This adds `SetDefaultModel`, which takes `model` and `reasoning_effort` as optional fields. If set, the field will overwrite what is in the user's `config.toml`. This reuses logic that was added to support the `/model` command in the TUI: https://github.com/openai/codex/pull/2799.
codex-protocol
This crate defines the "types" for the protocol used by Codex CLI, which includes both "internal types" for communication between codex-core and codex-tui, as well as "external types" used with codex mcp.
This crate should have minimal dependencies.
Ideally, we should avoid "material business logic" in this crate, as we can always introduce Ext-style traits to add functionality to types in other crates.