CLAUDE_REPL_VARIANT

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_REPL_VARIANT is a Claude Code environment variable: Selects which REPL implementation to load. Multiple variants coexist in the native binary; this key lets Anthropic A/B-test REPL behavior without separate builds. Removed between v2.1.269 and v2.1.283, so current releases ignore it. It is not in the official reference.

Status	Removed between v2.1.269 and v2.1.283
Added	Added in v2.1.108
Category	Other
Official docs	Not listed

How to set it

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

export CLAUDE_REPL_VARIANT=<value>
claude

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

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

Release notes that mention it

Related variables

CLAUDE_CODE_REPL: Boolean toggle for the new native REPL path introduced by v2.1.113's native-binary launcher.
CLAUDE_REPL_MODE: Sets the operating mode for the REPL interface.
CLAUDE_REPL_MODE0: Prototype naming for the REPL mode configuration.
CLAUDE_CODE_ARTIFACT_REPL
CLAUDE_CODE_ARTIFACT_TEXT_VARIANT
CLAUDE_REPL_VERBOSE
ANTHROPIC_BETAS: Comma-separated beta feature headers.
ANTHROPIC_CUSTOM_HEADERS: Custom HTTP headers (newline-separated Key: Value).

Frequently asked questions

What does CLAUDE_REPL_VARIANT do?

Selects which REPL implementation to load. Multiple variants coexist in the native binary; this key lets Anthropic A/B-test REPL behavior without separate builds.

Which Claude Code version has CLAUDE_REPL_VARIANT?

Removed between v2.1.269 and v2.1.283, so current releases ignore it.

How do I set CLAUDE_REPL_VARIANT?

Export it before starting Claude Code (export CLAUDE_REPL_VARIANT=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.