fix(exec): isolate exec session managers

tests/tools/test_exec_session_tools.py

@@ -7,6 +7,7 @@ import subprocess
 import sys
 import time
 
+from nanobot.agent.tools.context import RequestContext, bind_request_context, reset_request_context
 from nanobot.agent.tools.exec_session import (
     ExecSessionManager,
     ListExecSessionsTool,
@@ -398,6 +399,56 @@ def test_list_exec_sessions_reports_running_commands(tmp_path):
     assert "Session terminated." in cleanup
 
 
+def test_exec_sessions_are_scoped_to_request_session_key(tmp_path):
+    async def run() -> tuple[str, str, str, str, str, str]:
+        manager = ExecSessionManager()
+        exec_tool = ExecTool(working_dir=str(tmp_path), timeout=5, session_manager=manager)
+        list_tool = ListExecSessionsTool(manager=manager)
+        stdin_tool = WriteStdinTool(manager=manager)
+        command = _python_command(
+            "import time; print('ready', flush=True); time.sleep(5)"
+        )
+
+        token_a = bind_request_context(
+            RequestContext(channel="cli", chat_id="a", session_key="cli:a")
+        )
+        try:
+            initial = await exec_tool.execute(command=command, yield_time_ms=100)
+            sid = _session_id(initial)
+            owner_listing = await list_tool.execute()
+        finally:
+            reset_request_context(token_a)
+
+        unbound_listing = await list_tool.execute()
+
+        token_b = bind_request_context(
+            RequestContext(channel="cli", chat_id="b", session_key="cli:b")
+        )
+        try:
+            other_listing = await list_tool.execute()
+            other_write = await stdin_tool.execute(session_id=sid, yield_time_ms=0)
+        finally:
+            reset_request_context(token_b)
+
+        token_a = bind_request_context(
+            RequestContext(channel="cli", chat_id="a", session_key="cli:a")
+        )
+        try:
+            cleanup = await stdin_tool.execute(session_id=sid, terminate=True, yield_time_ms=0)
+        finally:
+            reset_request_context(token_a)
+
+        return sid, owner_listing, unbound_listing, other_listing, other_write, cleanup
+
+    sid, owner_listing, unbound_listing, other_listing, other_write, cleanup = asyncio.run(run())
+
+    assert sid in owner_listing
+    assert unbound_listing == "No active exec sessions."
+    assert other_listing == "No active exec sessions."
+    assert other_write == f"Error: exec session not found: {sid!r}"
+    assert "Session terminated." in cleanup
+
+
 def test_list_exec_sessions_reports_empty_state():
     result = asyncio.run(ListExecSessionsTool(manager=ExecSessionManager()).execute())