CLAUDE_CODE_DISABLE_SUBAGENT_HANDBACK

Updated November 2, 2026 by Alex Sorokoletov

CLAUDE_CODE_DISABLE_SUBAGENT_HANDBACK is a Claude Code environment variable: When set, turns off subagent handback; when unset, the value falls back to CLAUDE_CODE_SENDMESSAGE_HANDBACK and then to a server-side setting. Added between v2.1.315 and v2.1.317 and still present in v2.1.317. It is not in the official reference.

How to set it

For one session, export it in the shell that starts Claude Code:

export CLAUDE_CODE_DISABLE_SUBAGENT_HANDBACK=<value>
claude

To apply it to every session, add it to the env object of a settings file:

// ~/.claude/settings.json
{
  "env": {
    "CLAUDE_CODE_DISABLE_SUBAGENT_HANDBACK": "<value>"
  }
}

Related variables

• CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS: Disable built-in agent types.
• CLAUDE_CODE_DISABLE_AGENT_VIEW: Disables Agent View.
• CLAUDE_CODE_DISABLE_AGENTS_FLEET: Kill switch for the entire agent fleet subsystem — no selection, no auto-relaunch, no fleet coordination.
• CLAUDE_CODE_DISABLE_EXPLORE_PLAN_AGENTS
• CLAUDE_CODE_DISABLE_WORKFLOWS
• CLAUDE_CODE_ENABLE_APPEND_SUBAGENT_PROMPT: Authorizes SDK callers to append a custom string to a subagent's system prompt via options.appendSubagentSystemPrompt.
• CLAUDE_CODE_FORK_SUBAGENT: Changelog-confirmed[1]: set to 1 to run subagents as forked processes (v2.1.117 on external builds, v2.1.121 extended to non-interactive SDK/-p sessions).
• CLAUDE_CODE_FORWARD_SUBAGENT_TEXT: Includes subagent text and thinking in stream-json output, paired with a new --forward-subagent-text flag.

Frequently asked questions

All variables, searchable: Claude Code environment variables.