fix: remove mcp-types from app server protocol (#4537)

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-rs/tui/src/app.rs

@@ -16,7 +16,7 @@ use codex_core::config::persist_model_selection;
 use codex_core::model_family::find_family_for_model;
 use codex_core::protocol::TokenUsage;
 use codex_core::protocol_config_types::ReasoningEffort as ReasoningEffortConfig;
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 use color_eyre::eyre::Result;
 use color_eyre::eyre::WrapErr;
 use crossterm::event::KeyCode;
@@ -451,7 +451,7 @@ mod tests {
     use codex_core::CodexAuth;
     use codex_core::ConversationManager;
     use codex_core::protocol::SessionConfiguredEvent;
-    use codex_protocol::mcp_protocol::ConversationId;
+    use codex_protocol::ConversationId;
     use ratatui::prelude::Line;
     use std::path::PathBuf;
     use std::sync::Arc;

codex-rs/tui/src/app_backtrack.rs

@@ -9,7 +9,7 @@ use crate::pager_overlay::Overlay;
 use crate::tui;
 use crate::tui::TuiEvent;
 use codex_core::protocol::ConversationPathResponseEvent;
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 use color_eyre::eyre::Result;
 use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;

codex-rs/tui/src/chatwidget.rs

@@ -41,7 +41,7 @@ use codex_core::protocol::TurnDiffEvent;
 use codex_core::protocol::UserMessageEvent;
 use codex_core::protocol::WebSearchBeginEvent;
 use codex_core::protocol::WebSearchEndEvent;
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 use codex_protocol::parse_command::ParsedCommand;
 use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;

codex-rs/tui/src/chatwidget/tests.rs

@@ -34,7 +34,7 @@ use codex_core::protocol::ReviewRequest;
 use codex_core::protocol::StreamErrorEvent;
 use codex_core::protocol::TaskCompleteEvent;
 use codex_core::protocol::TaskStartedEvent;
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 use crossterm::event::KeyCode;
 use crossterm::event::KeyEvent;
 use crossterm::event::KeyModifiers;

codex-rs/tui/src/lib.rs

@@ -5,6 +5,7 @@
 #![deny(clippy::disallowed_methods)]
 use app::App;
 pub use app::AppExitInfo;
+use codex_app_server_protocol::AuthMode;
 use codex_core::AuthManager;
 use codex_core::BUILT_IN_OSS_MODEL_PROVIDER_ID;
 use codex_core::CodexAuth;
@@ -19,7 +20,6 @@ use codex_core::protocol::AskForApproval;
 use codex_core::protocol::SandboxPolicy;
 use codex_ollama::DEFAULT_OSS_MODEL;
 use codex_protocol::config_types::SandboxMode;
-use codex_protocol::mcp_protocol::AuthMode;
 use opentelemetry_appender_tracing::layer::OpenTelemetryTracingBridge;
 use std::fs::OpenOptions;
 use std::path::PathBuf;

codex-rs/tui/src/onboarding/auth.rs

@@ -27,7 +27,7 @@ use ratatui::widgets::Paragraph;
 use ratatui::widgets::WidgetRef;
 use ratatui::widgets::Wrap;
 
-use codex_protocol::mcp_protocol::AuthMode;
+use codex_app_server_protocol::AuthMode;
 use std::sync::RwLock;
 
 use crate::LoginStatus;

codex-rs/tui/src/onboarding/onboarding_screen.rs

@@ -11,7 +11,7 @@ use ratatui::style::Color;
 use ratatui::widgets::Clear;
 use ratatui::widgets::WidgetRef;
 
-use codex_protocol::mcp_protocol::AuthMode;
+use codex_app_server_protocol::AuthMode;
 
 use crate::LoginStatus;
 use crate::onboarding::auth::AuthModeWidget;

codex-rs/tui/src/status/card.rs

@@ -7,7 +7,7 @@ use codex_common::create_config_summary_entries;
 use codex_core::config::Config;
 use codex_core::protocol::SandboxPolicy;
 use codex_core::protocol::TokenUsage;
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 use ratatui::prelude::*;
 use ratatui::style::Stylize;
 use std::collections::BTreeSet;