fix(gateway): harden digest logging and align antigravity ops

- avoid panic by using safe UUID prefix truncation in Gemini digest fallback logs\n- remove unconditional Antigravity 429 full-body debug logs and honor log truncation config\n- align Antigravity quick preset mappings to opus 4.6-thinking targets only\n- restore scope rate-limit aggregation/output in ops availability stats

backend/internal/service/antigravity_gateway_service.go

@@ -1950,11 +1950,6 @@ func parseAntigravitySmartRetryInfo(body []byte) *antigravitySmartRetryInfo {
 	isResourceExhausted := status == googleRPCStatusResourceExhausted
 	isUnavailable := status == googleRPCStatusUnavailable
 
-	// 调试日志：打印 RESOURCE_EXHAUSTED 的完整响应
-	if isResourceExhausted {
-		log.Printf("[Antigravity-Debug] 429 RESOURCE_EXHAUSTED full body: %s", string(body))
-	}
-
 	if !isResourceExhausted && !isUnavailable {
 		return nil
 	}
@@ -2208,8 +2203,10 @@ func (s *AntigravityGatewayService) handleUpstreamError(
 	// ========== 原有逻辑，保持不变 ==========
 	// 429 使用 Gemini 格式解析（从 body 解析重置时间）
 	if statusCode == 429 {
-		// 调试日志：打印 429 响应的完整 body
-		log.Printf("[Antigravity-Debug] 429 response full body: %s", string(body))
+		// 调试日志遵循统一日志开关与长度限制，避免无条件记录完整上游响应体。
+		if logBody, maxBytes := s.getLogConfig(); logBody {
+			log.Printf("[Antigravity-Debug] 429 response body: %s", truncateString(string(body), maxBytes))
+		}
 
 		useScopeLimit := quotaScope != ""
 		resetAt := ParseGeminiRateLimitResetTime(body)