{"version":"2.1.301","anchor":"agent-message-routing-gets-session-full-and-own-agents-only","canonical_anchor":"agent-message-routing-gets-session-full-and-own-agents-only","heading":"Messaging or resuming helper agents can now be refused when a session is full","tier":"notice","area":"Subagents","scope":"individual","heads_up":true,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.301\/e\/agent-message-routing-gets-session-full-and-own-agents-only","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.301","markdown":"### Messaging or resuming helper agents can now be refused when a session is full\n\nSending a message to a running agent now fails when the session is full, and resuming a stopped agent can be refused on a conflict\n\n**What**\n\nClaude can send messages to other agents, such as subagents (helper agents it starts to work on part of a task). Two cases now behave differently:\n\n- A running agent: if the session has no room left, the message is not sent and Claude gets a failure message instead. Before, the message was always queued.\n\n- A stopped agent: Claude Code first works out which agent to resume. If that runs into a conflict, it refuses unless the agent belongs to the one asking.\n\nWhen a stopped agent is resumed, the result now also gives the ID of the agent that was brought back.\n\n**Why**\n\nIn sessions with limited room, Claude may now be told it cannot message or resume an agent, rather than the message being queued anyway.\n\n- Area: Subagents\n- Tier: You'll notice\n- Useful: 3\/5\n- Signal: 3\/5\n- Scope: individual\n- Heads-up: yes"}