5881c0d6d4
We continue the separation between `codex app-server` and `codex mcp-server`. In particular, we introduce a new crate, `codex-app-server-protocol`, and migrate `codex-rs/protocol/src/mcp_protocol.rs` into it, renaming it `codex-rs/app-server-protocol/src/protocol.rs`. Because `ConversationId` was defined in `mcp_protocol.rs`, we move it into its own file, `codex-rs/protocol/src/conversation_id.rs`, and because it is referenced in a ton of places, we have to touch a lot of files as part of this PR. We also decide to get away from proper JSON-RPC 2.0 semantics, so we also introduce `codex-rs/app-server-protocol/src/jsonrpc_lite.rs`, which is basically the same `JSONRPCMessage` type defined in `mcp-types` except with all of the `"jsonrpc": "2.0"` removed. Getting rid of `"jsonrpc": "2.0"` makes our serialization logic considerably simpler, as we can lean heavier on serde to serialize directly into the wire format that we use now.
codex-common
This crate is designed for utilities that need to be shared across other crates in the workspace, but should not go in core.
For narrow utility features, the pattern is to add introduce a new feature under [features] in Cargo.toml and then gate it with #[cfg] in lib.rs, as appropriate.