feat(v3): T22-T23 harness 级工具扩展 + 工作区选择后端

- T22 工具内核：edit_file（old_string 唯一命中才替换，防误改）、search_files
  （跨文件内容搜索，跳过 .git/node_modules 与二进制大文件）、run_command
  （allow_shell 默认关；超时+输出截断+Windows CREATE_NO_WINDOW）
- T23 工作区选择（参考 deepseek-harness 打开文件夹体验）：/agent/fs 磁盘目录浏览
  （空 path 列 Windows 盘符）、/agent/workspaces 最近列表持久化、
  POST /agent 接受 workspace（须存在目录），运行状态记录所用工作区
- 新增测试 12 项，全量 274 passed

gateway/api.py

@@ -501,11 +501,13 @@ try:
 
     @app.post("/agent", tags=["agent"])
     async def agent_run(req: dict):
-        """提交智能体任务：{"task": "...", "pool_id": "可选模型条目"}。
+        """提交智能体任务：{"task", "pool_id"?, "workspace"?}。
 
+        workspace 为用户选择的工作目录（绝对路径）；缺省用设置里的 agent.workspace_dir。
         立即返回 request_id；过程事件经 GET /agent/{id}/stream (SSE) 推送。
         """
         from gateway.agent import get_agent_service, new_request_id
+        from router_system.tools import WorkspaceTools
 
         task = str((req or {}).get("task") or "").strip()
         if not task:
@@ -514,23 +516,36 @@ try:
             raise HTTPException(status_code=400, detail="task 过长（>8000）")
         pool_id = str((req or {}).get("pool_id") or "")
 
+        s = settings_store().to_dict()
+        agent_cfg = s.get("agent", {})
+        ws_raw = str((req or {}).get("workspace") or "").strip()
+        if ws_raw:
+            ws_path = Path(ws_raw)
+            if not ws_path.exists():
+                raise HTTPException(status_code=400, detail=f"工作目录不存在: {ws_raw}")
+            if not ws_path.is_dir():
+                raise HTTPException(status_code=400, detail=f"不是目录: {ws_raw}")
+            workspace_dir = str(ws_path.resolve())
+        else:
+            workspace_dir = agent_cfg.get("workspace_dir", "agent_workspace")
+
         chat, model, used_pool_id = _resolve_agent_chat(pool_id)
         service = get_agent_service()
         request_id = new_request_id()
-        info = service.register(request_id, task, model, used_pool_id)
+        info = service.register(request_id, task, model, used_pool_id,
+                                workspace=workspace_dir)
         if info is None:
             raise HTTPException(status_code=503, detail="智能体同时运行任务已达上限")
 
-        s = settings_store().to_dict()
-        agent_cfg = s.get("agent", {})
-
         async def _run():
             try:
                 await service.run(
                     info, chat,
-                    workspace_dir=agent_cfg.get("workspace_dir", "agent_workspace"),
+                    workspace_dir=workspace_dir,
                     max_rounds=int(agent_cfg.get("max_rounds", 8)),
                     token_cap=int(agent_cfg.get("token_cap", 20000)),
+                    allow_shell=bool(agent_cfg.get("allow_shell", False)),
+                    shell_timeout_s=int(agent_cfg.get("shell_timeout_s", 20)),
                 )
             except Exception as exc:
                 import traceback
@@ -541,7 +556,50 @@ try:
                 service._write_status(info)
 
         info.asyncio_task = asyncio.create_task(_run())
-        return {"request_id": request_id, "status": "running", "model": model}
+        return {"request_id": request_id, "status": "running", "model": model,
+                "workspace": workspace_dir}
+
+    @app.get("/agent/fs", tags=["agent"])
+    async def agent_fs_browse(path: str = ""):
+        """目录选择器：浏览本地文件系统（只列子目录，不读文件内容）。"""
+        from router_system.tools import browse_directories
+        return browse_directories(path)
+
+    @app.get("/agent/workspaces", tags=["agent"])
+    async def agent_workspaces():
+        """当前工作区 + 最近打开列表。"""
+        s = settings_store().to_dict()
+        agent_cfg = s.get("agent", {})
+        current = agent_cfg.get("workspace_dir", "agent_workspace")
+        return {"current": current, "recent": list(agent_cfg.get("recent_workspaces", []))}
+
+    @app.post("/agent/workspaces", tags=["agent"])
+    async def agent_open_workspace(req: dict):
+        """打开（或创建）一个工作目录：设为当前并记入最近列表。"""
+        path = str((req or {}).get("path") or "").strip()
+        create = bool((req or {}).get("create", False))
+        if not path:
+            raise HTTPException(status_code=400, detail="path 不能为空")
+        p = Path(path)
+        if not p.exists():
+            if not create:
+                raise HTTPException(status_code=400,
+                                    detail=f"目录不存在: {path}（可勾选“新建目录”）")
+            try:
+                p.mkdir(parents=True, exist_ok=True)
+            except OSError as e:
+                raise HTTPException(status_code=400, detail=f"创建失败: {e}")
+        elif not p.is_dir():
+            raise HTTPException(status_code=400, detail=f"不是目录: {path}")
+        resolved = str(p.resolve())
+        store = settings_store()
+        store.update({"agent": {"workspace_dir": resolved}})
+        merged = store.to_dict().get("agent", {})
+        recent = [w for w in merged.get("recent_workspaces", []) if w != resolved]
+        recent.insert(0, resolved)
+        store.update({"agent": {"recent_workspaces": recent[:8]}})
+        return {"ok": True, "current": resolved,
+                "recent": store.to_dict().get("agent", {}).get("recent_workspaces", [])}
 
     @app.get("/agent/{request_id}/status", tags=["agent"])
     async def agent_status(request_id: str):
@@ -585,22 +643,22 @@ try:
         )
 
     @app.get("/agent/workspace", tags=["agent"])
-    async def agent_workspace(path: str = ""):
-        """列出智能体工作区（默认根目录；path 指定子目录）。越界返回 400。"""
+    async def agent_workspace(path: str = "", root: str = ""):
+        """列出智能体工作区内容。root 可指定其他已选工作目录（默认用设置值）。越界/非法返回 400。"""
         from router_system.tools import ToolError, WorkspaceTools
-        s = settings_store().to_dict()
-        tools = WorkspaceTools(s.get("agent", {}).get("workspace_dir", "agent_workspace"))
+        base = _agent_workspace_root(root)
+        tools = WorkspaceTools(base)
         try:
             return tools.list_dir(path)
         except ToolError as e:
             raise HTTPException(status_code=400, detail=str(e))
 
     @app.get("/agent/file", tags=["agent"])
-    async def agent_file(path: str):
-        """读取智能体工作区内文件（前端预览，越界即 400）。"""
+    async def agent_file(path: str, root: str = ""):
+        """读取智能体工作区内文件（前端预览，越界即 400）。root 同 /agent/workspace。"""
         from router_system.tools import ToolError, WorkspaceTools
-        s = settings_store().to_dict()
-        tools = WorkspaceTools(s.get("agent", {}).get("workspace_dir", "agent_workspace"))
+        base = _agent_workspace_root(root)
+        tools = WorkspaceTools(base)
         try:
             result = tools.read_file(path)
         except ToolError as e:
@@ -609,6 +667,17 @@ try:
             raise HTTPException(status_code=404, detail=result.get("error", "读取失败"))
         return result
 
+    def _agent_workspace_root(root: str = "") -> str:
+        """解析工作区根：显式 root（须为已存在目录）> 设置值。"""
+        root = (root or "").strip()
+        if root:
+            p = Path(root)
+            if not p.is_dir():
+                raise HTTPException(status_code=400, detail=f"工作目录不存在: {root}")
+            return str(p.resolve())
+        s = settings_store().to_dict()
+        return s.get("agent", {}).get("workspace_dir", "agent_workspace")
+
     # ---------------- 模型设置（用户可调整） ----------------
     @app.get("/config", tags=["settings"])
     async def get_config():