refactor: thread app_config through lead and subagent task path (#2666)

* refactor: thread app config through lead prompt

* fix: honor explicit app config across runtime paths

* style: format subagent executor tests

* fix: thread resolved app config and guard subagents-only fallback

Address two PR review findings:

1. _create_summarization_middleware passed the original (possibly None)
   app_config into create_chat_model, forcing the model factory back to
   ambient get_app_config() and risking config drift between the
   middleware's resolved view and the model's view. Pass the resolved
   AppConfig instance through end-to-end.

2. get_available_subagent_names accepted Any-typed config and forwarded
   it to is_host_bash_allowed, which reads ``.sandbox``. A
   SubagentsAppConfig (also accepted upstream as a sum-type input) has
   no ``.sandbox`` attribute and would be silently treated as "no
   sandbox configured", incorrectly disabling the bash subagent. Guard
   on hasattr and fall back to ambient lookup otherwise.

Adds regression tests for both paths.

* chore: simplify hasattr guard and tighten regression tests

- Collapse if/else into ternary in get_available_subagent_names; hasattr(None, ...) is False so the explicit None check was redundant.
- Drop comments that narrate the change rather than explain non-obvious WHY (test names already convey intent).
- Replace stringly-typed sentinel "no-arg" in regression test with direct args tuple comparison.

---------

Co-authored-by: greatmengqi <chenmengqi.0376@bytedance.com>

backend/packages/harness/deerflow/subagents/executor.py

@@ -168,6 +168,8 @@ def _get_isolated_subagent_loop() -> asyncio.AbstractEventLoop:
             _isolated_subagent_loop_thread = thread
             _isolated_subagent_loop_started = started_event
 
+        if _isolated_subagent_loop is None:
+            raise RuntimeError("Isolated subagent event loop is not initialized")
         return _isolated_subagent_loop
 
 
@@ -308,8 +310,10 @@ class SubagentExecutor:
         try:
             from deerflow.skills.storage import get_or_new_skill_storage
 
+            storage_kwargs = {"app_config": self.app_config} if self.app_config is not None else {}
+            storage = await asyncio.to_thread(get_or_new_skill_storage, **storage_kwargs)
             # Use asyncio.to_thread to avoid blocking the event loop (LangGraph ASGI requirement)
-            all_skills = await asyncio.to_thread(get_or_new_skill_storage().load_skills, enabled_only=True)
+            all_skills = await asyncio.to_thread(storage.load_skills, enabled_only=True)
             logger.info(f"[trace={self.trace_id}] Subagent {self.config.name} loaded {len(all_skills)} enabled skills from disk")
         except Exception:
             logger.warning(f"[trace={self.trace_id}] Failed to load skills for subagent {self.config.name}", exc_info=True)
@@ -395,6 +399,10 @@ class SubagentExecutor:
                 status=SubagentStatus.RUNNING,
                 started_at=datetime.now(),
             )
+        ai_messages = result.ai_messages
+        if ai_messages is None:
+            ai_messages = []
+            result.ai_messages = ai_messages
 
         try:
             agent = self._create_agent()
@@ -404,10 +412,12 @@ class SubagentExecutor:
             run_config: RunnableConfig = {
                 "recursion_limit": self.config.max_turns,
             }
-            context = {}
+            context: dict[str, Any] = {}
             if self.thread_id:
                 run_config["configurable"] = {"thread_id": self.thread_id}
                 context["thread_id"] = self.thread_id
+            if self.app_config is not None:
+                context["app_config"] = self.app_config
 
             logger.info(f"[trace={self.trace_id}] Subagent {self.config.name} starting async execution with max_turns={self.config.max_turns}")
 
@@ -454,13 +464,13 @@ class SubagentExecutor:
                         message_id = message_dict.get("id")
                         is_duplicate = False
                         if message_id:
-                            is_duplicate = any(msg.get("id") == message_id for msg in result.ai_messages)
+                            is_duplicate = any(msg.get("id") == message_id for msg in ai_messages)
                         else:
-                            is_duplicate = message_dict in result.ai_messages
+                            is_duplicate = message_dict in ai_messages
 
                         if not is_duplicate:
-                            result.ai_messages.append(message_dict)
-                            logger.info(f"[trace={self.trace_id}] Subagent {self.config.name} captured AI message #{len(result.ai_messages)}")
+                            ai_messages.append(message_dict)
+                            logger.info(f"[trace={self.trace_id}] Subagent {self.config.name} captured AI message #{len(ai_messages)}")
 
             logger.info(f"[trace={self.trace_id}] Subagent {self.config.name} completed async execution")