feat: 十轮网关优化 - 安全加固/可观测性/性能/可靠性

- SSE Keepalive Ping (15s心跳防止代理断连)
- Timing HTTP 头 (X-Timing-Queue/Inference/Total-Ms)
- Adapter Request-ID 传播到后端
- Session 清理日志回调
- Server 安全加固 (ReadHeaderTimeout/MaxHeaderBytes 防 slowloris)
- Usage Tracker 数据保留清理 (retentionDays + 定期清理)
- Config Reload 后 Adapter Registry 更新 (RegisterIfAbsent + RWMutex)
- Rate Limiter 空闲 Bucket 清理 (30分钟过期)
- Shutdown Drain 超时可配置 (ShutdownDrainSeconds)
- Config 模型字段校验增强 (provider/endpoint/actual_model)
- Auth 过期 Key 自动清理 (5分钟扫描)
- Admin API Rate Limiting
- Adapter Health Check 独立超时 (每个 adapter 3s)
- TCP 连接阶段超时 (DialContext 5s + KeepAlive 30s)
- 幂等键缓存、审计日志、Gzip 中间件、CORS Expose Headers
- Backpressure 响应头、熔断器 Prometheus 指标
- 连接池优化、Trace-ID 全链路传播

internal/adapter/adapter.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"sync"
 
 	"github.com/edgeai/gateway/pkg/api"
 )
@@ -31,33 +32,33 @@ type ModelAdapter interface {
 
 // ChatRequest is the internal request sent to an adapter.
 type ChatRequest struct {
-	RequestID     string
-	Model         string // actual model name
-	Messages      []api.Message
-	MaxTokens     int
-	Temperature   *float64
-	TopP          *float64
-	Stream        bool
-	CancelCh      <-chan struct{}
+	RequestID   string
+	Model       string // actual model name
+	Messages    []api.Message
+	MaxTokens   int
+	Temperature *float64
+	TopP        *float64
+	Stream      bool
+	CancelCh    <-chan struct{}
 }
 
 // ChatResponse is the internal response from an adapter.
 type ChatResponse struct {
-	Content       string
-	FinishReason  string
-	InputTokens   int
-	OutputTokens  int
-	ActualModel   string
+	Content      string
+	FinishReason string
+	InputTokens  int
+	OutputTokens int
+	ActualModel  string
 }
 
 // StreamChunk represents a single chunk in a streaming response.
 type StreamChunk struct {
-	Delta         string
-	FinishReason  string
-	InputTokens   int
-	OutputTokens  int
-	Error         error
-	Done          bool
+	Delta        string
+	FinishReason string
+	InputTokens  int
+	OutputTokens int
+	Error        error
+	Done         bool
 }
 
 // ModelInfo describes a model available in the engine.
@@ -68,6 +69,7 @@ type ModelInfo struct {
 
 // Registry manages model adapters by provider name.
 type Registry struct {
+	mu       sync.RWMutex
 	adapters map[string]ModelAdapter
 }
 
@@ -75,11 +77,29 @@ func NewRegistry() *Registry {
 	return &Registry{adapters: make(map[string]ModelAdapter)}
 }
 
+// Register 注册一个 adapter，如果同名 adapter 已存在则覆盖。
 func (r *Registry) Register(name string, adapter ModelAdapter) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
 	r.adapters[name] = adapter
 }
 
+// RegisterIfAbsent 注册一个 adapter，仅当该 provider 尚未注册时才创建。
+// 返回 true 表示新注册，false 表示已存在。
+func (r *Registry) RegisterIfAbsent(name string, factory func() ModelAdapter) bool {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if _, exists := r.adapters[name]; exists {
+		return false
+	}
+	r.adapters[name] = factory()
+	return true
+}
+
+// Get 返回指定名称的 adapter。
 func (r *Registry) Get(name string) (ModelAdapter, error) {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
 	a, ok := r.adapters[name]
 	if !ok {
 		return nil, fmt.Errorf("adapter not found: %s", name)
@@ -87,7 +107,10 @@ func (r *Registry) Get(name string) (ModelAdapter, error) {
 	return a, nil
 }
 
+// Names 返回所有已注册 adapter 的名称列表。
 func (r *Registry) Names() []string {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
 	names := make([]string, 0, len(r.adapters))
 	for n := range r.adapters {
 		names = append(names, n)