I inadvertently regressed support for the Responses API when adding support for the chat completions API in https://github.com/openai/codex/pull/862. This should get both APIs working again, but the chat completions codepath seems more complex than necessary. I'll try to clean that up shortly, but I want to get things working again ASAP.
codex-core
This crate implements the business logic for Codex. It is designed to be used by the various Codex UIs written in Rust.
Though for non-Rust UIs, we are also working to define a protocol for talking to Codex. See:
You can use the proto subcommand using the executable in the cli crate to speak the protocol using newline-delimited-JSON over stdin/stdout.