fix: use macros to ensure request/response symmetry (#4529)

Manually curating `protocol-ts/src/lib.rs` was error-prone, as expected.
I finally asked Codex to write some Rust macros so we can ensure that:

- For every variant of `ClientRequest` and `ServerRequest`, there is an
associated `params` and `response` type.
- All response types are included automatically in the output of `codex
generate-ts`.

codex-rs/app-server/src/codex_message_processor.rs

@@ -36,7 +36,6 @@ use codex_core::protocol::ReviewDecision;
 use codex_login::ServerOptions as LoginServerOptions;
 use codex_login::ShutdownHandle;
 use codex_login::run_login_server;
-use codex_protocol::mcp_protocol::APPLY_PATCH_APPROVAL_METHOD;
 use codex_protocol::mcp_protocol::AddConversationListenerParams;
 use codex_protocol::mcp_protocol::AddConversationSubscriptionResponse;
 use codex_protocol::mcp_protocol::ApplyPatchApprovalParams;
@@ -47,11 +46,10 @@ use codex_protocol::mcp_protocol::AuthStatusChangeNotification;
 use codex_protocol::mcp_protocol::ClientRequest;
 use codex_protocol::mcp_protocol::ConversationId;
 use codex_protocol::mcp_protocol::ConversationSummary;
-use codex_protocol::mcp_protocol::EXEC_COMMAND_APPROVAL_METHOD;
-use codex_protocol::mcp_protocol::ExecArbitraryCommandResponse;
 use codex_protocol::mcp_protocol::ExecCommandApprovalParams;
 use codex_protocol::mcp_protocol::ExecCommandApprovalResponse;
 use codex_protocol::mcp_protocol::ExecOneOffCommandParams;
+use codex_protocol::mcp_protocol::ExecOneOffCommandResponse;
 use codex_protocol::mcp_protocol::FuzzyFileSearchParams;
 use codex_protocol::mcp_protocol::FuzzyFileSearchResponse;
 use codex_protocol::mcp_protocol::GetUserAgentResponse;
@@ -76,6 +74,7 @@ use codex_protocol::mcp_protocol::SendUserMessageResponse;
 use codex_protocol::mcp_protocol::SendUserTurnParams;
 use codex_protocol::mcp_protocol::SendUserTurnResponse;
 use codex_protocol::mcp_protocol::ServerNotification;
+use codex_protocol::mcp_protocol::ServerRequestPayload;
 use codex_protocol::mcp_protocol::SessionConfiguredNotification;
 use codex_protocol::mcp_protocol::SetDefaultModelParams;
 use codex_protocol::mcp_protocol::SetDefaultModelResponse;
@@ -632,7 +631,7 @@ impl CodexMessageProcessor {
             .await
             {
                 Ok(output) => {
-                    let response = ExecArbitraryCommandResponse {
+                    let response = ExecOneOffCommandResponse {
                         exit_code: output.exit_code,
                         stdout: output.stdout.text,
                         stderr: output.stderr.text,
@@ -1268,9 +1267,8 @@ async fn apply_bespoke_event_handling(
                 reason,
                 grant_root,
             };
-            let value = serde_json::to_value(&params).unwrap_or_default();
             let rx = outgoing
-                .send_request(APPLY_PATCH_APPROVAL_METHOD, Some(value))
+                .send_request(ServerRequestPayload::ApplyPatchApproval(params))
                 .await;
             // TODO(mbolin): Enforce a timeout so this task does not live indefinitely?
             tokio::spawn(async move {
@@ -1290,9 +1288,8 @@ async fn apply_bespoke_event_handling(
                 cwd,
                 reason,
             };
-            let value = serde_json::to_value(&params).unwrap_or_default();
             let rx = outgoing
-                .send_request(EXEC_COMMAND_APPROVAL_METHOD, Some(value))
+                .send_request(ServerRequestPayload::ExecCommandApproval(params))
                 .await;
 
             // TODO(mbolin): Enforce a timeout so this task does not live indefinitely?

codex-rs/app-server/src/outgoing_message.rs

@@ -3,6 +3,7 @@ use std::sync::atomic::AtomicI64;
 use std::sync::atomic::Ordering;
 
 use codex_protocol::mcp_protocol::ServerNotification;
+use codex_protocol::mcp_protocol::ServerRequestPayload;
 use mcp_types::JSONRPC_VERSION;
 use mcp_types::JSONRPCError;
 use mcp_types::JSONRPCErrorError;
@@ -38,8 +39,7 @@ impl OutgoingMessageSender {
 
     pub(crate) async fn send_request(
         &self,
-        method: &str,
-        params: Option<serde_json::Value>,
+        request: ServerRequestPayload,
     ) -> oneshot::Receiver<Result> {
         let id = RequestId::Integer(self.next_request_id.fetch_add(1, Ordering::Relaxed));
         let outgoing_message_id = id.clone();
@@ -49,6 +49,14 @@ impl OutgoingMessageSender {
             request_id_to_callback.insert(id, tx_approve);
         }
 
+        let method = request.method();
+        let params_value = request.into_params_value();
+        let params = if params_value.is_null() {
+            None
+        } else {
+            Some(params_value)
+        };
+
         let outgoing_message = OutgoingMessage::Request(OutgoingRequest {
             id: outgoing_message_id,
             method: method.to_string(),