codex/sdk/python

Codex App Server Python SDK (Experimental)

Experimental Python SDK for codex app-server JSON-RPC v2 over stdio, with a small default surface optimized for real scripts and apps.

The generated wire-model layer is sourced from the pinned openai-codex-cli-bin runtime package and exposed as Pydantic models with snake_case Python fields that serialize back to the app-server’s camelCase wire format. The package root exports the ergonomic client API; public app-server value and event types live in codex_app_server.types.

Install

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

Published SDK builds pin an exact openai-codex-cli-bin runtime dependency with the same version as the SDK. For local repo development, either pass AppServerConfig(codex_bin=...) to point at a local build explicitly, or use the repo examples/notebook bootstrap which installs the pinned runtime package automatically.

Quickstart

from codex_app_server import Codex

with Codex() as codex:
    thread = codex.thread_start(model="gpt-5")
    result = thread.run("Say hello in one sentence.")
    print(result.final_response)
    print(len(result.items))

result.final_response is None when the turn completes without a final-answer or phase-less assistant message item.

Docs map

• Golden path tutorial: docs/getting-started.md
• API reference (signatures + behavior): docs/api-reference.md
• Common decisions and pitfalls: docs/faq.md
• Runnable examples index: examples/README.md
• Jupyter walkthrough notebook: notebooks/sdk_walkthrough.ipynb

Examples

Start here:

cd sdk/python
python examples/01_quickstart_constructor/sync.py
python examples/01_quickstart_constructor/async.py

Runtime packaging

The repo no longer checks codex binaries into sdk/python.

Published SDK builds are pinned to an exact openai-codex-cli-bin package version, and that runtime package carries the platform-specific binary for the target wheel. The SDK package version and runtime package version must match.

For local repo development, the checked-in sdk/python-runtime package is only a template for staged release artifacts. Editable installs should use an explicit codex_bin override for manual SDK usage; the repo examples and notebook bootstrap the pinned runtime package automatically.

Maintainer workflow

cd sdk/python
uv sync
python scripts/update_sdk_artifacts.py generate-types
python scripts/update_sdk_artifacts.py \
  stage-sdk \
  /tmp/codex-python-release/openai-codex-app-server-sdk \
  --codex-version <codex-release-tag-or-pep440-version>
python scripts/update_sdk_artifacts.py \
  stage-runtime \
  /tmp/codex-python-release/openai-codex-cli-bin \
  /path/to/codex \
  --codex-version <codex-release-tag-or-pep440-version>

Pass --platform-tag ... to stage-runtime when the wheel should be tagged for a Rust target that differs from the Python build host. The intended one-off matrix is macosx_11_0_arm64, macosx_10_9_x86_64, musllinux_1_1_aarch64, musllinux_1_1_x86_64, win_arm64, and win_amd64.

This supports the CI release flow:

• run generate-types before packaging
• stage openai-codex-app-server-sdk once with an exact openai-codex-cli-bin==... dependency
• stage openai-codex-cli-bin on each supported platform runner with the same pinned runtime version
• build and publish openai-codex-cli-bin as platform wheels only through PyPI trusted publishing; do not publish an sdist

Compatibility and versioning

• Package: openai-codex-app-server-sdk
• Runtime package: openai-codex-cli-bin
• Python: >=3.10
• Target protocol: Codex app-server JSON-RPC v2
• Versioning rule: the SDK package version is the underlying Codex runtime version

Notes

• Codex() is eager and performs startup + initialize in the constructor.
• Use context managers (with Codex() as codex:) to ensure shutdown.
• Prefer thread.run("...") for the common case. Use thread.turn(...) when you need streaming, steering, or interrupt control.
• For transient overload, use retry_on_overload from the package root.