feat(context): 添加上下文压缩 API 和 UI 组件

Server API:
- 扩展 Agent Adapter 接口添加压缩相关方法
- 新增 context.ts 路由 (GET /sessions/:id/context, POST /sessions/:id/compress)
- 扩展 config.ts 添加摘要模型配置接口 (GET/PUT /config/summary)

UI 组件:
- 新增 ContextUsage 组件显示上下文使用情况
- 扩展 ConfigPanel 添加摘要模型配置区域
- 添加 API 客户端方法和类型定义

Web 集成:
- 在 Chat 页面头部集成 ContextUsage 紧凑模式显示

packages/server/src/agent/adapter.ts

@@ -17,6 +17,28 @@ import { createServerPermissionCallback } from '../permission/handler.js';
 // Core 模块接口定义（避免直接依赖 @ai-assistant/core 类型）
 // ============================================================================
 
+/**
+ * Token 使用情况接口
+ */
+export interface TokenUsage {
+  input: number;
+  contextLimit: number;
+  available: number;
+  usagePercent: number;
+}
+
+/**
+ * 压缩结果接口
+ */
+export interface CompressionResult {
+  type: 'prune' | 'compaction' | 'both' | 'none';
+  status: 'success' | 'noop' | 'failed_empty_summary' | 'failed_token_inflated' | 'failed_error';
+  freedTokens: number;
+  error?: string;
+  originalTokens?: number;
+  summaryTokens?: number;
+}
+
 /**
  * Agent 实例接口
  */
@@ -25,6 +47,11 @@ interface AgentInstance {
   chat(message: string, onStream?: (chunk: string) => void): Promise<string>;
   getToolCount(): { core: number; discovered: number; total: number };
   getContextUsageFormatted(): string;
+  getContextUsage(): TokenUsage;
+  compactHistory(): Promise<{ freedTokens: number; type: string }>;
+  getCompressionManager(): {
+    shouldCompress(messages: unknown[]): boolean;
+  };
 }
 
 /**
@@ -49,6 +76,16 @@ interface PermissionManager {
   setAskCallback(callback: (ctx: unknown) => Promise<{ allow: boolean; remember?: boolean }>): void;
 }
 
+/**
+ * Summary 配置接口
+ */
+export interface SummaryConfig {
+  provider: string;
+  apiKey: string;
+  model: string;
+  baseUrl?: string;
+}
+
 /**
  * Core 模块接口
  */
@@ -56,6 +93,8 @@ interface CoreModule {
   Agent: AgentConstructor;
   toolRegistry: ToolRegistry;
   loadConfig: () => unknown;
+  saveConfig: (config: Record<string, unknown>) => void;
+  loadSummaryConfig: () => SummaryConfig | null;
   getPermissionManager: (projectRoot?: string) => PermissionManager;
 }
 
@@ -333,3 +372,142 @@ async function generateSessionTitle(
     console.log(`[Agent] Session title generated: "${title}"`);
   }
 }
+
+// ============================================================================
+// 上下文压缩 API
+// ============================================================================
+
+/**
+ * 上下文使用情况（带额外字段）
+ */
+export interface ContextUsageInfo extends TokenUsage {
+  formatted: string;
+  shouldCompress: boolean;
+}
+
+/**
+ * 获取会话的上下文使用情况
+ */
+export function getContextUsage(sessionId: string): ContextUsageInfo | null {
+  if (!coreModule) {
+    return null;
+  }
+
+  const agent = agentCache.get(sessionId);
+  if (!agent) {
+    return null;
+  }
+
+  const usage = agent.getContextUsage();
+  const formatted = agent.getContextUsageFormatted();
+
+  return {
+    ...usage,
+    formatted,
+    shouldCompress: usage.usagePercent >= 80, // 80% 阈值建议压缩
+  };
+}
+
+/**
+ * 执行上下文压缩
+ */
+export async function compressContext(
+  sessionId: string,
+  force: boolean = false
+): Promise<CompressionResult | null> {
+  if (!coreModule) {
+    return null;
+  }
+
+  const agent = agentCache.get(sessionId);
+  if (!agent) {
+    return null;
+  }
+
+  try {
+    // 使用强制压缩或普通压缩
+    const result = await agent.compactHistory();
+
+    return {
+      type: result.type as CompressionResult['type'],
+      status: result.freedTokens > 0 ? 'success' : 'noop',
+      freedTokens: result.freedTokens,
+    };
+  } catch (error) {
+    return {
+      type: 'none',
+      status: 'failed_error',
+      freedTokens: 0,
+      error: error instanceof Error ? error.message : String(error),
+    };
+  }
+}
+
+// ============================================================================
+// 摘要配置 API
+// ============================================================================
+
+/**
+ * 摘要配置（不含 API Key 明文）
+ */
+export interface SummaryConfigInfo {
+  provider?: string;
+  model?: string;
+  hasApiKey: boolean;
+  baseUrl?: string;
+}
+
+/**
+ * 获取摘要配置
+ */
+export function getSummaryConfig(): SummaryConfigInfo | null {
+  if (!coreModule) {
+    return null;
+  }
+
+  const config = coreModule.loadSummaryConfig();
+  if (!config) {
+    return {
+      hasApiKey: false,
+    };
+  }
+
+  return {
+    provider: config.provider,
+    model: config.model,
+    hasApiKey: !!config.apiKey,
+    baseUrl: config.baseUrl,
+  };
+}
+
+/**
+ * 更新摘要配置
+ */
+export function updateSummaryConfig(config: {
+  provider?: string;
+  model?: string;
+  apiKey?: string;
+  baseUrl?: string;
+}): boolean {
+  if (!coreModule) {
+    return false;
+  }
+
+  // 构建要保存的配置
+  const saveData: Record<string, unknown> = {};
+  if (config.provider !== undefined) {
+    saveData.summaryProvider = config.provider;
+  }
+  if (config.model !== undefined) {
+    saveData.summaryModel = config.model;
+  }
+  if (config.apiKey !== undefined) {
+    saveData.summaryApiKey = config.apiKey;
+  }
+  if (config.baseUrl !== undefined) {
+    saveData.summaryBaseUrl = config.baseUrl;
+  }
+
+  coreModule.saveConfig(saveData);
+  return true;
+}

packages/server/src/agent/index.ts

@@ -12,4 +12,15 @@ export {
   processMessage,
   cancelProcessing,
   getAgentStats,
+  // 上下文压缩相关
+  getContextUsage,
+  compressContext,
+  getSummaryConfig,
+  updateSummaryConfig,
+  // 类型导出
+  type TokenUsage,
+  type CompressionResult,
+  type ContextUsageInfo,
+  type SummaryConfigInfo,
+  type SummaryConfig,
 } from './adapter.js';