CLAUDE_RUNNER_ALIVE_EVERY_MS
A Claude Code environment variable, read out of the shipped bundle. It has been in the build since v2.1.309, including the newest one read.
Runner sessions now print a notice when a turn starts before the session's start-up message, with optional heartbeats via CLAUDE_RUNNER_ALIVE_EVERY_MS
Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.309.
In the changelogs
2Releases whose published page names CLAUDE_RUNNER_ALIVE_EVERY_MS.
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v2.1.309
Runner output now signals life while a session's start-up is delayed
Runner sessions now print a notice when a turn starts before the session's start-up message, with optional heartbeats via
CLAUDE_RUNNER_ALIVE_EVERY_MSfound in this entry's text
-
v2.1.309
Runners pass CLAUDE_RUNNER_ALIVE_EVERY_MS and can apply session tokens while running
CLAUDE_RUNNER_ALIVE_EVERY_MS is now passed through, and session and OAuth tokens can be applied while running in a certain mode
named in this entry, found in this entry's text
First cited
1The earliest release whose published evidence quoted CLAUDE_RUNNER_ALIVE_EVERY_MS was v2.1.309, 22 Oct 2026. That is the oldest release this project wrote about it, so it is a floor on the name's age and not the release that introduced it. It is not a presence reading: which builds carried the name is the table below.
Presence across releases
1Build by build
1One row per release since the first build this name was read out of. Absent means the build was read and the name was not in it, never mined means no bundle for that release was ever archived, and a declared type or a default is only ever what that release's own bundle stated.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the environment variable does. All environment variables.