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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.239 Home All releases olderv2.1.238 v2.1.240newer
Claude Code v2.1.239

Hosted cloud sessions can spawn a separate vitals reporting process, off unless a binary path is pinned

Not switched on
Useful1 Signal3
Cloud Sessions not in their notes

Hosted cloud sessions can spawn a separate health-reporting helper, which never resolves on a normal install.

A vitals-emitter-guest child process is built in pinned mode, so nothing resolves outside hosted cloud workers.

--token-fileCLAUDE_CODE_DISABLE_VITALS_EMITTER
What

Sessions running on Anthropic's hosted cloud workers can launch an external helper called vitals-emitter-guest as a child process that reports session health back to the service. It only starts when there is an SDK URL, a remote session id and a readable session token file, so anyone running the CLI locally never sees it. The cloud session launcher builds the emitter in pinned mode, and in that mode the path resolver will not search PATH, so on a normal install nothing resolves and nothing spawns.

Details
  • The child is invoked with --session-id, --api-url and --token-file.
  • The binary path comes from the VITALS_EMITTER_BIN environment variable, which must be absolute, otherwise a PATH lookup, otherwise a fallback of /root/.local/bin/vitals-emitter-guest; pinned mode skips the PATH lookup entirely, so with no absolute VITALS_EMITTER_BIN the emitter resolves to nothing and stays off.
  • Setting CLAUDE_CODE_DISABLE_VITALS_EMITTER turns it off, and essential-traffic-only mode bails out of it too.
  • The child runs with a scrubbed environment holding only PATH, HOME, TMPDIR, the proxy variables and SSL_CERT_FILE.
  • The process is supervised: respawned with backoff, stopped with SIGTERM then SIGKILL, and its stderr is piped into the log.
  • Telemetry under the name ccr_vitals_emitter records success, spawn_failed and exited_unexpectedly.
  • None of this machinery is present in 2.1.238.
Evidence

[vitals] kill switch or essential-traffic-only set; guest vitals disabled, [vitals] VITALS_EMITTER_BIN not set; guest vitals disabled (this launcher does not search PATH)

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.239 →