Tiny Console Chat Loop

This page turns the earlier pieces into a small interactive assistant. It uses one agent, one session, one branch, and a loop that keeps reading console input until you press Enter on an empty line.

Continue in the same HpdAgentQuickstart folder from Hello Agent, or create a fresh console app with the same packages.

Add Program.cs

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

var agent = await new AgentBuilder()
    .WithOpenAI(model: "gpt-5-mini")
    .WithInstructions("You are a concise helpful assistant.")
    .BuildAsync();

var (sessionId, branchId) = await agent.CreateSessionAsync("getting-started-chat-loop");

using var output = agent.Subscribe<TextDeltaEvent>(evt => Console.Write(evt.Text));
using var finished = agent.Subscribe<MessageTurnFinishedEvent>(_ => Console.WriteLine());

while (true)
{
    Console.Write("\nYou: ");
    var input = Console.ReadLine();

    if (string.IsNullOrWhiteSpace(input))
        break;

    Console.Write("Agent: ");
    _ = await agent.RunAsync(input, sessionId, branchId);
}

Run it:

dotnet run

Try:

You: My project is called Atlas. Remember that.
You: What is my project called?

You Succeeded If

The second answer should refer to Atlas. That means the loop is reusing the same session and branch, so the agent receives prior conversation history.

What Happens

CreateSessionAsync(...) creates the conversation container and default branch.

Subscribe<TextDeltaEvent>(...) prints text as it arrives.

The while loop reads user input and calls RunAsync(...) for each turn. Passing the same sessionId and branchId keeps the conversation coherent.

The subscriptions observe the run. They do not start the run by themselves; RunAsync(...) still performs each turn.

Common Mistakes

If the agent forgets earlier messages, make sure every RunAsync(...) call uses the same sessionId and branchId.

If nothing prints, make sure the text subscription is registered before the loop calls RunAsync(...).

If the process restart loses history, add Save Sessions And State.

Next

Next: save conversations in Save Sessions And State.

Optional: add behavior around turns in Middleware.