Stream Reasoning Events over AG-UI

reasoning_agent.py

"""
Stream Reasoning Events over AG-UI
==================================

Enable Agno's reasoning loop and translate its reasoning lifecycle into
AG-UI REASONING_START, content, and end events before the final answer.

Prerequisites: OPENAI_API_KEY
Run: .venvs/demo/bin/python cookbook/05_agent_os/16_agui/reasoning_agent.py
Try: POST a multi-step logic problem to http://localhost:7777/reasoning/agui
"""

from agno.agent import Agent
from agno.db.sqlite import SqliteDb
from agno.models.openai import OpenAIResponses
from agno.os import AgentOS
from agno.os.interfaces.agui import AGUI

# ---------------------------------------------------------------------------
# Create Reasoning Agent
# ---------------------------------------------------------------------------

db = SqliteDb(
    id="agui-reasoning-db",
    db_file="tmp/agui_reasoning.db",
)

reasoning_agent = Agent(
    id="agui-reasoning-agent",
    name="AG-UI Reasoning Agent",
    model=OpenAIResponses(id="gpt-5.6"),
    db=db,
    reasoning_model=OpenAIResponses(id="o3-mini"),
    instructions="Solve the problem carefully, then give a concise final answer.",
)

agent_os = AgentOS(
    id="agui-reasoning-os",
    description="AgentOS translating Agno reasoning events to AG-UI.",
    agents=[reasoning_agent],
    interfaces=[AGUI(agent=reasoning_agent, prefix="/reasoning")],
)
app = agent_os.get_app()

# ---------------------------------------------------------------------------
# Run Reasoning Server
# ---------------------------------------------------------------------------

if __name__ == "__main__":
    agent_os.serve(app=app)

An explicit reasoning_model runs as a separate, tool-free reasoning stage before the main model response. show_full_reasoning=True displays the reasoning data Agno receives; it cannot reveal a provider's private internal trace. Some adapters use the reasoning stage's answer text when separate reasoning content is unavailable. A failed reasoning stage can still be followed by a main-model answer, so a completed run alone does not prove the reasoning stage succeeded.

OpenAI schedules o3-mini and o4-mini for shutdown on October 23, 2026. The provider lifecycle notice lists their replacements. Check the selected replacement's reasoning and service-tier support before changing the source model ID.

Run the Example

Set up your virtual environment

uv venv --python 3.12
source .venv/bin/activate

Install dependencies

uv pip install -U "agno[agui,os]" openai

Export your OpenAI API key

export OPENAI_API_KEY="your_openai_api_key_here"

Run the example

Save the code above as reasoning_agent.py, then run:

python reasoning_agent.py

Send a request

With the server running in another terminal:

Save this complete AG-UI request as agui-input.json. Replace content with the prompt for this example. Use a fresh runId for each run; keep threadId only when continuing the same session.

agui-input.json

{
  "threadId": "example-thread-1",
  "runId": "example-run-1",
  "state": {},
  "messages": [
    {"id": "example-message-1", "role": "user", "content": "Hello"}
  ],
  "tools": [],
  "context": [],
  "forwardedProps": {}
}

The endpoint accepts this object, rather than a JSON string or the REST run endpoint's message form field. The response is an SSE stream whose data values are AG-UI event objects. Inspect RUN_ERROR and RUN_FINISHED events; an HTTP 200 only establishes that the stream opened.

curl --no-buffer -H "Content-Type: application/json" --data-binary @agui-input.json http://localhost:7777/reasoning/agui

Full source: cookbook/05_agent_os/16_agui/reasoning_agent.py