diff --git a/surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex/__init__.py b/surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex/__init__.py
new file mode 100644
index 000000000..17c33b8ab
--- /dev/null
+++ b/surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex/__init__.py
@@ -0,0 +1,25 @@
+"""Per-turn cooperative busy-lock middleware + cancel primitives (main-agent)."""
+
+from .builder import build_busy_mutex_mw
+from .middleware import (
+    BusyMutexMiddleware,
+    end_turn,
+    get_cancel_event,
+    get_cancel_state,
+    is_cancel_requested,
+    manager,
+    request_cancel,
+    reset_cancel,
+)
+
+__all__ = [
+    "BusyMutexMiddleware",
+    "build_busy_mutex_mw",
+    "end_turn",
+    "get_cancel_event",
+    "get_cancel_state",
+    "is_cancel_requested",
+    "manager",
+    "request_cancel",
+    "reset_cancel",
+]
diff --git a/surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex.py b/surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex/builder.py
similarity index 85%
rename from surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex.py
rename to surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex/builder.py
index c550a1207..0daf87e0b 100644
--- a/surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex.py
+++ b/surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex/builder.py
@@ -3,10 +3,11 @@
 from __future__ import annotations
 
 from app.agents.chat.multi_agent_chat.shared.feature_flags import AgentFeatureFlags
-from app.agents.chat.multi_agent_chat.shared.middleware.busy_mutex import (
+from app.agents.chat.multi_agent_chat.shared.middleware.flags import enabled
+
+from .middleware import (
     BusyMutexMiddleware,
 )
-from app.agents.chat.multi_agent_chat.shared.middleware.flags import enabled
 
 
 def build_busy_mutex_mw(flags: AgentFeatureFlags) -> BusyMutexMiddleware | None:
diff --git a/surfsense_backend/app/agents/chat/multi_agent_chat/shared/middleware/busy_mutex.py b/surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex/middleware.py
similarity index 100%
rename from surfsense_backend/app/agents/chat/multi_agent_chat/shared/middleware/busy_mutex.py
rename to surfsense_backend/app/agents/chat/multi_agent_chat/main_agent/middleware/busy_mutex/middleware.py
diff --git a/surfsense_backend/app/routes/new_chat_routes.py b/surfsense_backend/app/routes/new_chat_routes.py
index 5b63ce52b..0e4e557be 100644
--- a/surfsense_backend/app/routes/new_chat_routes.py
+++ b/surfsense_backend/app/routes/new_chat_routes.py
@@ -24,18 +24,18 @@ from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.future import select
 from sqlalchemy.orm import selectinload
 
+from app.agents.chat.multi_agent_chat.main_agent.middleware.busy_mutex import (
+    get_cancel_state,
+    is_cancel_requested,
+    manager,
+    request_cancel,
+)
 from app.agents.chat.multi_agent_chat.shared.filesystem_selection import (
     ClientPlatform,
     FilesystemMode,
     FilesystemSelection,
     LocalFilesystemMount,
 )
-from app.agents.chat.multi_agent_chat.shared.middleware.busy_mutex import (
-    get_cancel_state,
-    is_cancel_requested,
-    manager,
-    request_cancel,
-)
 from app.config import config
 from app.db import (
     ChatComment,
diff --git a/surfsense_backend/app/tasks/chat/streaming/errors/classifier.py b/surfsense_backend/app/tasks/chat/streaming/errors/classifier.py
index 6ae5af40f..6b37df343 100644
--- a/surfsense_backend/app/tasks/chat/streaming/errors/classifier.py
+++ b/surfsense_backend/app/tasks/chat/streaming/errors/classifier.py
@@ -7,7 +7,7 @@ import logging
 import time
 from typing import Any, Literal
 
-from app.agents.chat.multi_agent_chat.shared.middleware.busy_mutex import (
+from app.agents.chat.multi_agent_chat.main_agent.middleware.busy_mutex import (
     get_cancel_state,
     is_cancel_requested,
 )
diff --git a/surfsense_backend/app/tasks/chat/streaming/flows/new_chat/orchestrator.py b/surfsense_backend/app/tasks/chat/streaming/flows/new_chat/orchestrator.py
index 3ab36680e..e33dca376 100644
--- a/surfsense_backend/app/tasks/chat/streaming/flows/new_chat/orchestrator.py
+++ b/surfsense_backend/app/tasks/chat/streaming/flows/new_chat/orchestrator.py
@@ -30,11 +30,11 @@ from typing import Any, Literal
 import anyio
 
 from app.agents.chat.multi_agent_chat import create_multi_agent_chat_deep_agent
+from app.agents.chat.multi_agent_chat.main_agent.middleware.busy_mutex import end_turn
 from app.agents.chat.multi_agent_chat.shared.filesystem_selection import (
     FilesystemMode,
     FilesystemSelection,
 )
-from app.agents.chat.multi_agent_chat.shared.middleware.busy_mutex import end_turn
 from app.db import ChatVisibility, async_session_maker
 from app.observability import otel as ot
 from app.services.new_streaming_service import VercelStreamingService
diff --git a/surfsense_backend/app/tasks/chat/streaming/flows/resume_chat/orchestrator.py b/surfsense_backend/app/tasks/chat/streaming/flows/resume_chat/orchestrator.py
index 327a2376e..6d0924850 100644
--- a/surfsense_backend/app/tasks/chat/streaming/flows/resume_chat/orchestrator.py
+++ b/surfsense_backend/app/tasks/chat/streaming/flows/resume_chat/orchestrator.py
@@ -24,11 +24,11 @@ from uuid import UUID
 import anyio
 
 from app.agents.chat.multi_agent_chat import create_multi_agent_chat_deep_agent
+from app.agents.chat.multi_agent_chat.main_agent.middleware.busy_mutex import end_turn
 from app.agents.chat.multi_agent_chat.shared.filesystem_selection import (
     FilesystemMode,
     FilesystemSelection,
 )
-from app.agents.chat.multi_agent_chat.shared.middleware.busy_mutex import end_turn
 from app.db import ChatVisibility, async_session_maker
 from app.observability import otel as ot
 from app.services.chat_session_state_service import set_ai_responding
diff --git a/surfsense_backend/app/tasks/chat/streaming/flows/shared/rate_limit_recovery.py b/surfsense_backend/app/tasks/chat/streaming/flows/shared/rate_limit_recovery.py
index b059828bf..29018fe07 100644
--- a/surfsense_backend/app/tasks/chat/streaming/flows/shared/rate_limit_recovery.py
+++ b/surfsense_backend/app/tasks/chat/streaming/flows/shared/rate_limit_recovery.py
@@ -17,7 +17,7 @@ from typing import Literal
 
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.agents.chat.multi_agent_chat.shared.middleware.busy_mutex import end_turn
+from app.agents.chat.multi_agent_chat.main_agent.middleware.busy_mutex import end_turn
 from app.observability import otel as ot
 from app.services.auto_model_pin_service import (
     mark_runtime_cooldown,
diff --git a/surfsense_backend/tests/unit/agents/new_chat/test_busy_mutex.py b/surfsense_backend/tests/unit/agents/new_chat/test_busy_mutex.py
index c9ce67206..5a39c6e66 100644
--- a/surfsense_backend/tests/unit/agents/new_chat/test_busy_mutex.py
+++ b/surfsense_backend/tests/unit/agents/new_chat/test_busy_mutex.py
@@ -4,7 +4,7 @@ from __future__ import annotations
 
 import pytest
 
-from app.agents.chat.multi_agent_chat.shared.middleware.busy_mutex import (
+from app.agents.chat.multi_agent_chat.main_agent.middleware.busy_mutex import (
     BusyMutexMiddleware,
     end_turn,
     get_cancel_event,