Codex App Server SDK — API Reference

Public surface of codex_app_server for app-server v2.

This SDK surface is experimental. The current implementation intentionally allows only one active turn consumer (Thread.run(), TurnHandle.stream(), or TurnHandle.run()) per client instance at a time.

Package Entry

from codex_app_server import (
    Codex,
    AsyncCodex,
    RunResult,
    Thread,
    AsyncThread,
    TurnHandle,
    AsyncTurnHandle,
    InitializeResponse,
    Input,
    InputItem,
    TextInput,
    ImageInput,
    LocalImageInput,
    SkillInput,
    MentionInput,
    TurnStatus,
)
from codex_app_server.generated.v2_all import ThreadItem, ThreadTokenUsage

• Version: codex_app_server.__version__
• Requires Python >= 3.10
• Canonical generated app-server models live in codex_app_server.generated.v2_all

Codex (sync)

Codex(config: AppServerConfig | None = None)

Properties/methods:

• metadata -> InitializeResponse
• close() -> None
• thread_start(*, approval_policy=None, base_instructions=None, config=None, cwd=None, developer_instructions=None, ephemeral=None, model=None, model_provider=None, personality=None, sandbox=None) -> Thread
• thread_list(*, archived=None, cursor=None, cwd=None, limit=None, model_providers=None, sort_key=None, source_kinds=None) -> ThreadListResponse
• thread_resume(thread_id: str, *, approval_policy=None, base_instructions=None, config=None, cwd=None, developer_instructions=None, model=None, model_provider=None, personality=None, sandbox=None) -> Thread
• thread_fork(thread_id: str, *, approval_policy=None, base_instructions=None, config=None, cwd=None, developer_instructions=None, model=None, model_provider=None, sandbox=None) -> Thread
• thread_archive(thread_id: str) -> ThreadArchiveResponse
• thread_unarchive(thread_id: str) -> Thread
• models(*, include_hidden: bool = False) -> ModelListResponse

Context manager:

with Codex() as codex:
    ...

AsyncCodex (async parity)

AsyncCodex(config: AppServerConfig | None = None)

Preferred usage:

async with AsyncCodex() as codex:
    ...

AsyncCodex initializes lazily. Context entry is the standard path because it ensures startup and shutdown are paired explicitly.

Properties/methods:

• metadata -> InitializeResponse
• close() -> Awaitable[None]
• thread_start(*, approval_policy=None, base_instructions=None, config=None, cwd=None, developer_instructions=None, ephemeral=None, model=None, model_provider=None, personality=None, sandbox=None) -> Awaitable[AsyncThread]
• thread_list(*, archived=None, cursor=None, cwd=None, limit=None, model_providers=None, sort_key=None, source_kinds=None) -> Awaitable[ThreadListResponse]
• thread_resume(thread_id: str, *, approval_policy=None, base_instructions=None, config=None, cwd=None, developer_instructions=None, model=None, model_provider=None, personality=None, sandbox=None) -> Awaitable[AsyncThread]
• thread_fork(thread_id: str, *, approval_policy=None, base_instructions=None, config=None, cwd=None, developer_instructions=None, ephemeral=None, model=None, model_provider=None, sandbox=None) -> Awaitable[AsyncThread]
• thread_archive(thread_id: str) -> Awaitable[ThreadArchiveResponse]
• thread_unarchive(thread_id: str) -> Awaitable[AsyncThread]
• models(*, include_hidden: bool = False) -> Awaitable[ModelListResponse]

Async context manager:

async with AsyncCodex() as codex:
    ...

Thread / AsyncThread

Thread and AsyncThread share the same shape and intent.

Thread

• run(input: str | Input, *, approval_policy=None, approvals_reviewer=None, cwd=None, effort=None, model=None, output_schema=None, personality=None, sandbox_policy=None, service_tier=None, summary=None) -> RunResult
• turn(input: Input, *, approval_policy=None, cwd=None, effort=None, model=None, output_schema=None, personality=None, sandbox_policy=None, summary=None) -> TurnHandle
• read(*, include_turns: bool = False) -> ThreadReadResponse
• set_name(name: str) -> ThreadSetNameResponse
• compact() -> ThreadCompactStartResponse

AsyncThread

• run(input: str | Input, *, approval_policy=None, approvals_reviewer=None, cwd=None, effort=None, model=None, output_schema=None, personality=None, sandbox_policy=None, service_tier=None, summary=None) -> Awaitable[RunResult]
• turn(input: Input, *, approval_policy=None, cwd=None, effort=None, model=None, output_schema=None, personality=None, sandbox_policy=None, summary=None) -> Awaitable[AsyncTurnHandle]
• read(*, include_turns: bool = False) -> Awaitable[ThreadReadResponse]
• set_name(name: str) -> Awaitable[ThreadSetNameResponse]
• compact() -> Awaitable[ThreadCompactStartResponse]

run(...) is the common-case convenience path. It accepts plain strings, starts the turn, consumes notifications until completion, and returns a small result object with:

• final_response: str | None
• items: list[ThreadItem]
• usage: ThreadTokenUsage | None

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

Use turn(...) when you need low-level turn control (stream(), steer(), interrupt()) or the canonical generated Turn from TurnHandle.run().

TurnHandle / AsyncTurnHandle

TurnHandle

• steer(input: Input) -> TurnSteerResponse
• interrupt() -> TurnInterruptResponse
• stream() -> Iterator[Notification]
• run() -> codex_app_server.generated.v2_all.Turn

Behavior notes:

• stream() and run() are exclusive per client instance in the current experimental build
• starting a second turn consumer on the same Codex instance raises RuntimeError

AsyncTurnHandle

• steer(input: Input) -> Awaitable[TurnSteerResponse]
• interrupt() -> Awaitable[TurnInterruptResponse]
• stream() -> AsyncIterator[Notification]
• run() -> Awaitable[codex_app_server.generated.v2_all.Turn]

Behavior notes:

• stream() and run() are exclusive per client instance in the current experimental build
• starting a second turn consumer on the same AsyncCodex instance raises RuntimeError

Inputs

@dataclass class TextInput: text: str
@dataclass class ImageInput: url: str
@dataclass class LocalImageInput: path: str
@dataclass class SkillInput: name: str; path: str
@dataclass class MentionInput: name: str; path: str

InputItem = TextInput | ImageInput | LocalImageInput | SkillInput | MentionInput
Input = list[InputItem] | InputItem

Generated Models

The SDK wrappers return and accept canonical generated app-server models wherever possible:

from codex_app_server.generated.v2_all import (
    AskForApproval,
    ThreadReadResponse,
    Turn,
    TurnStartParams,
    TurnStatus,
)

Retry + errors

from codex_app_server import (
    retry_on_overload,
    JsonRpcError,
    MethodNotFoundError,
    InvalidParamsError,
    ServerBusyError,
    is_retryable_error,
)

• retry_on_overload(...) retries transient overload errors with exponential backoff + jitter.
• is_retryable_error(exc) checks if an exception is transient/overload-like.

Example

from codex_app_server import Codex

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