CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_MODE is a Claude Code environment variable. Added between v2.1.128 and v2.1.138 and still present in v2.1.294. It is listed in the official reference.

How to set it

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

export CLAUDE_CODE_ENABLE_OPUS_4_7_FAST_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_ENABLE_OPUS_4_7_FAST_MODE": "<value>"
  }
}

Related variables

• CLAUDE_CODE_OPUS_4_6_FAST_MODE_OVERRIDE: Pin Fast mode to Opus 4.6.
• CLAUDE_CODE_DISABLE_FAST_MODE: Disable the /fast toggle that uses the same model with faster output.
• CLAUDE_CODE_SKIP_FAST_MODE_NETWORK_ERRORS: Controls whether Claude Code suppresses or bypasses network errors that occur specifically in fast mode.
• CLAUDE_CODE_SKIP_FAST_MODE_ORG_CHECK: Disables the organization-level eligibility check for fast mode.
• ANTHROPIC_DEFAULT_OPUS_MODEL: Override Opus model ID.
• ANTHROPIC_DEFAULT_OPUS_MODEL_DESCRIPTION
• ANTHROPIC_DEFAULT_OPUS_MODEL_NAME
• ANTHROPIC_DEFAULT_OPUS_MODEL_SUPPORTED_CAPABILITIES

Frequently asked questions

All variables, searchable: Claude Code environment variables.