CLAUDE_CODE_SUBAGENT_HISTORY

Updated October 23, 2026 by Alex Sorokoletov

CLAUDE_CODE_SUBAGENT_HISTORY is a Claude Code environment variable: Gates a subagent history view; when unset the view falls back to the tengu_rustling_crescent feature gate, which is off by default. Present in v2.1.307, with no mention in that release's changelog. Removed in v2.1.310, so current releases ignore it. 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_SUBAGENT_HISTORY=<value>
claude

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

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

Release notes that mention it

• Claude Code Version Tracker: Undocumented Env Vars, Feature Gates & Models
• claude-code-env-vars-v2-1-307

Related variables

• CLAUDE_CODE_ENABLE_APPEND_SUBAGENT_PROMPT: Authorizes SDK callers to append a custom string to a subagent's system prompt via options.appendSubagentSystemPrompt.
• CLAUDE_CODE_FORK_SUBAGENT: Changelog-confirmed[1]: set to 1 to run subagents as forked processes (v2.1.117 on external builds, v2.1.121 extended to non-interactive SDK/-p sessions).
• CLAUDE_CODE_FORWARD_SUBAGENT_TEXT: Includes subagent text and thinking in stream-json output, paired with a new --forward-subagent-text flag.
• CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH: Nesting-depth cap on delegation, default 1 — subagents no longer spawn their own subagents, and the team roster stays flat.
• CLAUDE_CODE_SUBAGENT_MODEL: Force a specific model for sub-agent operations.
• CLAUDE_CODE_SUBAGENT_MODEL_FORCE
• CLAUDE_CODE_SUBAGENT_MODELU: The trailing-U variant flagged as a likely typo in v2.1.84 has been removed.
• CLAUDE_CODE_SUBAGENT_PROMPT_CACHE_TTL

Frequently asked questions

All variables, searchable: Claude Code environment variables.