Source Intelligence

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 v2.1.251 Home All releases olderv2.1.250
Claude Code v2.1.251

Live presence on artifacts, switched off in this build

Not switched on
Useful3 Signal5
Artifacts Notable not in their notes

Artifacts can show who else is viewing live, but only if you set an environment variable.

A full presence websocket subsystem is built and off unless a remote flag or env var enables it.

Feature flag
tengu_brass_plover Off in both readings

The flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.

This account: off · anonymous baseline: off · compiled default in v2.1.251: on

Read once, for one account on one subscription tier, against v2.1.251. It isn't a statement about your account. What a flag value here can and cannot tell you

CLAUDE_CODE_ARTIFACT_PRESENCE
What

A new subsystem opens a websocket to /api/frame/sync to track who is currently viewing an artifact, with owner and account verification, token refresh over the connection, reconnect and backoff, and its own telemetry. It is off by default: it turns on only if the remote config flag tengu_brass_plover is enabled or the environment variable CLAUDE_CODE_ARTIFACT_PRESENCE is set.

Details
  • The environment variable takes precedence over the remote flag; with neither, the check returns false and nothing connects.
  • Telemetry events under the "artifact_presence" name cover connection failures and stalls, including closed_4403, ws_open_error and stall_run_started.
Usage
CLAUDE_CODE_ARTIFACT_PRESENCE=1 claude
Evidence

tengu_brass_plover

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

See this entry in the whole of v2.1.251 →