<h2>What's changed</h2> <ul> <li>Subagent forking is now on by default: a <code>subagent_type: "fork"</code> subagent inherits the full conversation and prompt cache, and non-teammate agent spawns in interactive sessions now run in the background by default</li> <li>Type <code>@</code> in the prompt to mention another Claude session by name; Claude then uses <code>SendMessage</code> to reach that session directly</li> <li><code>SendMessage</code> now delivers to a bare name that exactly matches one live session, instead of asking to confirm with a ref first</li> <li>Interactive sessions on one