feat: 任务实时链路 SSE (#61)

host.py：回合通知摘要成链路条目，增量追加到 <state>/host-traces/<task>.jsonl（上限 5000 行）；dispatch/run/goal/delegate 设链路文件
cloud/server.py：GET /tasks/{id}/trace 快照 + /trace/stream SSE（snapshot → entry → done；worktree 在别机时空链路 + 说明）
console：详情链路区，运行中 fetch 流式渲染（EventSource 不能带 X-API-Key 头），终态走快照；DOM 上限 1000 条
单测：test_host_trace 7 + test_task_trace 6；host 49、cloud 525、deploy 14 全过

Co-authored-by: host <host@test.local>

host.py

@@ -118,6 +118,72 @@ def default_codex_bin():
     return "codex"
 
 
+# 实时链路：单条通知里 item 的上限行数（防失控回合把文件写爆）。
+TRACE_MAX_LINES = 5000
+
+
+def _summarize_trace_item(method, params):
+    """app-server 通知 → 链路条目列表（实时链路用）。
+
+    只取过程事实，不取大文本：命令截 500 字、消息截 300 字、
+    思考摘要截 200 字；fileChange 一项一变化拆多条。
+    返回 [] 表示该通知不进链路（userMessage 等）。
+    ts 取通知的 completedAtMs/startedAtMs（毫秒 epoch），
+    没有时为 None，服务端展示时按无时间处理。
+    """
+    item = (params or {}).get("item")
+    if not isinstance(item, dict):
+        return []
+    item_type = item.get("type")
+    item_id = item.get("id") or ""
+    ts = params.get("completedAtMs") or params.get("startedAtMs")
+    if item_type == "commandExecution":
+        return [{"kind": "exec", "id": item_id, "ts": ts,
+                 "command": (item.get("command") or "")[:500],
+                 "cwd": item.get("cwd") or "",
+                 "exitCode": item.get("exitCode"),
+                 "durationMs": item.get("durationMs")}]
+    if item_type == "fileChange":
+        entries = []
+        for ch in item.get("changes") or []:
+            if not isinstance(ch, dict):
+                continue
+            path = ch.get("path") or ""
+            entries.append({"kind": "file",
+                            "id": item_id + ":" + path, "ts": ts,
+                            "path": path, "change": ch.get("kind") or "",
+                            "status": item.get("status") or ""})
+        return entries
+    if item_type == "agentMessage":
+        text = item.get("text") or ""
+        if not text:
+            return []
+        return [{"kind": "message", "id": item_id, "ts": ts,
+                 "phase": item.get("phase") or "", "text": text[:300]}]
+    if item_type == "reasoning":
+        summary = item.get("summary") or item.get("content") or []
+        text = " ".join(s for s in summary if isinstance(s, str)).strip()
+        if not text:
+            return []
+        return [{"kind": "reasoning", "id": item_id, "ts": ts,
+                 "summary": text[:200]}]
+    if item_type == "mcpToolCall":
+        return [{"kind": "tool", "id": item_id, "ts": ts,
+                 "server": item.get("server") or "",
+                 "tool": item.get("tool") or "",
+                 "status": item.get("status") or ""}]
+    if item_type == "functionCallOutput":
+        return [{"kind": "call", "id": item_id, "ts": ts,
+                 "name": item.get("name") or ""}]
+    if item_type == "plan":
+        text = item.get("text") or ""
+        if not text:
+            return []
+        return [{"kind": "plan", "id": item_id, "ts": ts,
+                 "text": text[:300]}]
+    return []
+
+
 class Server:
     """单个 app-server 进程，多 thread 并发。"""
 
@@ -133,8 +199,48 @@ class Server:
         self.events = []
         self.events_lock = threading.Lock()
         self.restart_count = 0
+        # 实时链路文件：set_trace_file 未调时为 None，回合本身
+        # 不受影响（写链路失败也绝不打断 _read_loop）。
+        self.trace_path = None
+        self._trace_lines = 0
         self._start()
 
+    def set_trace_file(self, state_path, task_name):
+        """链路文件定到 <state_dir>/host-traces/<task_name>.jsonl。
+
+        state_dir 与 state 文件同目录：本地 worker 是
+        /opt/codex-app-server/work，容器内是 /app/work（经挂载
+        落到宿主同一目录），服务端按同一规则读。目录建不出
+        时 trace_path 保持 None，不影响回合。
+        """
+        try:
+            safe = re.sub(r"[^A-Za-z0-9_.-]", "-", str(task_name))
+            trace_dir = os.path.join(
+                os.path.dirname(os.path.abspath(state_path)),
+                "host-traces")
+            os.makedirs(trace_dir, exist_ok=True)
+            self.trace_path = os.path.join(trace_dir, safe + ".jsonl")
+            self._trace_lines = 0
+        except Exception:
+            self.trace_path = None
+
+    def _append_trace(self, msg):
+        """通知 → 摘要条目 → 追加写链路文件（每事件开合一次文件，
+        进程被杀也不丢已写行；行数到 TRACE_MAX_LINES 即停）。"""
+        if self.trace_path is None or \
+                self._trace_lines >= TRACE_MAX_LINES:
+            return
+        entries = _summarize_trace_item(msg.get("method"),
+                                        msg.get("params") or {})
+        if not entries:
+            return
+        with open(self.trace_path, "a", encoding="utf-8") as f:
+            for entry in entries:
+                if self._trace_lines >= TRACE_MAX_LINES:
+                    break
+                f.write(json.dumps(entry, ensure_ascii=False) + "\n")
+                self._trace_lines += 1
+
     def _start(self):
         env = dict(os.environ)
         if self.codex_home:
@@ -206,6 +312,11 @@ class Server:
                     thread_id = params["thread"].get("id")
                 with self.events_lock:
                     self.events.append(msg)
+                if self.trace_path is not None:
+                    try:
+                        self._append_trace(msg)
+                    except Exception:
+                        pass
                 if msg.get("method") == "turn/completed" and thread_id:
                     q = self.turn_queues.get(thread_id)
                     if q is not None:
@@ -1708,6 +1819,16 @@ def main():
         return
     srv = Server(codex_bin=args.codex_bin, codex_home=args.codex_home,
                  approval=args.approval)
+    # 实时链路：只给跑 turn 的命令设链路文件（dispatch/run/goal/
+    # delegate）；只读命令不设。名字映射与 worker 派发一致：
+    # dispatch/goal/delegate 用 --name，run 用 --task。
+    _trace_name = None
+    if args.cmd in ("dispatch", "goal", "delegate"):
+        _trace_name = getattr(args, "name", None)
+    elif args.cmd == "run":
+        _trace_name = getattr(args, "task", None)
+    if _trace_name:
+        srv.set_trace_file(args.state, _trace_name)
     try:
         srv.initialize()
         if args.cmd == "dispatch":