feat: v0.8.0 流语义补全 · 会话可靠 · 恢复力 — finish_reason 全链路贯通根治"思考中停止" · 2445 用例全量回归

P0 会话可靠性收口（根治"模型思考着会话就停止"）：
- P0-1 finish_reason 全链路贯通：DONE 事件与 IterationStep 新增 finishReason，OpenAI 共享 SSE / Anthropic message_delta.stop_reason / Ollama done_reason 三路采集，TRACE 层弃用硬编码 'stop' 记录真值
- P0-2 空响应守卫 + 降级重试：零产出流→可重试错误走退避；思考耗尽输出预算（reasoning-only + length）→自动关闭思考降级重试一次；仍失败→OUTPUT_LENGTH_EXCEEDED 结构化错误 + 故障转移；附带根治 abort 恰逢零工具调用轮被 COMPLETED 抢占的真实缺陷
- P0-3 思考×能力×预算三对齐：DeepSeek/MiMo/Agnes/Ollama 四家 supportsThinking=false 强制不发思考参数；小输出预算告警；设置页联动提示
- P0-4 渲染层可见性：截断/空完成/友好错误三类提示，i18n 全部出层
- P0-5 回归四件套：reasoning-only 终止判定、集成级空闲超时、504 引擎重试归类、思考中 abort→USER_INTERRUPT、P4-2 强制收尾路径

FEAT-1：LLM 设置新增「最大输出上限」——Provider 支持矩阵显隐 + 模型上限钳制提示 + 超限保存警告 + llm.maxTokens 热生效

P1 修复面收口：
- 渲染层三缺陷根治：后台会话回放缓冲（2000 条/4MB 有界 + agent:getReplayState + 事件总线）+ abort 双层自愈 + sendMessage 收尾兜底 + 中断卡片清扫
- 工具 abort 信号全覆盖：web_search/web_fetch/http_request/code_search/git 系列/delegate_task 全部接入引擎中断；web_search 时间预算收敛（720s→≤240s）；移除伪造 ToolExecutionContext 与死代码
- 安全：本地 Pinned CONNECT 代理根治浏览器通道 DNS rebinding（校验期 IP pinning，可注入 resolver 表测）；配置 URL 域名解析深校验（DeepCheckSoftFailure 软失败）；SSE 空 error 帧防御修复；Ollama generate/embed AbortSignal.any 合并
- 缺陷清单：UTF-16 BOM 读取、tmp 同毫秒碰撞（nanoid 后缀）、code_search JS 回退参数对称（case_sensitive/前后文独立）、list_directory include_node_modules、崩溃自愈退避（60s 窗 ≥3 次停 reload）、MemoryViewer/Sidebar i18n 收口

P2 能力演进：
- 会话回收站：SCHEMA_VERSION 3 + 迁移 10（deleted_at，存在性守卫），软删除/恢复/彻底删除/30 天自动清理（启动+24h），searchMessages 聚合剔除，Sidebar 回收站面板
- 会话回放播放器：sessions:listRecordings/readRecording（白名单+目录边界+20MB 上限），SessionReplayPlayer 时间轴/步进/变速，Trace 面板入口
- electron-updater 自动更新：双轨（手动 feed 比对保留），生产环境启动静默检查 + update:status 广播 + app:updateInstall + LogsSettings UpdatePanel + builder publish 配置
- @ 文件提及：workspace.listFiles/readFileClip（边界/512KB/NUL 拒绝/MEMORY.md 保护），ChatInput Fuse 联想+键盘导航+附件管线注入
- MCP Resources/Prompts 发现：可选能力 try/catch 降级，mcp:listServerContents，MCPSettings 展开视图
- 文档对齐：内部 API 标准 HTML（Adapter 清单补 MiMo/已实现注记/STREAM_RESET/DONE.finishReason/ repetition_truncation 映射）；README v0.8.0 亮点表

P3 测试基建：
- 新增 4 个测试文件：engine-stream-contract（6）、engine-stream-reliability（4：集成空闲超时/504 重试/思考中 abort/P4-2 强制收尾）、thinking-capability-gate（7）、pinned-proxy（9，含深校验 5）、session-trash（5，DB 域）、use-agent-stream hook 级（5）、agent.test 回放缓冲（2）
- 契约更新：orchestrator 被中断 SubAgent success=false（abort 优先级修复语义）、SSE 空 error 帧、UTF-16 正常读取、DeepSeek 未配置思考显式 disabled、迁移矩阵 v2→3
- 弱断言根治：registry WEBP 单向断言、hooks-contracts 自比恒真、memory 空 token 补强

全量验证：typecheck 0 错误 / lint 0 问题 / 系统 Node 2144 通过（301 DB 用例按 ABI 跳过）/ Electron ABI 2445/2445 全量通过 0 跳过

electron/harness/tools/built-in/web-search.ts

@@ -338,9 +338,15 @@ function parse360Regex(html: string): SearchResult[] {
 // 探测经 ssrfPinnedFetch（DNS pinning），重定向不自动跟随（3xx 即视为可达 ——
 // 链接活性已证明，且跟跳目标不再绕过校验）。
 
-async function checkReachability(urls: string[], concurrency = 5): Promise<Map<string, boolean>> {
+async function checkReachability(
+  urls: string[],
+  signal?: AbortSignal,
+  concurrency = 5,
+): Promise<Map<string, boolean>> {
   const result = new Map<string, boolean>();
   for (let i = 0; i < urls.length; i += concurrency) {
+    // v0.8.0 P1-2: abort 后立即终止预检批次
+    if (signal?.aborted) break;
     const batch = urls.slice(i, i + concurrency);
     const checks = batch.map(async (url) => {
       try {
@@ -349,7 +355,13 @@ async function checkReachability(urls: string[], concurrency = 5): Promise<Map<s
           result.set(url, false);
           return;
         }
-        const resp = await ssrfPinnedFetch(url, { method: 'HEAD', redirect: 'manual' }, 3_000);
+        // v0.8.0 P1-2: 透传引擎级 abort signal
+        const resp = await ssrfPinnedFetch(
+          url,
+          { method: 'HEAD', redirect: 'manual' },
+          3_000,
+          signal,
+        );
         result.set(url, resp.ok || (resp.status >= 300 && resp.status < 400));
       } catch {
         result.set(url, false);
@@ -424,9 +436,14 @@ export class WebSearchTool implements IMetonaTool {
     private webFetchTool: WebFetchTool,
   ) {}
 
-  async execute(args: Record<string, unknown>, _context: ToolExecutionContext): Promise<unknown> {
+  async execute(args: Record<string, unknown>, context: ToolExecutionContext): Promise<unknown> {
     const query = args.query as string;
 
+    // v0.8.0 P1-2: abort 立即生效（后续各阶段均携带本 signal）
+    if (context.signal?.aborted) {
+      return { success: false, query, results: [], error: 'Search aborted' };
+    }
+
     // 读取 SearXNG 配置
     const searxngConfig = this.readSearXNGConfig();
     const useSearXNG = searxngConfig.enabled && !!searxngConfig.url;
@@ -463,12 +480,23 @@ export class WebSearchTool implements IMetonaTool {
     let engineStats: Record<string, string>;
 
     if (useSearXNG) {
-      const searxResult = await this.searchSearXNG(query, searxngConfig, maxResults, timeRange);
+      const searxResult = await this.searchSearXNG(
+        query,
+        searxngConfig,
+        maxResults,
+        timeRange,
+        context.signal,
+      );
       results = searxResult.results;
       mode = 'searxng';
       engineStats = searxResult.engineStats;
     } else {
-      const builtinResult = await this.searchBuiltinEngines(query, maxResults, timeRange);
+      const builtinResult = await this.searchBuiltinEngines(
+        query,
+        maxResults,
+        timeRange,
+        context.signal,
+      );
       results = builtinResult.results;
       mode = 'builtin';
       engineStats = builtinResult.engineStats;
@@ -479,7 +507,7 @@ export class WebSearchTool implements IMetonaTool {
 
     // 可达性预检
     const topUrls = deduped.slice(0, Math.min(20, deduped.length)).map((r) => r.url);
-    const reachabilityMap = await checkReachability(topUrls);
+    const reachabilityMap = await checkReachability(topUrls, context.signal);
     for (const r of deduped) {
       r.reachable = reachabilityMap.get(r.url) ?? false;
     }
@@ -489,11 +517,17 @@ export class WebSearchTool implements IMetonaTool {
 
     // 摘要增强
     if (enhanceSnippets) {
-      await this.enhanceSnippets(sorted, 3);
+      await this.enhanceSnippets(sorted, 3, context);
     }
 
     // 自动抓取完整内容
-    const fetchedContent = await this.autoFetch(query, sorted, searxngConfig.fetch_mode, fetchTop);
+    const fetchedContent = await this.autoFetch(
+      query,
+      sorted,
+      searxngConfig.fetch_mode,
+      fetchTop,
+      context,
+    );
 
     // 格式化输出
     const formatted = this.formatResults(query, sorted);
@@ -536,6 +570,7 @@ export class WebSearchTool implements IMetonaTool {
     config: SearXNGConfig,
     maxResults: number,
     timeRange: string,
+    signal?: AbortSignal,
   ): Promise<{ results: SearchResult[]; engineStats: Record<string, string> }> {
     const results: SearchResult[] = [];
     const engineStats: Record<string, string> = {};
@@ -549,6 +584,8 @@ export class WebSearchTool implements IMetonaTool {
     let page = 1;
 
     while (results.length < maxResults && page <= maxPages) {
+      // v0.8.0 P1-2: abort 后停止翻页
+      if (signal?.aborted) break;
       const params = new URLSearchParams();
       params.set('q', query);
       params.set('format', config.format || 'json');
@@ -564,7 +601,8 @@ export class WebSearchTool implements IMetonaTool {
       const pageResults: SearchResult[] = [];
 
       try {
-        const response = await fetchWithTimeout(searchUrl, { headers }, 15_000);
+        // v0.8.0 P1-2: SearXNG 请求携带引擎级 abort signal
+        const response = await fetchWithTimeout(searchUrl, { headers }, 15_000, signal);
         if (!response.ok) {
           throw new Error(`SearXNG API error: ${response.status} ${response.statusText}`);
         }
@@ -625,6 +663,7 @@ export class WebSearchTool implements IMetonaTool {
     query: string,
     maxResults: number,
     timeRange: string,
+    signal?: AbortSignal,
   ): Promise<{ results: SearchResult[]; engineStats: Record<string, string> }> {
     const searchPromises = ENGINES.map(async (engine) => {
       try {
@@ -639,6 +678,7 @@ export class WebSearchTool implements IMetonaTool {
             },
           },
           8_000,
+          signal,
         );
 
         if (!response.ok) {
@@ -689,16 +729,23 @@ export class WebSearchTool implements IMetonaTool {
 
   // ===== 摘要增强（委托给 WebFetchTool） =====
 
-  private async enhanceSnippets(results: SearchResult[], maxEnhance: number): Promise<void> {
+  private async enhanceSnippets(
+    results: SearchResult[],
+    maxEnhance: number,
+    context: ToolExecutionContext,
+  ): Promise<void> {
     let enhanced = 0;
     for (const r of results) {
+      // v0.8.0 P1-2: abort 后停止增强
+      if (context.signal?.aborted) break;
       if (enhanced >= maxEnhance) break;
       if (r.snippet.length < 30 && r.reachable) {
         try {
-          const fetchResult = (await this.webFetchTool.execute(
-            { url: r.url },
-            { sessionId: '', workspacePath: '', iteration: 0, requestId: '' },
-          )) as { success: boolean; content?: string };
+          // v0.8.0 P1-2: 透传真实执行上下文（signal）—— 移除"伪造空上下文"
+          const fetchResult = (await this.webFetchTool.execute({ url: r.url }, context)) as {
+            success: boolean;
+            content?: string;
+          };
 
           if (fetchResult.success && fetchResult.content) {
             const text = fetchResult.content.slice(0, 200);
@@ -729,13 +776,21 @@ export class WebSearchTool implements IMetonaTool {
     results: SearchResult[],
     fetchMode: string,
     fetchTop: number,
+    context: ToolExecutionContext,
   ): Promise<Array<{ url: string; title: string; content: string }>> {
+    // v0.8.0 P1-2 根治: 时间预算收敛 —— 旧实现最坏耗时（8 条 × 3 并发 × 单次
+    // web_fetch 240s ≈ 720s）远超工具自身 300s 超时，registry 层超时后整次调用
+    // 作废（已抓取内容全部丢弃）。现以 deadline 为界：剩余预算不足一次最小
+    // 抓取（30s）即停，已抓取内容照常返回。
+    const BUDGET_RATIO = 0.8;
+    const MIN_FETCH_BUDGET_MS = 30_000;
+    const deadlineMs = Date.now() + 300_000 * BUDGET_RATIO;
+
     // 相关性评分（不过滤，relevance=0 的结果也参与抓取候选）
-    const withRelevance = results.map((r) => ({
+    const filtered = results.map((r) => ({
       result: r,
       relevance: computeRelevance(query, r),
     }));
-    const filtered = withRelevance.length > 0 ? withRelevance : [];
 
     // 确定抓取数量：fetchTop 已在 execute() 中综合了配置面板和工具参数
     const topN = Math.min(fetchTop, 8, filtered.length);
@@ -761,9 +816,10 @@ export class WebSearchTool implements IMetonaTool {
     }): Promise<{ url: string; title: string; content: string } | null> => {
       try {
         // 委托给 WebFetchTool — 享受三阶段回退策略（HTTP + 反爬 + 浏览器渲染）
+        // v0.8.0 P1-2: 透传真实执行上下文（signal）—— 移除"伪造空上下文"
         const fetchResult = (await this.webFetchTool.execute(
           { url: item.result.url },
-          { sessionId: '', workspacePath: '', iteration: 0, requestId: '' },
+          context,
         )) as { success: boolean; content?: string };
 
         if (fetchResult.success && fetchResult.content) {
@@ -779,9 +835,18 @@ export class WebSearchTool implements IMetonaTool {
       }
     };
 
-    // 并行批次抓取（并发 3）
+    // 并行批次抓取（并发 3，时间预算收敛）
     const CONCURRENCY = 3;
     for (let i = 0; i < toFetch.length; i += CONCURRENCY) {
+      // v0.8.0 P1-2: 剩余预算不足一次最小抓取 → 停止，保留已抓取内容
+      const remaining = deadlineMs - Date.now();
+      if (context.signal?.aborted || remaining < MIN_FETCH_BUDGET_MS) {
+        logTool(
+          'web_search',
+          `Auto-fetch budget stop: fetched=${fetched.length}, remaining=${Math.max(0, remaining)}ms, aborted=${!!context.signal?.aborted}`,
+        );
+        break;
+      }
       const batch = toFetch.slice(i, i + CONCURRENCY);
       const settled = await Promise.allSettled(batch.map((item) => fetchOne(item)));
       for (const r of settled) {