Follow-up PR to #5569. Add Keyring Support for Auth Storage in Codex CLI as well as a hybrid mode (default to persisting in keychain but fall back to file when unavailable.) It also refactors out the keyringstore implementation from rmcp-client [here](https://github.com/openai/codex/blob/main/codex-rs/rmcp-client/src/oauth.rs) to a new keyring-store crate. There will be a follow-up that picks the right credential mode depending on the config, instead of hardcoding `AuthCredentialsStoreMode::File`.
codex-core
This crate implements the business logic for Codex. It is designed to be used by the various Codex UIs written in Rust.
Dependencies
Note that codex-core makes some assumptions about certain helper utilities being available in the environment. Currently, this support matrix is:
macOS
Expects /usr/bin/sandbox-exec to be present.
Linux
Expects the binary containing codex-core to run the equivalent of codex sandbox linux (legacy alias: codex debug landlock) when arg0 is codex-linux-sandbox. See the codex-arg0 crate for details.
All Platforms
Expects the binary containing codex-core to simulate the virtual apply_patch CLI when arg1 is --codex-run-as-apply-patch. See the codex-arg0 crate for details.