Recent Claude Code CLI versions no longer emit the cch=... signature field in
their x-anthropic-billing-header system block (issue #3358). sub2api still
injected cch=00000 when mimicking Claude Code for OAuth accounts and optionally
signed it, so mimicked requests now diverge from real CLI traffic — the opposite
of what the mimicry is for.
- buildBillingAttributionText emits the block without the cch=00000 segment;
cc_version + cc_entrypoint=cli are kept (detection and Anthropic's first-party
signal rely on the block, not on cch).
- Retire signing: remove the two enableCCH signBillingHeaderCCH call sites in
buildUpstreamRequest / buildCountTokensRequest and delete the now-dead
signBillingHeaderCCH, cchPlaceholderRe, cchSeed, xxHash64Seeded helpers.
- enable_cch_signing is now a documented no-op (kept for backward compat).
- Drop the obsolete signing tests (TestSignBillingHeaderCCH, TestXXHash64Seeded,
TestSanitizeMustBeBeforeCCHSigning_HashConsistency) and update the prompt test
to assert the injected block no longer carries cch=.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
- Sync cc_version in x-anthropic-billing-header with the fingerprint
User-Agent version, preserving the message-derived suffix
- Implement xxHash64-based CCH signing to replace the cch=00000
placeholder with a computed hash
- Add admin toggle (enable_cch_signing) under gateway forwarding settings,
disabled by default
