Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
TelemetryArea: what it touches
Internal ChangesKind: in v2.1.275,
Internal ChangesSection of the release
What
Claude Code now sends a telemetry event called tengu_thinking_drop whenever "thinking" blocks (the model's intermediate reasoning content) are removed from a request before it's sent, for example when there's a mismatch between the prefix of prior turns and the model currently bound to the session. The event records how many blocks and turns were affected, why they were dropped, which message positions were involved, and details of the client-side change that triggered the request.
Why
This gives visibility into a case where reasoning content silently gets stripped out, which should help diagnose situations where thinking output unexpectedly disappears from a conversation.
