Meridian.Hosting 1.0.0

Meridian.Hosting

The services.AddMeridian(...) front door — one fluent registration call that wires up multi-provider models, embeddings/retrieval, agents/tools/memory/workflows, and observability. Referencing this package alone pulls in the entire Meridian stack (Meridian.Context, Meridian.Models, Meridian.Knowledge, Meridian.Agents, Meridian.Observability) — this is the package most applications should install.

Meridian is an opinionated .NET 10 AI framework built on the Microsoft Agent Framework (MAF). It's a modern .NET framework first — .NET applications reference it directly, no COM involved — and the same engine is also reachable from COM-based applications (VB6, Visual FoxPro, Delphi, VBA) through a COM Callable Wrapper, so a legacy codebase doesn't have to stay frozen out of what's possible with AI today. See the repository for the full story, architecture diagrams, and the COM interop guide.

Install

dotnet add package Meridian.Hosting

Quick start

using Meridian.Hosting;

services.AddMeridian(options => {
    options.AddModel(model => {
        model.DefaultProvider = ModelProvider.AzureOpenAI;
        model.AzureOpenAI.ResourceName = "my-resource";
        model.AzureOpenAI.ChatDeploymentName = "gpt-4o";
        model.AzureOpenAI.EmbeddingDeploymentName = "text-embedding-3-small";
        model.FallbackProviders.Add(ModelProvider.OpenAI);
        model.Pipeline.EnableOpenTelemetry = true;
        model.Pipeline.EnableRetry = true;
    });

    options.AddEmbeddings();
    options.AddSemanticStore();
    options.AddHybridRetrieval();      // vector + keyword fusion; use AddRetrieval() for pure semantic search
    options.AddRagContextBuilder();    // batteries-included retrieval -> numbered context -> prompt
    options.AddMemory();
    options.AddImages();               // generation, editing, vision analysis (AzureOpenAI / OpenAI)

    options.AddTool("getWeather", (string city) => $"It's sunny in {city}.");

    options.AddAgent("assistant", agent => {
        agent.Instructions = "You are a concise, helpful assistant.";
        agent.ToolNames.Add("getWeather");
        agent.EnableSearchTool = true;  // lets the agent search the knowledge base mid-conversation
        agent.EnableTracing = true;
    });
});

var agent = serviceProvider.GetRequiredService<IMeridianAgentRegistry>().Get("assistant");
var session = await agent.CreateSessionAsync();
var response = await agent.RunAsync("What's the weather in Seattle?", session);
Console.WriteLine(response.Text);

Feature surface

Switch model providers — or add fallback providers tried in order — by changing ModelOptions inside AddModel(...); no other code in your application changes. Supported providers: Azure OpenAI, OpenAI, Anthropic (Claude), Google Gemini, Perplexity, and Azure AI Inference (Foundry).

Reaching it from COM (VB6, Visual FoxPro, Delphi, VBA)

The same engine configured via AddMeridian(...) is exposed through Meridian.Interop.Com's five COM-creatable classes — Meridian.ChatService, Meridian.AgentService, Meridian.EmbeddingService, Meridian.MemoryService, Meridian.ImageService — callable from any COM host in a few lines:

Dim chat As Object
Set chat = CreateObject("Meridian.ChatService")
Debug.Print chat.Chat("What's 2 + 2?")

Meridian.Interop.Com isn't published to NuGet (it's a RID-specific dotnet publish artifact, not a library you reference) — see COM-INTEROP.md in the repository for the full registration and calling guide.

License

MIT © Angel Hernandez