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Sweep 22 Oct 2026 · 21:04Z Build v2.1.309 528 read Stable v2.1.308 Latest v2.1.309 Next v2.1.309 Feeds RSS JSON llms.txt llms-full.txt Unofficial

Claude Code v2.1.221 ·

Background-session telemetry records how a session was attached

Background session telemetry now records whether an attach was cold, spare or adopted.

Under the hood Internal Changes
JSON All of v2.1.221
Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
TelemetryArea: what it touches
Internal ChangesKind: in v2.1.221,
Internal ChangesSection of the release
What

Background and daemon dispatch and attach telemetry now emit a via property describing the attach path, sanitized so only three values can ever be reported.

Details
  • Allow-list is cold, spare and adopted; anything else becomes undefined.
  • The value is read from the daemon's attach ack (Nr.op === "attach") and from the dispatch source.
  • The previous build emits no such field.
Evidence

new Set(["cold", "spare", "adopted"])

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 →

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