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All of v2.1.176 Home All releases olderv2.1.175 v2.1.177newer
Claude Code v2.1.176

Explicit Fork Selection for Agent Tool

What

The subagent_type: "fork" value is now a named, explicitly-selectable agent type rather than the implicit default when no subagent_type is provided. This makes multi-agent code clearer and avoids accidental forking.

Details
  • Omitting subagent_type (when the fork experiment is active) previously implicitly created a fork; now the behavior is documented as explicit opt-in via "fork"
  • Remote sessions cannot use isolation: "remote" with fork — a clear error is returned
  • Other named agent types still start with zero context
  • The Agent tool description has been updated to reflect this
Evidence

Updated Agent tool description (search for "(except subagent_type: \"fork\")" and "Fork cannot use isolation: \"remote\"")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.176 →