diff --git a/README.md b/README.md
index ca1aade939..e3201b5fbc 100644
--- a/README.md
+++ b/README.md
@@ -1920,6 +1920,10 @@ overwriting them with an unevaluated fallback — so the Settings UI shows
 whether `lark-cli` will actually be present in the sandbox at chat time, rather
 than a green status hiding a later `command not found`.
 
+The optional [Lark CLI broker image](docker/lark-cli-broker/README.md) bundles
+its required Python helper modules, so the sidecar runs without a separate
+DeerFlow harness installation.
+
 In Lark broker mode, AIO's fresh Bash runs close inherited pipe stdin. Persistent
 terminal commands keep their input; the shim ignores terminal stdin. Explicit
 pipelines, heredocs, and file redirections still supply input normally, and the
diff --git a/backend/packages/harness/deerflow/integrations/lark_broker.py b/backend/packages/harness/deerflow/integrations/lark_broker.py
index d4eddfcbb8..18d360a9c8 100644
--- a/backend/packages/harness/deerflow/integrations/lark_broker.py
+++ b/backend/packages/harness/deerflow/integrations/lark_broker.py
@@ -11,8 +11,8 @@ loopback. The sandbox gets a tiny ``lark-cli`` shim on ``PATH`` that forwards
 argv/stdin to the broker, so the raw credential files never exist in the sandbox
 filesystem.
 
-Everything here is Python-3-stdlib only so the same module can run inside the
-minimal broker sidecar image without extra dependencies.
+The broker and its bundled DeerFlow utility modules use only Python's standard
+library, so the minimal sidecar needs no third-party Python packages.
 """
 
 from __future__ import annotations
@@ -32,6 +32,8 @@ from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 from pathlib import Path
 from typing import Any
 
+# Keep the standalone image's Python COPY list in sync with this import and its
+# transitive dependencies: docker/lark-cli-broker/Dockerfile.
 from deerflow.utils.atomic_write import cleanup_failed_atomic_write
 
 logger = logging.getLogger(__name__)
diff --git a/backend/tests/AGENTS.md b/backend/tests/AGENTS.md
index 2213a68b0d..596fbafb20 100644
--- a/backend/tests/AGENTS.md
+++ b/backend/tests/AGENTS.md
@@ -1,5 +1,10 @@
 # Backend Tests
 
+`test_lark_broker_image.py` stages Python files from the broker Dockerfile's
+final-stage COPY instructions. Run shim installation and the health endpoint
+under `-I -S`, adding only the staged script directory to the import path;
+repository paths or installed Harness packages would hide missing image files.
+
 When adding a scoped `AGENTS.md`, update `EXPECTED_GUIDANCE_PATHS` in
 `test_agent_guidance_check.py` in the same change. The explicit inventory pins
 guidance ownership and extends hard-budget checks to each approved guide.
diff --git a/backend/tests/test_lark_broker_image.py b/backend/tests/test_lark_broker_image.py
new file mode 100644
index 0000000000..b5a094eb19
--- /dev/null
+++ b/backend/tests/test_lark_broker_image.py
@@ -0,0 +1,95 @@
+"""Exercise the broker image's Python file layout without an installed harness."""
+
+from __future__ import annotations
+
+import json
+import shlex
+import shutil
+import subprocess
+import sys
+import textwrap
+from pathlib import Path
+
+import pytest
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+
+
+@pytest.fixture
+def image_broker(tmp_path: Path) -> Path:
+    dockerfile = REPO_ROOT / "docker/lark-cli-broker/Dockerfile"
+    runtime_stage = dockerfile.read_text(encoding="utf-8").replace("\\\n", " ").rsplit("\nFROM ", 1)[1]
+    image_root = tmp_path / "image"
+    for instruction in runtime_stage.splitlines():
+        words = shlex.split(instruction, comments=True)
+        if not words or words[0] != "COPY" or words[1].startswith("--from="):
+            continue
+        for source in words[1:-1]:
+            if not source.endswith(".py"):
+                continue
+            destination = image_root / words[-1].lstrip("/")
+            if words[-1].endswith("/"):
+                destination /= Path(source).name
+            destination.parent.mkdir(parents=True, exist_ok=True)
+            shutil.copyfile(REPO_ROOT / source, destination)
+    return image_root / "opt/broker/lark_broker.py"
+
+
+def run_isolated(broker: Path, code: str, *args: str) -> subprocess.CompletedProcess[str]:
+    bootstrap = "import runpy, sys\nfrom pathlib import Path\nbroker = Path(sys.argv.pop(1))\nsys.path.insert(0, str(broker.parent))\n"
+    # -I ignores inherited PYTHONPATH and -S skips installed editable packages.
+    # Only the image's script directory is added back, matching its entrypoint.
+    return subprocess.run(
+        [sys.executable, "-I", "-S", "-c", bootstrap + textwrap.dedent(code), str(broker), *args],
+        cwd=broker.parent,
+        capture_output=True,
+        text=True,
+        encoding="utf-8",
+        timeout=30,
+        check=False,
+    )
+
+
+def test_image_installs_shim_without_harness(image_broker: Path, tmp_path: Path) -> None:
+    runtime = tmp_path / "runtime"
+    completed = run_isolated(image_broker, 'runpy.run_path(str(broker), run_name="__main__")', "install-shim", str(runtime))
+
+    assert completed.returncode == 0, completed.stderr
+    launcher = runtime / "bin/lark-cli"
+    shim = runtime / "bin/lark-cli-shim.py"
+    assert launcher.read_text(encoding="utf-8").startswith("#!/bin/sh\n")
+    assert str(shim) in launcher.read_text(encoding="utf-8")
+    assert shim.read_text(encoding="utf-8").startswith("#!/usr/bin/env python3\n")
+    assert json.loads((runtime / ".deerflow-lark-cli-runtime.json").read_text(encoding="utf-8"))["kind"] == "shim"
+
+
+def test_image_serves_health_without_harness(image_broker: Path) -> None:
+    completed = run_isolated(
+        image_broker,
+        """
+        import json
+        import threading
+        from http.client import HTTPConnection
+
+        module = runpy.run_path(str(broker))
+        config = module["BrokerConfig"](lark_cli_path=sys.executable, config_dir="config", data_dir="data", port=0)
+        with module["serve"](config) as server:
+            thread = threading.Thread(target=server.serve_forever, daemon=True)
+            thread.start()
+            try:
+                connection = HTTPConnection(*server.server_address[:2], timeout=5)
+                try:
+                    connection.request("GET", "/v1/health")
+                    response = connection.getresponse()
+                    assert response.status == 200
+                    assert json.loads(response.read()) == {"ok": True}
+                finally:
+                    connection.close()
+            finally:
+                server.shutdown()
+                thread.join(timeout=5)
+                assert not thread.is_alive()
+        """,
+    )
+
+    assert completed.returncode == 0, completed.stderr
diff --git a/docker/lark-cli-broker/Dockerfile b/docker/lark-cli-broker/Dockerfile
index 49ffe37505..70658fa212 100644
--- a/docker/lark-cli-broker/Dockerfile
+++ b/docker/lark-cli-broker/Dockerfile
@@ -54,15 +54,18 @@ COPY docker/lark-cli-init/build-runtime.sh /usr/local/bin/build-runtime.sh
 RUN chmod +x /usr/local/bin/build-runtime.sh \
     && LARK_CLI_VERSION="${LARK_CLI_VERSION}" /usr/local/bin/build-runtime.sh /opt/lark-cli
 
-# ── Final image: python3 + the staged real binary + the broker module ────────
+# ── Final image: python3 + the staged real binary + the broker runtime ───────
 FROM python:3.12-slim
 
 ARG LARK_CLI_VERSION=v1.0.65
 ENV LARK_CLI_VERSION=${LARK_CLI_VERSION}
 
 COPY --from=builder /opt/lark-cli /opt/lark-cli
-# Single stdlib-only module drives both install-shim and serve.
+# Bundle the broker's stdlib-only dependency closure without installing the harness.
 COPY backend/packages/harness/deerflow/integrations/lark_broker.py /opt/broker/lark_broker.py
+COPY backend/packages/harness/deerflow/utils/atomic_write.py \
+     backend/packages/harness/deerflow/utils/file_revision_metadata.py \
+     /opt/broker/deerflow/utils/
 COPY docker/lark-cli-broker/entrypoint.sh /usr/local/bin/lark-cli-broker
 RUN chmod +x /usr/local/bin/lark-cli-broker
 
diff --git a/docker/lark-cli-broker/README.md b/docker/lark-cli-broker/README.md
index c409494b66..640a739e51 100644
--- a/docker/lark-cli-broker/README.md
+++ b/docker/lark-cli-broker/README.md
@@ -39,6 +39,9 @@ image ships Python 3, so the default path needs no configuration.
 
 ## Build
 
+The image bundles the broker script and its shared atomic-write helper modules.
+It requires no separate DeerFlow harness installation for either mode.
+
 Build context is the **repo root** (the broker module lives under `backend/`):
 
 ```bash
diff --git a/docker/lark-cli-broker/entrypoint.sh b/docker/lark-cli-broker/entrypoint.sh
index 4646fe4c7d..179db60c41 100644
--- a/docker/lark-cli-broker/entrypoint.sh
+++ b/docker/lark-cli-broker/entrypoint.sh
@@ -1,14 +1,14 @@
 #!/bin/sh
 # DeerFlow lark-cli broker entrypoint (Pattern B, issue #4338).
 #
-# Dispatches to one of two modes on the single stdlib-only module:
+# Dispatches to one of two modes on the broker script:
 #
 #   install-shim [dest]   write the shim + runtime marker into the shared
 #                         emptyDir (init-container mode), then exit 0.
 #   serve                 run the broker HTTP server on loopback (sidecar mode).
 #
-# The module is copied to /opt/broker/lark_broker.py and run as a script; it has
-# no third-party dependencies, so no harness install is needed in this image.
+# The script and its shared helpers live under /opt/broker and use only the
+# Python standard library; no harness installation is needed in this image.
 set -eu
 
 MODULE="/opt/broker/lark_broker.py"