diff --git a/agent/evals/telemetry.py b/agent/evals/telemetry.py
index 6e3505f..e209bc1 100644
--- a/agent/evals/telemetry.py
+++ b/agent/evals/telemetry.py
@@ -10,14 +10,48 @@
 
 _LOCK = threading.Lock()
 _SECRET_RE = re.compile(r"(?i)(api[_-]?key|token|password|secret)(\s*[=:]\s*)([^\s,;]+)")
+_ENV_SECRET_MARKERS = ("API_KEY", "_TOKEN", "_SECRET", "_PASSWORD", "_DSN")
+# 变量名命中标记不代表取值就是密钥材料：仓库里允许 X_API_KEY_HELPER_DISABLED=1
+# 这类布尔开关存在。取值过短时（0/1/true/no）把它当密钥做子串替换，除了会改写
+# payload 里的无关内容，还会先把文本改掉，让后面真正的长密钥再也匹配不上。
+#
+# 契约：短于该长度的取值一律按普通配置处理，任何形式都不替换——包括 JSON 的
+# 引号形式。{"password": "s3cr3t"} 不会被 _SECRET_RE 拦截，因为该正则要求标记名
+# 后面紧跟 = 或 :，引号挡在中间时匹配不到；具名短密钥只有写成 password=s3cr3t
+# 这种无引号形式才会被替换。
+_ENV_SECRET_MIN_LENGTH = 8
+# 取值替换的边界：出现在标识符字符内部时一律不替换，所以 postgres 不会把
+# postgresql 或 postgres_user 切成 [REDACTED]。下划线属于标识符字符，连字符不是
+# ——它在路径和命令行里是分隔符，仍算合法边界。
+_IDENTIFIER_CHAR = r"[A-Za-z0-9_]"
+
+
+def _environment_secrets() -> tuple[str, ...]:
+    """收集需要脱敏的环境变量取值，长取值排在前，保证优先匹配更长的密钥。"""
+
+    secrets = {
+        value
+        for key, value in os.environ.items()
+        if len(value) >= _ENV_SECRET_MIN_LENGTH
+        and any(marker in key.upper() for marker in _ENV_SECRET_MARKERS)
+    }
+    return tuple(sorted(secrets, key=len, reverse=True))
+
+
+def _redact_environment_secrets(text: str) -> str:
+    """只替换作为完整标识符出现的密钥取值。"""
+
+    secrets = _environment_secrets()
+    if not secrets:
+        return text
+    alternation = "|".join(re.escape(secret) for secret in secrets)
+    return re.sub(rf"(?<!{_IDENTIFIER_CHAR})(?:{alternation})(?!{_IDENTIFIER_CHAR})", "[REDACTED]", text)
 
 
 def _redact(value: Any) -> Any:
     if isinstance(value, str):
         redacted = _SECRET_RE.sub(r"\1\2[REDACTED]", value)
-        for key, secret in os.environ.items():
-            if any(marker in key.upper() for marker in ("API_KEY", "_TOKEN", "_SECRET", "_PASSWORD", "_DSN")) and secret:
-                redacted = redacted.replace(secret, "[REDACTED]")
+        redacted = _redact_environment_secrets(redacted)
         return redacted[:8000]
     if isinstance(value, dict):
         return {str(key): _redact(item) for key, item in value.items()}
diff --git a/tests/unit/test_eval_telemetry.py b/tests/unit/test_eval_telemetry.py
new file mode 100644
index 0000000..20bb258
--- /dev/null
+++ b/tests/unit/test_eval_telemetry.py
@@ -0,0 +1,96 @@
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+from agent.evals import telemetry
+
+
+def test_short_config_flag_is_not_treated_as_a_secret(monkeypatch) -> None:
+    """变量名命中 ``API_KEY`` 不代表取值是密钥材料。
+
+    仓库允许 ``X_API_KEY_HELPER_DISABLED=1`` 这类布尔开关存在。把这种短取值
+    当成密钥做全局子串替换，会连同 payload 里任意同名片段一起改写。
+    """
+
+    monkeypatch.setenv("CODING_AGENT_API_KEY_HELPER_DISABLED", "1")
+    payload = {"repo_path": "C:/work/pytest-201/projects/target-repo", "attempt": "1"}
+
+    assert telemetry._redact(payload) == payload
+
+
+def test_recorded_event_keeps_workspace_path_intact(tmp_path: Path, monkeypatch) -> None:
+    """回归：evals 事件里的工作区路径不能被环境开关改写。"""
+
+    monkeypatch.setenv("CODING_AGENT_EVAL_MODE", "1")
+    monkeypatch.setenv("CODING_AGENT_API_KEY_HELPER_DISABLED", "1")
+    monkeypatch.setenv("EVAL_EVENT_FILE", str(tmp_path / "events.jsonl"))
+    repo_path = "C:/work/pytest-201/projects/target-repo"
+
+    telemetry.record_eval_event("workspace_binding", {"repo_path": repo_path})
+
+    event = json.loads((tmp_path / "events.jsonl").read_text(encoding="utf-8").strip())
+    assert event["payload"]["repo_path"] == repo_path
+
+
+def test_environment_secret_is_still_redacted(monkeypatch) -> None:
+    """真实密钥取值仍然必须被脱敏。"""
+
+    dsn = "postgresql://eval:sup3rsecret@127.0.0.1:5432/eval_db"
+    monkeypatch.setenv("POSTGRES_DSN", dsn)
+
+    redacted = telemetry._redact({"connection": dsn, "note": f"connected via {dsn}"})
+
+    assert dsn not in json.dumps(redacted)
+    assert redacted == {"connection": "[REDACTED]", "note": "connected via [REDACTED]"}
+
+
+def test_long_secret_is_redacted_without_corrupting_longer_tokens(monkeypatch) -> None:
+    """只替换独立出现的取值：``postgres`` 不应改写 ``postgresql``。"""
+
+    monkeypatch.setenv("POSTGRES_PASSWORD", "postgres")
+
+    assert telemetry._redact("driver=postgresql host=db") == "driver=postgresql host=db"
+    assert telemetry._redact("password is postgres") == "password is [REDACTED]"
+
+
+def test_compound_identifiers_are_not_split_by_a_secret_value(monkeypatch) -> None:
+    """下划线属于标识符字符：``postgres_user`` 不应变成 ``[REDACTED]_user``。"""
+
+    monkeypatch.setenv("POSTGRES_PASSWORD", "postgres")
+    payload = {"repo_path": "/work/postgres_backup", "id": "postgres_user"}
+
+    assert telemetry._redact(payload) == payload
+
+
+def test_values_shorter_than_the_threshold_are_plain_configuration(monkeypatch) -> None:
+    """契约：短于 ``_ENV_SECRET_MIN_LENGTH`` 的取值不是密钥材料，任何形式都不替换。
+
+    包含 JSON 的引号形式——``_SECRET_RE`` 要求标记名后紧跟 ``=`` 或 ``:``，
+    引号挡在中间时匹配不到，因此 ``{"password": "s3cr3t"}`` 保持原样。只有
+    无引号的 ``password=s3cr3t`` 才会被 ``_SECRET_RE`` 拦截。
+    """
+
+    monkeypatch.setenv("REVIEW_PASSWORD", "s3cr3t")
+    payload = {"password": "s3cr3t"}
+
+    assert telemetry._redact(payload) == payload
+    assert telemetry._redact('{"password": "s3cr3t"}') == '{"password": "s3cr3t"}'
+    assert telemetry._redact("password=s3cr3t") == "password=[REDACTED]"
+
+
+def test_long_environment_secret_is_redacted_inside_nested_payloads(monkeypatch) -> None:
+    """对照：达到阈值的密钥在字典取值与 JSON 字符串里都仍然被脱敏。"""
+
+    dsn = "postgresql://eval:sup3rsecret@127.0.0.1:5432/eval_db"
+    monkeypatch.setenv("POSTGRES_DSN", dsn)
+    embedded = json.dumps({"dsn": dsn})
+
+    redacted = telemetry._redact({"payload": {"content": embedded}})
+
+    assert dsn in embedded
+    assert redacted["payload"]["content"] == '{"dsn": "[REDACTED]"}'
+
+
+def test_name_value_secret_pattern_is_still_masked() -> None:
+    assert telemetry._redact("token=abc123def456") == "token=[REDACTED]"