diff --git a/theme/src/index.ts b/theme/src/index.ts
index 8a26324..79a5f71 100644
--- a/theme/src/index.ts
+++ b/theme/src/index.ts
@@ -76,7 +76,6 @@ export type {
   SelectableCardProps,
   StatusTextProps,
   UsageRecordSurfaceProps,
-  UsageServiceTierFastResolver,
 } from './plugin.js';
 
 // 插件前端 SDK：样式注入、主题同步、Tailwind bridge 和公共组件
diff --git a/theme/src/plugin.tsx b/theme/src/plugin.tsx
index a01a8ad..1e5e250 100644
--- a/theme/src/plugin.tsx
+++ b/theme/src/plugin.tsx
@@ -123,14 +123,6 @@ export interface UsageRecordSurfaceProps {
   context?: Record<string, unknown>;
 }
 
-/**
- * 平台插件自行判断某条 usage 的 service_tier 是否应展示为 fast。
- *
- * 不同上游平台可能使用不同字段值表达 fast/priority/flex 等服务层级，
- * Core 只负责调用该函数并套用统一 fast 样式，不内置平台语义。
- */
-export type UsageServiceTierFastResolver = (context?: Record<string, unknown>) => boolean;
-
 export interface PluginFrontendModule {
   routes?: PluginRouteDefinition[];
   menuItems?: PluginMenuItemDefinition[];
@@ -145,7 +137,6 @@ export interface PluginFrontendModule {
    * Core 只提供表格骨架与回退渲染，不内置平台语义。
    */
   usageModelMeta?: ComponentType<UsageRecordSurfaceProps>;
-  isUsageServiceTierFast?: UsageServiceTierFastResolver;
   usageMetricDetail?: ComponentType<UsageRecordSurfaceProps>;
   usageCostDetail?: ComponentType<UsageRecordSurfaceProps>;
   platformIcon?: ComponentType<PluginPlatformIconProps>;