Support sudo password flow for shell commands

prompts/roles/action.md

@@ -12,9 +12,6 @@ Available tools:
   Args: {"path": "."}
 - search_files: search text inside files in the current workspace.
   Args: {"query": "text to find", "path": ".", "glob": "*.py"}
-- os_update_check: check available operating system package updates without
-  refreshing package manager caches and without sudo.
-  Args: {}
 - shell_exec_safe: run a safe allowlisted shell command in the current workspace.
   Args: {"command": "pwd"}
 
@@ -24,6 +21,9 @@ follow-up information. Return actions=[] when the observations are sufficient
 for the thinker to answer.
 Use only the listed tools. Keep actions minimal and directly tied to the user's
 request. Do not invent tool names.
-For user requests like "check updates in the system", use os_update_check.
-Do not use apt update, apt-get update, sudo, su, or package installation commands
-for update checks.
+For user requests like "check updates in the system", use shell_exec_safe with
+`apt list --upgradable`. Do not use apt update, apt-get update, sudo, su, or
+package installation commands for a read-only update check.
+For commands that genuinely require elevated privileges, use the real system
+command with `sudo` through shell_exec_safe. DuckLM will ask the user for
+approval and then for the sudo password when the command needs it.