python/sdk/src/deepseek_harness/client.py

from __future__ import annotations

import json
import os
import queue
import subprocess
import threading
import time
import uuid
from collections import deque
from dataclasses import dataclass
from pathlib import Path
from typing import Callable, TypeAlias, TypeVar

from pydantic import BaseModel

from .errors import JsonRpcError, TransportClosedError
from .models import IncomingRequest, InitializeResponse, JsonObject, JsonValue, Notification

ModelT = TypeVar("ModelT", bound=BaseModel)
NotificationFilter: TypeAlias = Callable[[Notification], bool]


@dataclass(slots=True)
class HarnessConfig:
    """Configuration for launching the local DeepSeek Harness SDK runtime."""

    dsh_bin: str | None = None
    profile: str = "sdk"
    patches: tuple[str, ...] = ()
    dsh_home: str | None = None
    cwd: str | None = None
    env: dict[str, str] | None = None
    initialize_timeout_seconds: float = 30.0
    request_timeout_seconds: float | None = None
    shutdown_timeout_seconds: float | None = 1.0


class HarnessClient:
    """Synchronous JSON-RPC client for the DeepSeek Harness SDK runtime over stdio."""

    def __init__(
        self,
        config: HarnessConfig | None = None,
        *,
        _launch_args: tuple[str, ...] | None = None,
    ) -> None:
        self.config = config or HarnessConfig()
        self._launch_args = _launch_args
        self._proc: subprocess.Popen[str] | None = None
        self._lock = threading.Lock()
        self._write_lock = threading.Lock()
        self._responses: dict[str, queue.Queue[JsonValue | BaseException]] = {}
        self._notifications: queue.Queue[Notification | BaseException] = queue.Queue()
        self._notification_subscribers: dict[
            str, tuple[queue.Queue[Notification | BaseException], NotificationFilter | None]
        ] = {}
        self._session_parents: dict[str, str] = {}
        self._requests: queue.Queue[IncomingRequest | BaseException] = queue.Queue()
        self._stderr_lines: deque[str] = deque(maxlen=400)
        self._reader_thread: threading.Thread | None = None
        self._stderr_thread: threading.Thread | None = None

    def __enter__(self) -> "HarnessClient":
        self.start()
        return self

    def __exit__(self, _exc_type, _exc, _tb) -> None:
        self.close()

    def start(self) -> None:
        if self._proc is not None:
            return
        with self._lock:
            self._session_parents.clear()
        env = os.environ.copy()
        if self.config.env:
            env.update(self.config.env)
        args = list(self._launch_args or self._default_launch_args(env))
        self._proc = subprocess.Popen(
            args,
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            text=True,
            encoding="utf-8",
            cwd=None if self.config.cwd is None else str(Path(self.config.cwd).resolve()),
            env=env,
            bufsize=1,
        )
        self._start_reader_thread()
        self._start_stderr_thread()

    def close(self) -> None:
        """Close the runtime after a bounded opportunity to flush durable state."""
        proc = self._proc
        if proc is None:
            return
        shutdown_completed = False
        try:
            self.request("shutdown", None, response_model=_ShutdownResponse, timeout_seconds=self.config.shutdown_timeout_seconds)
            shutdown_completed = True
        except Exception as exc:
            self._stderr_lines.append(f"shutdown request failed: {exc}")
        if proc.stdin:
            try:
                proc.stdin.close()
            except Exception as exc:
                self._stderr_lines.append(f"stdin close failed: {exc}")
        if shutdown_completed:
            try:
                proc.wait(timeout=self.config.shutdown_timeout_seconds)
            except subprocess.TimeoutExpired:
                pass
        if proc.poll() is None:
            try:
                proc.terminate()
            except ProcessLookupError:
                pass
        if proc.poll() is None:
            try:
                proc.wait(timeout=self.config.shutdown_timeout_seconds)
            except subprocess.TimeoutExpired:
                proc.kill()
                proc.wait()
        self._proc = None
        self._fail_waiters(self._runtime_closed_error("DeepSeek Harness runtime closed"))
        if self._reader_thread and self._reader_thread.is_alive():
            self._reader_thread.join(timeout=0.5)
        if self._stderr_thread and self._stderr_thread.is_alive():
            self._stderr_thread.join(timeout=0.5)

    def initialize(
        self,
        *,
        cwd: str,
        provider: str,
        model: str,
        reasoning_effort: str | None = None,
        max_tokens: int | None = None,
    ) -> InitializeResponse:
        payload: JsonObject = {
            "cwd": str(Path(cwd).resolve()),
            "provider": provider,
            "model": model,
        }
        if reasoning_effort is not None:
            payload["reasoningEffort"] = reasoning_effort
        if max_tokens is not None:
            payload["maxTokens"] = max_tokens
        try:
            return self.request(
                "initialize",
                payload,
                response_model=InitializeResponse,
                timeout_seconds=self.config.initialize_timeout_seconds,
            )
        except TimeoutError as error:
            self.close()
            raise TimeoutError(f"{error}\nselected dsh profile {self.config.profile!r}") from error
        except BaseException as error:
            self.close()
            diagnostics = self._runtime_diagnostics()
            if isinstance(error, JsonRpcError) and diagnostics:
                raise JsonRpcError(
                    error.code,
                    f"{error.message}\n{diagnostics}",
                    error.data,
                ) from error
            raise

    def session_prompt(
        self,
        session_id: str,
        content_blocks: list[JsonObject],
        *,
        on_notification: Callable[[Notification], None] | None = None,
        notification_subscription: "NotificationSubscription | None" = None,
    ) -> str:
        payload: JsonObject = {"sessionId": session_id, "contentBlocks": content_blocks}
        response = self.request(
            "session/prompt",
            payload,
            response_model=_SessionPromptResponse,
            on_notification=on_notification,
            notification_filter=self._notification_belongs_to_session_tree(session_id),
            notification_subscription=notification_subscription,
        )
        return response.messageId

    def request(
        self,
        method: str,
        params: JsonObject | None,
        *,
        response_model: type[ModelT],
        timeout_seconds: float | None = None,
        on_notification: Callable[[Notification], None] | None = None,
        notification_filter: NotificationFilter | None = None,
        notification_subscription: "NotificationSubscription | None" = None,
    ) -> ModelT:
        result = self._request_raw(
            method,
            params,
            timeout_seconds=timeout_seconds,
            on_notification=on_notification,
            notification_filter=notification_filter,
            notification_subscription=notification_subscription,
        )
        if not isinstance(result, dict):
            raise TypeError(f"{method} response must be a JSON object")
        return response_model.model_validate(result)

    def notify(self, method: str, params: JsonObject | None = None) -> None:
        message: JsonObject = {"jsonrpc": "2.0", "method": method}
        if params is not None:
            message["params"] = params
        self._write_message(message)

    def next_notification(self) -> Notification:
        item = self._notifications.get()
        if isinstance(item, BaseException):
            raise item
        return item

    def subscribe_notifications(
        self,
        notification_filter: NotificationFilter | None = None,
    ) -> "NotificationSubscription":
        subscription_id = str(uuid.uuid4())
        notifications: queue.Queue[Notification | BaseException] = queue.Queue()
        with self._lock:
            self._notification_subscribers[subscription_id] = (notifications, notification_filter)
        return NotificationSubscription(self, subscription_id, notifications)

    def subscribe_session_notifications(self, session_id: str) -> "NotificationSubscription":
        """Subscribe to a session and descendants discovered from subagent lifecycle edges."""
        return self.subscribe_notifications(self._notification_belongs_to_session_tree(session_id))

    def next_request(self) -> IncomingRequest:
        item = self._requests.get()
        if isinstance(item, BaseException):
            raise item
        return item

    def respond(self, request_id: str | int, result: JsonValue) -> None:
        self._write_message({"jsonrpc": "2.0", "id": request_id, "result": result})

    def respond_error(
        self,
        request_id: str | int,
        *,
        code: int,
        message: str,
        data: JsonValue | None = None,
    ) -> None:
        error: JsonObject = {"code": code, "message": message}
        if data is not None:
            error["data"] = data
        self._write_message({"jsonrpc": "2.0", "id": request_id, "error": error})

    def _request_raw(
        self,
        method: str,
        params: JsonObject | None = None,
        *,
        timeout_seconds: float | None = None,
        on_notification: Callable[[Notification], None] | None = None,
        notification_filter: NotificationFilter | None = None,
        notification_subscription: "NotificationSubscription | None" = None,
    ) -> JsonValue:
        request_id = str(uuid.uuid4())
        waiter: queue.Queue[JsonValue | BaseException] = queue.Queue(maxsize=1)
        temp_subscription: NotificationSubscription | None = None
        subscription = notification_subscription
        with self._lock:
            self._responses[request_id] = waiter
        if on_notification is not None and subscription is None:
            temp_subscription = self.subscribe_notifications(notification_filter)
            subscription = temp_subscription
        try:
            message: JsonObject = {"jsonrpc": "2.0", "id": request_id, "method": method}
            if params is not None:
                message["params"] = params
            self._write_message(message)
        except BaseException:
            with self._lock:
                self._responses.pop(request_id, None)
            if temp_subscription is not None:
                temp_subscription.close()
            raise
        timeout = self.config.request_timeout_seconds if timeout_seconds is None else timeout_seconds
        deadline = None if timeout is None else time.monotonic() + timeout
        try:
            while True:
                if on_notification is not None and subscription is not None:
                    subscription.drain(on_notification)
                wait_timeout = None
                if on_notification is not None:
                    wait_timeout = 0.05
                if deadline is not None:
                    remaining = deadline - time.monotonic()
                    if remaining <= 0:
                        with self._lock:
                            self._responses.pop(request_id, None)
                        diagnostics = self._runtime_diagnostics()
                        suffix = f"\n{diagnostics}" if diagnostics else ""
                        raise TimeoutError(
                            f"{method} timed out waiting for DeepSeek Harness runtime{suffix}"
                        )
                    wait_timeout = remaining if wait_timeout is None else min(wait_timeout, remaining)
                try:
                    item = waiter.get(timeout=wait_timeout)
                    if on_notification is not None and subscription is not None:
                        subscription.drain(on_notification)
                    break
                except queue.Empty:
                    continue
        except BaseException:
            with self._lock:
                self._responses.pop(request_id, None)
            if temp_subscription is not None:
                temp_subscription.close()
            raise
        finally:
            if temp_subscription is not None:
                temp_subscription.close()
        if isinstance(item, BaseException):
            raise item
        return item

    def _write_message(self, message: JsonObject) -> None:
        proc = self._proc
        if proc is None or proc.stdin is None:
            raise TransportClosedError("DeepSeek Harness runtime is not running")
        try:
            payload = json.dumps(message, separators=(",", ":")) + "\n"
            with self._write_lock:
                proc.stdin.write(payload)
                proc.stdin.flush()
        except Exception as exc:
            raise self._runtime_closed_error("Failed to write to DeepSeek Harness runtime") from exc

    def _start_reader_thread(self) -> None:
        self._reader_thread = threading.Thread(target=self._reader_loop, name="dsh-runtime-reader", daemon=True)
        self._reader_thread.start()

    def _start_stderr_thread(self) -> None:
        self._stderr_thread = threading.Thread(target=self._stderr_loop, name="dsh-runtime-stderr", daemon=True)
        self._stderr_thread.start()

    def _reader_loop(self) -> None:
        proc = self._proc
        if proc is None or proc.stdout is None:
            return
        try:
            for line in proc.stdout:
                if not line.strip():
                    continue
                try:
                    message = json.loads(line)
                except json.JSONDecodeError:
                    continue
                self._handle_message(message)
        except BaseException as exc:
            self._fail_waiters(exc)
        finally:
            self._fail_waiters(self._runtime_closed_error("DeepSeek Harness runtime stdout closed"))

    def _stderr_loop(self) -> None:
        proc = self._proc
        if proc is None or proc.stderr is None:
            return
        for line in proc.stderr:
            self._stderr_lines.append(line.rstrip())

    def _handle_message(self, message: object) -> None:
        if not isinstance(message, dict):
            return
        msg_id = message.get("id")
        method = message.get("method")
        if isinstance(msg_id, (str, int)) and isinstance(method, str):
            params = message.get("params")
            self._requests.put(IncomingRequest(id=msg_id, method=method, payload=params if isinstance(params, dict) else {}))
            return
        if isinstance(msg_id, (str, int)):
            with self._lock:
                waiter = self._responses.pop(str(msg_id), None)
            if waiter is None:
                return
            if isinstance(message.get("error"), dict):
                err = message["error"]
                waiter.put(JsonRpcError(_int_or_none(err.get("code")), str(err.get("message", "JSON-RPC error")), err.get("data")))
            else:
                waiter.put(message.get("result"))
            return
        if isinstance(method, str):
            params = message.get("params")
            notification = Notification(method=method, payload=params if isinstance(params, dict) else {})
            with self._lock:
                self._record_session_relationship_locked(notification)
                subscribers = list(self._notification_subscribers.items())
            delivered = False
            for subscription_id, (subscriber, predicate) in subscribers:
                try:
                    matches = predicate is None or predicate(notification)
                except BaseException as exc:
                    with self._lock:
                        current = self._notification_subscribers.get(subscription_id)
                        if current is not None and current[0] is subscriber:
                            self._notification_subscribers.pop(subscription_id, None)
                    subscriber.put(exc)
                    continue
                if matches:
                    subscriber.put(notification)
                    delivered = True
            if not delivered:
                self._notifications.put(notification)

    def _fail_waiters(self, exc: BaseException) -> None:
        with self._lock:
            waiters = list(self._responses.values())
            self._responses.clear()
            subscribers = list(self._notification_subscribers.values())
            self._notification_subscribers.clear()
        for waiter in waiters:
            waiter.put(exc)
        for subscriber, _predicate in subscribers:
            subscriber.put(exc)
        self._notifications.put(exc)
        self._requests.put(exc)

    def _runtime_closed_error(self, reason: str) -> TransportClosedError:
        diagnostics = self._runtime_diagnostics()
        return TransportClosedError(f"{reason}\n{diagnostics}" if diagnostics else reason)

    def _runtime_diagnostics(self) -> str:
        """Return available subprocess state for transport failures and timeouts."""
        proc = self._proc
        if (
            proc is not None
            and proc.poll() is not None
            and self._stderr_thread is not None
            and self._stderr_thread.is_alive()
            and threading.current_thread() is not self._stderr_thread
        ):
            self._stderr_thread.join(timeout=0.1)

        parts: list[str] = []
        if proc is not None:
            exit_code = proc.poll()
            if exit_code is not None:
                parts.append(f"exit code: {exit_code}")
        if self._stderr_lines:
            parts.append("stderr tail:\n" + "\n".join(self._stderr_lines))
        return "\n".join(parts)

    def _default_launch_args(self, env: dict[str, str]) -> tuple[str, ...]:
        if self.config.dsh_bin is None:
            try:
                from deepseek_harness_runtime import resolve_bundled_launch_args
            except ImportError as exc:
                raise FileNotFoundError(
                    "Unable to locate the bundled DeepSeek Harness dsh runtime. "
                    "Install deepseek-harness-runtime-bin."
                ) from exc
            base = resolve_bundled_launch_args()
        else:
            base = (str(Path(self.config.dsh_bin).expanduser().resolve()),)

        if self.config.dsh_home is not None:
            if not self.config.dsh_home.strip():
                raise ValueError("HarnessConfig requires a non-empty dsh_home")
            env["DSH_HOME"] = str(Path(self.config.dsh_home).expanduser().resolve())
        elif not env.get("DSH_HOME", "").strip():
            raise ValueError(
                "HarnessConfig requires an explicit dsh_home or non-empty DSH_HOME; "
                "the Python SDK never uses ~/.dsh implicitly"
            )

        patches = tuple(
            argument
            for patch in self.config.patches
            for argument in ("--patch", str(Path(patch).expanduser().resolve()))
        )
        return (*base, "--profile", self.config.profile, *patches)

    def _unsubscribe_notifications(self, subscription_id: str) -> None:
        with self._lock:
            self._notification_subscribers.pop(subscription_id, None)

    def _record_session_relationship_locked(self, notification: Notification) -> None:
        if notification.method != "subagent.started":
            return
        parent_id = notification.payload.get("parentSessionId")
        child_id = notification.payload.get("childSessionId")
        if (
            isinstance(parent_id, str)
            and parent_id
            and isinstance(child_id, str)
            and child_id
            and parent_id != child_id
        ):
            self._session_parents[child_id] = parent_id

    def _notification_belongs_to_session_tree(self, session_id: str) -> NotificationFilter:
        def belongs(notification: Notification) -> bool:
            payload = notification.payload
            if notification.method in {"subagent.started", "subagent.finished"}:
                parent_id = payload.get("parentSessionId")
                if (
                    isinstance(parent_id, str)
                    and self._session_is_descendant_of(parent_id, session_id)
                ):
                    return True
                return payload.get("childSessionId") == session_id
            related_id = payload.get("sessionId")
            return (
                isinstance(related_id, str)
                and self._session_is_descendant_of(related_id, session_id)
            )

        return belongs

    def _session_is_descendant_of(self, session_id: str, root_session_id: str) -> bool:
        current = session_id
        visited: set[str] = set()
        while current not in visited:
            if current == root_session_id:
                return True
            visited.add(current)
            parent = self._session_parents.get(current)
            if parent is None:
                return False
            current = parent
        return False


class NotificationSubscription:
    def __init__(
        self,
        client: HarnessClient,
        subscription_id: str,
        notifications: queue.Queue[Notification | BaseException],
    ) -> None:
        self._client = client
        self._subscription_id = subscription_id
        self._notifications = notifications
        self._closed = False

    def __enter__(self) -> "NotificationSubscription":
        return self

    def __exit__(self, _exc_type, _exc, _tb) -> None:
        self.close()

    def close(self) -> None:
        if self._closed:
            return
        self._closed = True
        self._client._unsubscribe_notifications(self._subscription_id)

    def next(self) -> Notification:
        item = self._notifications.get()
        if isinstance(item, BaseException):
            raise item
        return item

    def drain(self, on_notification: Callable[[Notification], None]) -> None:
        while True:
            try:
                item = self._notifications.get_nowait()
            except queue.Empty:
                return
            if isinstance(item, BaseException):
                raise item
            on_notification(item)


class _SessionPromptResponse(BaseModel):
    messageId: str


class _ShutdownResponse(BaseModel):
    pass


def _int_or_none(value: object) -> int | None:
    return value if isinstance(value, int) else None