Under the hoodTier: how much it should matter to you
3Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
Usage & LimitsArea: what it touches
Internal ChangesKind: in v2.1.227,
What probably matters to youSection of the release
What
The attribution header sent with API requests can now include a prompt id alongside the existing previous-request id. Each is emitted only if it matches a strict shape, a req_ prefix for the request id and a UUID for the prompt id, and only under first-party auth. Setting CLAUDE_CODE_ATTRIBUTION_HEADER suppresses the header entirely.
Evidence
cc_prompt_id=${n};
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
