diff --git a/frontend/src/features/api-keys/components/StandaloneKeyFormDialog.vue b/frontend/src/features/api-keys/components/StandaloneKeyFormDialog.vue
index 5f8cde6..35b9b13 100644
--- a/frontend/src/features/api-keys/components/StandaloneKeyFormDialog.vue
+++ b/frontend/src/features/api-keys/components/StandaloneKeyFormDialog.vue
@@ -132,7 +132,7 @@
               type="number"
               min="1"
               max="10000"
-              placeholder="100"
+              placeholder="留空不限制"
               class="h-10"
               @update:model-value="(v) => form.rate_limit = parseNumberInput(v, { min: 1, max: 10000 })"
             />
@@ -376,7 +376,7 @@ const form = ref<StandaloneKeyFormData>({
   initial_balance_usd: 10,
   expire_days: undefined,
   never_expire: true,
-  rate_limit: 100,
+  rate_limit: undefined,
   auto_delete_on_expiry: false,
   allowed_providers: [],
   allowed_api_formats: [],
@@ -389,7 +389,7 @@ function resetForm() {
     initial_balance_usd: 10,
     expire_days: undefined,
     never_expire: true,
-    rate_limit: 100,
+    rate_limit: undefined,
     auto_delete_on_expiry: false,
     allowed_providers: [],
     allowed_api_formats: [],
@@ -408,7 +408,7 @@ function loadKeyData() {
     initial_balance_usd: props.apiKey.initial_balance_usd,
     expire_days: props.apiKey.expire_days,
     never_expire: props.apiKey.never_expire,
-    rate_limit: props.apiKey.rate_limit || 100,
+    rate_limit: props.apiKey.rate_limit,
     auto_delete_on_expiry: props.apiKey.auto_delete_on_expiry,
     allowed_providers: props.apiKey.allowed_providers || [],
     allowed_api_formats: props.apiKey.allowed_api_formats || [],
diff --git a/frontend/src/features/usage/components/RequestDetailDrawer.vue b/frontend/src/features/usage/components/RequestDetailDrawer.vue
index 23f891a..3603707 100644
--- a/frontend/src/features/usage/components/RequestDetailDrawer.vue
+++ b/frontend/src/features/usage/components/RequestDetailDrawer.vue
@@ -25,7 +25,7 @@
                 </h3>
                 <div class="flex items-center gap-1 text-sm font-mono text-muted-foreground bg-muted px-2 py-0.5 rounded">
                   <span>{{ detail?.model || '-' }}</span>
-                  <template v-if="detail?.target_model">
+                  <template v-if="detail?.target_model && detail.target_model !== detail.model">
                     <svg
                       xmlns="http://www.w3.org/2000/svg"
                       viewBox="0 0 20 20"
diff --git a/frontend/src/views/admin/SystemSettings.vue b/frontend/src/views/admin/SystemSettings.vue
index 2de1583..0a0e0b6 100644
--- a/frontend/src/views/admin/SystemSettings.vue
+++ b/frontend/src/views/admin/SystemSettings.vue
@@ -185,32 +185,13 @@
         </div>
       </CardSection>
 
-      <!-- API Key 管理配置 -->
+      <!-- 独立余额 Key 过期管理 -->
       <CardSection
-        title="API Key 管理"
-        description="API Key 相关配置"
+        title="独立余额 Key 过期管理"
+        description="独立余额 Key 的过期处理策略（普通用户 Key 不会过期）"
       >
         <div class="grid grid-cols-1 md:grid-cols-2 gap-6">
-          <div>
-            <Label
-              for="api-key-expire"
-              class="block text-sm font-medium"
-            >
-              API密钥过期天数
-            </Label>
-            <Input
-              id="api-key-expire"
-              v-model.number="systemConfig.api_key_expire_days"
-              type="number"
-              placeholder="0"
-              class="mt-1"
-            />
-            <p class="mt-1 text-xs text-muted-foreground">
-              0 表示永不过期
-            </p>
-          </div>
-
-          <div class="flex items-center h-full pt-6">
+          <div class="flex items-center h-full">
             <div class="flex items-center space-x-2">
               <Checkbox
                 id="auto-delete-expired-keys"
@@ -224,7 +205,7 @@
                   自动删除过期 Key
                 </Label>
                 <p class="text-xs text-muted-foreground">
-                  关闭时仅禁用过期 Key
+                  关闭时仅禁用过期 Key，不会物理删除
                 </p>
               </div>
             </div>
@@ -448,6 +429,25 @@
               避免单次操作过大影响性能
             </p>
           </div>
+
+          <div>
+            <Label
+              for="audit-log-retention-days"
+              class="block text-sm font-medium"
+            >
+              审计日志保留天数
+            </Label>
+            <Input
+              id="audit-log-retention-days"
+              v-model.number="systemConfig.audit_log_retention_days"
+              type="number"
+              placeholder="30"
+              class="mt-1"
+            />
+            <p class="mt-1 text-xs text-muted-foreground">
+              超过后删除审计日志记录
+            </p>
+          </div>
         </div>
 
         <!-- 清理策略说明 -->
@@ -460,6 +460,7 @@
             <p>2. <strong>压缩日志阶段</strong>: body 字段被压缩存储，节省空间</p>
             <p>3. <strong>统计阶段</strong>: 仅保留 tokens、成本等统计信息</p>
             <p>4. <strong>归档删除</strong>: 超过保留期限后完全删除记录</p>
+            <p>5. <strong>审计日志</strong>: 独立清理，记录用户登录、操作等安全事件</p>
           </div>
         </div>
       </CardSection>
@@ -796,8 +797,7 @@ interface SystemConfig {
   // 用户注册
   enable_registration: boolean
   require_email_verification: boolean
-  // API Key 管理
-  api_key_expire_days: number
+  // 独立余额 Key 过期管理
   auto_delete_expired_keys: boolean
   // 日志记录
   request_log_level: string
@@ -811,6 +811,7 @@ interface SystemConfig {
   header_retention_days: number
   log_retention_days: number
   cleanup_batch_size: number
+  audit_log_retention_days: number
 }
 
 const loading = ref(false)
@@ -845,8 +846,7 @@ const systemConfig = ref<SystemConfig>({
   // 用户注册
   enable_registration: false,
   require_email_verification: false,
-  // API Key 管理
-  api_key_expire_days: 0,
+  // 独立余额 Key 过期管理
   auto_delete_expired_keys: false,
   // 日志记录
   request_log_level: 'basic',
@@ -860,6 +860,7 @@ const systemConfig = ref<SystemConfig>({
   header_retention_days: 90,
   log_retention_days: 365,
   cleanup_batch_size: 1000,
+  audit_log_retention_days: 30,
 })
 
 // 计算属性：KB 和 字节 之间的转换
@@ -901,8 +902,7 @@ async function loadSystemConfig() {
       // 用户注册
       'enable_registration',
       'require_email_verification',
-      // API Key 管理
-      'api_key_expire_days',
+      // 独立余额 Key 过期管理
       'auto_delete_expired_keys',
       // 日志记录
       'request_log_level',
@@ -916,6 +916,7 @@ async function loadSystemConfig() {
       'header_retention_days',
       'log_retention_days',
       'cleanup_batch_size',
+      'audit_log_retention_days',
     ]
 
     for (const key of configs) {
@@ -960,12 +961,7 @@ async function saveSystemConfig() {
         value: systemConfig.value.require_email_verification,
         description: '是否需要邮箱验证'
       },
-      // API Key 管理
-      {
-        key: 'api_key_expire_days',
-        value: systemConfig.value.api_key_expire_days,
-        description: 'API密钥过期天数'
-      },
+      // 独立余额 Key 过期管理
       {
         key: 'auto_delete_expired_keys',
         value: systemConfig.value.auto_delete_expired_keys,
@@ -1023,6 +1019,11 @@ async function saveSystemConfig() {
         value: systemConfig.value.cleanup_batch_size,
         description: '每批次清理的记录数'
       },
+      {
+        key: 'audit_log_retention_days',
+        value: systemConfig.value.audit_log_retention_days,
+        description: '审计日志保留天数'
+      },
     ]
 
     const promises = configItems.map(item =>
diff --git a/src/api/admin/api_keys/routes.py b/src/api/admin/api_keys/routes.py
index 3e84b16..133c7d7 100644
--- a/src/api/admin/api_keys/routes.py
+++ b/src/api/admin/api_keys/routes.py
@@ -223,7 +223,7 @@ class AdminCreateStandaloneKeyAdapter(AdminApiAdapter):
             allowed_providers=self.key_data.allowed_providers,
             allowed_api_formats=self.key_data.allowed_api_formats,
             allowed_models=self.key_data.allowed_models,
-            rate_limit=self.key_data.rate_limit or 100,
+            rate_limit=self.key_data.rate_limit,  # None 表示不限制
             expire_days=self.key_data.expire_days,
             initial_balance_usd=self.key_data.initial_balance_usd,
             is_standalone=True,  # 标记为独立Key
diff --git a/src/api/announcements/routes.py b/src/api/announcements/routes.py
index 786727d..c8642c4 100644
--- a/src/api/announcements/routes.py
+++ b/src/api/announcements/routes.py
@@ -140,7 +140,7 @@ class AnnouncementOptionalAuthAdapter(ApiAdapter):
         if not authorization or not authorization.lower().startswith("bearer "):
             return None
 
-        token = authorization.replace("Bearer ", "").strip()
+        token = authorization[7:].strip()
         try:
             payload = await AuthService.verify_token(token, token_type="access")
             user_id = payload.get("user_id")
diff --git a/src/api/base/pipeline.py b/src/api/base/pipeline.py
index d0fffc5..1418040 100644
--- a/src/api/base/pipeline.py
+++ b/src/api/base/pipeline.py
@@ -177,7 +177,7 @@ class ApiRequestPipeline:
         if not authorization or not authorization.lower().startswith("bearer "):
             raise HTTPException(status_code=401, detail="缺少管理员凭证")
 
-        token = authorization.replace("Bearer ", "").strip()
+        token = authorization[7:].strip()
         try:
             payload = await self.auth_service.verify_token(token, token_type="access")
         except HTTPException:
@@ -204,7 +204,7 @@ class ApiRequestPipeline:
         if not authorization or not authorization.lower().startswith("bearer "):
             raise HTTPException(status_code=401, detail="缺少用户凭证")
 
-        token = authorization.replace("Bearer ", "").strip()
+        token = authorization[7:].strip()
         try:
             payload = await self.auth_service.verify_token(token, token_type="access")
         except HTTPException:
diff --git a/src/api/handlers/base/base_handler.py b/src/api/handlers/base/base_handler.py
index 5e10cd2..c200aa1 100644
--- a/src/api/handlers/base/base_handler.py
+++ b/src/api/handlers/base/base_handler.py
@@ -28,7 +28,7 @@
 from __future__ import annotations
 
 import time
-from typing import Any, Callable, Dict, Optional, Protocol, runtime_checkable
+from typing import TYPE_CHECKING, Any, Callable, Dict, Optional, Protocol, runtime_checkable
 
 from fastapi import Request
 from fastapi.responses import JSONResponse, StreamingResponse
@@ -43,6 +43,9 @@ from src.services.provider.format import normalize_api_format
 from src.services.system.audit import audit_service
 from src.services.usage.service import UsageService
 
+if TYPE_CHECKING:
+    from src.api.handlers.base.stream_context import StreamContext
+
 
 
 class MessageTelemetry:
@@ -399,6 +402,41 @@ class BaseMessageHandler:
         # 创建后台任务，不阻塞当前流
         asyncio.create_task(_do_update())
 
+    def _update_usage_to_streaming_with_ctx(self, ctx: "StreamContext") -> None:
+        """更新 Usage 状态为 streaming，同时更新 provider 和 target_model
+
+        使用 asyncio 后台任务执行数据库更新，避免阻塞流式传输
+
+        Args:
+            ctx: 流式上下文，包含 provider_name 和 mapped_model
+        """
+        import asyncio
+        from src.database.database import get_db
+
+        target_request_id = self.request_id
+        provider = ctx.provider_name
+        target_model = ctx.mapped_model
+
+        async def _do_update() -> None:
+            try:
+                db_gen = get_db()
+                db = next(db_gen)
+                try:
+                    UsageService.update_usage_status(
+                        db=db,
+                        request_id=target_request_id,
+                        status="streaming",
+                        provider=provider,
+                        target_model=target_model,
+                    )
+                finally:
+                    db.close()
+            except Exception as e:
+                logger.warning(f"[{target_request_id}] 更新 Usage 状态为 streaming 失败: {e}")
+
+        # 创建后台任务，不阻塞当前流
+        asyncio.create_task(_do_update())
+
     def _log_request_error(self, message: str, error: Exception) -> None:
         """记录请求错误日志，对业务异常不打印堆栈
 
diff --git a/src/api/handlers/base/chat_handler_base.py b/src/api/handlers/base/chat_handler_base.py
index 2dc0501..d450b61 100644
--- a/src/api/handlers/base/chat_handler_base.py
+++ b/src/api/handlers/base/chat_handler_base.py
@@ -297,11 +297,15 @@ class ChatHandlerBase(BaseMessageHandler, ABC):
         # 创建类型安全的流式上下文
         ctx = StreamContext(model=model, api_format=api_format)
 
+        # 创建更新状态的回调闭包（可以访问 ctx）
+        def update_streaming_status() -> None:
+            self._update_usage_to_streaming_with_ctx(ctx)
+
         # 创建流处理器
         stream_processor = StreamProcessor(
             request_id=self.request_id,
             default_parser=self.parser,
-            on_streaming_start=self._update_usage_to_streaming,
+            on_streaming_start=update_streaming_status,
         )
 
         # 定义请求函数
diff --git a/src/api/handlers/base/cli_handler_base.py b/src/api/handlers/base/cli_handler_base.py
index f9f569c..698e0ad 100644
--- a/src/api/handlers/base/cli_handler_base.py
+++ b/src/api/handlers/base/cli_handler_base.py
@@ -532,7 +532,7 @@ class CliMessageHandlerBase(BaseMessageHandler):
             async for chunk in stream_response.aiter_raw():
                 # 在第一次输出数据前更新状态为 streaming
                 if not streaming_status_updated:
-                    self._update_usage_to_streaming(ctx.request_id)
+                    self._update_usage_to_streaming_with_ctx(ctx)
                     streaming_status_updated = True
 
                 buffer += chunk
@@ -816,7 +816,7 @@ class CliMessageHandlerBase(BaseMessageHandler):
 
             # 在第一次输出数据前更新状态为 streaming
             if prefetched_chunks:
-                self._update_usage_to_streaming(ctx.request_id)
+                self._update_usage_to_streaming_with_ctx(ctx)
 
             # 先处理预读的字节块
             for chunk in prefetched_chunks:
diff --git a/src/clients/redis_client.py b/src/clients/redis_client.py
index 1337679..4d67cd6 100644
--- a/src/clients/redis_client.py
+++ b/src/clients/redis_client.py
@@ -120,7 +120,7 @@ class RedisClientManager:
         if self._circuit_open_until and time.time() < self._circuit_open_until:
             remaining = self._circuit_open_until - time.time()
             logger.warning(
-                "Redis 客户端处于熔断状态，跳过初始化，剩余 %.1f 秒 (last_error: %s)",
+                "Redis 客户端处于熔断状态，跳过初始化，剩余 {:.1f} 秒 (last_error: {})",
                 remaining,
                 self._last_error,
             )
@@ -200,7 +200,7 @@ class RedisClientManager:
             if self._consecutive_failures >= self._circuit_threshold:
                 self._circuit_open_until = time.time() + self._circuit_reset_seconds
                 logger.warning(
-                    "Redis 初始化连续失败 %s 次，开启熔断 %s 秒。"
+                    "Redis 初始化连续失败 {} 次，开启熔断 {} 秒。"
                     "熔断期间以下功能将降级: 缓存亲和性、分布式并发控制、RPM限流。"
                     "可通过管理 API /api/admin/system/redis/reset-circuit 手动重置。",
                     self._consecutive_failures,
diff --git a/src/config/settings.py b/src/config/settings.py
index 3239789..ab1b375 100644
--- a/src/config/settings.py
+++ b/src/config/settings.py
@@ -105,6 +105,13 @@ class Config:
         self.llm_api_rate_limit = int(os.getenv("LLM_API_RATE_LIMIT", "100"))
         self.public_api_rate_limit = int(os.getenv("PUBLIC_API_RATE_LIMIT", "60"))
 
+        # 可信代理配置
+        # TRUSTED_PROXY_COUNT: 信任的代理层数（默认 1，即信任最近一层代理）
+        # 设置为 0 表示不信任任何代理头，直接使用连接 IP
+        # 当服务部署在 Nginx/CloudFlare 等反向代理后面时，设置为对应的代理层数
+        # 如果服务直接暴露公网，应设置为 0 以防止 IP 伪造
+        self.trusted_proxy_count = int(os.getenv("TRUSTED_PROXY_COUNT", "1"))
+
         # 异常处理配置
         # 设置为 True 时，ProxyException 会传播到路由层以便记录 provider_request_headers
         # 设置为 False 时，使用全局异常处理器统一处理
diff --git a/src/database/database.py b/src/database/database.py
index 99f5b5e..dce62c1 100644
--- a/src/database/database.py
+++ b/src/database/database.py
@@ -153,7 +153,7 @@ def _log_pool_capacity():
     total_estimated = theoretical * workers
     safe_limit = config.pg_max_connections - config.pg_reserved_connections
     logger.info(
-        "数据库连接池配置: pool_size=%s, max_overflow=%s, workers=%s, total_estimated=%s, safe_limit=%s",
+        "数据库连接池配置: pool_size={}, max_overflow={}, workers={}, total_estimated={}, safe_limit={}",
         config.db_pool_size,
         config.db_max_overflow,
         workers,
@@ -162,7 +162,7 @@ def _log_pool_capacity():
     )
     if total_estimated > safe_limit:
         logger.warning(
-            "数据库连接池总需求可能超过 PostgreSQL 限制: %s > %s (pg_max_connections - reserved)，"
+            "数据库连接池总需求可能超过 PostgreSQL 限制: {} > {} (pg_max_connections - reserved)，"
             "建议调整 DB_POOL_SIZE/DB_MAX_OVERFLOW 或减少 worker 数",
             total_estimated,
             safe_limit,
@@ -260,7 +260,8 @@ def get_db(request: Request = None) -> Generator[Session, None, None]:  # type:
 
     2. **管理后台 API**：
        - 路由层显式调用 db.commit()
-       - 每个操作独立提交，不依赖中间件
+       - 提交后设置 request.state.tx_committed_by_route = True
+       - 中间件看到此标志后跳过 commit，只负责 close
 
     3. **后台任务/调度器**：
        - 使用独立 Session（通过 create_session() 或 next(get_db())）
@@ -271,6 +272,17 @@ def get_db(request: Request = None) -> Generator[Session, None, None]:  # type:
     - FastAPI 请求：通过 Depends(get_db) 注入，支持中间件管理的 session 复用
     - 非请求上下文：直接调用 get_db()，退化为独立 session 模式
 
+    路由层提交事务示例
+    ==================
+    ```python
+    @router.post("/example")
+    async def example(request: Request, db: Session = Depends(get_db)):
+        # ... 业务逻辑 ...
+        db.commit()
+        request.state.tx_committed_by_route = True  # 告知中间件已提交
+        return {"message": "success"}
+    ```
+
     注意事项
     ========
     - 本函数不自动提交事务
diff --git a/src/main.py b/src/main.py
index 87f956e..dd32e77 100644
--- a/src/main.py
+++ b/src/main.py
@@ -49,7 +49,7 @@ async def initialize_providers():
             # 从数据库加载所有活跃的提供商
             providers = (
                 db.query(Provider)
-                .filter(Provider.is_active == True)
+                .filter(Provider.is_active.is_(True))
                 .order_by(Provider.provider_priority.asc())
                 .all()
             )
@@ -122,6 +122,7 @@ async def lifespan(app: FastAPI):
     logger.info("初始化全局Redis客户端...")
     from src.clients.redis_client import get_redis_client
 
+    redis_client = None
     try:
         redis_client = await get_redis_client(require_redis=config.require_redis)
         if redis_client:
@@ -133,6 +134,7 @@ async def lifespan(app: FastAPI):
             logger.exception("[ERROR] Redis连接失败，应用启动中止")
             raise
         logger.warning(f"Redis连接失败，但配置允许降级，将继续使用内存模式: {e}")
+        redis_client = None
 
     # 初始化并发管理器（内部会使用Redis）
     logger.info("初始化并发管理器...")
@@ -312,7 +314,7 @@ if frontend_dist.exists():
         仅对非API路径生效
         """
         # 如果是API路径，不处理
-        if full_path.startswith("api/") or full_path.startswith("v1/"):
+        if full_path in {"api", "v1"} or full_path.startswith(("api/", "v1/")):
             raise HTTPException(status_code=404, detail="Not Found")
 
         # 返回index.html，让前端路由处理
diff --git a/src/middleware/plugin_middleware.py b/src/middleware/plugin_middleware.py
index a262c19..7fcc33c 100644
--- a/src/middleware/plugin_middleware.py
+++ b/src/middleware/plugin_middleware.py
@@ -1,16 +1,17 @@
 """
-统一的插件中间件
+统一的插件中间件（纯 ASGI 实现）
 负责协调所有插件的调用
+
+注意：使用纯 ASGI middleware 而非 BaseHTTPMiddleware，
+以避免 Starlette 已知的流式响应兼容性问题。
 """
 
+import hashlib
 import time
-from typing import Any, Awaitable, Callable, Optional
+from typing import Optional
 
-from fastapi import HTTPException, Request
-from fastapi.responses import JSONResponse
-from sqlalchemy.orm import Session
-from starlette.middleware.base import BaseHTTPMiddleware
-from starlette.responses import Response as StarletteResponse
+from starlette.requests import Request
+from starlette.types import ASGIApp, Message, Receive, Scope, Send
 
 from src.config import config
 from src.core.logger import logger
@@ -18,20 +19,25 @@ from src.plugins.manager import get_plugin_manager
 from src.plugins.rate_limit.base import RateLimitResult
 
 
-
-class PluginMiddleware(BaseHTTPMiddleware):
+class PluginMiddleware:
     """
-    统一的插件调用中间件
+    统一的插件调用中间件（纯 ASGI 实现）
 
     职责:
     - 性能监控
     - 限流控制 (可选)
+    - 数据库会话生命周期管理
 
     注意: 认证由各路由通过 Depends() 显式声明，不在中间件层处理
+
+    为什么使用纯 ASGI 而非 BaseHTTPMiddleware:
+    - BaseHTTPMiddleware 会缓冲整个响应体，对流式响应不友好
+    - BaseHTTPMiddleware 与 StreamingResponse 存在已知兼容性问题
+    - 纯 ASGI 可以直接透传流式响应，无额外开销
     """
 
-    def __init__(self, app: Any) -> None:
-        super().__init__(app)
+    def __init__(self, app: ASGIApp) -> None:
+        self.app = app
         self.plugin_manager = get_plugin_manager()
 
         # 从配置读取速率限制值
@@ -61,152 +67,159 @@ class PluginMiddleware(BaseHTTPMiddleware):
             "/v1/completions",
         ]
 
-    async def dispatch(
-        self, request: Request, call_next: Callable[[Request], Awaitable[StarletteResponse]]
-    ) -> StarletteResponse:
-        """处理请求并调用相应插件"""
+    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
+        """ASGI 入口点"""
+        if scope["type"] != "http":
+            # 非 HTTP 请求（如 WebSocket）直接透传
+            await self.app(scope, receive, send)
+            return
+
+        # 构建 Request 对象以便复用现有逻辑
+        request = Request(scope, receive, send)
 
         # 记录请求开始时间
         start_time = time.time()
+
+        # 设置 request.state 属性
+        # 注意：Starlette 的 Request 对象总是有 state 属性（State 实例）
         request.state.request_id = request.headers.get("x-request-id", "")
         request.state.start_time = start_time
         # 标记：若请求过程中通过 Depends(get_db) 创建了会话，则由本中间件统一管理其生命周期
         request.state.db_managed_by_middleware = True
 
-        response = None
-        exception_to_raise = None
+        # 1. 限流检查（在调用下游之前）
+        rate_limit_result = await self._call_rate_limit_plugins(request)
+        if rate_limit_result and not rate_limit_result.allowed:
+            # 限流触发，返回429
+            await self._send_rate_limit_response(send, rate_limit_result)
+            return
 
+        # 2. 预处理插件调用
+        await self._call_pre_request_plugins(request)
+
+        # 用于捕获响应状态码
+        response_status_code: int = 0
+
+        async def send_wrapper(message: Message) -> None:
+            nonlocal response_status_code
+
+            if message["type"] == "http.response.start":
+                response_status_code = message.get("status", 0)
+
+            await send(message)
+
+        # 3. 调用下游应用
+        exception_occurred: Optional[Exception] = None
         try:
-            # 1. 限流插件调用（可选功能）
-            rate_limit_result = await self._call_rate_limit_plugins(request)
-            if rate_limit_result and not rate_limit_result.allowed:
-                # 限流触发，返回429
-                headers = rate_limit_result.headers or {}
-                raise HTTPException(
-                    status_code=429,
-                    detail=rate_limit_result.message or "Rate limit exceeded",
-                    headers=headers,
-                )
-
-            # 2. 预处理插件调用
-            await self._call_pre_request_plugins(request)
-
-            # 处理请求
-            response = await call_next(request)
-
-            # 3. 提交关键数据库事务（在返回响应前）
-            # 这确保了 Usage 记录、配额扣减等关键数据在响应返回前持久化
-            try:
-                db = getattr(request.state, "db", None)
-                if isinstance(db, Session):
-                    db.commit()
-            except Exception as commit_error:
-                logger.error(f"关键事务提交失败: {commit_error}")
-                try:
-                    if isinstance(db, Session):
-                        db.rollback()
-                except Exception:
-                    pass
-                await self._call_error_plugins(request, commit_error, start_time)
-                # 返回 500 错误，因为数据可能不一致
-                response = JSONResponse(
-                    status_code=500,
-                    content={
-                        "type": "error",
-                        "error": {
-                            "type": "database_error",
-                            "message": "数据保存失败，请重试",
-                        },
-                    },
-                )
-                # 跳过后处理插件，直接返回错误响应
-                return response
-
-            # 4. 后处理插件调用（监控等，非关键操作）
-            # 这些操作失败不应影响用户响应
-            await self._call_post_request_plugins(request, response, start_time)
-
-            # 注意：不在此处添加限流响应头，因为在BaseHTTPMiddleware中
-            # 响应返回后修改headers会导致Content-Length不匹配错误
-            # 限流响应头已在返回429错误时正确包含（见上面的HTTPException）
-
-        except RuntimeError as e:
-            if str(e) == "No response returned.":
-                db = getattr(request.state, "db", None)
-                if isinstance(db, Session):
-                    try:
-                        db.rollback()
-                    except Exception:
-                        pass
-
-                logger.error("Downstream handler completed without returning a response")
-
-                await self._call_error_plugins(request, e, start_time)
-
-                if isinstance(db, Session):
-                    try:
-                        db.commit()
-                    except Exception:
-                        pass
-
-                response = JSONResponse(
-                    status_code=500,
-                    content={
-                        "type": "error",
-                        "error": {
-                            "type": "internal_error",
-                            "message": "Internal server error: downstream handler returned no response.",
-                        },
-                    },
-                )
-            else:
-                exception_to_raise = e
-
+            await self.app(scope, receive, send_wrapper)
         except Exception as e:
-            # 回滚数据库事务
-            db = getattr(request.state, "db", None)
-            if isinstance(db, Session):
-                try:
-                    db.rollback()
-                except Exception:
-                    pass
-
+            exception_occurred = e
             # 错误处理插件调用
             await self._call_error_plugins(request, e, start_time)
+            raise
+        finally:
+            # 4. 数据库会话清理（无论成功与否）
+            await self._cleanup_db_session(request, exception_occurred)
 
-            # 尝试提交错误日志
-            if isinstance(db, Session):
+        # 5. 后处理插件调用（仅在成功时）
+        if not exception_occurred and response_status_code > 0:
+            await self._call_post_request_plugins(request, response_status_code, start_time)
+
+    async def _send_rate_limit_response(
+        self, send: Send, result: RateLimitResult
+    ) -> None:
+        """发送 429 限流响应"""
+        import json
+
+        body = json.dumps({
+            "type": "error",
+            "error": {
+                "type": "rate_limit_error",
+                "message": result.message or "Rate limit exceeded",
+            },
+        }).encode("utf-8")
+
+        headers = [(b"content-type", b"application/json")]
+        if result.headers:
+            for key, value in result.headers.items():
+                headers.append((key.lower().encode(), str(value).encode()))
+
+        await send({
+            "type": "http.response.start",
+            "status": 429,
+            "headers": headers,
+        })
+        await send({
+            "type": "http.response.body",
+            "body": body,
+        })
+
+    async def _cleanup_db_session(
+        self, request: Request, exception: Optional[Exception]
+    ) -> None:
+        """清理数据库会话
+
+        事务策略：
+        - 如果 request.state.tx_committed_by_route 为 True，说明路由已自行提交，中间件只负责 close
+        - 否则由中间件统一 commit/rollback
+
+        这避免了双重提交的问题，同时保持向后兼容。
+        """
+        from sqlalchemy.orm import Session
+
+        db = getattr(request.state, "db", None)
+        if not isinstance(db, Session):
+            return
+
+        # 检查是否由路由层已经提交
+        tx_committed_by_route = getattr(request.state, "tx_committed_by_route", False)
+
+        try:
+            if exception is not None:
+                # 发生异常，回滚事务（无论谁负责提交）
+                try:
+                    db.rollback()
+                except Exception as rollback_error:
+                    logger.debug(f"回滚事务时出错（可忽略）: {rollback_error}")
+            elif not tx_committed_by_route:
+                # 正常完成且路由未自行提交，由中间件提交事务
                 try:
                     db.commit()
-                except:
-                    pass
-
-            exception_to_raise = e
-
+                except Exception as commit_error:
+                    logger.error(f"关键事务提交失败: {commit_error}")
+                    try:
+                        db.rollback()
+                    except Exception:
+                        pass
+            # 如果 tx_committed_by_route 为 True，跳过 commit（路由已提交）
         finally:
-            db = getattr(request.state, "db", None)
-            if isinstance(db, Session):
-                try:
-                    db.close()
-                except Exception as close_error:
-                    # 连接池会处理连接的回收，这里的异常不应影响响应
-                    logger.debug(f"关闭数据库连接时出错（可忽略）: {close_error}")
-
-        # 在 finally 块之后处理异常和响应
-        if exception_to_raise:
-            raise exception_to_raise
-
-        return response
+            # 关闭会话，归还连接到连接池
+            try:
+                db.close()
+            except Exception as close_error:
+                logger.debug(f"关闭数据库连接时出错（可忽略）: {close_error}")
 
     def _get_client_ip(self, request: Request) -> str:
         """
         获取客户端 IP 地址，支持代理头
+
+        注意：此方法信任 X-Forwarded-For 和 X-Real-IP 头，
+        仅当服务部署在可信代理（如 Nginx、CloudFlare）后面时才安全。
+        如果服务直接暴露公网，攻击者可伪造这些头绕过限流。
         """
+        # 从配置获取可信代理层数（默认为 1，即信任最近一层代理）
+        trusted_proxy_count = getattr(config, "trusted_proxy_count", 1)
+
         # 优先从代理头获取真实 IP
         forwarded_for = request.headers.get("x-forwarded-for")
         if forwarded_for:
-            # X-Forwarded-For 可能包含多个 IP，取第一个
-            return forwarded_for.split(",")[0].strip()
+            # X-Forwarded-For 格式: "client, proxy1, proxy2"
+            # 从右往左数 trusted_proxy_count 个，取其左边的第一个
+            ips = [ip.strip() for ip in forwarded_for.split(",")]
+            if len(ips) > trusted_proxy_count:
+                return ips[-(trusted_proxy_count + 1)]
+            elif ips:
+                return ips[0]
 
         real_ip = request.headers.get("x-real-ip")
         if real_ip:
@@ -248,13 +261,11 @@ class PluginMiddleware(BaseHTTPMiddleware):
             auth_header = request.headers.get("authorization", "")
             api_key = request.headers.get("x-api-key", "")
 
-            if auth_header.startswith("Bearer "):
+            if auth_header.lower().startswith("bearer "):
                 api_key = auth_header[7:]
 
             if api_key:
                 # 使用 API Key 的哈希作为限制 key（避免日志泄露完整 key）
-                import hashlib
-
                 key_hash = hashlib.sha256(api_key.encode()).hexdigest()[:16]
                 key = f"llm_api_key:{key_hash}"
                 request.state.rate_limit_key_type = "api_key"
@@ -319,7 +330,10 @@ class PluginMiddleware(BaseHTTPMiddleware):
                     )
                 else:
                     # 限流触发，记录日志
-                    logger.warning(f"速率限制触发: {getattr(request.state, 'rate_limit_key_type', 'unknown')}")
+                    logger.warning(
+                        "速率限制触发: {}",
+                        getattr(request.state, "rate_limit_key_type", "unknown"),
+                    )
                 return result
             return None
         except Exception as e:
@@ -332,7 +346,7 @@ class PluginMiddleware(BaseHTTPMiddleware):
         pass
 
     async def _call_post_request_plugins(
-        self, request: Request, response: StarletteResponse, start_time: float
+        self, request: Request, status_code: int, start_time: float
     ) -> None:
         """调用请求后的插件"""
 
@@ -345,8 +359,8 @@ class PluginMiddleware(BaseHTTPMiddleware):
                 monitor_labels = {
                     "method": request.method,
                     "endpoint": request.url.path,
-                    "status": str(response.status_code),
-                    "status_class": f"{response.status_code // 100}xx",
+                    "status": str(status_code),
+                    "status_class": f"{status_code // 100}xx",
                 }
 
                 # 记录请求计数
@@ -368,6 +382,7 @@ class PluginMiddleware(BaseHTTPMiddleware):
         self, request: Request, error: Exception, start_time: float
     ) -> None:
         """调用错误处理插件"""
+        from fastapi import HTTPException
 
         duration = time.time() - start_time
 
@@ -380,7 +395,7 @@ class PluginMiddleware(BaseHTTPMiddleware):
                         error=error,
                         context={
                             "endpoint": f"{request.method} {request.url.path}",
-                            "request_id": request.state.request_id,
+                            "request_id": getattr(request.state, "request_id", ""),
                             "duration": duration,
                         },
                     )
diff --git a/src/plugins/auth/jwt.py b/src/plugins/auth/jwt.py
index f04eefc..1427e63 100644
--- a/src/plugins/auth/jwt.py
+++ b/src/plugins/auth/jwt.py
@@ -3,6 +3,7 @@ JWT认证插件
 支持JWT Bearer token认证
 """
 
+import hashlib
 from typing import Optional
 
 from fastapi import Request
@@ -46,8 +47,8 @@ class JwtAuthPlugin(AuthPlugin):
             logger.debug("未找到JWT token")
             return None
 
-        # 记录认证尝试的详细信息
-        logger.info(f"JWT认证尝试 - 路径: {request.url.path}, Token前20位: {token[:20]}...")
+        token_fingerprint = hashlib.sha256(token.encode()).hexdigest()[:12]
+        logger.info(f"JWT认证尝试 - 路径: {request.url.path}, token_fp={token_fingerprint}")
 
         try:
             # 验证JWT token
diff --git a/src/services/auth/jwt_blacklist.py b/src/services/auth/jwt_blacklist.py
index 54239cf..2015769 100644
--- a/src/services/auth/jwt_blacklist.py
+++ b/src/services/auth/jwt_blacklist.py
@@ -63,14 +63,16 @@ class JWTBlacklistService:
 
             if ttl_seconds <= 0:
                 # Token 已经过期，不需要加入黑名单
-                logger.debug(f"Token 已过期，无需加入黑名单: {token[:10]}...")
+                token_fp = JWTBlacklistService._get_token_hash(token)[:12]
+                logger.debug("Token 已过期，无需加入黑名单: token_fp={}", token_fp)
                 return True
 
             # 存储到 Redis，设置 TTL 为 Token 过期时间
             # 值存储为原因字符串
             await redis_client.setex(redis_key, ttl_seconds, reason)
 
-            logger.info(f"Token 已加入黑名单: {token[:10]}... (原因: {reason}, TTL: {ttl_seconds}s)")
+            token_fp = JWTBlacklistService._get_token_hash(token)[:12]
+            logger.info("Token 已加入黑名单: token_fp={} (原因: {}, TTL: {}s)", token_fp, reason, ttl_seconds)
             return True
 
         except Exception as e:
@@ -109,7 +111,8 @@ class JWTBlacklistService:
             if exists:
                 # 获取黑名单原因（可选）
                 reason = await redis_client.get(redis_key)
-                logger.warning(f"检测到黑名单 Token: {token[:10]}... (原因: {reason})")
+                token_fp = JWTBlacklistService._get_token_hash(token)[:12]
+                logger.warning("检测到黑名单 Token: token_fp={} (原因: {})", token_fp, reason)
                 return True
 
             return False
@@ -148,9 +151,11 @@ class JWTBlacklistService:
             deleted = await redis_client.delete(redis_key)
 
             if deleted:
-                logger.info(f"Token 已从黑名单移除: {token[:10]}...")
+                token_fp = JWTBlacklistService._get_token_hash(token)[:12]
+                logger.info("Token 已从黑名单移除: token_fp={}", token_fp)
             else:
-                logger.debug(f"Token 不在黑名单中: {token[:10]}...")
+                token_fp = JWTBlacklistService._get_token_hash(token)[:12]
+                logger.debug("Token 不在黑名单中: token_fp={}", token_fp)
 
             return bool(deleted)
 
diff --git a/src/services/auth/service.py b/src/services/auth/service.py
index ca6ea05..9eb04a0 100644
--- a/src/services/auth/service.py
+++ b/src/services/auth/service.py
@@ -3,6 +3,7 @@
 """
 
 import os
+import hashlib
 import secrets
 from datetime import datetime, timedelta, timezone
 from typing import Any, Dict, Optional
@@ -169,7 +170,8 @@ class AuthService:
         key_record.last_used_at = datetime.now(timezone.utc)
         db.commit()  # 立即提交事务,释放数据库锁,避免阻塞后续请求
 
-        logger.debug(f"API认证成功: 用户 {user.email} (Key: {api_key[:10]}...)")
+        api_key_fp = hashlib.sha256(api_key.encode()).hexdigest()[:12]
+        logger.debug("API认证成功: 用户 {} (api_key_fp={})", user.email, api_key_fp)
         return user, key_record
 
     @staticmethod
diff --git a/src/services/system/cleanup_scheduler.py b/src/services/system/cleanup_scheduler.py
index 0ecb7fd..647f429 100644
--- a/src/services/system/cleanup_scheduler.py
+++ b/src/services/system/cleanup_scheduler.py
@@ -21,7 +21,7 @@ from sqlalchemy.orm import Session
 
 from src.core.logger import logger
 from src.database import create_session
-from src.models.database import Usage
+from src.models.database import AuditLog, Usage
 from src.services.system.config import SystemConfigService
 from src.services.system.scheduler import get_scheduler
 from src.services.system.stats_aggregator import StatsAggregatorService
@@ -91,6 +91,15 @@ class CleanupScheduler:
             name="Pending状态清理",
         )
 
+        # 审计日志清理 - 凌晨 4 点执行
+        scheduler.add_cron_job(
+            self._scheduled_audit_cleanup,
+            hour=4,
+            minute=0,
+            job_id="audit_cleanup",
+            name="审计日志清理",
+        )
+
         # 启动时执行一次初始化任务
         asyncio.create_task(self._run_startup_tasks())
 
@@ -145,6 +154,10 @@ class CleanupScheduler:
         """Pending 清理任务（定时调用）"""
         await self._perform_pending_cleanup()
 
+    async def _scheduled_audit_cleanup(self):
+        """审计日志清理任务（定时调用）"""
+        await self._perform_audit_cleanup()
+
     # ========== 实际任务实现 ==========
 
     async def _perform_stats_aggregation(self, backfill: bool = False):
@@ -330,6 +343,70 @@ class CleanupScheduler:
         finally:
             db.close()
 
+    async def _perform_audit_cleanup(self):
+        """执行审计日志清理任务"""
+        db = create_session()
+        try:
+            # 检查是否启用自动清理
+            if not SystemConfigService.get_config(db, "enable_auto_cleanup", True):
+                logger.info("自动清理已禁用，跳过审计日志清理")
+                return
+
+            # 获取审计日志保留天数（默认 30 天，最少 7 天）
+            audit_retention_days = max(
+                SystemConfigService.get_config(db, "audit_log_retention_days", 30),
+                7,  # 最少保留 7 天，防止误配置删除所有审计日志
+            )
+            batch_size = SystemConfigService.get_config(db, "cleanup_batch_size", 1000)
+
+            cutoff_time = datetime.now(timezone.utc) - timedelta(days=audit_retention_days)
+
+            logger.info(f"开始清理 {audit_retention_days} 天前的审计日志...")
+
+            total_deleted = 0
+            while True:
+                # 先查询要删除的记录 ID（分批）
+                records_to_delete = (
+                    db.query(AuditLog.id)
+                    .filter(AuditLog.created_at < cutoff_time)
+                    .limit(batch_size)
+                    .all()
+                )
+
+                if not records_to_delete:
+                    break
+
+                record_ids = [r.id for r in records_to_delete]
+
+                # 执行删除
+                result = db.execute(
+                    delete(AuditLog)
+                    .where(AuditLog.id.in_(record_ids))
+                    .execution_options(synchronize_session=False)
+                )
+
+                rows_deleted = result.rowcount
+                db.commit()
+
+                total_deleted += rows_deleted
+                logger.debug(f"已删除 {rows_deleted} 条审计日志，累计 {total_deleted} 条")
+
+                await asyncio.sleep(0.1)
+
+            if total_deleted > 0:
+                logger.info(f"审计日志清理完成，共删除 {total_deleted} 条记录")
+            else:
+                logger.info("无需清理的审计日志")
+
+        except Exception as e:
+            logger.exception(f"审计日志清理失败: {e}")
+            try:
+                db.rollback()
+            except Exception:
+                pass
+        finally:
+            db.close()
+
     async def _perform_cleanup(self):
         """执行清理任务"""
         db = create_session()
diff --git a/src/services/usage/service.py b/src/services/usage/service.py
index 0cbd236..4f62e5c 100644
--- a/src/services/usage/service.py
+++ b/src/services/usage/service.py
@@ -1217,15 +1217,19 @@ class UsageService:
         request_id: str,
         status: str,
         error_message: Optional[str] = None,
+        provider: Optional[str] = None,
+        target_model: Optional[str] = None,
     ) -> Optional[Usage]:
         """
-        快速更新使用记录状态（不更新其他字段）
+        快速更新使用记录状态
 
         Args:
             db: 数据库会话
             request_id: 请求ID
             status: 新状态 (pending, streaming, completed, failed)
             error_message: 错误消息（仅在 failed 状态时使用）
+            provider: 提供商名称（可选，streaming 状态时更新）
+            target_model: 映射后的目标模型名（可选）
 
         Returns:
             更新后的 Usage 记录，如果未找到则返回 None
@@ -1239,6 +1243,10 @@ class UsageService:
         usage.status = status
         if error_message:
             usage.error_message = error_message
+        if provider:
+            usage.provider = provider
+        if target_model:
+            usage.target_model = target_model
 
         db.commit()
 
diff --git a/src/services/usage/stream.py b/src/services/usage/stream.py
index f922d08..68e10ef 100644
--- a/src/services/usage/stream.py
+++ b/src/services/usage/stream.py
@@ -457,7 +457,7 @@ class StreamUsageTracker:
 
         logger.debug(f"ID:{self.request_id} | 开始跟踪流式响应 | 估算输入tokens:{self.input_tokens}")
 
-        # 更新状态为 streaming
+        # 更新状态为 streaming，同时更新 provider
         if self.request_id:
             try:
                 from src.services.usage.service import UsageService
@@ -465,6 +465,7 @@ class StreamUsageTracker:
                     db=self.db,
                     request_id=self.request_id,
                     status="streaming",
+                    provider=self.provider,
                 )
             except Exception as e:
                 logger.warning(f"更新使用记录状态为 streaming 失败: {e}")
diff --git a/src/services/user/apikey.py b/src/services/user/apikey.py
index d6220aa..87fabc2 100644
--- a/src/services/user/apikey.py
+++ b/src/services/user/apikey.py
@@ -210,7 +210,15 @@ class ApiKeyService:
 
     @staticmethod
     def check_rate_limit(db: Session, api_key: ApiKey, window_minutes: int = 1) -> tuple[bool, int]:
-        """检查速率限制"""
+        """检查速率限制
+
+        Returns:
+            (is_allowed, remaining): 是否允许请求，剩余可用次数
+            当 rate_limit 为 None 时表示不限制，返回 (True, -1)
+        """
+        # 如果 rate_limit 为 None，表示不限制
+        if api_key.rate_limit is None:
+            return True, -1  # -1 表示无限制
 
         # 计算时间窗口
         window_start = datetime.now(timezone.utc) - timedelta(minutes=window_minutes)
diff --git a/src/utils/auth_utils.py b/src/utils/auth_utils.py
index 57c07c0..715e18a 100644
--- a/src/utils/auth_utils.py
+++ b/src/utils/auth_utils.py
@@ -3,6 +3,7 @@
 提供统一的用户认证和授权功能
 """
 
+import hashlib
 from typing import Optional
 
 from fastapi import Depends, Header, HTTPException, status
@@ -44,10 +45,17 @@ async def get_current_user(
             payload = await AuthService.verify_token(token, token_type="access")
         except HTTPException as token_error:
             # 保持原始的HTTP状态码（如401 Unauthorized），不要转换为403
-            logger.error(f"Token验证失败: {token_error.status_code}: {token_error.detail}, Token前10位: {token[:10]}...")
+            token_fp = hashlib.sha256(token.encode()).hexdigest()[:12]
+            logger.error(
+                "Token验证失败: {}: {}, token_fp={}",
+                token_error.status_code,
+                token_error.detail,
+                token_fp,
+            )
             raise  # 重新抛出原始异常，保持状态码
         except Exception as token_error:
-            logger.error(f"Token验证失败: {token_error}, Token前10位: {token[:10]}...")
+            token_fp = hashlib.sha256(token.encode()).hexdigest()[:12]
+            logger.error("Token验证失败: {}, token_fp={}", token_error, token_fp)
             raise ForbiddenException("无效的Token")
 
         user_id = payload.get("user_id")
@@ -63,7 +71,8 @@ async def get_current_user(
             raise ForbiddenException("无效的认证凭据")
 
         # 仅在DEBUG模式下记录详细信息
-        logger.debug(f"尝试获取用户: user_id={user_id}, token前10位: {token[:10]}...")
+        token_fp = hashlib.sha256(token.encode()).hexdigest()[:12]
+        logger.debug("尝试获取用户: user_id={}, token_fp={}", user_id, token_fp)
 
         # 确保user_id是字符串格式（UUID）
         if not isinstance(user_id, str):
diff --git a/src/utils/request_utils.py b/src/utils/request_utils.py
index 931b766..4aaeebe 100644
--- a/src/utils/request_utils.py
+++ b/src/utils/request_utils.py
@@ -7,29 +7,47 @@ from typing import Optional
 
 from fastapi import Request
 
+from src.config import config
+
 
 def get_client_ip(request: Request) -> str:
     """
     获取客户端真实IP地址
 
     按优先级检查：
-    1. X-Forwarded-For 头（支持代理链）
+    1. X-Forwarded-For 头（支持代理链，根据可信代理数量提取）
     2. X-Real-IP 头（Nginx 代理）
     3. 直接客户端IP
 
+    安全说明：
+    - 此函数根据 TRUSTED_PROXY_COUNT 配置来决定信任的代理层数
+    - 当 TRUSTED_PROXY_COUNT=0 时，不信任任何代理头，直接使用连接 IP
+    - 当服务直接暴露公网时，应设置 TRUSTED_PROXY_COUNT=0 以防止 IP 伪造
+
     Args:
         request: FastAPI Request 对象
 
     Returns:
         str: 客户端IP地址，如果无法获取则返回 "unknown"
     """
+    trusted_proxy_count = config.trusted_proxy_count
+
+    # 如果不信任任何代理，直接返回连接 IP
+    if trusted_proxy_count == 0:
+        if request.client and request.client.host:
+            return request.client.host
+        return "unknown"
+
     # 优先检查 X-Forwarded-For 头（可能包含代理链）
     forwarded_for = request.headers.get("X-Forwarded-For")
     if forwarded_for:
-        # X-Forwarded-For 格式: "client, proxy1, proxy2"，取第一个（真实客户端）
-        client_ip = forwarded_for.split(",")[0].strip()
-        if client_ip:
-            return client_ip
+        # X-Forwarded-For 格式: "client, proxy1, proxy2"
+        # 从右往左数 trusted_proxy_count 个，取其左边的第一个
+        ips = [ip.strip() for ip in forwarded_for.split(",") if ip.strip()]
+        if len(ips) > trusted_proxy_count:
+            return ips[-(trusted_proxy_count + 1)]
+        elif ips:
+            return ips[0]
 
     # 检查 X-Real-IP 头（通常由 Nginx 设置）
     real_ip = request.headers.get("X-Real-IP")
@@ -91,20 +109,32 @@ def get_request_metadata(request: Request) -> dict:
     }
 
 
-def extract_ip_from_headers(headers: dict) -> str:
+def extract_ip_from_headers(headers: dict, trusted_proxy_count: Optional[int] = None) -> str:
     """
     从HTTP头字典中提取IP地址（用于中间件等场景）
 
     Args:
         headers: HTTP头字典
+        trusted_proxy_count: 可信代理层数，None 时使用配置值
 
     Returns:
         str: 客户端IP地址
     """
+    if trusted_proxy_count is None:
+        trusted_proxy_count = config.trusted_proxy_count
+
+    # 如果不信任任何代理，返回 unknown（调用方需要用其他方式获取连接 IP）
+    if trusted_proxy_count == 0:
+        return "unknown"
+
     # 检查 X-Forwarded-For
     forwarded_for = headers.get("x-forwarded-for", "")
     if forwarded_for:
-        return forwarded_for.split(",")[0].strip()
+        ips = [ip.strip() for ip in forwarded_for.split(",") if ip.strip()]
+        if len(ips) > trusted_proxy_count:
+            return ips[-(trusted_proxy_count + 1)]
+        elif ips:
+            return ips[0]
 
     # 检查 X-Real-IP
     real_ip = headers.get("x-real-ip", "")
diff --git a/tests/api/test_pipeline.py b/tests/api/test_pipeline.py
index 8e9afb8..9ffab60 100644
--- a/tests/api/test_pipeline.py
+++ b/tests/api/test_pipeline.py
@@ -361,3 +361,61 @@ class TestPipelineAdminAuth:
 
         assert result == mock_user
         assert mock_request.state.user_id == "admin-123"
+
+    @pytest.mark.asyncio
+    async def test_authenticate_admin_lowercase_bearer(self, pipeline: ApiRequestPipeline) -> None:
+        """测试 bearer (小写) 前缀也能正确解析"""
+        mock_user = MagicMock()
+        mock_user.id = "admin-123"
+        mock_user.is_active = True
+
+        mock_request = MagicMock()
+        mock_request.headers = {"authorization": "bearer valid-token"}
+        mock_request.state = MagicMock()
+
+        mock_db = MagicMock()
+        mock_db.query.return_value.filter.return_value.first.return_value = mock_user
+
+        with patch.object(
+            pipeline.auth_service,
+            "verify_token",
+            new_callable=AsyncMock,
+            return_value={"user_id": "admin-123"},
+        ) as mock_verify:
+            result = await pipeline._authenticate_admin(mock_request, mock_db)
+
+        mock_verify.assert_awaited_once_with("valid-token", token_type="access")
+        assert result == mock_user
+
+
+class TestPipelineUserAuth:
+    """测试普通用户 JWT 认证"""
+
+    @pytest.fixture
+    def pipeline(self) -> ApiRequestPipeline:
+        return ApiRequestPipeline()
+
+    @pytest.mark.asyncio
+    async def test_authenticate_user_lowercase_bearer(self, pipeline: ApiRequestPipeline) -> None:
+        """测试 bearer (小写) 前缀也能正确解析"""
+        mock_user = MagicMock()
+        mock_user.id = "user-123"
+        mock_user.is_active = True
+
+        mock_request = MagicMock()
+        mock_request.headers = {"authorization": "bearer valid-token"}
+        mock_request.state = MagicMock()
+
+        mock_db = MagicMock()
+        mock_db.query.return_value.filter.return_value.first.return_value = mock_user
+
+        with patch.object(
+            pipeline.auth_service,
+            "verify_token",
+            new_callable=AsyncMock,
+            return_value={"user_id": "user-123"},
+        ) as mock_verify:
+            result = await pipeline._authenticate_user(mock_request, mock_db)
+
+        mock_verify.assert_awaited_once_with("valid-token", token_type="access")
+        assert result == mock_user