feat(gateway): 实现负载感知的账号调度优化

- 新增调度配置：粘性会话排队、兜底排队、负载计算、槽位清理
- 实现账号级等待队列和批量负载查询（Redis Lua 脚本）
- 三层选择策略：粘性会话优先 → 负载感知选择 → 兜底排队
- 后台定期清理过期槽位，防止资源泄漏
- 集成到所有网关处理器（Claude/Gemini/OpenAI）

backend/internal/config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"fmt"
 	"strings"
+	"time"
 
 	"github.com/spf13/viper"
 )
@@ -119,6 +120,26 @@ type GatewayConfig struct {
 	// ConcurrencySlotTTLMinutes: 并发槽位过期时间（分钟）
 	// 应大于最长 LLM 请求时间，防止请求完成前槽位过期
 	ConcurrencySlotTTLMinutes int `mapstructure:"concurrency_slot_ttl_minutes"`
+
+	// Scheduling: 账号调度相关配置
+	Scheduling GatewaySchedulingConfig `mapstructure:"scheduling"`
+}
+
+// GatewaySchedulingConfig accounts scheduling configuration.
+type GatewaySchedulingConfig struct {
+	// 粘性会话排队配置
+	StickySessionMaxWaiting  int           `mapstructure:"sticky_session_max_waiting"`
+	StickySessionWaitTimeout time.Duration `mapstructure:"sticky_session_wait_timeout"`
+
+	// 兜底排队配置
+	FallbackWaitTimeout time.Duration `mapstructure:"fallback_wait_timeout"`
+	FallbackMaxWaiting  int           `mapstructure:"fallback_max_waiting"`
+
+	// 负载计算
+	LoadBatchEnabled bool `mapstructure:"load_batch_enabled"`
+
+	// 过期槽位清理周期（0 表示禁用）
+	SlotCleanupInterval time.Duration `mapstructure:"slot_cleanup_interval"`
 }
 
 func (s *ServerConfig) Address() string {
@@ -323,6 +344,12 @@ func setDefaults() {
 	viper.SetDefault("gateway.max_upstream_clients", 5000)
 	viper.SetDefault("gateway.client_idle_ttl_seconds", 900)
 	viper.SetDefault("gateway.concurrency_slot_ttl_minutes", 15) // 并发槽位过期时间（支持超长请求）
+	viper.SetDefault("gateway.scheduling.sticky_session_max_waiting", 3)
+	viper.SetDefault("gateway.scheduling.sticky_session_wait_timeout", 45*time.Second)
+	viper.SetDefault("gateway.scheduling.fallback_wait_timeout", 30*time.Second)
+	viper.SetDefault("gateway.scheduling.fallback_max_waiting", 100)
+	viper.SetDefault("gateway.scheduling.load_batch_enabled", true)
+	viper.SetDefault("gateway.scheduling.slot_cleanup_interval", 30*time.Second)
 
 	// TokenRefresh
 	viper.SetDefault("token_refresh.enabled", true)
@@ -411,6 +438,21 @@ func (c *Config) Validate() error {
 	if c.Gateway.ConcurrencySlotTTLMinutes <= 0 {
 		return fmt.Errorf("gateway.concurrency_slot_ttl_minutes must be positive")
 	}
+	if c.Gateway.Scheduling.StickySessionMaxWaiting <= 0 {
+		return fmt.Errorf("gateway.scheduling.sticky_session_max_waiting must be positive")
+	}
+	if c.Gateway.Scheduling.StickySessionWaitTimeout <= 0 {
+		return fmt.Errorf("gateway.scheduling.sticky_session_wait_timeout must be positive")
+	}
+	if c.Gateway.Scheduling.FallbackWaitTimeout <= 0 {
+		return fmt.Errorf("gateway.scheduling.fallback_wait_timeout must be positive")
+	}
+	if c.Gateway.Scheduling.FallbackMaxWaiting <= 0 {
+		return fmt.Errorf("gateway.scheduling.fallback_max_waiting must be positive")
+	}
+	if c.Gateway.Scheduling.SlotCleanupInterval < 0 {
+		return fmt.Errorf("gateway.scheduling.slot_cleanup_interval must be non-negative")
+	}
 	return nil
 }
 

backend/internal/config/config_test.go

@@ -1,6 +1,11 @@
 package config
 
-import "testing"
+import (
+	"testing"
+	"time"
+
+	"github.com/spf13/viper"
+)
 
 func TestNormalizeRunMode(t *testing.T) {
 	tests := []struct {
@@ -21,3 +26,45 @@ func TestNormalizeRunMode(t *testing.T) {
 		}
 	}
 }
+
+func TestLoadDefaultSchedulingConfig(t *testing.T) {
+	viper.Reset()
+
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("Load() error: %v", err)
+	}
+
+	if cfg.Gateway.Scheduling.StickySessionMaxWaiting != 3 {
+		t.Fatalf("StickySessionMaxWaiting = %d, want 3", cfg.Gateway.Scheduling.StickySessionMaxWaiting)
+	}
+	if cfg.Gateway.Scheduling.StickySessionWaitTimeout != 45*time.Second {
+		t.Fatalf("StickySessionWaitTimeout = %v, want 45s", cfg.Gateway.Scheduling.StickySessionWaitTimeout)
+	}
+	if cfg.Gateway.Scheduling.FallbackWaitTimeout != 30*time.Second {
+		t.Fatalf("FallbackWaitTimeout = %v, want 30s", cfg.Gateway.Scheduling.FallbackWaitTimeout)
+	}
+	if cfg.Gateway.Scheduling.FallbackMaxWaiting != 100 {
+		t.Fatalf("FallbackMaxWaiting = %d, want 100", cfg.Gateway.Scheduling.FallbackMaxWaiting)
+	}
+	if !cfg.Gateway.Scheduling.LoadBatchEnabled {
+		t.Fatalf("LoadBatchEnabled = false, want true")
+	}
+	if cfg.Gateway.Scheduling.SlotCleanupInterval != 30*time.Second {
+		t.Fatalf("SlotCleanupInterval = %v, want 30s", cfg.Gateway.Scheduling.SlotCleanupInterval)
+	}
+}
+
+func TestLoadSchedulingConfigFromEnv(t *testing.T) {
+	viper.Reset()
+	t.Setenv("GATEWAY_SCHEDULING_STICKY_SESSION_MAX_WAITING", "5")
+
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("Load() error: %v", err)
+	}
+
+	if cfg.Gateway.Scheduling.StickySessionMaxWaiting != 5 {
+		t.Fatalf("StickySessionMaxWaiting = %d, want 5", cfg.Gateway.Scheduling.StickySessionMaxWaiting)
+	}
+}