CLAUDE_PTY_HEARTBEAT_MS

Updated October 14, 2026 by Alex Sorokoletov

CLAUDE_PTY_HEARTBEAT_MS is a Claude Code environment variable. Added between v2.1.143 and v2.1.212 and still present in v2.1.295. It is not in the official reference.

Status	Present in v2.1.295
Added	Added between v2.1.143 and v2.1.212
Category	Other
Official docs	Not listed

How to set it

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

export CLAUDE_PTY_HEARTBEAT_MS=<value>
claude

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

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

Related variables

CLAUDE_PTY_RECORD: Enables PTY session recording for a background agent — captures the raw terminal byte stream as a bit-for-bit replay artifact, not just a transcript.
CLAUDE_PTY_HOST_EXEC
CLAUDE_PTY_HOST_NO_STABLE_PATH
CLAUDE_PTY_ORPHAN_CHECK_MS
ANTHROPIC_BETAS: Comma-separated beta feature headers.
ANTHROPIC_CUSTOM_HEADERS: Custom HTTP headers (newline-separated Key: Value).
ANTHROPIC_FEDERATION_RULE_ID
ANTHROPIC_ORGANIZATION_ID

Frequently asked questions

Which Claude Code version has CLAUDE_PTY_HEARTBEAT_MS?

Added between v2.1.143 and v2.1.212 and still present in v2.1.295.

How do I set CLAUDE_PTY_HEARTBEAT_MS?

Export it before starting Claude Code (export CLAUDE_PTY_HEARTBEAT_MS=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.