fix(exec): isolate exec session managers

nanobot/agent/loop.py

@@ -28,6 +28,7 @@ from nanobot.agent.model_runtime import ModelRuntimeResolver
 from nanobot.agent.runner import _MAX_INJECTIONS_PER_TURN, AgentRunner, AgentRunSpec
 from nanobot.agent.subagent import SubagentManager
 from nanobot.agent.tools.context import RequestContext, bind_request_context, reset_request_context
+from nanobot.agent.tools.exec_session import ExecSessionManager
 from nanobot.agent.tools.file_state import FileStateStore, bind_file_states, reset_file_states
 from nanobot.agent.tools.message import MessageTool
 from nanobot.agent.tools.registry import ToolRegistry
@@ -355,6 +356,7 @@ class AgentLoop:
         # One file-read/write tracker per logical session. The tool registry is
         # shared by this loop, so tools resolve the active state via contextvars.
         self._file_state_store = FileStateStore()
+        self._exec_session_manager = ExecSessionManager()
         self.runner = AgentRunner()
         self.subagents = SubagentManager(
             workspace=workspace,
@@ -540,6 +542,7 @@ class AgentLoop:
             bus=self.bus,
             subagent_manager=self.subagents,
             cron_service=self.cron_service,
+            exec_session_manager=self._exec_session_manager,
             sessions=self.sessions,
             provider_snapshot_loader=provider_snapshot_loader,
             image_generation_provider_configs=self._image_generation_provider_configs,