feat: 使用量轮询接口添加 API 格式转换字段

- 前端：添加 api_format、endpoint_api_format、has_format_conversion 类型定义
- 前端：轮询时同步更新格式转换相关字段
- 后端：查询时返回格式转换字段，包含历史数据兼容逻辑
- 后端：优化 import 位置提升性能

frontend/src/api/me.ts

@@ -223,6 +223,9 @@ export const meApi = {
       rate_multiplier?: number | null
       response_time_ms: number | null
       first_byte_time_ms: number | null
+      api_format?: string | null
+      endpoint_api_format?: string | null
+      has_format_conversion?: boolean | null
     }>
   }> {
     const params = ids ? { ids } : {}

frontend/src/api/usage.ts

@@ -201,6 +201,9 @@ export const usageApi = {
       first_byte_time_ms: number | null
       provider?: string | null
       api_key_name?: string | null
+      api_format?: string | null
+      endpoint_api_format?: string | null
+      has_format_conversion?: boolean | null
     }>
   }> {
     const params = ids?.length ? { ids: ids.join(',') } : {}

frontend/src/views/shared/Usage.vue

@@ -290,6 +290,10 @@ async function pollActiveRequests() {
       record.rate_multiplier = update.rate_multiplier ?? undefined
       record.response_time_ms = update.response_time_ms ?? undefined
       record.first_byte_time_ms = update.first_byte_time_ms ?? undefined
+      // API 格式/格式转换：streaming 时已可确定，轮询时同步更新
+      if (update.api_format !== undefined) record.api_format = update.api_format
+      if (update.endpoint_api_format !== undefined) record.endpoint_api_format = update.endpoint_api_format
+      if (update.has_format_conversion !== undefined) record.has_format_conversion = update.has_format_conversion
       // 管理员接口返回额外字段
       if ('provider' in update && typeof update.provider === 'string') {
         record.provider = update.provider

src/services/usage/service.py

@@ -10,6 +10,7 @@ from typing import Any, Dict, List, Optional, Tuple
 from sqlalchemy import func
 from sqlalchemy.orm import Session
 
+from src.core.api_format.metadata import can_passthrough
 from src.core.logger import logger
 from src.models.database import ApiKey, Provider, ProviderAPIKey, Usage, User, UserRole
 from src.services.model.cost import ModelCostService
@@ -1959,6 +1960,10 @@ class UsageService:
             Usage.first_byte_time_ms,  # 首字时间 (TTFB)
             Usage.created_at,
             Usage.provider_endpoint_id,
+            # API 格式 / 格式转换（streaming 状态时已可确定）
+            Usage.api_format,
+            Usage.endpoint_api_format,
+            Usage.has_format_conversion,
         )
 
         # 管理员轮询：可附带 provider 与上游 key 名称（注意：不要在普通用户接口暴露上游 key 信息）
@@ -2008,6 +2013,18 @@ class UsageService:
 
         result: List[Dict[str, Any]] = []
         for r in records:
+            api_format = getattr(r, "api_format", None)
+            endpoint_api_format = getattr(r, "endpoint_api_format", None)
+            has_format_conversion = getattr(r, "has_format_conversion", None)
+
+            # 兼容历史数据：当 streaming 状态已拿到两个格式但 has_format_conversion 为空时，回填推断结果
+            if (
+                has_format_conversion is None
+                and api_format
+                and endpoint_api_format
+            ):
+                has_format_conversion = not can_passthrough(api_format, endpoint_api_format)
+
             item: Dict[str, Any] = {
                 "id": r.id,
                 "status": "failed" if r.id in timeout_ids else r.status,
@@ -2021,6 +2038,12 @@ class UsageService:
                 "response_time_ms": r.response_time_ms,
                 "first_byte_time_ms": r.first_byte_time_ms,  # 首字时间 (TTFB)
             }
+            if api_format:
+                item["api_format"] = api_format
+            if endpoint_api_format:
+                item["endpoint_api_format"] = endpoint_api_format
+            if has_format_conversion is not None:
+                item["has_format_conversion"] = bool(has_format_conversion)
             if include_admin_fields:
                 item["provider"] = r.provider_name
                 item["api_key_name"] = r.api_key_name