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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial
HomeReleasesv2.1.221entry #77

Claude Code v2.1.221 ·

Background sessions emit "interactive-mark" frames

Background sessions now send readiness marks so attaching knows when a session is actually interactive.

Under the hood Notable Internal Changes
JSON All of v2.1.221
Under the hoodTier: how much it should matter to you
3Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
SessionsArea: what it touches
Internal ChangesKind: in v2.1.221,
What probably matters to youSection of the release
What

A new frame type flows from a background or rendezvous session to the daemon, carrying interactivity marks used to decide attach readiness.

Details
  • marks are queued before the socket is up
  • deduped to at most two, one per kind, per record
  • replayed to attachers that advertise the imark capability, forwarded with the attacher's own nonce
  • included in the session snapshot
  • new marksCapable and bootingForAttachMetrics accessors derive attach-readiness from the marks, feeding "marks capable" attach metrics
  • malformed frames are dropped with a warning and counted via a new event
  • none of this exists in v2.1.220
Evidence

dropped malformed rv interactive-mark frame, tengu_bg_imark_malformed

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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