Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
Usage & LimitsArea: what it touches
Internal ChangesKind: in v2.1.284,
Internal ChangesSection of the release
What
The x-anthropic-billing-header is a label Claude Code attaches to its requests. It already carried cc_prev_req, cc_prompt_id, cc_turn_origin and cc_workload. It now also adds cc_prompt_index and cc_turn_index (roughly, which prompt and which turn of the session a request belongs to) when:
both values are present,
the connection is direct to Anthropic (firstParty), and
an extra check (xs()) passes.
The pattern that strips these fields out now removes the two new ones as well. The existing opt-out through CLAUDE_CODE_ATTRIBUTION_HEADER still applies.
Why
Requests sent directly to Anthropic now say where they fall within a session. If you do not want the attribution information sent, CLAUDE_CODE_ATTRIBUTION_HEADER remains the setting to 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 doubtOne additional condition on when the header is sent was not identified.
