qwen-code/packages/sdk-python

qwen-code-sdk

Experimental Python SDK for programmatic access to Qwen Code through the stream-json protocol.

Installation

pip install qwen-code-sdk

For preview releases, enable pre-release resolution:

pip install --pre qwen-code-sdk

Requirements

• Python >=3.10
• External qwen CLI installed and available in PATH

You can also point the SDK at an explicit CLI binary or script with path_to_qwen_executable.

Before using the SDK, verify that the CLI works in the same environment:

qwen --version

Quick Start

import asyncio

from qwen_code_sdk import (
    is_sdk_assistant_message,
    is_sdk_result_message,
    query,
)


def text_from_message(message):
    content = message.get("message", {}).get("content", [])
    if not isinstance(content, list):
        return repr(content)
    texts = [
        block.get("text", "")
        for block in content
        if isinstance(block, dict) and block.get("type") == "text"
    ]
    return "".join(texts) if texts else "[no text content]"


def print_result(message):
    if message.get("is_error"):
        error = message.get("error") or {}
        print(f"Error: {error.get('message', 'Unknown error')}")
        return
    print(message.get("result", ""))


async def main() -> None:
    async with query(
        "List the top-level packages in this repository.",
        {
            "cwd": "/path/to/project",
            "path_to_qwen_executable": "qwen",
        },
    ) as result:
        async for message in result:
            if is_sdk_assistant_message(message):
                print(text_from_message(message))
            elif is_sdk_result_message(message):
                print_result(message)


asyncio.run(main())

asyncio.run() is appropriate for standalone scripts. If your application already runs an event loop, such as Jupyter, FastAPI, or pytest-asyncio, call await main() instead.

Sync API

from qwen_code_sdk import is_sdk_result_message, query_sync


with query_sync(
    "Say hello",
    {
        "cwd": "/path/to/project",
        "path_to_qwen_executable": "qwen",
    },
) as result:
    for message in result:
        if is_sdk_result_message(message):
            if message.get("is_error"):
                error = message.get("error") or {}
                print(f"Error: {error.get('message', 'Unknown error')}")
            else:
                print(message.get("result", ""))

Main APIs

• query(prompt, options=None) -> Query
• query_sync(prompt, options=None) -> SyncQuery
• Query.close(), interrupt(), set_model(), set_permission_mode()
• Query.supported_commands(), mcp_server_status(), get_session_id()

prompt accepts either a single str or an AsyncIterable[SDKUserMessage] for multi-turn sessions.

Common Options

options = {
    "cwd": "/path/to/project",
    "path_to_qwen_executable": "qwen",
    "model": "qwen-plus",
    "permission_mode": "plan",
    "max_session_turns": 1,
    "env": {
        "OPENAI_MODEL": "qwen-plus",
    },
    "timeout": {
        "control_request": 60,
        "can_use_tool": 60,
        "stream_close": 60,
    },
}

Common fields:

• cwd: working directory used by the CLI
• path_to_qwen_executable: qwen, an absolute binary path, or a .js CLI bundle
• model: model override for this session
• permission_mode: one of default, plan, auto-edit, auto, or yolo; auto lets an LLM classifier approve tool calls; yolo auto-approves all tools, so use it only in trusted or sandboxed environments
• env: extra environment variables passed to the CLI process
• system_prompt / append_system_prompt: override or extend the system prompt
• core_tools, exclude_tools, allowed_tools: constrain tool availability
• timeout: seconds for control requests, permission callbacks, and stream close waits

env is merged on top of the parent process environment. Set secrets such as OPENAI_API_KEY in the parent environment or a secrets manager rather than hardcoding them in source.

Multi-Turn Sessions

For multi-turn use cases, pass an async iterable of SDKUserMessage objects. Use a stable UUID for session_id when you want to correlate messages:

import asyncio

from qwen_code_sdk import SDKUserMessage, is_sdk_result_message, query

SESSION_ID = "123e4567-e89b-12d3-a456-426614174000"


async def prompts():
    first: SDKUserMessage = {
        "type": "user",
        "session_id": SESSION_ID,
        "message": {"role": "user", "content": "Create a short project summary."},
        "parent_tool_use_id": None,
    }
    yield first

    second: SDKUserMessage = {
        "type": "user",
        "session_id": SESSION_ID,
        "message": {"role": "user", "content": "Also list the test files."},
        "parent_tool_use_id": None,
    }
    yield second


async def main():
    async with query(
        prompts(),
        {
            "cwd": "/path/to/project",
            "path_to_qwen_executable": "qwen",
            "session_id": SESSION_ID,
        },
    ) as result:
        async for message in result:
            if is_sdk_result_message(message):
                if message.get("is_error"):
                    error = message.get("error") or {}
                    print(f"Error: {error.get('message', 'Unknown error')}")
                else:
                    print(message.get("result", ""))


asyncio.run(main())

All messages in the async iterable must be known upfront. The SDK sends them sequentially to the CLI but cannot feed a prior response back into the generator. If you need conversational turn-taking, manage each turn as a separate query() call.

Permission Callback

import asyncio
from pathlib import Path

from qwen_code_sdk import is_sdk_result_message, query

PROJECT_ROOT = Path("/path/to/project").resolve()


def project_path(tool_name, tool_input):
    key = "path" if tool_name == "list_directory" else "file_path"
    raw_path = tool_input.get(key)
    if not isinstance(raw_path, str) or not raw_path:
        return None

    resolved = (PROJECT_ROOT / raw_path).resolve()
    try:
        resolved.relative_to(PROJECT_ROOT)
    except ValueError:
        return None
    return resolved


async def can_use_tool(tool_name, tool_input, context):
    if tool_name in {"read_file", "list_directory", "write_file"}:
        resolved = project_path(tool_name, tool_input)
        if resolved is None:
            return {
                "behavior": "deny",
                "message": "Only project-local paths are allowed",
            }

        if tool_name == "write_file" and resolved.suffix != ".md":
            return {"behavior": "deny", "message": "Only .md files can be written"}

        return {"behavior": "allow", "updatedInput": tool_input}

    return {
        "behavior": "deny",
        "message": f"{tool_name} is not allowed by this application",
    }


async def main():
    async with query(
        "Update README.md with a one paragraph summary.",
        {
            "cwd": str(PROJECT_ROOT),
            "path_to_qwen_executable": "qwen",
            "can_use_tool": can_use_tool,
        },
    ) as result:
        async for message in result:
            if is_sdk_result_message(message):
                if message.get("is_error"):
                    error = message.get("error") or {}
                    print(f"Error: {error.get('message', 'Unknown error')}")
                else:
                    print(message.get("result", ""))


asyncio.run(main())

The callback defaults to deny. If it does not return within timeout.can_use_tool seconds, the SDK auto-denies the tool request. The default timeout is 60 seconds.

The context argument includes cancel_event, suggestions, and blocked_path when the CLI provides a path-specific permission target. can_use_tool must be an async def callback accepting (tool_name, tool_input, context). stderr must accept a single str.

Handling ask_user_question

When the model needs a decision from the user it calls the built-in ask_user_question tool. This flows through the same can_use_tool callback: tool_input carries a questions list, and you return the collected answers via updatedInput["answers"]. answers is a dict keyed by the question's index (as a string), where each value is the label of the chosen option (or free-form text when the user picks "Other").

async def can_use_tool(tool_name, tool_input, context):
    if tool_name == "ask_user_question":
        questions = tool_input["questions"]

        # Present the questions to the user however your app sees fit,
        # then build an index-keyed map of their answers.
        answers = {}
        for index, question in enumerate(questions):
            answers[str(index)] = await prompt_user_to_choose(question)

        # Return the answers through updatedInput["answers"] — the CLI
        # forwards them to the tool so the model receives the decisions.
        return {
            "behavior": "allow",
            "updatedInput": {**tool_input, "answers": answers},
        }

    return {"behavior": "allow", "updatedInput": tool_input}

If you return allow without any answers, the tool reports that no answer was provided; return deny to signal the user declined.

Runtime Controls

Control methods can be called while a session is active:

import asyncio

from qwen_code_sdk import is_sdk_result_message, query


async def main():
    async with query(
        "Inspect this project and wait for my next instruction.",
        {
            "cwd": "/path/to/project",
            "path_to_qwen_executable": "qwen",
        },
    ) as result:
        commands = await result.supported_commands()
        print(commands)

        await result.set_permission_mode("plan")
        await result.set_model("qwen-plus")

        async for message in result:
            if is_sdk_result_message(message):
                if message.get("is_error"):
                    error = message.get("error") or {}
                    print(f"Error: {error.get('message', 'Unknown error')}")
                else:
                    print(message.get("result", ""))


asyncio.run(main())

Use interrupt() to cancel the current CLI operation and close() to clean up the underlying process.

Resuming Sessions

import asyncio

from qwen_code_sdk import is_sdk_result_message, query


async def main():
    # Resume a known session.
    async with query(
        "Continue from the previous state.",
        {
            "path_to_qwen_executable": "qwen",
            "resume": "123e4567-e89b-12d3-a456-426614174000",
        },
    ) as result:
        async for message in result:
            if is_sdk_result_message(message):
                if message.get("is_error"):
                    error = message.get("error") or {}
                    print(f"Error: {error.get('message', 'Unknown error')}")
                else:
                    print(message.get("result", ""))


asyncio.run(main())

To continue the latest session instead:

import asyncio

from qwen_code_sdk import is_sdk_result_message, query


async def main():
    async with query(
        "Continue the last session.",
        {
            "path_to_qwen_executable": "qwen",
            "continue_session": True,
        },
    ) as latest:
        async for message in latest:
            if is_sdk_result_message(message):
                if message.get("is_error"):
                    error = message.get("error") or {}
                    print(f"Error: {error.get('message', 'Unknown error')}")
                else:
                    print(message.get("result", ""))


asyncio.run(main())

Use only one of resume, continue_session, or session_id in a request. The SDK raises ValidationError if these session options are combined.

Error Handling

• ValidationError: invalid query options or malformed session identifiers
• ControlRequestTimeoutError: CLI control operation exceeded timeout
• ProcessExitError: qwen exited with a non-zero code
• AbortError: query or control request was cancelled

from qwen_code_sdk import (
    ProcessExitError,
    ValidationError,
    is_sdk_result_message,
    query_sync,
)

try:
    with query_sync("Say hello", {"path_to_qwen_executable": "qwen"}) as result:
        for message in result:
            if is_sdk_result_message(message):
                if message.get("is_error"):
                    error = message.get("error") or {}
                    print(f"Error: {error.get('message', 'Unknown error')}")
                else:
                    print(message.get("result", ""))
except ValidationError as exc:
    print(f"Invalid SDK options: {exc}")
except ProcessExitError as exc:
    print(f"qwen exited with {exc.exit_code}: {exc}")

Current Scope

0.1.x is intentionally narrow:

• Uses external qwen CLI via process transport
• Targets stream-json parity with the TypeScript SDK core flow
• Does not yet implement ACP transport
• Does not yet embed MCP servers inside the SDK process

See developer documentation for more detail.