diff --git a/CHANGELOG.md b/CHANGELOG.md
index 01d720fbf6..9d270058d5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4602,6 +4602,14 @@ This release closes that milestone with **439 merged pull requests**.
   coverage stays excluded. A new test pins the concurrent startup and the
   wait-for-every-shard failure reporting with offline worker doubles.
   ([#6324])
+- **integrations:** Lark/Feishu CLI output is decoded as UTF-8 instead of with
+  the host locale. `lark-cli` (a native binary shipped through the
+  `@larksuite/cli` npm package) and npm both write UTF-8 to a pipe, but every
+  capture in `lark_cli.py` passed `text=True` without an `encoding`, so a host
+  whose ANSI code page is not UTF-8 (cp936, cp1252) silently mangled non-ASCII
+  fields — `auth status --json` returned a garbled `userName`, and an
+  undecodable byte could kill the reader thread and leave `stdout` as `None`,
+  reporting a healthy CLI as unavailable. ([#6590])
 
 ## [2.1.0] — 2026-09-24
 
@@ -9464,3 +9472,4 @@ with **180 merged pull requests** since the first 2.0 milestone tag.
 [#6580]: https://github.com/bytedance/deer-flow/pull/6580
 [#6582]: https://github.com/bytedance/deer-flow/pull/6582
 [#6588]: https://github.com/bytedance/deer-flow/pull/6588
+[#6590]: https://github.com/bytedance/deer-flow/pull/6590
diff --git a/CHANGELOG_zh.md b/CHANGELOG_zh.md
index 3f04c78d86..e20f236390 100644
--- a/CHANGELOG_zh.md
+++ b/CHANGELOG_zh.md
@@ -3586,6 +3586,13 @@
   `make test-shard` 与 CI 的分片方式不变，live 与阻塞 I/O 测试仍被排除。
   新增测试用离线 worker 替身固定了分片并行启动与“等待全部分片再报失败”
   的行为。([#6324])
+- **集成：** Lark/Feishu CLI 的输出改为按 UTF-8 解码，不再使用宿主 locale。
+  `lark-cli`（通过 `@larksuite/cli` npm 包分发的原生二进制）与 npm 都会向管道
+  写入 UTF-8，但 `lark_cli.py` 中的每一处捕获都只传了 `text=True` 而未指定
+  `encoding`，因此在 ANSI 代码页非 UTF-8 的宿主上（cp936、cp1252）非 ASCII
+  字段会被静默破坏——`auth status --json` 返回的 `userName` 变成乱码，而无法
+  解码的字节还可能让读取线程异常退出、使 `stdout` 变成 `None`，从而把一个正常
+  的 CLI 报告为不可用。([#6590])
 
 ## [2.1.0] — 2026-09-24
 
@@ -7622,3 +7629,4 @@ DeerFlow 2.0 是围绕"超级智能体"框架的彻底重写，核心包含子
 [#6580]: https://github.com/bytedance/deer-flow/pull/6580
 [#6582]: https://github.com/bytedance/deer-flow/pull/6582
 [#6588]: https://github.com/bytedance/deer-flow/pull/6588
+[#6590]: https://github.com/bytedance/deer-flow/pull/6590
diff --git a/backend/packages/harness/deerflow/integrations/lark_cli.py b/backend/packages/harness/deerflow/integrations/lark_cli.py
index c6a9dd4e20..f218499908 100644
--- a/backend/packages/harness/deerflow/integrations/lark_cli.py
+++ b/backend/packages/harness/deerflow/integrations/lark_cli.py
@@ -97,6 +97,14 @@ INTEGRATION_ID = "lark-cli"
 FALLBACK_LARK_CLI_VERSION = "v1.0.65"
 LARK_CLI_NPM_VERSION = FALLBACK_LARK_CLI_VERSION.removeprefix("v")
 LARK_CLI_NPM_PACKAGE = "@larksuite/cli"
+# ``lark-cli`` is a native binary (installed by the npm package's Node wrapper)
+# and npm itself always write UTF-8 to a pipe, so every capture of their output
+# must be decoded as UTF-8 rather than with the host locale. On a host whose ANSI
+# code page is not UTF-8 (cp936, cp1252) the locale decode silently mangles every
+# non-ASCII field -- ``auth status --json`` reports a CJK ``userName``, documents
+# titles come back garbled -- and can kill the pipe reader thread outright when a
+# byte sequence is invalid in the code page, leaving ``stdout`` as ``None``.
+LARK_CLI_SUBPROCESS_ENCODING = "utf-8"
 LARK_CLI_GITHUB_REPO = "larksuite/cli"
 LARK_CLI_LATEST_RELEASE_API = f"https://api.github.com/repos/{LARK_CLI_GITHUB_REPO}/releases/latest"
 LARK_CLI_SOURCE_ARCHIVE_ENV = "DEER_FLOW_LARK_CLI_SKILLS_ARCHIVE"
@@ -1534,6 +1542,8 @@ def _probe_lark_cli_at_path(path: str) -> LarkCliProbe:
             check=False,
             capture_output=True,
             text=True,
+            encoding=LARK_CLI_SUBPROCESS_ENCODING,
+            errors="replace",
             timeout=5,
         )
     except Exception as exc:  # noqa: BLE001 - probe boundary
@@ -1569,6 +1579,8 @@ def probe_lark_auth(user_id: str, *, verify: bool = False) -> LarkAuthProbe:
             check=False,
             capture_output=True,
             text=True,
+            encoding=LARK_CLI_SUBPROCESS_ENCODING,
+            errors="replace",
             timeout=8,
             env=lark_cli_env(user_id),
         )
@@ -2339,6 +2351,8 @@ def _install_managed_gateway_lark_cli(version: str) -> LarkCliProbe:
         check=False,
         capture_output=True,
         text=True,
+        encoding=LARK_CLI_SUBPROCESS_ENCODING,
+        errors="replace",
         timeout=LARK_CLI_NPM_INSTALL_TIMEOUT_SECONDS,
         env={**os.environ, "npm_config_update_notifier": "false"},
     )
@@ -2491,6 +2505,8 @@ def _run_lark_config_init(*, app_id: str, app_secret: str, brand: str, env: dict
             check=False,
             capture_output=True,
             text=True,
+            encoding=LARK_CLI_SUBPROCESS_ENCODING,
+            errors="replace",
             timeout=15,
             env=env,
         )
@@ -2593,6 +2609,8 @@ def _revoke_lark_auth_from_snapshot(snapshot: Path) -> None:
             check=False,
             capture_output=True,
             text=True,
+            encoding=LARK_CLI_SUBPROCESS_ENCODING,
+            errors="replace",
             timeout=15,
             env=_lark_cli_env_for_directories(config_dir=snapshot / "config", data_dir=data_dir),
         )
@@ -2619,6 +2637,8 @@ def _run_lark_cli_json(
                 check=False,
                 capture_output=True,
                 text=True,
+                encoding=LARK_CLI_SUBPROCESS_ENCODING,
+                errors="replace",
                 timeout=timeout,
                 env=lark_cli_env(user_id),
             )
diff --git a/backend/tests/test_lark_cli_subprocess_encoding.py b/backend/tests/test_lark_cli_subprocess_encoding.py
new file mode 100644
index 0000000000..d5663a0819
--- /dev/null
+++ b/backend/tests/test_lark_cli_subprocess_encoding.py
@@ -0,0 +1,182 @@
+"""Every capture of ``lark-cli`` / npm output decodes as UTF-8, not the locale.
+
+``lark-cli`` is a native binary shipped through the ``@larksuite/cli`` npm
+package (``bin`` is the Node wrapper ``scripts/run.js``, which ``execFileSync``es
+the downloaded binary), and npm writes its own output as UTF-8. Both therefore
+put UTF-8 bytes on the pipe regardless of the host's ANSI code page. Decoding
+those bytes with ``locale.getencoding()`` -- cp936 on a Chinese Windows host,
+cp1252 on a Western one -- silently corrupts every non-ASCII field the CLI
+returns (a CJK ``userName`` from ``auth status --json``, a document title) and
+can kill the pipe reader thread, which surfaces as ``stdout is None`` rather
+than as an exception.
+
+The tests drive the real functions with a stand-in CLI that emits non-ASCII
+UTF-8, and force the locale decoding path without depending on the host code
+page: the module's ``subprocess.run`` reference is wrapped so a text-mode call
+that names no codec is decoded with one that mangles UTF-8, while a call that
+pins its own ``encoding`` is passed through untouched. That reproduces the
+behaviour of the pre-fix call sites on a cp936/cp1252 host even when the test
+host itself is UTF-8.
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import stat
+import subprocess
+import sys
+import textwrap
+from pathlib import Path
+
+import pytest
+
+from deerflow.config import paths as paths_module
+from deerflow.config.paths import Paths
+from deerflow.integrations import lark_cli
+
+# A code page that cannot represent the payload below and is not UTF-8.
+MANGLING_CODEPAGE = "cp1252"
+
+EXPECTED_USER = "\u5f20\u4f1f"  # 张伟
+EXPECTED_TITLE = "\u5b63\u5ea6\u590d\u76d8"  # 季度复盘
+EXPECTED_VERSION = "lark-cli v1.0.65 \u5f20\u4f1f"  # the CLI's --version payload
+
+_FAKE_CLI_BODY = f"""\
+import json
+import os
+import sys
+
+if "--version" in sys.argv[1:]:
+    os.write(1, {EXPECTED_VERSION!r}.encode("utf-8"))
+    raise SystemExit(0)
+
+payload = {{
+    "userName": {EXPECTED_USER!r},
+    "title": {EXPECTED_TITLE!r},
+    "verification_url": "https://open.feishu.cn/verify",
+}}
+os.write(1, json.dumps(payload, ensure_ascii=False).encode("utf-8"))
+"""
+
+
+@pytest.fixture
+def fake_cli(tmp_path: Path) -> tuple[list[str], str]:
+    """A stand-in CLI emitting UTF-8 non-ASCII JSON, as argv and as a path.
+
+    The interpreter path can contain non-ASCII characters (a checkout under a
+    CJK directory), so the Windows shim is written in the ANSI code page that
+    ``cmd.exe`` itself uses to read a ``.cmd`` file; otherwise the shim cannot
+    find its own interpreter. The Python body is always UTF-8.
+    """
+    body = textwrap.dedent(_FAKE_CLI_BODY)
+    script = tmp_path / "fake_lark_cli.py"
+    script.write_text(body, encoding="utf-8")
+    argv = [sys.executable, str(script)]
+
+    if os.name != "nt":
+        script.chmod(script.stat().st_mode | stat.S_IEXEC)
+        launcher = tmp_path / "lark-cli"
+        launcher.write_text(f"#!{sys.executable}\n{body}", encoding="utf-8")
+        launcher.chmod(launcher.stat().st_mode | stat.S_IEXEC)
+        return argv, str(launcher)
+
+    launcher = tmp_path / "lark-cli.cmd"
+    launcher.write_text(f'@echo off\r\n"{sys.executable}" "{script}" %*\r\n', encoding="mbcs")
+    return argv, str(launcher)
+
+
+@pytest.fixture
+def locale_decoding(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Make ``lark_cli`` capture text the way a non-UTF-8 host code page would.
+
+    A call that names its own codec is passed through untouched, so a pinned
+    ``encoding="utf-8"`` still wins; a text-mode call that names none is decoded
+    with a code page that cannot represent non-ASCII -- exactly what happens on
+    cp936/cp1252 when the locale supplies the codec. Emulating it here keeps
+    these tests meaningful on a host (or CI runner) whose own locale is UTF-8,
+    where the unpatched flip would otherwise pass on the pre-fix code too.
+
+    ``locale.getencoding`` is deliberately not patched: ``lark_cli`` never calls
+    it, so pinning it would document a redirection that does not happen.
+    """
+    real_run = subprocess.run
+
+    def locale_run(*args, **kwargs):
+        if (kwargs.get("text") or kwargs.get("universal_newlines")) and "encoding" not in kwargs:
+            kwargs["encoding"] = MANGLING_CODEPAGE
+            kwargs["errors"] = "replace"
+        return real_run(*args, **kwargs)
+
+    monkeypatch.setattr(lark_cli.subprocess, "run", locale_run)
+
+
+@pytest.fixture(autouse=True)
+def isolated_paths(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
+    """Keep the suite off the live runtime home.
+
+    ``_run_lark_cli_json`` and ``probe_lark_auth`` reach
+    ``ensure_lark_cli_credential_tree`` through the global ``get_paths()``
+    singleton, so without this every run would create and harden a real
+    ``<cwd>/.deer-flow/users/alice/integrations/lark-cli/{config,data}`` tree --
+    the same directory a live deployment keeps real per-user Lark credentials
+    in -- in whatever directory pytest runs from. The sibling
+    ``test_lark_cli_integration.py`` isolates it the same way.
+    """
+    monkeypatch.setattr(paths_module, "_paths", Paths(base_dir=tmp_path / "home"))
+
+
+def test_run_lark_cli_json_decodes_utf8_output_regardless_of_locale(fake_cli, locale_decoding: None) -> None:
+    """``_run_lark_cli_json`` must return the CLI's non-ASCII fields intact."""
+    argv, _launcher = fake_cli
+
+    data = lark_cli._run_lark_cli_json([*argv, "auth", "status", "--json"], user_id="alice", timeout=20)
+
+    assert data["userName"] == EXPECTED_USER
+    assert data["title"] == EXPECTED_TITLE
+
+
+def test_probe_lark_auth_decodes_utf8_user_name(fake_cli, locale_decoding: None, monkeypatch: pytest.MonkeyPatch) -> None:
+    """The frequently-polled status probe reports the real CJK account name."""
+    _argv, launcher = fake_cli
+    monkeypatch.setattr(lark_cli, "_resolve_lark_cli_path", lambda: launcher)
+    monkeypatch.setattr(lark_cli, "read_lark_app_config", lambda _user_id: {"configured": True})
+
+    probe = lark_cli.probe_lark_auth("alice")
+
+    assert probe.status == "authenticated"
+    assert probe.user == EXPECTED_USER
+
+
+def test_probe_lark_cli_at_path_decodes_utf8_version_output(fake_cli, locale_decoding: None) -> None:
+    """The probe's reported version keeps a non-ASCII byte intact.
+
+    Asserting only ``available``/``error`` would not guard the pin: the probe
+    returns ``available=True, version=output or None`` for any non-empty output
+    with a zero exit code, so a mojibake version string still passes. Naming the
+    expected text is what fails on the unpinned call site.
+    """
+    _argv, launcher = fake_cli
+
+    probe = lark_cli._probe_lark_cli_at_path(launcher)
+
+    assert probe.available is True
+    assert probe.error is None
+    assert probe.version == EXPECTED_VERSION
+
+
+def test_unpinned_capture_corrupts_the_same_output(fake_cli) -> None:
+    """Control: without the pin, the locale decode corrupts the payload.
+
+    Asserted directly so the failure mode stays documented on hosts whose own
+    locale happens to be UTF-8 (where this records that the pin is what keeps
+    the decode correct elsewhere rather than re-testing the corruption).
+    """
+    argv, _launcher = fake_cli
+
+    unpinned = subprocess.run(argv, check=False, capture_output=True, text=True)
+    raw = unpinned.stdout or ""
+    if raw.strip() and json.loads(raw)["userName"] == EXPECTED_USER:
+        # A UTF-8 host locale: the locale decode happens to be correct here.
+        return
+    assert EXPECTED_USER not in raw