Move Antigravity schema-preservation policy into the format crate and expose provider-aware Chat and Responses builders through the existing gateway root seam. Preserve legacy conversion and scoped Responses history behavior without weakening architecture tests.
Validated: 61 standalone architecture tests, 947 format tests, 527 transport tests, 2 actual-source planner tests, and gateway cargo check.
Preserve tool schemas across provider-scoped format conversion and OpenAI gateway planners until the Antigravity boundary. Bound reference expansion, safely merge schema constraints, and lower unsupported Claude unions.
Drop unsigned historical Claude thinking without changing Gemini behavior. Add cross-format regression fixtures and retain the project's original error output policy.
Validation: 945 format tests and 527 transport tests passed; gateway cargo check passed.
wangpengxiang