Claude Code forks subagents by default and adds session @-mentions

Version 2.1.232, released August 13, 2026, changes two defaults around how a Claude Code session relates to other agents — its own subagents, and other Claude Code sessions entirely.

Forking is now the default

A subagent spawned with subagent_type: "fork" inherits the full parent conversation and its prompt cache, instead of starting from a blank context. As of 2.1.232, subagent forking is on by default. The same release also changes non-teammate agent spawns in interactive sessions to run in the background by default, rather than blocking the conversation while they work.

Reaching another session by name

Cross-session SendMessage isn't new — it landed in 2.1.224 (August 7, 2026) along with ListAgents for discovering sessions across any of your machines. 2.1.232 makes addressing more direct: type @ in the prompt to mention another Claude Code session by name, and Claude uses SendMessage to reach it. A bare name that exactly matches one live session now delivers immediately, instead of asking you to confirm with a [ref] suffix first.

Because names now double as direct addresses, Claude Code also started enforcing uniqueness: starting or renaming a session to a name another live session already holds gets a name-word-word variant instead of silently colliding, and you're told about it.

See the Claude Code sheet for the current subagent and session-messaging surface.