AI Chat Overview

AI Chat is a complete, modular AI application delivered as a single ServiceStack plugin. Registering ChatFeature mounts a full multi-provider Chat UI at /chat that runs inside your App's existing security boundary - using your App's users, your App's database and your App's file system.

What you get

Capability	Where it lives
Multi-provider Chat UI	`/chat`
OpenAI-compatible Chat Completions API	`POST /v1/chat/completions`
In-process client for your own C# code	`IChatClient`
Discovery + invocation of your App's own APIs	API Tools
MCP Server for external AI Assistants	`/chat/mcp`
Managed RAG over your documents	Gemini File Search
PDF template designer	`/chat/pdf`
Production PDF rendering	`IPdfRenderer` + `PdfFeature`
Cost, token and activity reporting	`/admin-ui/chat`

Two plugins

AI Chat ships as two independent plugins in the ServiceStack.AI.Chat package:

Plugin	Provides	Requires
`ChatFeature`	Chat UI, providers, tools, API Tools, MCP, RAG, PDF Studio	An AI provider API key
`PdfFeature`	Published PDF template management + rendering	The `typst` CLI

PdfFeature has no dependency on ChatFeature - an App can deploy production PDF rendering without installing any AI capability at all. See Rendering PDFs.

Architecture

Everything in AI Chat above the hosting layer is an extension. The Chat UI is assembled at runtime from the Vue components each installed extension registers, and the server half of each extension owns its own routes, tools, tables and background workers.

services.AddPlugin(new ChatFeature {
    RequireAuth = true,
    DisableExtensions = ["computer"],   // remove a capability from server + UI together
    Tools = {
        EnableApiTools = true,          // on by default
        EnableFilesystemTools = false,  // off by default
        EnableCodeExecution = false,    // off by default
    },
});

A disabled extension registers no routes, no tools and no UI components. See Extensions for the full list and Custom Extensions for adding your own.

Where state lives

State	Location
Threads, requests, media	Your App's database via OrmLite (`ChatThread`, `ChatRequest`, `ChatMedia`)
Config	`App_Data/chat/llms.json`, `App_Data/chat/providers.json`
Per-user files	`App_Data/chat/user/{user}/`
Content-addressed cache	`App_Data/chat/cache/`
Published PDF templates	`App_Data/pdf/`

Nothing is stored outside your application. See Data & Storage.

Security posture

Question	Answer
Who can reach `/chat`?	Whoever `RequireAuth` and `RequiredRole` allow, enforced by your existing auth
Can one user see another's threads, media or projects?	No - state is scoped to the authenticated identity
What can an Agent call?	Only APIs the signed-in user is authorized to call
Can it write files or run code?	Only if you enable those tools, and only within configured directories
What is exposed over MCP?	Nothing until you name tool groups
Does it require an outbound AI provider?	Only the providers you configure