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Documentation Index

Fetch the complete documentation index at: https://allhandsai-codex-agent-server-user-docs.mintlify.app/llms.txt

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Run a local Agent Server when you want a backend process to host OpenHands conversations over HTTP and WebSocket. This is the simplest setup for testing Agent Canvas-style backends, local integrations, and client-server SDK applications.

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Install

Create a Python environment and install the same release of the server package and SDK packages it uses: 
python -m venv .venv
source .venv/bin/activate
export OPENHANDS_VERSION="1.24.0"
pip install -U \
  "openhands-sdk==$OPENHANDS_VERSION" \
  "openhands-tools==$OPENHANDS_VERSION" \
  "openhands-workspace==$OPENHANDS_VERSION" \
  "openhands-agent-server==$OPENHANDS_VERSION"

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Start Without Authentication

For local development on your own machine, start the server on loopback: 
python -m openhands.agent_server --host 127.0.0.1 --port 8000
Verify that it is running: 
curl http://127.0.0.1:8000/health
Open the API docs at http://127.0.0.1:8000/docs. If SESSION_API_KEY or OH_SESSION_API_KEYS_* is already set in your shell, the server will require that key for /api/* requests. Unset those variables for unauthenticated local-only testing.
This unauthenticated mode is only appropriate for local development. Do not bind an unauthenticated server to a public or shared network interface.

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Start With an API Key

Set a session API key before starting the server: 
export OH_SESSION_API_KEYS_0="$(openssl rand -hex 32)"
export OH_SECRET_KEY="$(openssl rand -hex 32)"

python -m openhands.agent_server --host 127.0.0.1 --port 8000
Requests to /api/* must include the session key. This request returns the conversation count when the key is accepted: 
curl \
  -H "X-Session-API-Key: $OH_SESSION_API_KEYS_0" \
  http://127.0.0.1:8000/api/conversations/count
Use OH_SECRET_KEY whenever you want conversations and stored settings to survive restarts with their sensitive values intact. Keep this value stable and store it in your normal secret manager.

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Connect From the SDK

Use Workspace(host=..., api_key=...) to connect SDK code to the server: 
import os

from pydantic import SecretStr

from openhands.sdk import Conversation, LLM, Workspace
from openhands.tools.preset.default import get_default_agent


llm = LLM(
    model=os.environ.get("LLM_MODEL", "anthropic/claude-sonnet-4-5-20250929"),
    api_key=SecretStr(os.environ["LLM_API_KEY"]),
)
agent = get_default_agent(llm=llm, cli_mode=True)

workspace = Workspace(
    host="http://127.0.0.1:8000",
    api_key=os.environ.get("OH_SESSION_API_KEYS_0"),
    working_dir="workspace/project",
)

conversation = Conversation(agent=agent, workspace=workspace)
conversation.send_message("Create a NOTES.md file with three facts about this project.")
conversation.run()
conversation.close()
If the server was started without OH_SESSION_API_KEYS_0, omit api_key.

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Connect From Another Service

For a backend service, configure two values:
  • The Agent Server URL, for example http://127.0.0.1:8000.
  • The session API key, passed as X-Session-API-Key on API requests or as api_key when using the SDK Workspace.
Keep the Agent Server bound to 127.0.0.1 when the backend runs on the same machine. If the backend runs on another host, use a private network or reverse proxy, enable TLS, and restrict network access to trusted callers.

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Configure CORS

Most backends call the Agent Server from server-side code and do not need CORS. If browser code calls the Agent Server directly, allow that origin: 
export OH_ALLOW_CORS_ORIGINS_0="https://your-frontend.example.com"
Localhost and 127.0.0.1 origins are allowed automatically.

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Run From the SDK Repository

When developing OpenHands/software-agent-sdk itself: 
git clone https://github.com/OpenHands/software-agent-sdk.git
cd software-agent-sdk
uv sync
uv run python -m openhands.agent_server --host 127.0.0.1 --port 8000

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Ready-to-Run Example

This example is available on GitHub: examples/02_remote_agent_server/01_convo_with_local_agent_server.py.
The example starts a local Agent Server subprocess, waits for it to become healthy, connects with Workspace(host=...), and runs a RemoteConversation. You can run the example code as-is.
The model name should follow the LiteLLM convention: provider/model_name (e.g., anthropic/claude-sonnet-4-5-20250929, openai/gpt-4o). The LLM_API_KEY should be the API key for your chosen provider.
ChatGPT Plus/Pro subscribers: You can use LLM.subscription_login() to authenticate with your ChatGPT account and access Codex models without consuming API credits. See the LLM Subscriptions guide for details.

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Troubleshooting

  • 401 Unauthorized: Check that the client sends X-Session-API-Key and that it matches OH_SESSION_API_KEYS_0.
  • Secrets are missing after restart: Set a stable OH_SECRET_KEY before starting the server.
  • The server is reachable locally but not from another machine: Use --host 0.0.0.0 only behind trusted network controls, then check firewall and proxy rules.
  • CORS errors in a browser: Set OH_ALLOW_CORS_ORIGINS_0 to the browser app origin.
  • Port conflict: Start with another port, for example --port 8001.

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Next Steps