CLAUDE_CODE_SENDMESSAGE_HANDBACK

Updated October 14, 2026 by Alex Sorokoletov

CLAUDE_CODE_SENDMESSAGE_HANDBACK is a Claude Code environment variable. Added in v2.1.285 and still present in v2.1.295. It is not in the official reference.

Status	Present in v2.1.295
Added	Added in v2.1.285
Category	Other
Official docs	Not listed

How to set it

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

export CLAUDE_CODE_SENDMESSAGE_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_SENDMESSAGE_HANDBACK": "<value>"
  }
}

Related variables

CLAUDE_CODE_HANDBACK_PROVENANCE
ANTHROPIC_BETAS: Comma-separated beta feature headers.
ANTHROPIC_CUSTOM_HEADERS: Custom HTTP headers (newline-separated Key: Value).
ANTHROPIC_FEDERATION_RULE_ID
ANTHROPIC_ORGANIZATION_ID
ANTHROPIC_WORKSPACE_ID
BETA_TRACING_ENDPOINT: Custom endpoint for beta tracing.
CLAUDE_AFK_COUNTDOWN_MS

Frequently asked questions

Which Claude Code version has CLAUDE_CODE_SENDMESSAGE_HANDBACK?

Added in v2.1.285 and still present in v2.1.295.

How do I set CLAUDE_CODE_SENDMESSAGE_HANDBACK?

Export it before starting Claude Code (export CLAUDE_CODE_SENDMESSAGE_HANDBACK=value), or add it to the "env" object in ~/.claude/settings.json to apply it to every session.

All variables, searchable: Claude Code environment variables.