perf: 会话统计增量聚合——emitStats/buildContextInfo 不再每轮全量遍历

apps/desktop/src/main/pi/agent-service.ts

@@ -467,13 +467,14 @@ export class AgentService {
    * 类目：消息 / 自定义工具 / 系统工具 / 系统提示词 / 技能 / 其他；
    * 技能块注入在系统提示词内，从提示词估算中拆出（不重复计数）。 */
   private buildContextInfo(session: AgentSession): ContextUsageInfo {
+    const agg = this.aggregateSession(session)
     const breakdown: ContextBreakdownEntry[] = [
-      { key: 'messages', label: '消息', tokens: 0 },
-      { key: 'customTools', label: '自定义工具', tokens: 0 },
-      { key: 'builtinTools', label: '系统工具', tokens: 0 },
+      { key: 'messages', label: '消息', tokens: agg.breakdown.get('messages') ?? 0 },
+      { key: 'customTools', label: '自定义工具', tokens: agg.breakdown.get('customTools') ?? 0 },
+      { key: 'builtinTools', label: '系统工具', tokens: agg.breakdown.get('builtinTools') ?? 0 },
       { key: 'systemPrompt', label: '系统提示词', tokens: 0 },
       { key: 'skills', label: '技能', tokens: 0 },
-      { key: 'other', label: '其他', tokens: 0 }
+      { key: 'other', label: '其他', tokens: agg.breakdown.get('other') ?? 0 }
     ]
     const byKey = new Map(breakdown.map((b) => [b.key, b]))
     const systemTokens = Math.ceil(session.systemPrompt.length / 4)
@@ -481,44 +482,12 @@ export class AgentService {
     byKey.get('systemPrompt')!.tokens = Math.max(0, systemTokens - skillsTokens)
     byKey.get('skills')!.tokens = skillsTokens
 
-    for (const message of session.messages) {
-      const m = message as { role?: string; toolName?: unknown; content?: unknown }
-      switch (m.role) {
-        case 'user':
-        case 'assistant':
-          byKey.get('messages')!.tokens += estimateMessageTokens(message)
-          break
-        case 'toolResult': {
-          const key =
-            typeof m.toolName === 'string' && CUSTOM_TOOL_NAMES.has(m.toolName) ? 'customTools' : 'builtinTools'
-          byKey.get(key)!.tokens += estimateMessageTokens(message)
-          break
-        }
-        // bash 执行、扩展注入、压缩/分支摘要等注入上下文的消息
-        case 'bashExecution':
-        case 'custom':
-        case 'compactionSummary':
-        case 'branchSummary':
-          byKey.get('other')!.tokens += estimateMessageTokens(message)
-          break
-        default:
-          break
-      }
-    }
     const usage = session.getContextUsage()
-    let lastOutputTokens: number | undefined
-    for (let i = session.messages.length - 1; i >= 0; i--) {
-      const m = session.messages[i] as { role?: string; usage?: { output?: unknown } }
-      if (m.role === 'assistant' && m.usage && typeof m.usage.output === 'number') {
-        lastOutputTokens = m.usage.output
-        break
-      }
-    }
     return {
       tokens: usage && typeof usage.tokens === 'number' ? usage.tokens : null,
       contextWindow: usage?.contextWindow ?? 0,
       percent: usage && typeof usage.percent === 'number' ? usage.percent : null,
-      ...(lastOutputTokens !== undefined ? { lastOutputTokens } : {}),
+      ...(agg.lastOutputTokens !== undefined ? { lastOutputTokens: agg.lastOutputTokens } : {}),
       breakdown
     }
   }
@@ -538,42 +507,114 @@ export class AgentService {
     return value
   }
 
+  // ---- 会话统计增量聚合 ----
+  // emitStats 每条 assistant 消息落地都会触发；长会话下每次全量遍历估算
+  // token 是 O(全部消息)。消息列表正常只追加：以「已聚合前缀长度 + 前缀
+  // 末条消息引用」为锚点，每次只聚合新增尾部；压缩/回溯/会话切换/运行时
+  // 重建后消息对象引用必变（或长度回退），锚点失配即自动整体重算。
+
+  private sessionAgg: {
+    count: number
+    anchor: unknown
+    cacheInput: number
+    cacheRead: number
+    cacheWrite: number
+    toolCalls: number
+    toolErrors: number
+    /** 消息侧 breakdown（systemPrompt/skills 在外层另算） */
+    breakdown: Map<string, number>
+    lastOutputTokens: number | undefined
+  } | null = null
+
+  private aggregateSession(session: AgentSession) {
+    const messages = session.messages
+    let agg = this.sessionAgg
+    if (
+      agg === null ||
+      messages.length < agg.count ||
+      (agg.count > 0 && messages[agg.count - 1] !== agg.anchor)
+    ) {
+      agg = {
+        count: 0,
+        anchor: null,
+        cacheInput: 0,
+        cacheRead: 0,
+        cacheWrite: 0,
+        toolCalls: 0,
+        toolErrors: 0,
+        breakdown: new Map([
+          ['messages', 0],
+          ['customTools', 0],
+          ['builtinTools', 0],
+          ['other', 0]
+        ]),
+        lastOutputTokens: undefined
+      }
+    }
+    for (let i = agg.count; i < messages.length; i++) {
+      const m = messages[i] as {
+        role?: string
+        toolName?: unknown
+        content?: unknown
+        isError?: unknown
+        usage?: { input?: unknown; output?: unknown; cacheRead?: unknown; cacheWrite?: unknown }
+      }
+      const bump = (key: string): void => {
+        agg!.breakdown.set(key, (agg!.breakdown.get(key) ?? 0) + estimateMessageTokens(messages[i]))
+      }
+      switch (m.role) {
+        case 'assistant': {
+          bump('messages')
+          if (m.usage) {
+            agg.cacheInput += Number(m.usage.input ?? 0) || 0
+            agg.cacheRead += Number(m.usage.cacheRead ?? 0) || 0
+            agg.cacheWrite += Number(m.usage.cacheWrite ?? 0) || 0
+            if (typeof m.usage.output === 'number') agg.lastOutputTokens = m.usage.output
+          }
+          if (Array.isArray(m.content)) {
+            for (const block of m.content as Array<{ type?: unknown }>) {
+              if (block && typeof block === 'object' && block.type === 'toolCall') agg.toolCalls += 1
+            }
+          }
+          break
+        }
+        case 'user':
+          bump('messages')
+          break
+        case 'toolResult': {
+          if (m.isError === true) agg.toolErrors += 1
+          bump(
+            typeof m.toolName === 'string' && CUSTOM_TOOL_NAMES.has(m.toolName) ? 'customTools' : 'builtinTools'
+          )
+          break
+        }
+        // bash 执行、扩展注入、压缩/分支摘要等注入上下文的消息
+        case 'bashExecution':
+        case 'custom':
+        case 'compactionSummary':
+        case 'branchSummary':
+          bump('other')
+          break
+        default:
+          break
+      }
+    }
+    agg.count = messages.length
+    agg.anchor = messages.length > 0 ? messages[messages.length - 1] : null
+    this.sessionAgg = agg
+    return agg
+  }
+
   private async emitStats(): Promise<void> {
     try {
       const runtime = await this.getRuntime()
       const session = runtime.session
       const stats = session.getSessionStats()
       const usage = session.getContextUsage()
+      const agg = this.aggregateSession(session)
       // 缓存命中率：读缓存 / 全部提示 token（input + cacheRead + cacheWrite），
       // 按本会话所有 assistant 响应聚合，0 表示会话内尚无任何响应
-      let cacheInput = 0
-      let cacheRead = 0
-      let cacheWrite = 0
-      let toolCalls = 0
-      let toolErrors = 0
-      for (const message of session.messages) {
-        const m = message as {
-          role?: string
-          usage?: { input?: unknown; cacheRead?: unknown; cacheWrite?: unknown }
-          content?: unknown
-          isError?: unknown
-        }
-        if (m.role === 'assistant') {
-          if (m.usage) {
-            cacheInput += Number(m.usage.input ?? 0) || 0
-            cacheRead += Number(m.usage.cacheRead ?? 0) || 0
-            cacheWrite += Number(m.usage.cacheWrite ?? 0) || 0
-          }
-          if (Array.isArray(m.content)) {
-            for (const block of m.content as Array<{ type?: unknown }>) {
-              if (block && typeof block === 'object' && block.type === 'toolCall') toolCalls += 1
-            }
-          }
-        } else if (m.role === 'toolResult' && m.isError === true) {
-          toolErrors += 1
-        }
-      }
-      const denominator = cacheInput + cacheRead + cacheWrite
+      const denominator = agg.cacheInput + agg.cacheRead + agg.cacheWrite
       const info: SessionStatsInfo = {
         tokens: { ...stats.tokens },
         cost: stats.cost,
@@ -581,15 +622,15 @@ export class AgentService {
         context: this.buildContextInfo(session),
         ...(denominator > 0
           ? {
-              cacheHitRate: Math.round((cacheRead / denominator) * 100),
-              cacheTokens: { read: cacheRead, write: cacheWrite, input: cacheInput }
+              cacheHitRate: Math.round((agg.cacheRead / denominator) * 100),
+              cacheTokens: { read: agg.cacheRead, write: agg.cacheWrite, input: agg.cacheInput }
             }
           : {}),
-        ...(toolCalls > 0
+        ...(agg.toolCalls > 0
           ? {
               toolStats: {
-                calls: toolCalls,
-                successRate: Math.round(((toolCalls - toolErrors) / toolCalls) * 100)
+                calls: agg.toolCalls,
+                successRate: Math.round(((agg.toolCalls - agg.toolErrors) / agg.toolCalls) * 100)
               }
             }
           : {})