diff --git a/lagent/serving/sandbox/__init__.py b/lagent/serving/sandbox/__init__.py
index b1472e8..1cbf090 100644
--- a/lagent/serving/sandbox/__init__.py
+++ b/lagent/serving/sandbox/__init__.py
@@ -12,9 +12,6 @@
     - ``SandboxSkillsLoader`` — see ``lagent.skills.sandbox_skills``
 """
 
-from .agent import SandboxAgent
-from .daemon import ActionDaemon, AgentDaemon, BaseDaemon, SkillsDaemon, async_lagent_call, lagent_call
-
 __all__ = [
     "BaseDaemon",
     "ActionDaemon",
@@ -24,3 +21,30 @@
     "lagent_call",
     "async_lagent_call",
 ]
+
+
+def __getattr__(name):
+    if name == "SandboxAgent":
+        from .agent import SandboxAgent
+
+        return SandboxAgent
+    if name in {
+        "BaseDaemon",
+        "ActionDaemon",
+        "SkillsDaemon",
+        "AgentDaemon",
+        "lagent_call",
+        "async_lagent_call",
+    }:
+        from .daemon import ActionDaemon, AgentDaemon, BaseDaemon, SkillsDaemon, async_lagent_call, lagent_call
+
+        values = {
+            "BaseDaemon": BaseDaemon,
+            "ActionDaemon": ActionDaemon,
+            "SkillsDaemon": SkillsDaemon,
+            "AgentDaemon": AgentDaemon,
+            "lagent_call": lagent_call,
+            "async_lagent_call": async_lagent_call,
+        }
+        return values[name]
+    raise AttributeError(name)
diff --git a/lagent/serving/sandbox/client_cli.py b/lagent/serving/sandbox/client_cli.py
new file mode 100644
index 0000000..6eaf2b2
--- /dev/null
+++ b/lagent/serving/sandbox/client_cli.py
@@ -0,0 +1,275 @@
+"""Small CLI client for Lagent sandbox daemons.
+
+This module is intentionally a client, not another runtime abstraction.  It
+turns the daemon's JSON socket protocol into rollout-friendly shell commands
+so an outer runner can record each phase as an explicit entry.
+"""
+
+from __future__ import annotations
+
+import argparse
+import asyncio
+import json
+import os
+import signal
+import struct
+import subprocess
+import sys
+import time
+from pathlib import Path
+from typing import Any
+
+_HEADER_FMT = "!I"
+_HEADER_SIZE = struct.calcsize(_HEADER_FMT)
+_MAX_MSG_SIZE = 64 * 1024 * 1024
+
+
+class DaemonCallError(RuntimeError):
+    pass
+
+
+def _call_json(sock: str, payload: dict[str, Any]) -> dict[str, Any]:
+    raw = asyncio.run(_async_call(sock, json.dumps(payload, ensure_ascii=False).encode()))
+    try:
+        obj = json.loads(raw or "{}")
+    except json.JSONDecodeError as exc:
+        raise DaemonCallError(f"invalid daemon response: {exc}: {raw[:500]}") from exc
+    if isinstance(obj, dict) and obj.get("error"):
+        raise DaemonCallError(str(obj["error"]))
+    if not isinstance(obj, dict):
+        raise DaemonCallError(f"daemon response must be a JSON object, got {type(obj).__name__}")
+    return obj
+
+
+async def _async_call(sock: str, payload: bytes) -> str:
+    reader, writer = await asyncio.open_unix_connection(sock)
+    try:
+        writer.write(struct.pack(_HEADER_FMT, len(payload)))
+        writer.write(payload)
+        await writer.drain()
+
+        header = await reader.readexactly(_HEADER_SIZE)
+        (length,) = struct.unpack(_HEADER_FMT, header)
+        if length > _MAX_MSG_SIZE:
+            raise DaemonCallError(f"daemon response too large: {length} bytes")
+        raw = await reader.readexactly(length)
+        return raw.decode()
+    finally:
+        writer.close()
+        await writer.wait_closed()
+
+
+def _write_json(path: str, obj: Any) -> None:
+    Path(path).write_text(json.dumps(obj, ensure_ascii=False, indent=4, default=str), encoding="utf-8")
+
+
+def _print_json(obj: Any) -> None:
+    print(json.dumps(obj, ensure_ascii=False, default=str), flush=True)
+
+
+def _tail_log(path: str | None, lines: int = 100) -> str:
+    if not path:
+        return ""
+    try:
+        content = Path(path).read_text(encoding="utf-8", errors="replace")
+    except Exception:
+        return ""
+    return "\n".join(content.splitlines()[-lines:])
+
+
+def _pid_alive(pid: int) -> bool:
+    try:
+        os.kill(pid, 0)
+        return True
+    except OSError:
+        return False
+
+
+def _read_pid(path: str | None) -> int | None:
+    if not path:
+        return None
+    try:
+        return int(Path(path).read_text(encoding="utf-8").strip())
+    except Exception:
+        return None
+
+
+def _die(message: str, code: int, *, log: str | None = None) -> int:
+    print(message, file=sys.stderr, flush=True)
+    tail = _tail_log(log)
+    if tail:
+        print(tail, file=sys.stderr, flush=True)
+    return code
+
+
+def cmd_wait_ready(args: argparse.Namespace) -> int:
+    deadline = time.monotonic() + args.timeout
+    while time.monotonic() <= deadline:
+        pid = _read_pid(args.pid_file)
+        if pid is not None and not _pid_alive(pid):
+            return _die(f"daemon pid {pid} exited before ready", 4, log=args.log)
+        try:
+            response = _call_json(args.sock, {"cmd": "ping"})
+        except Exception:
+            time.sleep(args.poll_interval)
+            continue
+        _print_json(response)
+        return 0
+    return _die(f"daemon did not become ready within {args.timeout}s", 4, log=args.log)
+
+
+def cmd_start_agent_daemon(args: argparse.Namespace) -> int:
+    try:
+        for path in (args.sock, args.pid_file):
+            if path and os.path.exists(path):
+                os.unlink(path)
+        log_path = Path(args.log)
+        log_path.parent.mkdir(parents=True, exist_ok=True)
+        log_mode = "w" if args.truncate_log else "a"
+        log_file = log_path.open(log_mode, encoding="utf-8", errors="replace")
+        cmd = [
+            sys.executable,
+            "-m",
+            "lagent.serving.sandbox.daemon",
+            "start",
+            "--mode",
+            args.mode,
+            "--config",
+            args.config,
+            "--sock",
+            args.sock,
+        ]
+        proc = subprocess.Popen(
+            cmd,
+            stdout=log_file,
+            stderr=subprocess.STDOUT,
+            start_new_session=True,
+            close_fds=True,
+        )
+        Path(args.pid_file).write_text(str(proc.pid), encoding="utf-8")
+        _print_json({"status": "started", "pid": proc.pid, "sock": args.sock, "log": args.log})
+        return 0
+    except Exception as exc:
+        return _die(f"failed to start daemon: {exc}", 4, log=args.log)
+
+
+def cmd_chat(args: argparse.Namespace) -> int:
+    try:
+        instruction = Path(args.instruction_file).read_text(encoding="utf-8")
+        response = _call_json(args.sock, {"cmd": "chat", "messages": [instruction]})
+        content = response.get("content", "")
+        if not isinstance(content, str):
+            content = json.dumps(content, ensure_ascii=False, default=str)
+        Path(args.response_out).write_text(content or "", encoding="utf-8")
+        _print_json(response)
+        return 0
+    except Exception as exc:
+        return _die(f"daemon error in chat: {exc}", 5, log=args.log)
+
+
+def _trajectory_payload(response: dict[str, Any]) -> dict[str, Any]:
+    state = response.get("state_dict", response)
+    if isinstance(state, dict) and "trajectory" in state:
+        return state
+    if isinstance(state, dict):
+        flat = []
+        for value in state.values():
+            if isinstance(value, list):
+                flat.extend(item for item in value if isinstance(item, dict))
+        return {"trajectory": flat, "raw": state}
+    return {"trajectory": state if isinstance(state, list) else [], "raw": state}
+
+
+def cmd_state_dict(args: argparse.Namespace) -> int:
+    try:
+        response = _call_json(args.sock, {"cmd": "state_dict"})
+        payload = _trajectory_payload(response)
+        _write_json(args.trajectory_out, payload)
+        _print_json({"status": "ok", "trajectory_out": args.trajectory_out})
+        return 0
+    except Exception as exc:
+        return _die(f"daemon error in state_dict: {exc}", 6, log=args.log)
+
+
+def cmd_get_messages(args: argparse.Namespace) -> int:
+    try:
+        response = _call_json(args.sock, {"cmd": "get_messages"})
+        _write_json(args.message_out, response)
+        _print_json({"status": "ok", "message_out": args.message_out})
+        return 0
+    except Exception as exc:
+        return _die(f"daemon error in get_messages: {exc}", 7, log=args.log)
+
+
+def cmd_shutdown(args: argparse.Namespace) -> int:
+    try:
+        response = _call_json(args.sock, {"cmd": "shutdown"})
+        _print_json(response)
+    except Exception:
+        pass
+    pid = _read_pid(args.pid_file)
+    if pid is not None and _pid_alive(pid):
+        try:
+            os.kill(pid, signal.SIGTERM)
+        except OSError:
+            pass
+    return 0
+
+
+def build_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(description="Lagent sandbox daemon client")
+    sub = parser.add_subparsers(dest="command", required=True)
+
+    p = sub.add_parser("wait-ready", help="Wait until daemon responds to ping")
+    p.add_argument("--sock", default="/tmp/lagent_agent.sock")
+    p.add_argument("--timeout", type=float, default=60.0)
+    p.add_argument("--poll-interval", type=float, default=1.0)
+    p.add_argument("--pid-file")
+    p.add_argument("--log")
+    p.set_defaults(func=cmd_wait_ready)
+
+    p = sub.add_parser("start-agent-daemon", help="Start an AgentDaemon in the background")
+    p.add_argument("--mode", choices=["agent"], default="agent")
+    p.add_argument("--config", required=True)
+    p.add_argument("--sock", default="/tmp/lagent_agent.sock")
+    p.add_argument("--pid-file", required=True)
+    p.add_argument("--log", required=True)
+    p.add_argument("--truncate-log", action="store_true")
+    p.set_defaults(func=cmd_start_agent_daemon)
+
+    p = sub.add_parser("chat", help="Send one instruction file to AgentDaemon.chat")
+    p.add_argument("--sock", default="/tmp/lagent_agent.sock")
+    p.add_argument("--instruction-file", required=True)
+    p.add_argument("--response-out", required=True)
+    p.add_argument("--log")
+    p.set_defaults(func=cmd_chat)
+
+    p = sub.add_parser("state-dict", help="Dump AgentDaemon.state_dict as trajectory JSON")
+    p.add_argument("--sock", default="/tmp/lagent_agent.sock")
+    p.add_argument("--trajectory-out", required=True)
+    p.add_argument("--log")
+    p.set_defaults(func=cmd_state_dict)
+
+    p = sub.add_parser("get-messages", help="Dump AgentDaemon.get_messages JSON")
+    p.add_argument("--sock", default="/tmp/lagent_agent.sock")
+    p.add_argument("--message-out", required=True)
+    p.add_argument("--log")
+    p.set_defaults(func=cmd_get_messages)
+
+    p = sub.add_parser("shutdown", help="Ask daemon to shutdown, then terminate pid file if needed")
+    p.add_argument("--sock", default="/tmp/lagent_agent.sock")
+    p.add_argument("--pid-file")
+    p.add_argument("--log")
+    p.set_defaults(func=cmd_shutdown)
+
+    return parser
+
+
+def main() -> int:
+    parser = build_parser()
+    args = parser.parse_args()
+    return args.func(args)
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())