{"version":"2.1.15","anchor":"api-billing-attribution-headers","canonical_anchor":"api-billing-attribution-headers","heading":"API Billing Attribution Headers","tier":null,"area":null,"scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.15\/e\/api-billing-attribution-headers","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.15","markdown":"### API Billing Attribution Headers\n\n**What**\n\nClaude Code now sends version and entrypoint information in API requests for better usage tracking and diagnostics.\n\n**Details**\n\n- Header format: `x-anthropic-billing-header: cc_version=2.1.15.{hash}; cc_entrypoint={entrypoint}`\n- The entrypoint is read from `CLAUDE_CODE_ENTRYPOINT` environment variable (defaults to \"unknown\")\n- Previously this header was stubbed to always return an empty string (gated by `tengu_ant_attribution_header_new` flag)\n\n**Evidence**\n\n`X61()` at line 158274 (attribution header generator, contains `\"x-anthropic-billing-header\"`)"}