CLAUDE_CODE_EXPERIMENTAL_CODE_MODE

Updated November 3, 2026 by Alex Sorokoletov

CLAUDE_CODE_EXPERIMENTAL_CODE_MODE is a Claude Code environment variable: Opts into the experimental code mode; set it to 'on' to enable, an unrecognized value is refused as a bad value, and anything else leaves it not asked. Added in v2.1.318 and still present in v2.1.318. 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_EXPERIMENTAL_CODE_MODE=<value>
claude

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

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

Release notes that mention it

• Claude Code Version Tracker: Undocumented Env Vars, Feature Gates & Models
• claude-code-env-vars-v2-1-318

Related variables

• CLAUDE_CODE_EXPERIMENTAL_CODE_MODE_RESTART: Signals a restart into the experimental code mode; when set it triggers the startup opt-in, then the value is read once and cleared.
• CLAUDE_CODE_EXPERIMENTAL_CODE_MODE_RESTARTED_FROM: Records the prior state the experimental code mode was restarted from; it is read into the restart tracking and then cleared.
• CLAUDE_CODE_PERFORCE_MODE: Activates Perforce VCS integration.
• CLAUDE_CODE_PLAN_MODE_INTERVIEW_PHASE: Enable interview phase in plan mode.
• CLAUDE_CODE_PLAN_MODE_REQUIRED: Require agents to use plan mode for all tasks.
• CLAUDE_CODE_SAFE_MODE
• CLAUDE_CODE_TODO_REMINDER_MODE: Set to override the todo reminder mode; off turns the reminders off, otherwise baseline is used.
• CLAUDE_REPL_MODE: Sets the operating mode for the REPL interface.

Frequently asked questions

All variables, searchable: Claude Code environment variables.