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Build a Chat Agent with a Graph

Create an agent whose graph is a simple RegexGuardrail → Generate chain, send a message, and get a streamed reply.

Prerequisites

Steps

  1. In the Project window: right-click → Create → Tryll → Workflow Asset. Name it ChatWorkflow.
  2. In the Inspector, expand Graph and add two nodes:
    • guard — Params type RegexGuardrail. Leave Triggered Exit empty (END) to drop jailbreaks silently, and set Not Triggered Exit = answer.
    • answer — Params type Generate. Default Exit stays empty (END).

Set Start Node = guard and Default Model Name = your model. 3. Attach a TryllAgentComponent to a GameObject and assign ChatWorkflow to its Workflow Asset field. 4. Wire events and send:

var agentComp = GetComponent<TryllAgentComponent>();

agentComp.OnAnswerText.AddListener(
    (nodeName, text, isDelta, isFinal) => chatText.text += text);
agentComp.OnTurnComplete.AddListener(
    (status, _, _) => typingIndicator.SetActive(false));

// When the agent is created, send the first message.
agentComp.OnAgentCreated.AddListener(() => agentComp.SendMessage("Hello!"));
  1. In the Content Browser, right-click → Tryll → Workflow Asset. Name it ChatWorkflow and open it. On the guard node, set Triggered Exit to "" (END) and Not Triggered Exit to "answer". The answer node's Default Exit can be left empty (END). Set Start Node = guard and Default Model Name = your model, as in the Unity steps.
  2. Add a UTryllAgentComponent to your actor and assign ChatWorkflow to its Workflow Asset slot.
  3. In Blueprint:
    • Bind On Agent Ready to a handler that calls Send Message.
    • Bind On Answer Text to append each chunk to a UI text block.
    • Bind On Turn Complete to flip the "typing" indicator off.
#include <tryll/TryllClient.h>

namespace TC = Tryll::Client;
namespace NP = Tryll::NodeParams;

NP::RegexGuardrailParamsT guardParams;
// guardParams.triggered_exit defaults to "" (END) — drop jailbreaks silently.
guardParams.not_triggered_exit = "answer";

TC::GraphDescription graph;
graph.AddRegexGuardrail("guard", guardParams)
     .AddGenerate("answer", NP::GenerateParamsT{})
     .SetStartNode("guard")
     .SetDefaultModelName("My Local Model");

auto agent = client.CreateAgent(graph);

// Register persistent callbacks, then send — fire-and-forget.
agent.SetOnAnswerText(
    [](std::string_view /*nodeName*/, std::string_view text, bool, bool)
    { std::cout << text << std::flush; });
agent.SetOnTurnComplete([](::Tryll::TurnStatus, std::string_view, std::int32_t)
    { std::cout << "\n"; });
agent.SendText("Hello!");

from tryll_client.graph import GraphDescription, RegexGuardrailParams, GenerateParams

# 1. Build the graph.
guard_params = RegexGuardrailParams(
    # triggered_exit defaults to "" (END) — drop jailbreaks silently.
    not_triggered_exit = "answer",
)

graph = (
    GraphDescription()
    .add_node("guard",  guard_params)
    .add_node("answer", GenerateParams())
    .set_start_node("guard")
    .set_default_model_name("My Local Model")
)

# 2. Create the agent.
agent = client.create_agent(graph)

# 3. Send a message. send_message blocks and returns the full reply.
reply = agent.send_message("Hello!")
print(reply)

Verify it worked

Server-side, with log_level set to "trace" in server-config.json, each node logs a start and an end line that names the exit it took. One turn through this graph includes:

[trace] [WORKFLOW] start  entry=ExecuteOnMessage
[trace] [NODE]     start  node=guard
[trace] [NODE]     end    node=guard  exit=not_triggered  duration_ms=0.2
[trace] [NODE]     start  node=answer
[trace] [NODE]     end    node=answer  exit=default  duration_ms=812.4
[trace] [WORKFLOW] end    status=success  total_ms=813.0

Client-side, Python returns the full reply string from send_message, while Unity, C++, and Unreal see each streamed chunk arrive in the OnAnswerText event / SetOnAnswerText callback / OnAnswerText delegate, followed by a TurnComplete with status Success.

Common pitfalls

  • Unknown or unacquired model. A graph whose model name is wrong, missing from models.json, or not yet on disk fails CreateAgent with error 3003 GraphCompilationFailed. Calling LoadModel with a name that is not in the catalog fails with 6005 ModelResolutionFailed. Double-check the name with client.list_models().
  • "Graph validation failed" (error 3003) — check for a bad start node name or duplicate node names in the graph. The same code covers an exit field that names a node not in the graph — fix the string, or leave it empty to route to END.
  • Silent nothing after sending. Check that the start node is not an always-END branch (e.g., guardrail that matches everything). The server log will show which route was taken.