunder itself is not meant to be only an AI app.

The part I care about more is the platform idea. In theory, packages could add developer tools, dashboards, automations, internal tools, research workflows, personal tools, or completely different workspace experiences.

It’s still early and definitely not perfect. I’m sure there are things I’ll need to rethink, especially around package boundaries, SDK design, and runtime behavior.

But it’s open-source now, and I thought this subreddit might find the .NET/Avalonia side interesting.

GitHub:
Sunder Core: https://github.com/Younics/sunder-core
Sunder Agent Packages: https://github.com/Younics/sunder-agent-package

I’d really appreciate feedback from people who have worked on desktop apps, plugin systems, Avalonia apps, SDKs, or local runtimes.

A few things I’m especially curious about:

- What would you be careful about in a package/plugin system like this?
- Would you approach this differently in .NET?
- What kind of package would you expect a workspace like this to support first?

Any feedback or criticism is welcome : )

Hey r/AvaloniaUI,

I wanted to share a project I’ve been building for a while
It started from a pretty simple frustration
I use a lot of different tools every day: editors, terminals, AI chats, dashboards, scripts, notes, local services, random internal tools. Most apps are great at what they do, but after some time I always end up adapting my workflow around the app.

I kept wishing I had a desktop workspace that worked more like:

“Start with a shell, then install the capabilities you need and organize them by your preference”

So I started building Sunder.

It’s an open-source, local-first desktop app built with .NET and Avalonia. The core idea is that the app itself stays relatively small, and features come from installable packages.

Right now it has:

- A desktop shell
- A local runtime host
- A CLI
- An SDK for package authors
- Package templates
- MSBuild package tooling
- A `.sunderpkg` archive format
- Package-contributed UI, settings, services, storage, secrets, and background work

The first package family I built is AI-agent oriented, because that was the itch I personally had first. I wanted local agent sessions, tools, memory, model providers, and execution targets inside the same desktop workspace.

But Sunder itself is not meant to be “an AI app”.

The part I care about more is the package model. I’d love for people to eventually be able to build packages for developer tools, dashboards, automations, research workflows, personal tools, or anything else that makes sense in a desktop workspace.

I’m not pretending this is perfect or finished. It’s still early, and I’m sure there are things I’ll need to rethink.

But it’s open-source now, and I’d really appreciate feedback from people who have experience with .NET desktop apps, plugin systems, SDK design, or Avalonia.

A few things I’m especially curious about:

- Would you trust/use Avalonia for this kind of desktop app?
- If you were designing a package/plugin system, what would you be careful about?
- Does separating the desktop shell from a local runtime host sound reasonable?
- What kind of package would you expect a workspace like this to support first?

Happy to answer questions or hear criticism : )