Workspace with the model-connector crate. contract.rs, envelope.rs and client.rs
are CodexConnector lib.rs moved verbatim under the rename rule (strip the leading
Codex from identifiers); schema id strings are unchanged, so the v2 wire is
unchanged. canonical_responses_body stays behind: it is OpenAI Responses lowering.
The moved tests keep their bodies; shared fixtures live in fixtures.rs.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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