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 v2.1.221 Home All releases olderv2.1.220 v2.1.222newer

Background attach telemetry gets cold-start and surface dimensions

Under the hood
Useful1 Signal0
Telemetry

Background attach events now record cold starts, surface and first frame details.

What

The tengu_bg_attach_outcome event carries considerably more detail about how an attach happened.

Details
  • New attributes: attach_cold, daemon_booted, first_frame_kind, surface, a validated via, plus message-count fields.
  • Those attribute names were added to the low-cardinality attribute allowlist.
  • via is now filtered against a fixed set (starting, running, resuming and so on) rather than passed through as-is.
Evidence

first_frame_kind

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

See this entry in the whole of v2.1.221 →