diff --git a/offline-backend-20260512/.env b/offline-backend-20260512/.env
index f5e4b4cf..3e28ef53 100644
--- a/offline-backend-20260512/.env
+++ b/offline-backend-20260512/.env
@@ -60,5 +60,6 @@ ELEMENT_STATE_FILE=/app/backend/.deer-flow/element-bot-token
 # PYTHON_TRUSTED_HOST=your-python-mirror
 MYSQL_DATABASE_URL=mysql+asyncmy://deerflow:deerflow123@192.168.0.123:3306/deerflow?charset=utf8mb4
 DEER_FLOW_NOTEBOOK_API_BASE=http://127.0.0.1:8003
-# 圆桌后台作业网关：inprocess=进程内驱动真模型；simulated=模拟（默认）
+# 圆桌后台作业网关：缺省即 inprocess（进程内驱动真模型，后台挂起开箱即用）；
+# 仅前端联调时显式设 simulated（真实进度但不调真模型）。本行可删，留作文档。
 ROUNDTABLE_JOB_GATEWAY=inprocess
diff --git a/offline-backend-20260512/backend/app/gateway/deps.py b/offline-backend-20260512/backend/app/gateway/deps.py
index 03a98168..109d32d2 100644
--- a/offline-backend-20260512/backend/app/gateway/deps.py
+++ b/offline-backend-20260512/backend/app/gateway/deps.py
@@ -38,6 +38,17 @@ if TYPE_CHECKING:
 T = TypeVar("T")
 
 
+def resolve_roundtable_gateway_mode(raw: str | None) -> str:
+    """解析 ``ROUNDTABLE_JOB_GATEWAY``：**默认 ``inprocess``（真模型后台挂起）**。
+
+    只有显式写 ``simulated`` 才用模拟网关（前端联调用：真实进度、不调真模型）；
+    缺省 / 空串 / 其它值一律落到 ``inprocess`` —— 部署时无需在 .env 里配置任何值，
+    后台挂起开箱即用（Phase 3b 已在 Windows 本地与内网 Docker 验证）。
+    """
+    mode = (raw or "").strip().lower()
+    return "simulated" if mode == "simulated" else "inprocess"
+
+
 def get_config(request: Request) -> AppConfig:
     """Return the app-scoped ``AppConfig`` stored on ``app.state``."""
     config = getattr(request.app.state, "config", None)
@@ -225,25 +236,17 @@ async def langgraph_runtime(app: FastAPI) -> AsyncGenerator[None, None]:
         _register_roundtable_job_default_store(app.state.roundtable_job_store)
 
         # 圆桌后台作业执行器：把编排引擎作为后台任务跑。
-        # 网关由环境变量 ``ROUNDTABLE_JOB_GATEWAY`` 选择：
-        #   - "inprocess"（Phase 3b）：进程内驱动真模型（leader/seat/report）；
-        #   - 其它/缺省（Phase 3a）：模拟网关，产生真实进度但不调真模型，供前端联调。
-        # 默认 simulated —— 真网关需在能起完整后端栈 + 真模型的环境验证后再开。
+        # 网关由环境变量 ``ROUNDTABLE_JOB_GATEWAY`` 选择（见 resolve_roundtable_gateway_mode）：
+        #   - 缺省 / "inprocess"（Phase 3b）：进程内驱动真模型（leader/seat/report）——**默认**，
+        #     部署时无需任何配置即可用后台挂起；
+        #   - 显式 "simulated"（Phase 3a）：模拟网关，产生真实进度但不调真模型，供前端联调。
         if app.state.roundtable_job_store is not None:
             import os
 
             from app.gateway.roundtable_job_executor import RoundtableJobExecutor
 
-            gateway_mode = (os.getenv("ROUNDTABLE_JOB_GATEWAY") or "simulated").strip().lower()
-            if gateway_mode == "inprocess":
-                from app.gateway.roundtable_inprocess_gateway import InProcessRoundtableGateway
-
-                _app = app  # 闭包捕获 app，供网关访问 app.state（checkpointer/thread_store）
-                gateway_factory = lambda p: InProcessRoundtableGateway(  # noqa: E731
-                    _app, user_id=p.user_id, agents=p.agents, model=p.model
-                )
-                logger.info("[roundtable-jobs] gateway = inprocess (real models)")
-            else:
+            gateway_mode = resolve_roundtable_gateway_mode(os.getenv("ROUNDTABLE_JOB_GATEWAY"))
+            if gateway_mode == "simulated":
                 from deerflow.agents.roundtable_orchestrator import SimulatedRoundtableGateway
 
                 # delay=3s/步：让模拟后台任务有可观察的进行中时长（切页/重连仍在跑）。
@@ -251,6 +254,14 @@ async def langgraph_runtime(app: FastAPI) -> AsyncGenerator[None, None]:
                     p.agents, mode=p.mode, delay=3.0
                 )
                 logger.info("[roundtable-jobs] gateway = simulated")
+            else:
+                from app.gateway.roundtable_inprocess_gateway import InProcessRoundtableGateway
+
+                _app = app  # 闭包捕获 app，供网关访问 app.state（checkpointer/thread_store）
+                gateway_factory = lambda p: InProcessRoundtableGateway(  # noqa: E731
+                    _app, user_id=p.user_id, agents=p.agents, model=p.model
+                )
+                logger.info("[roundtable-jobs] gateway = inprocess (real models, default)")
 
             app.state.roundtable_job_executor = RoundtableJobExecutor(
                 app.state.roundtable_job_store,