deepseek-harness/python/sdk/tests/test_client.py

from __future__ import annotations

import json
import inspect
import sys
import threading
import time
from pathlib import Path

import pytest

from deepseek_harness import DeepSeekHarness, HarnessClient, HarnessConfig


def test_high_level_sdk_runs_turn_and_collects_final_response(tmp_path: Path) -> None:
    script = tmp_path / "fake_runtime.py"
    env_dump = tmp_path / "env.json"
    script.write_text(
        """
import json
import os
import sys

env_dump = os.environ["ENV_DUMP"]
json.dump({
    "DEEPSEEK_API_KEY": os.environ.get("DEEPSEEK_API_KEY"),
    "DEEPSEEK_BASE_URL": os.environ.get("DEEPSEEK_BASE_URL"),
    "DSH_CWD": os.environ.get("DSH_CWD"),
    "DSH_SESSION_ROOT": os.environ.get("DSH_SESSION_ROOT"),
    "DSH_CORDIS_CONFIG": os.environ.get("DSH_CORDIS_CONFIG"),
}, open(env_dump, "w"))

for line in sys.stdin:
    msg = json.loads(line)
    method = msg.get("method")
    if method == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-runtime"}}}), flush=True)
    elif method == "session/prompt":
        params = msg.get("params") or {}
        print(json.dumps({
            "jsonrpc": "2.0",
            "method": "session.event",
            "params": {
                "sessionId": params["sessionId"],
                "event": {
                    "type": "assistant/message",
                    "data": {"content": [{"type": "text", "text": "hello from runtime"}]},
                },
            },
        }), flush=True)
        print(json.dumps({
            "jsonrpc": "2.0",
            "method": "session.finished",
            "params": {"sessionId": params["sessionId"], "status": "ok"},
        }), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"accepted": True}}), flush=True)
    elif method == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    with DeepSeekHarness(
        model="deepseek-v4-flash",
        cwd=str(tmp_path),
        cordis=str(tmp_path / "cordis.yml"),
        session_root=str(tmp_path / "sessions"),
        launch_args_override=(sys.executable, str(script)),
        env={
            "ENV_DUMP": str(env_dump),
            "DEEPSEEK_API_KEY": "env-key",
            "DEEPSEEK_BASE_URL": "http://127.0.0.1:4321",
        },
    ) as harness:
        result = harness.run("say hello", session_id="main")

    assert result.status == "ok"
    assert result.final_response == "hello from runtime"
    assert result.events[0]["type"] == "assistant/message"
    dumped_env = json.loads(env_dump.read_text())
    assert dumped_env["DEEPSEEK_API_KEY"] == "env-key"
    assert dumped_env["DEEPSEEK_BASE_URL"] == "http://127.0.0.1:4321"
    assert dumped_env["DSH_CWD"] == str(tmp_path)
    assert dumped_env["DSH_SESSION_ROOT"] == str(tmp_path / "sessions")
    assert dumped_env["DSH_CORDIS_CONFIG"] == str(tmp_path / "cordis.yml")


def test_session_run_invokes_notification_callback_before_returning(tmp_path: Path) -> None:
    script = tmp_path / "fake_runtime.py"
    script.write_text(
        """
import json
import sys

for line in sys.stdin:
    msg = json.loads(line)
    method = msg.get("method")
    if method == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-runtime"}}}), flush=True)
    elif method == "session/prompt":
        print(json.dumps({"jsonrpc": "2.0", "method": "subagent.started", "params": {"parentSessionId": "main", "childSessionId": "child"}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "method": "session.finished", "params": {"sessionId": "main", "status": "ok"}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"accepted": True}}), flush=True)
    elif method == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    seen: list[str] = []
    with DeepSeekHarness(
        launch_args_override=(sys.executable, str(script)),
        cwd=str(tmp_path),
    ) as harness:
        session = harness.start_session("main")
        result = session.run(
            "spawn a helper",
            on_notification=lambda notification: seen.append(notification.method),
        )

    assert result.status == "ok"
    assert seen == ["subagent.started", "session.finished"]


def test_relative_cwd_is_absolute_in_process_environment_and_wire(
    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
) -> None:
    script = tmp_path / "capture_cwd.py"
    capture = tmp_path / "cwd.json"
    script.write_text(
        """
import json
import os
import sys

for line in sys.stdin:
    msg = json.loads(line)
    if msg.get("method") == "initialize":
        json.dump({"process": os.getcwd(), "environment": os.environ.get("DSH_CWD"), "wire": msg["params"]["cwd"]}, open(os.environ["CAPTURE"], "w"))
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-runtime"}}}), flush=True)
    elif msg.get("method") == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )
    monkeypatch.chdir(tmp_path)

    with DeepSeekHarness(
        cwd=".",
        runtime_cwd=".",
        launch_args_override=(sys.executable, str(script)),
        env={"CAPTURE": str(capture)},
    ):
        pass

    expected = str(tmp_path.resolve())
    assert json.loads(capture.read_text()) == {
        "process": expected,
        "environment": expected,
        "wire": expected,
    }


def test_session_run_includes_subagent_finished_for_parent_session(tmp_path: Path) -> None:
    script = tmp_path / "fake_runtime.py"
    script.write_text(
        """
import json
import sys

for line in sys.stdin:
    msg = json.loads(line)
    method = msg.get("method")
    if method == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-runtime"}}}), flush=True)
    elif method == "session/prompt":
        print(json.dumps({"jsonrpc": "2.0", "method": "subagent.started", "params": {"parentSessionId": "main", "childSessionId": "child"}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "method": "subagent.finished", "params": {"parentSessionId": "main", "childSessionId": "child", "status": "ok", "stopReason": "completed"}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "method": "session.finished", "params": {"sessionId": "main", "status": "ok"}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"accepted": True}}), flush=True)
    elif method == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    with DeepSeekHarness(
        launch_args_override=(sys.executable, str(script)),
        cwd=str(tmp_path),
    ) as harness:
        result = harness.run("spawn a helper", session_id="main")

    assert result.status == "ok"
    assert [notification.method for notification in result.notifications] == [
        "subagent.started",
        "subagent.finished",
        "session.finished",
    ]


def test_session_run_ignores_notifications_for_other_sessions(tmp_path: Path) -> None:
    script = tmp_path / "fake_runtime.py"
    script.write_text(
        """
import json
import sys

for line in sys.stdin:
    msg = json.loads(line)
    method = msg.get("method")
    if method == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-runtime"}}}), flush=True)
    elif method == "session/prompt":
        params = msg.get("params") or {}
        print(json.dumps({"jsonrpc": "2.0", "method": "session.event", "params": {"sessionId": "other", "event": {"type": "assistant/message", "data": {"content": [{"type": "text", "text": "wrong session"}]}}}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "method": "session.finished", "params": {"sessionId": "other", "status": "ok"}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "method": "session.event", "params": {"sessionId": params["sessionId"], "event": {"type": "assistant/message", "data": {"content": [{"type": "text", "text": "right session"}]}}}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "method": "session.finished", "params": {"sessionId": params["sessionId"], "status": "ok"}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"accepted": True}}), flush=True)
    elif method == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    with DeepSeekHarness(
        launch_args_override=(sys.executable, str(script)),
        cwd=str(tmp_path),
    ) as harness:
        result = harness.run("stay in your lane", session_id="main")

    assert result.status == "ok"
    assert result.final_response == "right session"
    assert [notification.payload.get("sessionId") for notification in result.notifications] == ["main", "main"]


def test_high_level_session_run_does_not_accumulate_global_notifications(tmp_path: Path) -> None:
    script = tmp_path / "fake_runtime.py"
    script.write_text(
        """
import json
import sys

for line in sys.stdin:
    msg = json.loads(line)
    method = msg.get("method")
    if method == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-runtime"}}}), flush=True)
    elif method == "session/prompt":
        params = msg.get("params") or {}
        print(json.dumps({"jsonrpc": "2.0", "method": "session.event", "params": {"sessionId": params["sessionId"], "event": {"type": "assistant/message", "data": {"content": [{"type": "text", "text": "ok"}]}}}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "method": "session.finished", "params": {"sessionId": params["sessionId"], "status": "ok"}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"accepted": True}}), flush=True)
    elif method == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    with DeepSeekHarness(launch_args_override=(sys.executable, str(script)), cwd=str(tmp_path)) as harness:
        result = harness.run("one turn", session_id="main")
        assert result.status == "ok"
        assert harness.client._notifications.qsize() == 0


def test_session_run_waits_for_late_finished_without_replaying_stale_notifications(tmp_path: Path) -> None:
    script = tmp_path / "fake_runtime.py"
    script.write_text(
        """
import json
import sys
import time

turn = 0
for line in sys.stdin:
    msg = json.loads(line)
    method = msg.get("method")
    if method == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-runtime"}}}), flush=True)
    elif method == "session/prompt":
        turn += 1
        params = msg.get("params") or {}
        session_id = params["sessionId"]
        if turn == 1:
            print(json.dumps({"jsonrpc": "2.0", "method": "session.event", "params": {"sessionId": session_id, "event": {"type": "assistant/message", "data": {"content": [{"type": "text", "text": "first"}]}}}}), flush=True)
            print(json.dumps({"jsonrpc": "2.0", "method": "session.finished", "params": {"sessionId": session_id, "status": "ok"}}), flush=True)
            print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"accepted": True}}), flush=True)
        else:
            print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"accepted": True}}), flush=True)
            time.sleep(0.05)
            print(json.dumps({"jsonrpc": "2.0", "method": "session.event", "params": {"sessionId": session_id, "event": {"type": "assistant/message", "data": {"content": [{"type": "text", "text": "second"}]}}}}), flush=True)
            print(json.dumps({"jsonrpc": "2.0", "method": "session.finished", "params": {"sessionId": session_id, "status": "ok"}}), flush=True)
    elif method == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    with DeepSeekHarness(launch_args_override=(sys.executable, str(script)), cwd=str(tmp_path)) as harness:
        first = harness.run("first turn", session_id="main")
        second = harness.run("second turn", session_id="main")

    assert first.final_response == "first"
    assert second.final_response == "second"
    assert [notification.payload.get("sessionId") for notification in second.notifications] == ["main", "main"]


def test_client_starts_subprocess_sends_requests_and_routes_notifications(tmp_path: Path) -> None:
    script = tmp_path / "fake_bridge.py"
    script.write_text(
        """
import json
import sys

for line in sys.stdin:
    msg = json.loads(line)
    method = msg.get("method")
    if method == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-dsh"}}}), flush=True)
    elif method == "session/prompt":
        params = msg.get("params") or {}
        print(json.dumps({"jsonrpc": "2.0", "method": "llm/request", "params": {"requestId": "req-1", "sessionId": params["sessionId"], "model": "dsagent", "messages": []}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"accepted": True}}), flush=True)
    elif method == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    with HarnessClient(
        HarnessConfig(launch_args_override=(sys.executable, str(script)))
    ) as client:
        init = client.initialize(cwd="/workspace", model="dsagent")
        assert init.serverInfo.name == "fake-dsh"

        client.session_prompt("main", [{"type": "text", "text": "fix it"}])
        notification = client.next_notification()
        assert notification.method == "llm/request"
        assert notification.payload["requestId"] == "req-1"
    assert notification.payload["sessionId"] == "main"


def test_client_keeps_unmatched_notifications_available_globally_while_subscribed() -> None:
    client = HarnessClient()
    with client.subscribe_session_notifications("main"):
        client._handle_message({
            "jsonrpc": "2.0",
            "method": "session.event",
            "params": {"sessionId": "other", "event": {"type": "assistant/message"}},
        })

        assert client._notifications.qsize() == 1
        notification = client._notifications.get_nowait()
        assert not isinstance(notification, BaseException)
        assert notification.method == "session.event"
        assert notification.payload["sessionId"] == "other"


def test_client_rejects_unaccepted_session_prompt_response(tmp_path: Path) -> None:
    script = tmp_path / "fake_bridge.py"
    script.write_text(
        """
import json
import sys

for line in sys.stdin:
    msg = json.loads(line)
    method = msg.get("method")
    if method == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-dsh"}}}), flush=True)
    elif method == "session/prompt":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"accepted": False}}), flush=True)
    elif method == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    with HarnessClient(HarnessConfig(launch_args_override=(sys.executable, str(script)))) as client:
        client.initialize(cwd="/workspace", model="dsagent")
        with pytest.raises(ValueError):
            client.session_prompt("main", [{"type": "text", "text": "fix it"}])


def test_client_routes_bridge_requests_and_sends_responses(tmp_path: Path) -> None:
    script = tmp_path / "fake_bridge.py"
    script.write_text(
        """
import json
import sys

for line in sys.stdin:
    msg = json.loads(line)
    method = msg.get("method")
    if method == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-dsh"}}}), flush=True)
        print(json.dumps({"jsonrpc": "2.0", "id": "bridge-req-1", "method": "llm.request", "params": {"requestId": "req-1", "sessionId": "main", "model": "dsagent", "messages": []}}), flush=True)
    elif "id" in msg and "method" not in msg:
        print(json.dumps({"jsonrpc": "2.0", "method": "response/seen", "params": {"result": msg.get("result")}}), flush=True)
    elif method == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    with HarnessClient(
        HarnessConfig(launch_args_override=(sys.executable, str(script)))
    ) as client:
        client.initialize(cwd="/workspace", model="dsagent")

        request = client.next_request()
        assert request.id == "bridge-req-1"
        assert request.method == "llm.request"
        assert request.payload["requestId"] == "req-1"

        client.respond(request.id, {"content_blocks": [{"type": "text", "text": "done"}]})
        notification = client.next_notification()
        assert notification.method == "response/seen"
        assert notification.payload["result"]["content_blocks"][0]["text"] == "done"


def test_client_ignores_non_json_stdout_lines(tmp_path: Path) -> None:
    script = tmp_path / "fake_bridge.py"
    script.write_text(
        """
import json
import sys

print("node warning: experimental loader", flush=True)
for line in sys.stdin:
    msg = json.loads(line)
    if msg.get("method") == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-dsh"}}}), flush=True)
    elif msg.get("method") == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    with HarnessClient(
        HarnessConfig(launch_args_override=(sys.executable, str(script)))
    ) as client:
        init = client.initialize(cwd="/workspace", model="dsagent")
        assert init.serverInfo.name == "fake-dsh"


def test_client_request_times_out_when_bridge_does_not_respond(tmp_path: Path) -> None:
    script = tmp_path / "fake_bridge.py"
    script.write_text(
        """
import time

time.sleep(60)
""".strip()
    )

    with HarnessClient(
        HarnessConfig(
            launch_args_override=(sys.executable, str(script)),
            request_timeout_seconds=0.1,
        )
    ) as client:
        start = time.monotonic()
        try:
            client.initialize(cwd="/workspace", model="dsagent")
        except TimeoutError:
            assert time.monotonic() - start < 2
        else:
            raise AssertionError("initialize should time out")


def test_client_close_times_out_when_shutdown_does_not_respond(tmp_path: Path) -> None:
    script = tmp_path / "fake_bridge.py"
    script.write_text(
        """
import json
import signal
import sys
import time

signal.signal(signal.SIGTERM, signal.SIG_IGN)

for line in sys.stdin:
    msg = json.loads(line)
    if msg.get("method") == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-dsh"}}}), flush=True)
    elif msg.get("method") == "shutdown":
        time.sleep(60)
""".strip()
    )

    client = HarnessClient(
        HarnessConfig(
            launch_args_override=(sys.executable, str(script)),
            shutdown_timeout_seconds=0.1,
        )
    )
    client.start()
    proc = client._proc
    assert proc is not None
    client.initialize(cwd="/workspace", model="dsagent")
    start = time.monotonic()
    client.close()
    assert time.monotonic() - start < 2
    assert proc.poll() is not None
    assert client._proc is None


def test_initialize_failure_reaps_started_runtime(tmp_path: Path) -> None:
    script = tmp_path / "rejecting_runtime.py"
    script.write_text(
        """
import json
import sys

for line in sys.stdin:
    msg = json.loads(line)
    if msg.get("method") == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "error": {"code": -32000, "message": "bad initialize"}}), flush=True)
    elif msg.get("method") == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    client = HarnessClient(HarnessConfig(launch_args_override=(sys.executable, str(script))))
    client.start()
    proc = client._proc
    assert proc is not None

    with pytest.raises(Exception, match="bad initialize"):
        client.initialize(cwd=".", model="dsagent")

    assert proc.wait(timeout=1) is not None
    assert client._proc is None


def test_public_signatures_omit_unsupported_wire_parameters() -> None:
    from deepseek_harness import DeepSeekHarnessConfig, Session

    assert "session_root" not in inspect.signature(HarnessClient.initialize).parameters
    assert "system_prompt" not in inspect.signature(HarnessClient.initialize).parameters
    assert "profile" not in inspect.signature(HarnessClient.session_prompt).parameters
    assert "profile" not in inspect.signature(DeepSeekHarness.run).parameters
    assert "profile" not in inspect.signature(Session.run).parameters
    assert "system_prompt" not in DeepSeekHarnessConfig.__dataclass_fields__
    assert "client_name" not in HarnessConfig.__dataclass_fields__
    assert "client_version" not in HarnessConfig.__dataclass_fields__


def test_client_close_is_idempotent_before_and_after_start(tmp_path: Path) -> None:
    HarnessClient().close()

    script = tmp_path / "fake_bridge.py"
    script.write_text(
        """
import json
import sys

for line in sys.stdin:
    msg = json.loads(line)
    if msg.get("method") == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-dsh"}}}), flush=True)
    elif msg.get("method") == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )

    client = HarnessClient(HarnessConfig(launch_args_override=(sys.executable, str(script))))
    client.start()
    client.initialize(cwd="/workspace", model="dsagent")
    client.close()
    client.close()


def test_runtime_closed_error_includes_stderr_tail(tmp_path: Path) -> None:
    script = tmp_path / "crashing_runtime.py"
    script.write_text(
        """
import sys

print("fatal bridge exploded", file=sys.stderr, flush=True)
sys.exit(42)
""".strip()
    )

    with HarnessClient(
        HarnessConfig(
            launch_args_override=(sys.executable, str(script)),
            request_timeout_seconds=2,
        )
    ) as client:
        with pytest.raises(Exception, match="fatal bridge exploded"):
            client.initialize(cwd="/workspace", model="dsagent")


def test_client_serializes_concurrent_writes(tmp_path: Path) -> None:
    script = tmp_path / "fake_bridge.py"
    output = tmp_path / "seen.jsonl"
    script.write_text(
        """
import json
import os
import sys

with open(os.environ["SEEN"], "w") as seen:
    for line in sys.stdin:
        seen.write(line)
        seen.flush()
        msg = json.loads(line)
        if "id" in msg and msg.get("method") == "initialize":
            print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "fake-dsh"}}}), flush=True)
        elif "id" in msg and msg.get("method") == "shutdown":
            print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
            break
""".strip()
    )

    with HarnessClient(
        HarnessConfig(
            launch_args_override=(sys.executable, str(script)),
            env={"SEEN": str(output)},
        )
    ) as client:
        client.initialize(cwd="/workspace", model="dsagent")
        threads = [
            threading.Thread(target=client.notify, args=(f"notice-{index}", {"index": index}))
            for index in range(50)
        ]
        for thread in threads:
            thread.start()
        for thread in threads:
            thread.join()

    for line in output.read_text().splitlines():
        json.loads(line)


def _install_fake_bundled_runtime(
    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
) -> Path:
    """Fake the deepseek-harness-runtime-bin package on sys.path.

    A stub exe that dumps DSH_CORDIS_CONFIG to $ENV_DUMP before serving
    initialize/shutdown, plus a module exposing the resolution surface the
    client consumes. Returns the fake bundled default config path.
    """
    runtime = tmp_path / "dsh-jsonrpc-agent"
    runtime.write_text(
        """#!/usr/bin/env python3
import json
import os
import sys

json.dump({"DSH_CORDIS_CONFIG": os.environ.get("DSH_CORDIS_CONFIG")}, open(os.environ["ENV_DUMP"], "w"))
for line in sys.stdin:
    msg = json.loads(line)
    if msg.get("method") == "initialize":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {"serverInfo": {"name": "bundled-runtime"}}}), flush=True)
    elif msg.get("method") == "shutdown":
        print(json.dumps({"jsonrpc": "2.0", "id": msg["id"], "result": {}}), flush=True)
        break
""".strip()
    )
    runtime.chmod(0o755)

    default_config = tmp_path / "default-cordis.yml"
    module_dir = tmp_path / "deepseek_harness_runtime"
    module_dir.mkdir()
    (module_dir / "__init__.py").write_text(
        f"""
def resolve_bundled_launch_args(mode=None):
    return ({str(runtime)!r},)


def bundled_default_config_path():
    return {str(default_config)!r}
""".strip()
    )

    monkeypatch.syspath_prepend(str(tmp_path))
    monkeypatch.delitem(sys.modules, "deepseek_harness_runtime", raising=False)
    return default_config


@pytest.mark.parametrize("ambient_config", [None, ""], ids=["unset", "empty-counts-as-absent"])
def test_client_default_launch_uses_bundled_runtime_and_injects_default_config(
    tmp_path: Path, monkeypatch: pytest.MonkeyPatch, ambient_config: str | None
) -> None:
    env_dump = tmp_path / "env.json"
    default_config = _install_fake_bundled_runtime(tmp_path, monkeypatch)
    if ambient_config is None:
        monkeypatch.delenv("DSH_CORDIS_CONFIG", raising=False)
    else:
        monkeypatch.setenv("DSH_CORDIS_CONFIG", ambient_config)

    with HarnessClient(HarnessConfig(env={"ENV_DUMP": str(env_dump)})) as client:
        init = client.initialize(cwd="/workspace", model="deepseek-v4-pro")

    assert init.serverInfo.name == "bundled-runtime"
    assert json.loads(env_dump.read_text())["DSH_CORDIS_CONFIG"] == str(default_config)


def test_client_respects_explicit_config_over_bundled_default(
    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
) -> None:
    env_dump = tmp_path / "env.json"
    _install_fake_bundled_runtime(tmp_path, monkeypatch)
    monkeypatch.delenv("DSH_CORDIS_CONFIG", raising=False)

    with HarnessClient(
        HarnessConfig(env={"ENV_DUMP": str(env_dump), "DSH_CORDIS_CONFIG": "./explicit.yml"})
    ) as client:
        client.initialize(cwd="/workspace", model="deepseek-v4-pro")

    assert json.loads(env_dump.read_text())["DSH_CORDIS_CONFIG"] == "./explicit.yml"


def test_client_reports_missing_bundled_runtime_dependency(monkeypatch: pytest.MonkeyPatch) -> None:
    monkeypatch.delitem(sys.modules, "deepseek_harness_runtime", raising=False)
    monkeypatch.setattr(sys, "path", [])

    with pytest.raises(FileNotFoundError, match="Install deepseek-harness-runtime-bin"):
        HarnessClient().start()