Messages to a stopped agent now say whether you stopped it

Claude can start helper agents and send them messages with the SendMessage tool. When a message goes to an agent that has stopped and is not resumed, the reply now depends on why it stopped:

• if you stopped it, it says the agent "was stopped by the user"
• otherwise, it says the agent "was stopped"

Both go on to say the agent was not resumed and that its work should be treated as cancelled. Before, the reply always said the agent was stopped by the user. When an agent is resumed, it now also keeps the critical reminders it inherited.