task_shell_start delegates to ExecShellTool, providing the same shell
execution capability as exec_shell. Previously, task_shell_start was
registered unconditionally in with_runtime_task_tools while exec_shell
was gated behind allow_shell, creating an inconsistent security gate.
This caused the model to try exec_shell first, fail, then fall back to
task_shell_start — wasting tokens and bypassing the intended security
boundary.
Split TaskShellStartTool and TaskShellWaitTool out of
with_runtime_task_tools into a new with_runtime_task_shell_tools method,
and gate both behind the allow_shell check in with_agent_tools.
Closes#2303
Hu Qiantao
ed81d13782