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 v2.1.248 Home All releases olderv2.1.247 v2.1.250newer
Claude Code v2.1.248

Cloud sessions can serve your local tools to the remote worker and sign their events

Not switched on
Useful3 Signal5
Cloud Sessions Notable

Cloud sessions can expose your local tools to the remote worker and sign events with a device key.

Served-tool channel and device-key event signing are wired into attach but require server enablement.

Feature flag
tengu_violin_wood 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 v2.1.248: on

Read once, for one account on one subscription tier, against v2.1.248. It isn't a statement about your account. What a flag value here can and cannot tell you

What

Attaching to a cloud session now opens a second channel that lets the remote worker call tools running on your own machine, and signs the events the session sends back using a key tied to the device you bound to your account. The attach path loads both pieces in parallel and hands the session its served tools, a slot for a single in-flight served call, a callback for served-settings changes and the event signer. None of it runs in this build unless it is switched on server-side.

Details
  • Only sessions whose descriptor lists served tools open the channel; viewer-only sessions are skipped.
  • At most one served tool call is held in flight at a time.
  • State changes are announced to the worker with the reasons worker_init, attached, reconnected and tools_changed.
  • Events are signed by a signer keyed on the bound device id, and the headless send path uses the sibling signer keyed on the id bound to that session.
  • Gated behind the flag tengu_violin_wood, whose value compiled into this build is false, so the whole path stays dark by default; the signing and tool-serving also require the device to have been bound to your account, and with that gate off none of it runs.
Evidence

deviceEventSignerOnceBoundHere, eventSigner, requestAnnounce("worker_init", {

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

See this entry in the whole of v2.1.248 →