Files
codex/sdk/python/docs/getting-started.md
Ahmed Ibrahim ebe75bb683 Route Python SDK turn notifications by ID (#21778)
## Why

The Python SDK previously protected the stdio transport with a single
active turn-consumer guard. That avoided competing reads from stdout,
but it also meant one `Codex`/`AsyncCodex` client could not stream
multiple active turns at the same time. Notifications could also arrive
before the caller received a `TurnHandle` and registered for streaming,
so the SDK needed an explicit routing layer instead of letting
individual API calls read directly from the shared transport.

## What Changed

- Added a private `MessageRouter` that owns per-request response queues,
per-turn notification queues, pending turn-notification replay, and
global notification delivery behind a single stdout reader thread.
- Generated typed notification routing metadata so turn IDs come from
known payload shapes instead of router-side attribute guessing, with
explicit fallback handling for unknown notification payloads.
- Updated sync and async turn streaming so `TurnHandle.stream()`/`run()`
and `stream_text()` consume only notifications for their own turn ID,
while `AsyncAppServerClient` no longer serializes all transport calls
behind one async lock.
- Cleared pending turn-notification buffers when unregistered turns
complete so never-consumed turn handles do not leave stale queues
behind.
- Removed the internal stream-until helper now that turn completion
waiting can register directly with routed turn notifications.
- Updated Python SDK docs and focused tests for concurrent transport
calls, interleaved turn routing, buffered early notifications, unknown
notification routing, async delegation, and routed turn completion
behavior.

## Validation

- `uv run --extra dev ruff format scripts/update_sdk_artifacts.py
src/codex_app_server/_message_router.py src/codex_app_server/client.py
src/codex_app_server/generated/notification_registry.py
tests/test_client_rpc_methods.py
tests/test_public_api_runtime_behavior.py
tests/test_async_client_behavior.py`
- `uv run --extra dev ruff check scripts/update_sdk_artifacts.py
src/codex_app_server/_message_router.py src/codex_app_server/client.py
src/codex_app_server/generated/notification_registry.py
tests/test_client_rpc_methods.py
tests/test_public_api_runtime_behavior.py
tests/test_async_client_behavior.py`
- `uv run --extra dev pytest tests/test_client_rpc_methods.py
tests/test_public_api_runtime_behavior.py
tests/test_async_client_behavior.py`
- `git diff --check`

---------

Co-authored-by: Codex <noreply@openai.com>
2026-05-09 04:16:23 +00:00

3.2 KiB

Getting Started

This is the fastest path from install to a multi-turn thread using the public SDK surface.

The SDK is experimental. Treat the API, bundled runtime strategy, and packaging details as unstable until the first public release.

1) Install

From repo root:

cd sdk/python
uv sync
source .venv/bin/activate

Requirements:

  • Python >=3.10
  • uv
  • installed openai-codex-cli-bin runtime package, or an explicit codex_bin override
  • local Codex auth/session configured

2) Run your first turn (sync)

from codex_app_server import Codex

with Codex() as codex:
    server = codex.metadata.serverInfo
    print("Server:", None if server is None else server.name, None if server is None else server.version)

    thread = codex.thread_start(model="gpt-5.4", config={"model_reasoning_effort": "high"})
    result = thread.run("Say hello in one sentence.")

    print("Thread:", thread.id)
    print("Text:", result.final_response)
    print("Items:", len(result.items))

What happened:

  • Codex() started and initialized codex app-server.
  • thread_start(...) created a thread.
  • thread.run("...") started a turn, consumed events until completion, and returned the final assistant response plus collected items and usage.
  • result.final_response is None when no final-answer or phase-less assistant message item completes for the turn.
  • use thread.turn(...) when you need a TurnHandle for streaming, steering, interrupting, or turn IDs/status
  • one client can consume multiple active turns concurrently; turn streams are routed by turn ID

3) Continue the same thread (multi-turn)

from codex_app_server import Codex

with Codex() as codex:
    thread = codex.thread_start(model="gpt-5.4", config={"model_reasoning_effort": "high"})

    first = thread.run("Summarize Rust ownership in 2 bullets.")
    second = thread.run("Now explain it to a Python developer.")

    print("first:", first.final_response)
    print("second:", second.final_response)

4) Async parity

Use async with AsyncCodex() as the normal async entrypoint. AsyncCodex initializes lazily, and context entry makes startup/shutdown explicit.

import asyncio
from codex_app_server import AsyncCodex


async def main() -> None:
    async with AsyncCodex() as codex:
        thread = await codex.thread_start(model="gpt-5.4", config={"model_reasoning_effort": "high"})
        result = await thread.run("Continue where we left off.")
        print(result.final_response)


asyncio.run(main())

5) Resume an existing thread

from codex_app_server import Codex

THREAD_ID = "thr_123"  # replace with a real id

with Codex() as codex:
    thread = codex.thread_resume(THREAD_ID)
    result = thread.run("Continue where we left off.")
    print(result.final_response)

6) Generated models

The convenience wrappers live at the package root, but the canonical app-server models live under:

from codex_app_server.generated.v2_all import Turn, TurnStatus, ThreadReadResponse

7) Next stops

  • API surface and signatures: docs/api-reference.md
  • Common decisions/pitfalls: docs/faq.md
  • End-to-end runnable examples: examples/README.md