You'll noticeTier: how much it should matter to you
4Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
SDKArea: what it touches
New FeaturesKind: in v2.1.287,
What probably matters to youSection of the release
What
The SDK is the toolkit programs use to run Claude Code and receive its output as a stream of messages. A message holding a single thinking block, the model's step-by-step reasoning streamed as it happens, can now carry an optional thinking_duration_ms field. It gives, in milliseconds, how long that block took to stream.
Why
Apps built on Claude Code can show how long the model thought. The field is marked as internal, so it may not be meant for general use.
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtIt is not confirmed that every program receiving these messages gets the field.
