diff --git a/src/components/AgentTracker.tsx b/src/components/AgentTracker.tsx
index 232a388..2821edf 100644
--- a/src/components/AgentTracker.tsx
+++ b/src/components/AgentTracker.tsx
@@ -78,7 +78,10 @@ export function AgentTracker() {
 
 function UsageBadge({ usage }: { usage?: Usage | null }) {
   if (!usage) return null
-  return <span className="effect-badge" title="token 用量与时长">
-    {usage.totalTokens > 0 ? `${usage.totalTokens} tok · ` : ''}{(usage.durationMs / 1000).toFixed(1)}s{usage.toolCalls > 0 ? ` · ${usage.toolCalls} 工具` : ''}
+  // N3 计费拆分：有上一请求数据时显示「+最近 · 累计（含缓存命中）」。
+  const last = (usage.lastPromptTokens ?? 0) + (usage.lastCompletionTokens ?? 0)
+  const cache = usage.cacheReadTokens ?? 0
+  return <span className="effect-badge" title={cache > 0 ? `token 用量与时长（缓存命中 ${cache}）` : 'token 用量与时长'}>
+    {last > 0 ? `+${last} · ` : ''}{usage.totalTokens > 0 ? `累计 ${usage.totalTokens} tok · ` : ''}{(usage.durationMs / 1000).toFixed(1)}s{usage.toolCalls > 0 ? ` · ${usage.toolCalls} 工具` : ''}
   </span>
 }
diff --git a/src/contracts.ts b/src/contracts.ts
index ec8ffd2..1c86755 100644
--- a/src/contracts.ts
+++ b/src/contracts.ts
@@ -60,6 +60,12 @@ export interface Usage {
   promptTokens: number; completionTokens: number; totalTokens: number;
   durationMs: number; toolCalls: number;
   model?: string;
+  // N3 计费拆分（additive；旧记录缺省为 0）：
+  // Last* 是最近一次请求的用量，Cache* 是缓存命中累计。
+  lastPromptTokens?: number;
+  lastCompletionTokens?: number;
+  cacheReadTokens?: number;
+  cacheWriteTokens?: number;
 }
 
 export interface Run {