# 429 请求过多 — 响应中缺少速率限制头

- **ID:** `api/rest-api-rate-limit-header-missing`
- **领域:** api
- **类别:** resource_error
- **验证级别:** ai_generated
- **修复率:** 75%

## 根因

API 服务器强制执行速率限制，但未包含标准头部（如 X-RateLimit-Remaining 或 Retry-After），导致客户端无法进行退避。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| REST API v2.1 | active | — | — |
| nginx rate limiting module v1.24 | active | — | — |
| AWS API Gateway v2 | active | — | — |

## 解决方案

1. ```
   Implement a fixed delay between requests (e.g., 1 second) to stay under the rate limit.
   ```
2. ```
   Use a token bucket algorithm client-side to self-throttle.
   ```

## 无效尝试

- **** — Without Retry-After, the client may back off too long or too short, leading to wasted time or continued throttling. (60% 失败率)
- **** — The issue is missing headers, not the limit value; increasing limit may not fix the client's inability to adapt. (70% 失败率)
- **** — Many APIs do not include retry info in the body; relying on it is fragile and non-standard. (80% 失败率)