DesktopAssistant

DesktopAssistant

A desktop AI agent application built with .NET 9 and Avalonia UI. Supports any OpenAI-compatible LLM provider, real-time MCP server installation, conversation branching, multiple simultaneous chats, and a sub-agent tree for divide-and-conquer task delegation.

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Features

Conversations

• Multiple simultaneous chats — open as many conversations as needed, each running independently
• Conversation branching — fork any message to explore alternative responses, similar to ChatGPT's branching model
• Manual summarization — right-click any message and summarize the preceding context; a SummaryNode is inserted into the message tree, keeping the context window lean without losing history
• Structured history reduction — uses a custom IChatHistoryReducer that asks the LLM to compact conversation history via a structured submit_history tool call, preserving roles, function calls, and function results as proper ChatMessageContent objects (compatible with agents using FunctionChoiceBehavior.Required)

Sub-Agents

• Sub-agent tree — enable per conversation; the agent can decompose its task and delegate parts of it to child agents, which can in turn decompose and delegate to their own children, forming a divide-and-conquer hierarchy rather than a single flat layer of helpers
• Configurable sub-agents — when creating a sub-agent the parent specifies its assistant profile (model, endpoint, temperature), system prompt, and whether the sub-agent can spawn its own sub-agents
• Task assignment to existing sub-agents — the parent agent can send new tasks to already-created sub-agents, not just create new ones
• Conversation tree — each sub-agent runs as a linked conversation visible in the sidebar, showing its status and relationship to the parent

AI & LLM

• OpenAI-compatible providers — works with OpenAI, Azure OpenAI, local models via Ollama, LM Studio, or any OpenAI-compatible endpoint
• Configurable profiles — multiple assistant profiles with independent model, endpoint, temperature, and token settings
• Per-conversation system prompt — set a custom system prompt for each conversation
• Semantic Kernel — powered by Microsoft Semantic Kernel for LLM orchestration
• Streaming responses — real-time token streaming

MCP (Model Context Protocol)

• Agent-driven installation — the agent has a built-in set of tools that let it install and configure MCP servers on its own, without user involvement
• Install from GitHub — the agent can install any MCP server directly from a GitHub repository URL
• Built-in server catalog — a curated list of popular servers is available to the agent as a knowledge base (Tavily Search, Exa Search, Filesystem, Git, Fetch, Memory, Playwright, Qdrant, MySQL/PostgreSQL/SQLite, Kubernetes, Docker, Sequential Thinking, and more)
• Manual management — users can install and manage servers directly by editing the config file
• No restart required — servers connect at runtime; new tools become available immediately
• Per-tool auto-approval — configure which tools run automatically without confirmation prompts

Security & Storage

• API keys via Windows DPAPI — credentials encrypted at rest, never stored in plain text
• SQLite database — local storage for conversations, messages, settings
• No telemetry — all data stays on your machine

UI

• Avalonia UI — cross-platform desktop framework with Fluent theme
• System theme detection — follows Windows dark/light mode
• Markdown rendering — assistant responses rendered as rich markdown

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Planned Features

• File support — work with images, documents, and other file types as conversation context
• Extended thinking — support for models with explicit reasoning/thinking steps
• Agent isolation — sandboxed execution environments per agent
• Daemon agents — long-running background agents and sub-agents
• Scheduled tasks — deferred and periodic task execution

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Architecture

Clean Architecture with four layers:

Domain          — entities, value objects, domain interfaces (no external dependencies)
Application     — use cases, application services, DTOs, interface definitions
Infrastructure  — LLM/SK integration, MCP, SQLite persistence, DPAPI security
UI              — Avalonia MVVM presentation layer (CommunityToolkit.Mvvm)

Key infrastructure components:

• KernelFactory — creates Semantic Kernel instances per assistant profile
• AgentKernelFactory — wraps KernelFactory, conditionally registering sub-agent tools and plugins
• ConversationSession — encapsulates the LLM turn loop, tool approval, and streaming for a single conversation
• ConversationSessionService — singleton session pool keyed by conversation ID
• SubagentService — manages sub-agent lifecycle and inter-agent communication
• SubagentPlugin — SK plugin exposing create_subagent, send_message_to_subagent, list_subagents tools to the LLM
• DpapiCredentialStore — Windows DPAPI credential store
• AvailableToolsService — aggregates static SK plugins and dynamic MCP tools
• SummarizationExecutor — orchestrates history compaction via ChatHistoryCompactionReducer (see src/DesktopAssistant.Infrastructure/AI/Summarization/)

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Requirements

• OS: Windows 10/11 (DPAPI credential storage is Windows-only)
• Runtime: .NET 9 SDK
• Node.js: Required for NPX-based MCP servers (most servers in the catalog)
• LLM provider: An API key for OpenAI or any compatible provider, or a locally running model

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Getting Started

1. Clone the repository

git clone https://github.com/00wz/DesktopAssistant.git
cd DesktopAssistant

2. Build and run

dotnet run --project src/DesktopAssistant.UI

Or open DesktopAssistant.sln in Visual Studio 2022 / JetBrains Rider and run the DesktopAssistant.UI project.

3. First-time setup

1. Open Settings → Profiles
2. Create an assistant profile — enter your LLM provider base URL and model ID
3. Your API key is stored securely via Windows DPAPI
4. Start a new conversation

4. Adding MCP servers

1. Open Settings → Tools
2. Browse the built-in catalog or enter a custom server command
3. The server connects immediately — no restart required
4. Configure per-tool auto-approval as needed

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Configuration

All settings are stored locally in a SQLite database (desktop_assistant.db) in the application directory.

Setting	Storage
API keys	Windows DPAPI (encrypted)
Assistant profiles	SQLite
Conversations & messages	SQLite
Tool auto-approval	SQLite
MCP server configs	SQLite

Logging is configured in appsettings.json via Serilog. Log files are written to the logs/ directory.

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Tech Stack

Component	Library / Version
UI Framework	Avalonia UI 11.3
MVVM	CommunityToolkit.Mvvm 8.4
LLM Orchestration	Microsoft Semantic Kernel 1.67
MCP Client	ModelContextProtocol 0.2
ORM	Entity Framework Core + SQLite 9.0
Logging	Serilog 4.1
Markdown	LiveMarkdown.Avalonia
Target Framework	.NET 9

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Contributing

Feedback and pull requests are welcome. For major changes, please open an issue first.

License

MIT