fix: add missing test coverage for Task 4 config integration

- Add validation tests for least_time and sticky configs
- Add algorithm tests for least_time and sticky
- Add SameSite validation in validateProxy

internal/config/validate.go

@@ -519,6 +519,12 @@ func validateProxy(p *ProxyConfig) error {
 		if p.Sticky.FallbackAlgo != "" && !loadbalance.IsValidAlgorithm(p.Sticky.FallbackAlgo) {
 			return fmt.Errorf("无效的 sticky fallback_balance: %s", p.Sticky.FallbackAlgo)
 		}
+		if p.Sticky.SameSite != "" {
+			validSameSites := []string{"Lax", "Strict", "None"}
+			if !slices.Contains(validSameSites, p.Sticky.SameSite) {
+				return fmt.Errorf("无效的 sticky same_site: %s（有效值: Lax, Strict, None）", p.Sticky.SameSite)
+			}
+		}
 	}
 
 	// 验证故障转移配置

internal/config/validate_test.go

@@ -170,6 +170,80 @@ func TestValidateProxy(t *testing.T) {
 			wantErr: true,
 			errMsg:  "无效的负载均衡算法",
 		},
+		{
+			name: "有效 least_time 配置 metric=header",
+			config: ProxyConfig{
+				Path:        "/api",
+				Targets:     []ProxyTarget{{URL: "http://backend:8080"}},
+				LoadBalance: "least_time",
+				LeastTime:   LeastTimeConfig{Metric: "header"},
+			},
+			wantErr: false,
+		},
+		{
+			name: "有效 least_time 配置 metric=last_byte",
+			config: ProxyConfig{
+				Path:        "/api",
+				Targets:     []ProxyTarget{{URL: "http://backend:8080"}},
+				LoadBalance: "least_time",
+				LeastTime:   LeastTimeConfig{Metric: "last_byte"},
+			},
+			wantErr: false,
+		},
+		{
+			name: "无效 least_time metric",
+			config: ProxyConfig{
+				Path:        "/api",
+				Targets:     []ProxyTarget{{URL: "http://backend:8080"}},
+				LoadBalance: "least_time",
+				LeastTime:   LeastTimeConfig{Metric: "invalid"},
+			},
+			wantErr: true,
+			errMsg:  "无效的 least_time metric",
+		},
+		{
+			name: "有效 sticky 配置",
+			config: ProxyConfig{
+				Path:        "/api",
+				Targets:     []ProxyTarget{{URL: "http://backend:8080"}},
+				LoadBalance: "sticky",
+				Sticky:      StickyConfig{Enabled: true, FallbackAlgo: "round_robin"},
+			},
+			wantErr: false,
+		},
+		{
+			name: "无效 sticky enabled=false",
+			config: ProxyConfig{
+				Path:        "/api",
+				Targets:     []ProxyTarget{{URL: "http://backend:8080"}},
+				LoadBalance: "sticky",
+				Sticky:      StickyConfig{Enabled: false},
+			},
+			wantErr: true,
+			errMsg:  "sticky.enabled 必须为 true",
+		},
+		{
+			name: "无效 sticky fallback_balance",
+			config: ProxyConfig{
+				Path:        "/api",
+				Targets:     []ProxyTarget{{URL: "http://backend:8080"}},
+				LoadBalance: "sticky",
+				Sticky:      StickyConfig{Enabled: true, FallbackAlgo: "invalid"},
+			},
+			wantErr: true,
+			errMsg:  "无效的 sticky fallback_balance",
+		},
+		{
+			name: "无效 sticky same_site",
+			config: ProxyConfig{
+				Path:        "/api",
+				Targets:     []ProxyTarget{{URL: "http://backend:8080"}},
+				LoadBalance: "sticky",
+				Sticky:      StickyConfig{Enabled: true, SameSite: "Invalid"},
+			},
+			wantErr: true,
+			errMsg:  "无效的 sticky same_site",
+		},
 	}
 
 	for _, tt := range tests {

internal/loadbalance/balancer_test.go

@@ -940,6 +940,8 @@ func TestIsValidAlgorithm(t *testing.T) {
 		{"ip_hash", "ip_hash", true},
 		{"consistent_hash", "consistent_hash", true},
 		{"random", "random", true},
+		{"least_time", "least_time", true},
+		{"sticky", "sticky", true},
 		{"invalid", "invalid", false},
 		{"empty", "", true}, // 空字符串有效（使用默认值）
 		{"unknown", "unknown-algorithm", false},