CLAUDE_CODE_SYNC_SESSION_REFS

Updated October 13, 2026 by Alex Sorokoletov

CLAUDE_CODE_SYNC_SESSION_REFS is a Claude Code environment variable: Enables syncing of session references in remote and child sessions. The gate function is true only when this variable is truthy and a CLAUDE_CODE_SESSION_ID is present, and the variable is a member of the env set propagated into remote sessions alongside CLAUDE_CODE_REMOTE, CLAUDE_CODE_CONTAINER_ID, and…. Added between v2.1.143 and v2.1.212 and still present in v2.1.294. 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_SYNC_SESSION_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_SYNC_SESSION_REFS": "<value>"
  }
}

Release notes that mention it

• Claude Code Version Tracker: Undocumented Env Vars, Feature Gates & Models
• claude-code-env-vars-v2-1-210

Related variables

• CLAUDE_BRIDGE_REATTACH_SESSION: Session identity used during bridge reconnection.
• CLAUDE_CODE_BRIDGE_SESSION_ID
• CLAUDE_CODE_CHILD_SESSION
• CLAUDE_CODE_EMIT_SESSION_STATE_EVENTS: Controls whether Claude Code emits session state change events.
• CLAUDE_CODE_FORCE_SESSION_PERSISTENCE
• CLAUDE_CODE_POST_FOR_SESSION_INGRESS_V2: Use POST-based session ingress v2.
• CLAUDE_CODE_REMOTE_SESSION_ID: Remote session identifier.
• CLAUDE_CODE_REMOTE_SESSION_ORIGIN: Provenance tag for cloud/remote sessions, checked against the value "review".

Frequently asked questions

All variables, searchable: Claude Code environment variables.