Build A Multi-Agent Workflow

A workflow connects multiple agents into a graph.

Use a workflow when the work is naturally split across roles, stages, or handoffs.

This page is an orchestration detour after the single-agent basics. If you are still on the first path, finish Save Sessions And State and ASP.NET Hosting first.

Add The Package

dotnet add package HPD-Agent.MultiAgent --version 0.5.0

Add Program.cs

using HPD.Agent;
using HPD.Agent.Providers.OpenAI;
using HPD.MultiAgent;

var workflow = await AgentWorkflow.Create()
    .WithName("launch-note")
    .AddAgent("researcher", agent =>
    {
        agent.WithOpenAI(model: "gpt-5-mini")
             .WithInstructions("Find the most important points. Keep the research concise.");
    })
    .AddAgent("writer", agent =>
    {
        agent.WithOpenAI(model: "gpt-5-mini")
             .WithInstructions("Turn the research into a short, friendly launch note.");
    })
    .From("researcher").To("writer")
    .BuildAsync();

using var started = workflow.Subscribe<WorkflowAgentStartedEvent>(evt =>
    Console.WriteLine($"{evt.AgentId} started"));

using var completed = workflow.Subscribe<WorkflowAgentCompletedEvent>(evt =>
    Console.WriteLine($"{evt.AgentId} finished"));

var result = await workflow.RunAsync("Explain why HPD Agent sessions and branches matter.");

if (!result.Success)
{
    throw new InvalidOperationException(result.Error, result.Exception);
}

Console.WriteLine(result.FinalAnswer);

Run it:

dotnet run

What Happens

AgentWorkflow.Create() starts a workflow graph.

AddAgent(...) adds named agent nodes.

From("researcher").To("writer") connects the researcher output to the writer input.

RunAsync(...) starts at the graph entry node and follows the graph until the workflow completes.

Workflow events let a UI or log show which node is running while the workflow executes.

Workflow Or Subagent

Use a workflow when the orchestration is explicit and graph-shaped.

Use a subagent when one agent should call another specialist as a tool during its own turn.

Next

Next: expose an agent over HTTP in ASP.NET Hosting, or return to the broader Getting Started path.

Go deeper: for workflow patterns, routing, handoffs, events, and configuration, see Multi-Agent Overview.