diff --git a/src/agentkit/channels/feishu.py b/src/agentkit/channels/feishu.py
index c9d4355..cfac706 100644
--- a/src/agentkit/channels/feishu.py
+++ b/src/agentkit/channels/feishu.py
@@ -36,8 +36,8 @@ logger = logging.getLogger(__name__)
 
 # 签名时间戳允许的最大偏移（秒）— 与飞书官方文档保持一致
 _SIGNATURE_MAX_AGE_SECONDS = 300
-# tenant_access_token 缓存 TTL（秒）— 飞书 token 实际有效期为 2h，留 5min 余量
-_TOKEN_CACHE_TTL = 300.0
+# tenant_access_token 缓存 TTL（秒）— 飞书 token 实际有效期 2h(7200s)，留 5min 余量
+_TOKEN_CACHE_TTL = 6900.0
 
 # 飞书开放平台 API 端点
 _TENANT_TOKEN_URL = "https://open.feishu.cn/open-apis/auth/v3/tenant_access_token/internal"
diff --git a/src/agentkit/channels/wecom.py b/src/agentkit/channels/wecom.py
index 429ca60..9535d35 100644
--- a/src/agentkit/channels/wecom.py
+++ b/src/agentkit/channels/wecom.py
@@ -34,6 +34,9 @@ from agentkit.channels.base import (
 
 logger = logging.getLogger(__name__)
 
+# 企微签名时间戳允许的最大偏移（秒）— 5 分钟窗口防重放
+_SIGNATURE_MAX_AGE_SECONDS = 300
+
 # access_token 缓存 TTL（秒）— 企微 token 有效期 2 小时
 _TOKEN_CACHE_TTL = 7200.0
 
@@ -206,6 +209,19 @@ class WeComMessageAdapter(MessageAdapter):
         if not msg_signature or not timestamp or not nonce:
             return False
 
+        # 时间戳新鲜度校验 — 5 分钟窗口防重放攻击
+        try:
+            ts_int = int(timestamp)
+        except (TypeError, ValueError):
+            return False
+        now = int(time.time())
+        if abs(now - ts_int) > _SIGNATURE_MAX_AGE_SECONDS:
+            logger.warning(
+                "企微 webhook 时间戳超出 %ds 窗口: ts=%s now=%d",
+                _SIGNATURE_MAX_AGE_SECONDS, timestamp, now,
+            )
+            return False
+
         encrypt = self._extract_encrypt(body)
         if not encrypt:
             return False
diff --git a/src/agentkit/llm/cache.py b/src/agentkit/llm/cache.py
index c58e724..b0f334c 100644
--- a/src/agentkit/llm/cache.py
+++ b/src/agentkit/llm/cache.py
@@ -783,14 +783,19 @@ class LitellmCacheManager:
         kb_caching_disabled: bool = False,
         user_id: str | None = None,
     ) -> bool:
-        """判断当前请求是否应该缓存（安全要求 c）。
+        """判断当前请求是否应该缓存（安全要求 a, c, e）。
 
-        - KB 设置 caching_disabled=True → 不缓存
-        - 其余情况缓存（user_id 为 None 时仍可缓存，但 key 不含 user scope）
+        - KB 设置 caching_disabled=True → 不缓存（要求 c）
+        - per_user_namespace 开启且 user_id 为 None → 不缓存（要求 a, e）
+          匿名请求无法做 per-user 隔离，缓存会导致跨用户泄漏，强制 no-cache。
         """
-        _ = user_id  # 预留：未来支持 per-user 缓存禁用
         if kb_caching_disabled:
             return False
+        if self._config.per_user_namespace and user_id is None:
+            # 安全要求 (a)(e)：per-user namespace 开启时拒绝匿名缓存，
+            # 避免不同匿名用户命中同一缓存键导致跨用户泄漏。
+            logger.debug("should_cache: per_user_namespace on but user_id=None — skip cache")
+            return False
         return True
 
     @staticmethod
diff --git a/src/agentkit/llm/cache_key.py b/src/agentkit/llm/cache_key.py
index 362b993..3a5211b 100644
--- a/src/agentkit/llm/cache_key.py
+++ b/src/agentkit/llm/cache_key.py
@@ -39,21 +39,23 @@ def generate_cache_key(
         64-character hex SHA-256 hash string.
     """
     system_prompt = _extract_system_prompt(messages)
-    components = [
-        _hash_str(model),
-        _hash_str(system_prompt),
-        _hash_json(messages),
-        _hash_str(f"{temperature:.2f}"),
-        _hash_json(tools),
-        _hash_str(tool_choice),
-        _hash_str(str(max_tokens)),
+    # 单次 SHA-256：用分隔符拼接所有组件，避免逐组件 hash 再 hash 的冗余计算。
+    # 分隔符使用长度前缀防止歧义（如 "ab" + "cd" vs "a" + "bcd"）。
+    parts = [
+        f"m:{model}",
+        f"s:{system_prompt}",
+        f"msg:{json.dumps(messages, sort_keys=True, ensure_ascii=False)}",
+        f"t:{temperature:.2f}",
+        f"tools:{json.dumps(tools, sort_keys=True, ensure_ascii=False) if tools is not None else 'null'}",
+        f"tc:{tool_choice}",
+        f"mt:{max_tokens}",
     ]
     # U17 — per-user namespace + ACL scope hash（安全要求 a, b, e）
     if user_id is not None:
-        components.append(_hash_str(f"user:{user_id}"))
+        parts.append(f"u:{user_id}")
     if kb_acl_hash is not None:
-        components.append(_hash_str(f"acl:{kb_acl_hash}"))
-    combined = "".join(components)
+        parts.append(f"a:{kb_acl_hash}")
+    combined = "\x1f".join(parts)  # US (Unit Separator) 防止组件内容注入分隔符
     return hashlib.sha256(combined.encode()).hexdigest()
 
 
@@ -63,15 +65,3 @@ def _extract_system_prompt(messages: list[dict[str, str]]) -> str:
         if msg.get("role") == "system":
             return msg.get("content", "")
     return ""
-
-
-def _hash_str(s: str) -> str:
-    """SHA-256 hash of a string."""
-    return hashlib.sha256(s.encode()).hexdigest()
-
-
-def _hash_json(obj: Any) -> str:
-    """SHA-256 hash of a JSON-serializable object."""
-    if obj is None:
-        return hashlib.sha256(b"null").hexdigest()
-    return hashlib.sha256(json.dumps(obj, sort_keys=True, ensure_ascii=False).encode()).hexdigest()
diff --git a/src/agentkit/llm/config.py b/src/agentkit/llm/config.py
index 3dbfcd0..6357582 100644
--- a/src/agentkit/llm/config.py
+++ b/src/agentkit/llm/config.py
@@ -74,21 +74,15 @@ class ProviderConfig:
     api_key_encrypted: str | None = None
     api_key_source: str = "plaintext"
 
-    def get_api_key(self, secrets_store: "SecretsStore | None" = None) -> str:
-        """同步读取 API Key。
+    def get_api_key(self) -> str:
+        """同步读取 API Key — 返回 plaintext。
 
-        双读窗口优先级：``api_key_encrypted`` + ``secrets_store`` > plaintext。
-        若加密列存在但解密失败（store 为 None 或解密异常），回退到 plaintext
-        ``api_key``，保证迁移期可用性。
-
-        注意：``SecretsStore.get_secret`` 是 async，本同步方法无法调用。
-        若 ``api_key_encrypted`` 已设置但 ``secrets_store`` 为 None，仍回退到
-        plaintext。需要解密时请用 ``aget_api_key``。
+        双读窗口的同步入口：无法 await ``SecretsStore.get_secret``，
+        因此加密列需通过异步方法 :meth:`aget_api_key` 读取。
+        本方法始终返回 plaintext ``api_key``（迁移期保证可用性）。
         """
-        if self.api_key_encrypted and secrets_store is not None:
-            # 同步上下文无法 await get_secret，调用方应改用 aget_api_key。
-            # 这里保持双读语义的回退：返回 plaintext。
-            logger.debug("get_api_key: encrypted key set but sync access — fallback to plaintext")
+        if self.api_key_encrypted:
+            logger.debug("get_api_key: encrypted key set — use aget_api_key for decryption")
         return self.api_key
 
     async def aget_api_key(self, secrets_store: "SecretsStore | None" = None) -> str:
diff --git a/src/agentkit/llm/gateway.py b/src/agentkit/llm/gateway.py
index 691eca9..f0d62e7 100644
--- a/src/agentkit/llm/gateway.py
+++ b/src/agentkit/llm/gateway.py
@@ -552,30 +552,39 @@ class LLMGateway:
                 )
 
             # 2. Token + cost limits (daily AND monthly)
-            await self._check_quota_period(quota_service, db, dept_id, "daily", "token_limit")
-            await self._check_quota_period(quota_service, db, dept_id, "daily", "cost_limit")
-            await self._check_quota_period(quota_service, db, dept_id, "monthly", "token_limit")
-            await self._check_quota_period(quota_service, db, dept_id, "monthly", "cost_limit")
+            # 优化：每个 period 只查一次 get_usage，复用 summary 检查 token + cost
+            for period in ("daily", "monthly"):
+                summary = self._get_usage_summary(dept_id, period)
+                current_tokens = int(summary.total_tokens)
+                current_cost_cents = float(summary.total_cost) * 100.0
+                await self._check_quota_value(
+                    quota_service, db, dept_id, period, "token_limit", current_tokens
+                )
+                await self._check_quota_value(
+                    quota_service, db, dept_id, period, "cost_limit", current_cost_cents
+                )
 
-    async def _check_quota_period(
+    def _get_usage_summary(self, department_id: str, period: str) -> UsageSummary:
+        """返回 department_id 在当前 period 的 usage summary（单次查询，供 token+cost 复用）。"""
+        now = datetime.now(timezone.utc)
+        if period == "monthly":
+            start = now.replace(day=1, hour=0, minute=0, second=0, microsecond=0)
+        else:
+            start = now.replace(hour=0, minute=0, second=0, microsecond=0)
+        return self._usage_tracker.get_usage(
+            department_id=department_id, start_time=start, end_time=now
+        )
+
+    async def _check_quota_value(
         self,
         quota_service: Any,
         db: Path,
         dept_id: str,
         period: str,
         quota_type: str,
+        current: float,
     ) -> None:
-        """Check a single quota (token_limit or cost_limit) for a period.
-
-        Raises :class:`QuotaExceededError` if the current usage exceeds
-        the configured limit. ``period`` is ``"daily"`` or ``"monthly"``;
-        ``quota_type`` is ``"token_limit"`` or ``"cost_limit"``.
-        """
-        if quota_type == "token_limit":
-            current = await self._get_current_usage_for_quota(dept_id, period)
-        else:
-            current = await self._get_current_cost_for_quota(dept_id, period)
-
+        """检查单个配额（token_limit 或 cost_limit）— current 由调用方预计算传入。"""
         allowed, _reason = await quota_service.check_quota(db, dept_id, quota_type, period, current)
         if not allowed:
             quota = await quota_service.get_quota(db, dept_id, quota_type, period)
@@ -587,38 +596,3 @@ class LLMGateway:
                 limit=limit,
                 current=current,
             )
-
-    async def _get_current_usage_for_quota(self, department_id: str, period: str) -> int:
-        """Return total tokens used by ``department_id`` in the current period.
-
-        ``period`` is ``"daily"`` or ``"monthly"``. For ``"daily"`` the
-        window is since 00:00 UTC today; for ``"monthly"`` since the
-        first of the current month.
-        """
-        now = datetime.now(timezone.utc)
-        if period == "monthly":
-            start = now.replace(day=1, hour=0, minute=0, second=0, microsecond=0)
-        else:
-            start = now.replace(hour=0, minute=0, second=0, microsecond=0)
-        summary = self._usage_tracker.get_usage(
-            department_id=department_id, start_time=start, end_time=now
-        )
-        return int(summary.total_tokens)
-
-    async def _get_current_cost_for_quota(self, department_id: str, period: str) -> float:
-        """Return total cost (in cents) for ``department_id`` in the current period.
-
-        ``period`` is ``"daily"`` or ``"monthly"``. Quota cost_limit is
-        stored in cents, so we convert the float USD cost from the usage
-        store to cents (×100) for comparison.
-        """
-        now = datetime.now(timezone.utc)
-        if period == "monthly":
-            start = now.replace(day=1, hour=0, minute=0, second=0, microsecond=0)
-        else:
-            start = now.replace(hour=0, minute=0, second=0, microsecond=0)
-        summary = self._usage_tracker.get_usage(
-            department_id=department_id, start_time=start, end_time=now
-        )
-        # cost_limit is stored in cents; convert from USD to cents.
-        return float(summary.total_cost) * 100.0
diff --git a/src/agentkit/server/app.py b/src/agentkit/server/app.py
index e8496e9..d01bede 100644
--- a/src/agentkit/server/app.py
+++ b/src/agentkit/server/app.py
@@ -556,6 +556,20 @@ async def lifespan(app: FastAPI):
     if cal_scheduler is not None:
         await cal_scheduler.stop()
 
+    # U10/U11 — 关闭渠道适配器并等待后台 webhook 任务完成
+    # 防止 httpx 连接泄漏和丢失正在处理的 IM 回复
+    from agentkit.server.routes.channels import _pending_webhook_tasks
+
+    if _pending_webhook_tasks:
+        logger.info("等待 %d 个后台 webhook 任务完成", len(_pending_webhook_tasks))
+        await asyncio.gather(*_pending_webhook_tasks, return_exceptions=True)
+    try:
+        from agentkit.server.routes.channels import close_all_adapters
+
+        await close_all_adapters()
+    except Exception:
+        logger.debug("close_all_adapters 异常已忽略")
+
 
 def _on_config_change(app: FastAPI, config: ServerConfig) -> None:
     """Handle config change by reloading affected components.
diff --git a/src/agentkit/server/routes/channels.py b/src/agentkit/server/routes/channels.py
index 71b46c2..22bf8e1 100644
--- a/src/agentkit/server/routes/channels.py
+++ b/src/agentkit/server/routes/channels.py
@@ -506,6 +506,15 @@ async def _process_inbound_message(
     适配器由 ``_adapter_cache`` 管理，不在 per-request 关闭（关闭会清空 token 缓存）。
     适配器类型不限 — 出站消息的 ``channel`` 取自入站消息以匹配平台。
     """
+
+    async def _direct_chat(llm_gateway: Any, routing: Any) -> str:
+        """DIRECT_CHAT 路径 — 直接调用 LLM（主路径与 ReAct 回退共用）。"""
+        response = await llm_gateway.chat(
+            messages=[{"role": "user", "content": message.content}],
+            model=routing.model or "default",
+        )
+        return response.content
+
     async with _get_webhook_semaphore():
         try:
             request_preprocessor = getattr(app_state, "request_preprocessor", None)
@@ -523,13 +532,8 @@ async def _process_inbound_message(
 
             final_content = ""
             execution_mode = getattr(routing, "execution_mode", None)
-            # DIRECT_CHAT 模式 — 直接调用 LLM
             if execution_mode == ExecutionMode.DIRECT_CHAT:
-                response = await llm_gateway.chat(
-                    messages=[{"role": "user", "content": message.content}],
-                    model=routing.model or "default",
-                )
-                final_content = response.content
+                final_content = await _direct_chat(llm_gateway, routing)
             else:
                 # REACT 或其他模式 — 优先使用 ReActEngine，失败回退到 DIRECT_CHAT
                 try:
@@ -544,11 +548,7 @@ async def _process_inbound_message(
                     final_content = getattr(result, "content", "") or ""
                 except Exception as exc:  # noqa: BLE001 — 回退路径需捕获全部异常
                     logger.warning("ReActEngine 执行失败，回退到 DIRECT_CHAT: %s", exc)
-                    response = await llm_gateway.chat(
-                        messages=[{"role": "user", "content": message.content}],
-                        model=routing.model or "default",
-                    )
-                    final_content = response.content
+                    final_content = await _direct_chat(llm_gateway, routing)
 
             if not final_content:
                 logger.warning("消息处理未产生内容 — 不发送回复")
@@ -620,9 +620,16 @@ async def channel_webhook(channel_id: str, request: Request) -> Any:
     except WeComURLVerification as e:
         # 企微 URL 验证 — 返回 XML 响应
         return Response(content=e.response_xml, media_type="application/xml")
+    except Exception as exc:  # noqa: BLE001 — 防止 receive_message 异常导致 500 触发平台重试风暴
+        logger.warning("receive_message 解析失败 channel=%s: %s", channel_id, exc)
+        return {"code": 0, "msg": "invalid_payload"}
 
     # 异步处理 — 不阻塞 webhook 响应（平台要求快速返回 200）
     # 持有 task 引用防止 GC 回收正在运行的后台任务
+    # 有界化：超过 2x 并发上限时拒绝新任务（防突发流量下 set 无界增长）
+    if len(_pending_webhook_tasks) >= _WEBHOOK_MAX_CONCURRENT * 2:
+        logger.warning("webhook 后台任务积压 %d，拒绝新任务", len(_pending_webhook_tasks))
+        raise HTTPException(status_code=429, detail="服务器繁忙，请稍后重试")
     task = asyncio.create_task(_process_inbound_message(request.app.state, adapter, message))
     _pending_webhook_tasks.add(task)
     task.add_done_callback(_pending_webhook_tasks.discard)
diff --git a/tests/unit/channels/test_wecom.py b/tests/unit/channels/test_wecom.py
index d0824c8..c47f8ef 100644
--- a/tests/unit/channels/test_wecom.py
+++ b/tests/unit/channels/test_wecom.py
@@ -17,6 +17,7 @@ from __future__ import annotations
 
 import base64
 import hashlib
+import time
 from unittest.mock import AsyncMock, MagicMock
 from xml.etree import ElementTree as ET
 
@@ -108,7 +109,7 @@ class TestSignatureVerification:
         inner_xml = _build_inner_xml({"MsgId": "m1", "Content": "hi"})
         body = _build_body(adapter, inner_xml)
         encrypt = adapter._extract_encrypt(body) or ""
-        ts, nonce = "1609459200", "n1"
+        ts, nonce = str(int(time.time())), "n1"
         sig = _signature(adapter.token, ts, nonce, encrypt)
         headers = {"msg_signature": sig, "timestamp": ts, "nonce": nonce}
         assert await adapter.verify_signature(headers, body) is True
@@ -118,10 +119,23 @@ class TestSignatureVerification:
         adapter = _make_adapter()
         inner_xml = _build_inner_xml({"MsgId": "m1", "Content": "hi"})
         body = _build_body(adapter, inner_xml)
-        ts, nonce = "1609459200", "n1"
+        ts, nonce = str(int(time.time())), "n1"
         headers = {"msg_signature": "tampered", "timestamp": ts, "nonce": nonce}
         assert await adapter.verify_signature(headers, body) is False
 
+    async def test_expired_timestamp_rejected(self):
+        """时间戳超出 5 分钟窗口返回 False（防重放）。"""
+        adapter = _make_adapter()
+        inner_xml = _build_inner_xml({"MsgId": "m1", "Content": "hi"})
+        body = _build_body(adapter, inner_xml)
+        encrypt = adapter._extract_encrypt(body) or ""
+        # 10 分钟前的时间戳 — 超出 300s 窗口
+        old_ts = str(int(time.time()) - 600)
+        nonce = "n1"
+        sig = _signature(adapter.token, old_ts, nonce, encrypt)
+        headers = {"msg_signature": sig, "timestamp": old_ts, "nonce": nonce}
+        assert await adapter.verify_signature(headers, body) is False
+
     async def test_missing_query_params(self):
         """缺少 msg_signature/timestamp/nonce 返回 False。"""
         adapter = _make_adapter()
diff --git a/tests/unit/llm/test_cache.py b/tests/unit/llm/test_cache.py
index 45cefe8..471d1ae 100644
--- a/tests/unit/llm/test_cache.py
+++ b/tests/unit/llm/test_cache.py
@@ -276,15 +276,27 @@ class TestKBCachingDisabled:
 
     def test_should_cache_returns_false_when_disabled(self):
         manager = LitellmCacheManager(LitellmCacheConfig(backend="memory"))
-        assert manager.should_cache(kb_caching_disabled=True) is False
+        assert manager.should_cache(kb_caching_disabled=True, user_id="u1") is False
 
     def test_should_cache_returns_true_when_enabled(self):
         manager = LitellmCacheManager(LitellmCacheConfig(backend="memory"))
-        assert manager.should_cache(kb_caching_disabled=False) is True
+        assert manager.should_cache(kb_caching_disabled=False, user_id="u1") is True
 
-    def test_should_cache_default_true(self):
+    def test_should_cache_default_with_user(self):
         manager = LitellmCacheManager(LitellmCacheConfig(backend="memory"))
-        assert manager.should_cache() is True
+        assert manager.should_cache(user_id="u1") is True
+
+    def test_should_cache_rejects_anonymous(self):
+        """安全要求 (a)(e) — per_user_namespace 开启且 user_id=None 时拒绝缓存。"""
+        manager = LitellmCacheManager(LitellmCacheConfig(backend="memory"))
+        assert manager.should_cache(user_id=None) is False
+
+    def test_should_cache_allows_anonymous_when_namespace_off(self):
+        """per_user_namespace=False 时匿名请求可缓存（向后兼容场景）。"""
+        cfg = LitellmCacheConfig(backend="memory")
+        cfg.per_user_namespace = False
+        manager = LitellmCacheManager(cfg)
+        assert manager.should_cache(user_id=None) is True
 
 
 # ---------------------------------------------------------------------------
diff --git a/tests/unit/llm/test_config_migration.py b/tests/unit/llm/test_config_migration.py
index 68e2895..d5ae86b 100644
--- a/tests/unit/llm/test_config_migration.py
+++ b/tests/unit/llm/test_config_migration.py
@@ -25,17 +25,9 @@ from agentkit.llm.config import LLMConfig, ProviderConfig
 
 
 def test_get_api_key_plaintext_no_store():
-    """无 secrets_store 时 get_api_key 返回 plaintext。"""
+    """get_api_key 返回 plaintext（同步入口，不处理加密列）。"""
     pconf = ProviderConfig(api_key="sk-xxx", base_url="", type="openai")
-    assert pconf.get_api_key(None) == "sk-xxx"
-
-
-def test_get_api_key_plaintext_with_store_sync():
-    """有 secrets_store 但同步调用 — 仍返回 plaintext（async 解密不可用）。"""
-    pconf = ProviderConfig(api_key="sk-xxx", base_url="", type="openai")
-    # 即使传 store，同步路径无法 decrypt，回退 plaintext
-    store = object()  # 任意非 None 对象
-    assert pconf.get_api_key(store) == "sk-xxx"  # type: ignore[arg-type]
+    assert pconf.get_api_key() == "sk-xxx"
 
 
 # ----------------------------------------------------------------------