Files
llmx/codex-rs/mcp-server/tests/codex_message_processor_flow.rs
Michael Bolin e7bad650ff feat: support traditional JSON-RPC request/response in MCP server (#2264)
This introduces a new set of request types that our `codex mcp`
supports. Note that these do not conform to MCP tool calls so that
instead of having to send something like this:

```json
{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "id": 42,
  "params": {
    "name": "newConversation",
    "arguments": {
      "model": "gpt-5",
      "approvalPolicy": "on-request"
    }
  }
}
```

we can send something like this:


```json
{
  "jsonrpc": "2.0",
  "method": "newConversation",
  "id": 42,
  "params": {
    "model": "gpt-5",
    "approvalPolicy": "on-request"
  }
}
```

Admittedly, this new format is not a valid MCP tool call, but we are OK
with that right now. (That is, not everything we might want to request
of `codex mcp` is something that is appropriate for an autonomous agent
to do.)

To start, this introduces four request types:

- `newConversation`
- `sendUserMessage`
- `addConversationListener`
- `removeConversationListener`

The new `mcp-server/tests/codex_message_processor_flow.rs` shows how
these can be used.

The types are defined on the `CodexRequest` enum, so we introduce a new
`CodexMessageProcessor` that is responsible for dealing with requests
from this enum. The top-level `MessageProcessor` has been updated so
that when `process_request()` is called, it first checks whether the
request conforms to `CodexRequest` and dispatches it to
`CodexMessageProcessor` if so.

Note that I also decided to use `camelCase` for the on-the-wire format,
as that seems to be the convention for MCP.

For the moment, the new protocol is defined in `wire_format.rs` within
the `mcp-server` crate, but in a subsequent PR, I will probably move it
to its own crate to ensure the protocol has minimal dependencies and
that we can codegen a schema from it.



---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/2264).
* #2278
* __->__ #2264
2025-08-13 17:36:29 -07:00

177 lines
6.6 KiB
Rust

#![allow(clippy::expect_used, clippy::unwrap_used)]
use std::path::Path;
use codex_core::spawn::CODEX_SANDBOX_NETWORK_DISABLED_ENV_VAR;
use codex_mcp_server::wire_format::AddConversationListenerParams;
use codex_mcp_server::wire_format::AddConversationSubscriptionResponse;
use codex_mcp_server::wire_format::NewConversationParams;
use codex_mcp_server::wire_format::NewConversationResponse;
use codex_mcp_server::wire_format::RemoveConversationListenerParams;
use codex_mcp_server::wire_format::RemoveConversationSubscriptionResponse;
use codex_mcp_server::wire_format::SendUserMessageParams;
use codex_mcp_server::wire_format::SendUserMessageResponse;
use mcp_test_support::McpProcess;
use mcp_test_support::create_final_assistant_message_sse_response;
use mcp_test_support::create_mock_chat_completions_server;
use mcp_test_support::create_shell_sse_response;
use mcp_types::JSONRPCResponse;
use mcp_types::RequestId;
use pretty_assertions::assert_eq;
use serde::de::DeserializeOwned;
use std::env;
use tempfile::TempDir;
use tokio::time::timeout;
const DEFAULT_READ_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(10);
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn test_codex_jsonrpc_conversation_flow() {
if env::var(CODEX_SANDBOX_NETWORK_DISABLED_ENV_VAR).is_ok() {
println!(
"Skipping test because it cannot execute when network is disabled in a Codex sandbox."
);
return;
}
let tmp = TempDir::new().expect("tmp dir");
// Temporary Codex home with config pointing at the mock server.
let codex_home = tmp.path().join("codex_home");
std::fs::create_dir(&codex_home).expect("create codex home dir");
let working_directory = tmp.path().join("workdir");
std::fs::create_dir(&working_directory).expect("create working directory");
// Create a mock model server that immediately ends each turn.
// Two turns are expected: initial session configure + one user message.
let responses = vec![
create_shell_sse_response(
vec!["ls".to_string()],
Some(&working_directory),
Some(5000),
"call1234",
)
.expect("create shell sse response"),
create_final_assistant_message_sse_response("Enjoy your new git repo!")
.expect("create final assistant message"),
];
let server = create_mock_chat_completions_server(responses).await;
create_config_toml(&codex_home, &server.uri()).expect("write config");
// Start MCP server and initialize.
let mut mcp = McpProcess::new(&codex_home).await.expect("spawn mcp");
timeout(DEFAULT_READ_TIMEOUT, mcp.initialize())
.await
.expect("init timeout")
.expect("init error");
// 1) newConversation
let new_conv_id = mcp
.send_new_conversation_request(NewConversationParams {
cwd: Some(working_directory.to_string_lossy().into_owned()),
..Default::default()
})
.await
.expect("send newConversation");
let new_conv_resp: JSONRPCResponse = timeout(
DEFAULT_READ_TIMEOUT,
mcp.read_stream_until_response_message(RequestId::Integer(new_conv_id)),
)
.await
.expect("newConversation timeout")
.expect("newConversation resp");
let new_conv_resp = to_response::<NewConversationResponse>(new_conv_resp)
.expect("deserialize newConversation response");
let NewConversationResponse {
conversation_id,
model,
} = new_conv_resp;
assert_eq!(model, "mock-model");
// 2) addConversationListener
let add_listener_id = mcp
.send_add_conversation_listener_request(AddConversationListenerParams { conversation_id })
.await
.expect("send addConversationListener");
let add_listener_resp: JSONRPCResponse = timeout(
DEFAULT_READ_TIMEOUT,
mcp.read_stream_until_response_message(RequestId::Integer(add_listener_id)),
)
.await
.expect("addConversationListener timeout")
.expect("addConversationListener resp");
let AddConversationSubscriptionResponse { subscription_id } =
to_response::<AddConversationSubscriptionResponse>(add_listener_resp)
.expect("deserialize addConversationListener response");
// 3) sendUserMessage (should trigger notifications; we only validate an OK response)
let send_user_id = mcp
.send_send_user_message_request(SendUserMessageParams {
conversation_id,
items: vec![codex_mcp_server::wire_format::InputItem::Text {
text: "text".to_string(),
}],
})
.await
.expect("send sendUserMessage");
let send_user_resp: JSONRPCResponse = timeout(
DEFAULT_READ_TIMEOUT,
mcp.read_stream_until_response_message(RequestId::Integer(send_user_id)),
)
.await
.expect("sendUserMessage timeout")
.expect("sendUserMessage resp");
let SendUserMessageResponse {} = to_response::<SendUserMessageResponse>(send_user_resp)
.expect("deserialize sendUserMessage response");
// Give the server time to process the user's request.
tokio::time::sleep(std::time::Duration::from_millis(5_000)).await;
// Could verify that some notifications were received?
// 4) removeConversationListener
let remove_listener_id = mcp
.send_remove_conversation_listener_request(RemoveConversationListenerParams {
subscription_id,
})
.await
.expect("send removeConversationListener");
let remove_listener_resp: JSONRPCResponse = timeout(
DEFAULT_READ_TIMEOUT,
mcp.read_stream_until_response_message(RequestId::Integer(remove_listener_id)),
)
.await
.expect("removeConversationListener timeout")
.expect("removeConversationListener resp");
let RemoveConversationSubscriptionResponse {} =
to_response(remove_listener_resp).expect("deserialize removeConversationListener response");
}
fn to_response<T: DeserializeOwned>(response: JSONRPCResponse) -> anyhow::Result<T> {
let value = serde_json::to_value(response.result)?;
let codex_response = serde_json::from_value(value)?;
Ok(codex_response)
}
// Helper: minimal config.toml pointing at mock provider.
fn create_config_toml(codex_home: &Path, server_uri: &str) -> std::io::Result<()> {
let config_toml = codex_home.join("config.toml");
std::fs::write(
config_toml,
format!(
r#"
model = "mock-model"
approval_policy = "never"
model_provider = "mock_provider"
[model_providers.mock_provider]
name = "Mock provider for test"
base_url = "{server_uri}/v1"
wire_api = "chat"
request_max_retries = 0
stream_max_retries = 0
"#
),
)
}