CLAUDE_CODE_BASE_REFS

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_BASE_REFS is a Claude Code environment variable: Specifies base git references (branches, tags, or SHAs) for diff comparison when Claude Code operates in a worktree or feature branch. In multi-worktree agent workflows — where several subagents run in parallel on isolated worktrees — each agent needs to know what "main" means for its context. Its release history is not tracked here. It is not in the official reference.

Status	Present in v2.1.294
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_BASE_REFS=<value>
claude

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

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

Release notes that mention it

Related variables

CLAUDE_BASE: Likely overrides the base URL or base configuration path for Claude Code.
CLAUDE_CODE_BASE_REF: Git base ref for diff operations.
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.

Frequently asked questions

What does CLAUDE_CODE_BASE_REFS do?

Specifies base git references (branches, tags, or SHAs) for diff comparison when Claude Code operates in a worktree or feature branch. In multi-worktree agent workflows — where several subagents run in parallel on isolated worktrees — each agent needs to know what "main" means for its context.

Which Claude Code version has CLAUDE_CODE_BASE_REFS?

Its release history is not tracked here.

How do I set CLAUDE_CODE_BASE_REFS?

Export it before starting Claude Code (export CLAUDE_CODE_BASE_REFS=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.