{"version":"2.1.227","anchor":"billing-attribution-header-carries-a-prompt-id-and-validates","canonical_anchor":"billing-attribution-header-carries-a-prompt-id-and-validates","heading":"Billing attribution header carries a prompt id and validates its values","tier":"internal","area":"Usage & Limits","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.227\/e\/billing-attribution-header-carries-a-prompt-id-and-validates","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.227","markdown":"### Billing attribution header carries a prompt id and validates its values\n\nUsage attribution headers can carry a prompt id, and one env var suppresses the header entirely.\n\n**What**\n\nThe 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.\n\n**Evidence**\n\n` cc_prompt_id=${n};`\n\n- Area: Usage & Limits\n- Names: `CLAUDE_CODE_ATTRIBUTION_HEADER`\n- Tier: Under the hood\n- Useful: 3\/5\n- Signal: 3\/5"}