Adds a case with the real block layout (attribution block, identity sentence,
task instructions) and asserts that user content mentioning Claude Code and
claude-sonnet-4-6 is forwarded unchanged.
Stripping the x-anthropic-billing-header line is not enough. Claude Code's
Agent SDK prompts (session title generation, and other SDK-driven calls) open
a separate system block with
You are a Claude agent, built on Anthropic's Claude Agent SDK.
and the Google upstream still rejects those requests with 429 RESOURCE_EXHAUSTED.
Measured on Sub2API 0.2.7, which already contains the attribution fix, using an isolated single-account group, waiting for the per-model cooldown
to expire before every request so that a previous failure could not turn later
results into 503:
original request replayed 429 (8/8)
same request, generic system prompt 200 (8/8)
attribution also removed client-side 429 (3/3)
attribution removed + identity neutralized 200 (3/3)
only 'Claude' replaced in system 200 (2/2)
only 'Anthropic' removed from system 200 (2/2)
output_config / max_tokens / non-stream no effect
The rewrite is anchored at the start of a system block, so user instructions that
merely mention Claude or Anthropic, and model ids such as claude-sonnet-4-6, are
left untouched. Scoped to the Antigravity transformer, as with the existing
attribution handling.
HuntercodeT