feat(agent): bind transport S-MCP — outils idea_* vivants de bout en bout (M5a-e) — §14.3.1

Dernier kilomètre de l'orchestration native : une CLI MCP réellement lancée
joint le serveur MCP du projet et ses outils idea_* aboutissent au vrai dispatch.

- M5a endpoint loopback par projet (interprocess UDS/named pipe, source unique
  mcp_endpoint, cleanup au close) — zéro port réseau, AppImage/SSH-safe.
- M5b sous-commande `idea mcp-server` : pont stdio↔loopback headless (avant init
  Tauri), handshake {"project","requester"}, endpoint-absent borné, EOF propre.
- M5c McpServerHandle boucle accept + serve_peer par pair ; requester réel
  propagé jusqu'à OrchestratorRequestProcessed (fin du "mcp" figé) ; isolation
  des pairs ; terminaison propre.
- M5d apply_mcp_config écrit la déclaration réelle (current_exe + --endpoint
  mcp_endpoint + --project simple-uuid + --requester) ; McpRuntime injecté comme
  donnée (application ne dépend pas de app-tauri).
- M5e smoke e2e sur vrai loopback : list/ask inline, cible PTY → erreur typée,
  JSON malformé → pas de panic, requester propagé.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
2026-06-10 18:09:41 +02:00
parent 6ca519b815
commit cf89b3b9a5
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//! The `idea mcp-server` **bridge** — a transparent stdio↔loopback tube (M5b).
//!
//! ## Where this sits in the bind (cadrage v5 §1.3, §2)
//!
//! An MCP CLI (Claude Code, Codex) reads a `{command,args}` declaration and
//! *spawns* `<exe IdeA> mcp-server --endpoint <…> --project <…> --requester <…>`.
//! That spawned process is **this bridge**: it must **bypass Tauri/WebKit** and run
//! headless. It speaks JSON-RPC (JSON Lines) to the CLI on **stdin/stdout**, and
//! relays every line, byte-for-byte, over the project's **loopback** (the Unix
//! socket / Windows named pipe bound by [`crate::state::AppState::ensure_mcp_server`]
//! at [`crate::mcp_endpoint::mcp_endpoint`]). The real `McpServer` (which holds the
//! `OrchestratorService`) lives in the Tauri process and answers in M5c.
//!
//! **Zero business logic.** The bridge knows only *stdio + loopback + JSON lines*:
//! no `OrchestratorService`, no use case (hexagonal boundary, cadrage §5). It never
//! parses the JSON-RPC payloads it carries.
//!
//! ## Handshake format (consumed by M5c)
//!
//! Right after connecting to the loopback, **before** any JSON-RPC traffic, the
//! bridge writes a **single newline-terminated JSON line** carrying the caller's
//! identity:
//!
//! ```text
//! {"project":"<project-id>","requester":"<requester-id>"}\n
//! ```
//!
//! - It is a **distinct line** from the JSON-RPC stream that follows: the server
//! (M5c) reads exactly one line off a fresh connection, parses it as this
//! handshake, then hands the rest of the stream to `McpServer::serve`.
//! - `requester` is the **real agent id** (cadrage §1.4) — it lets the server tag
//! `OrchestratorRequestProcessed.requester_id` with the actual agent instead of
//! the frozen `"mcp"` placeholder. When `--requester` is omitted the field is the
//! empty string.
//! - Both values are JSON strings, so any future id shape stays escape-safe.
//!
//! ## Failure posture (never hang)
//!
//! - **Endpoint absent / unreachable** ⇒ connect with a **bounded timeout**; on
//! timeout or connect error, return a **non-zero** exit code immediately. Never
//! block forever waiting for a listener that will never appear.
//! - **stdin EOF** (the CLI closed) ⇒ **clean exit, code 0**; the loopback
//! connection is dropped (closed) on the way out.
//! - **Missing required args** ⇒ a clear error on stderr and a non-zero code.
use std::process::ExitCode;
use std::time::Duration;
use interprocess::local_socket::tokio::Stream as LocalSocketStream;
use interprocess::local_socket::traits::tokio::Stream as _;
use interprocess::local_socket::{GenericFilePath, ToFsName as _};
use tokio::io::{
AsyncBufReadExt, AsyncRead, AsyncWrite, AsyncWriteExt, BufReader,
};
/// How long the bridge waits to connect to the project loopback before giving up.
/// Bounded so an absent/unreachable endpoint fails fast instead of hanging.
const CONNECT_TIMEOUT: Duration = Duration::from_secs(5);
/// Parsed `mcp-server` invocation arguments.
///
/// `--endpoint` is **required** (without it the bridge has nowhere to relay).
/// `--project` and `--requester` are optional identity hints forwarded verbatim in
/// the handshake; a missing one becomes the empty string.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct BridgeArgs {
/// The loopback address to connect to (the `--endpoint` value, i.e.
/// [`crate::mcp_endpoint::McpEndpoint::as_cli_arg`]).
pub endpoint: String,
/// The project id (`--project`), forwarded in the handshake. Empty if absent.
pub project: String,
/// The requesting agent id (`--requester`), forwarded in the handshake. Empty
/// if absent.
pub requester: String,
}
impl BridgeArgs {
/// Parses `mcp-server`'s own arguments (i.e. `argv` **after** the `mcp-server`
/// subcommand token). Recognises `--endpoint`, `--project`, `--requester`, each
/// taking the following token as its value.
///
/// # Errors
/// Returns a human-readable message when `--endpoint` is missing, when a flag is
/// given without a value, or when an unknown flag is encountered.
pub fn parse<I, S>(args: I) -> Result<Self, String>
where
I: IntoIterator<Item = S>,
S: Into<String>,
{
let mut endpoint: Option<String> = None;
let mut project = String::new();
let mut requester = String::new();
let mut it = args.into_iter().map(Into::into);
while let Some(flag) = it.next() {
match flag.as_str() {
"--endpoint" => {
endpoint = Some(
it.next()
.ok_or_else(|| "--endpoint requires a value".to_string())?,
);
}
"--project" => {
project = it
.next()
.ok_or_else(|| "--project requires a value".to_string())?;
}
"--requester" => {
requester = it
.next()
.ok_or_else(|| "--requester requires a value".to_string())?;
}
other => {
return Err(format!("unknown argument: {other}"));
}
}
}
let endpoint = endpoint.ok_or_else(|| "--endpoint is required".to_string())?;
Ok(Self {
endpoint,
project,
requester,
})
}
/// The first handshake line the bridge writes on the loopback (newline
/// included). See the module docs for the format consumed by M5c.
fn handshake_line(&self) -> Vec<u8> {
let line = serde_json::json!({
"project": self.project,
"requester": self.requester,
})
.to_string();
let mut bytes = line.into_bytes();
bytes.push(b'\n');
bytes
}
}
/// Synchronous entry point called from `main`/`lib::run` when `argv[1] ==
/// "mcp-server"`. Parses the args, stands up a Tokio runtime, and runs the bridge.
///
/// Returns the process [`ExitCode`]: `0` on a clean stdin-EOF shutdown, non-zero on
/// any argument/connection/relay failure. Never blocks indefinitely (connect is
/// time-bounded).
#[must_use]
pub fn run_mcp_bridge<I, S>(args: I) -> ExitCode
where
I: IntoIterator<Item = S>,
S: Into<String>,
{
let args = match BridgeArgs::parse(args) {
Ok(a) => a,
Err(e) => {
eprintln!("idea mcp-server: {e}");
return ExitCode::FAILURE;
}
};
// A current-thread runtime is enough: the bridge is two coupled I/O loops, no
// CPU work. Keeps the headless process lean (no Tauri, no webview).
let runtime = match tokio::runtime::Builder::new_current_thread()
.enable_io()
.enable_time()
.build()
{
Ok(rt) => rt,
Err(e) => {
eprintln!("idea mcp-server: failed to start runtime: {e}");
return ExitCode::FAILURE;
}
};
runtime.block_on(async move {
match bridge_over_loopback(&args).await {
Ok(()) => ExitCode::SUCCESS,
Err(e) => {
eprintln!("idea mcp-server: {e}");
ExitCode::FAILURE
}
}
})
}
/// Connects to the project loopback at `args.endpoint` (time-bounded) and relays
/// between the **real stdio** of this process and that connection.
async fn bridge_over_loopback(args: &BridgeArgs) -> Result<(), String> {
let conn = connect_loopback(&args.endpoint).await?;
// Split the duplex loopback into independent owned halves so the two relay
// directions can run without sharing a lock.
let (lp_read, lp_write) = tokio::io::split(conn);
relay(
args,
tokio::io::stdin(),
tokio::io::stdout(),
lp_read,
lp_write,
)
.await
}
/// Connects to the loopback endpoint with a bounded timeout. An absent or
/// unreachable endpoint surfaces as an `Err` (⇒ non-zero exit), **never a hang**.
async fn connect_loopback(endpoint: &str) -> Result<LocalSocketStream, String> {
let name = endpoint
.to_fs_name::<GenericFilePath>()
.map_err(|e| format!("invalid endpoint {endpoint:?}: {e}"))?;
match tokio::time::timeout(CONNECT_TIMEOUT, LocalSocketStream::connect(name)).await {
Ok(Ok(stream)) => Ok(stream),
Ok(Err(e)) => Err(format!("cannot connect to endpoint {endpoint:?}: {e}")),
Err(_) => Err(format!(
"timed out connecting to endpoint {endpoint:?} after {}s",
CONNECT_TIMEOUT.as_secs()
)),
}
}
/// The transparent relay, generic over its four streams so tests drive it with
/// in-memory pipes (no real stdio, no real socket).
///
/// Sequence:
/// 1. Write the **handshake line** (`project`+`requester`) to the loopback.
/// 2. Loop: read one **line** from the CLI (`cli_in`) → write it to the loopback;
/// read one **line** from the loopback → write it to the CLI (`cli_out`).
/// 3. **CLI stdin EOF** ⇒ stop, return `Ok(())` (clean code 0). Dropping the
/// loopback writer closes that direction of the connection.
///
/// The loop is request/response paced (one CLI line in, one loopback line back),
/// matching the JSON Lines `StdioTransport` the server speaks. A loopback that
/// closes mid-exchange surfaces as an error (non-zero exit).
async fn relay<CIn, COut, LIn, LOut>(
args: &BridgeArgs,
cli_in: CIn,
mut cli_out: COut,
lp_read: LIn,
mut lp_write: LOut,
) -> Result<(), String>
where
CIn: AsyncRead + Unpin,
COut: AsyncWrite + Unpin,
LIn: AsyncRead + Unpin,
LOut: AsyncWrite + Unpin,
{
// 1. Handshake (identity) before any JSON-RPC byte.
lp_write
.write_all(&args.handshake_line())
.await
.map_err(|e| format!("handshake write failed: {e}"))?;
lp_write
.flush()
.await
.map_err(|e| format!("handshake flush failed: {e}"))?;
let mut cli_reader = BufReader::new(cli_in);
let mut lp_reader = BufReader::new(lp_read);
let mut cli_line = String::new();
let mut lp_line = String::new();
loop {
// 2a. CLI → loopback (one line). EOF ⇒ clean shutdown.
cli_line.clear();
let n = cli_reader
.read_line(&mut cli_line)
.await
.map_err(|e| format!("stdin read failed: {e}"))?;
if n == 0 {
// CLI closed stdin: nothing more to forward. Clean exit.
return Ok(());
}
lp_write
.write_all(cli_line.as_bytes())
.await
.map_err(|e| format!("loopback write failed: {e}"))?;
lp_write
.flush()
.await
.map_err(|e| format!("loopback flush failed: {e}"))?;
// 2b. loopback → CLI (one line). EOF here is a server hangup mid-exchange.
lp_line.clear();
let m = lp_reader
.read_line(&mut lp_line)
.await
.map_err(|e| format!("loopback read failed: {e}"))?;
if m == 0 {
return Err("loopback closed before answering".to_string());
}
cli_out
.write_all(lp_line.as_bytes())
.await
.map_err(|e| format!("stdout write failed: {e}"))?;
cli_out
.flush()
.await
.map_err(|e| format!("stdout flush failed: {e}"))?;
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::sync::Arc;
use interprocess::local_socket::tokio::Listener as LocalSocketListener;
use interprocess::local_socket::traits::tokio::Listener as _;
use interprocess::local_socket::{GenericFilePath, ListenerOptions};
use tokio::io::AsyncReadExt as _;
// ---- argument parsing -------------------------------------------------
#[test]
fn parses_all_three_flags() {
let a = BridgeArgs::parse([
"--endpoint", "/tmp/x.sock", "--project", "p1", "--requester", "agent-7",
])
.unwrap();
assert_eq!(a.endpoint, "/tmp/x.sock");
assert_eq!(a.project, "p1");
assert_eq!(a.requester, "agent-7");
}
#[test]
fn endpoint_is_required() {
let err = BridgeArgs::parse(["--project", "p1"]).unwrap_err();
assert!(err.contains("--endpoint"), "got: {err}");
}
#[test]
fn project_and_requester_default_to_empty() {
let a = BridgeArgs::parse(["--endpoint", "/tmp/x.sock"]).unwrap();
assert_eq!(a.project, "");
assert_eq!(a.requester, "");
}
#[test]
fn flag_without_value_is_an_error() {
assert!(BridgeArgs::parse(["--endpoint"]).is_err());
assert!(BridgeArgs::parse(["--endpoint", "/x", "--project"]).is_err());
}
#[test]
fn unknown_flag_is_an_error() {
let err = BridgeArgs::parse(["--endpoint", "/x", "--bogus"]).unwrap_err();
assert!(err.contains("unknown"), "got: {err}");
}
#[test]
fn handshake_line_carries_identity_as_json() {
let a = BridgeArgs {
endpoint: "/tmp/x.sock".into(),
project: "proj".into(),
requester: "rq".into(),
};
let line = a.handshake_line();
assert_eq!(*line.last().unwrap(), b'\n');
let v: serde_json::Value =
serde_json::from_slice(&line[..line.len() - 1]).unwrap();
assert_eq!(v["project"], "proj");
assert_eq!(v["requester"], "rq");
}
// ---- relay (in-memory streams, no socket) -----------------------------
/// Nominal relay over in-memory duplex pipes: handshake reaches the fake
/// server, a scripted request is forwarded, and the canned response comes back
/// on the CLI stdout.
#[tokio::test]
async fn relay_forwards_handshake_request_and_response() {
// CLI stdin: one JSON-RPC request line, then EOF.
let cli_in = b"{\"method\":\"tools/call\",\"id\":1}\n".to_vec();
let mut cli_out: Vec<u8> = Vec::new();
// The "loopback" is a duplex pipe: the bridge writes to `lp_write`/reads
// from `lp_read`; the fake server reads from `srv_read`/writes to
// `srv_write`.
let (lp_read, srv_write) = tokio::io::duplex(4096); // server → bridge
let (srv_read, lp_write) = tokio::io::duplex(4096); // bridge → server
let args = BridgeArgs {
endpoint: "unused".into(),
project: "proj-1".into(),
requester: "agent-9".into(),
};
// Fake server: read handshake line, then read the request line, then answer.
let server = tokio::spawn(async move {
let mut reader = BufReader::new(srv_read);
let mut handshake = String::new();
reader.read_line(&mut handshake).await.unwrap();
let mut request = String::new();
reader.read_line(&mut request).await.unwrap();
let mut w = srv_write;
w.write_all(b"{\"result\":\"ok\",\"id\":1}\n").await.unwrap();
w.flush().await.unwrap();
(handshake, request)
});
relay(
&args,
&cli_in[..],
&mut cli_out,
lp_read,
lp_write,
)
.await
.unwrap();
let (handshake, request) = server.await.unwrap();
let hs: serde_json::Value =
serde_json::from_str(handshake.trim_end()).unwrap();
assert_eq!(hs["project"], "proj-1");
assert_eq!(hs["requester"], "agent-9");
assert_eq!(request.trim_end(), "{\"method\":\"tools/call\",\"id\":1}");
assert_eq!(
String::from_utf8(cli_out).unwrap(),
"{\"result\":\"ok\",\"id\":1}\n"
);
}
/// stdin EOF with no request ⇒ relay returns `Ok` (code 0), having still sent
/// the handshake.
#[tokio::test]
async fn relay_clean_exit_on_immediate_eof() {
let cli_in: &[u8] = b""; // immediate EOF
let mut cli_out: Vec<u8> = Vec::new();
let (lp_read, srv_write) = tokio::io::duplex(4096);
let (srv_read, lp_write) = tokio::io::duplex(4096);
let args = BridgeArgs {
endpoint: "unused".into(),
project: "p".into(),
requester: String::new(),
};
let server = tokio::spawn(async move {
let mut reader = BufReader::new(srv_read);
let mut handshake = String::new();
reader.read_line(&mut handshake).await.unwrap();
// Keep srv_write alive until the bridge drops its writer (EOF).
let mut buf = Vec::new();
let _ = reader.read_to_end(&mut buf).await;
drop(srv_write);
handshake
});
relay(&args, cli_in, &mut cli_out, lp_read, lp_write)
.await
.expect("clean EOF exit");
let handshake = server.await.unwrap();
assert!(handshake.contains("\"project\":\"p\""));
assert!(cli_out.is_empty(), "no response expected on immediate EOF");
}
// ---- end-to-end over a real loopback ----------------------------------
fn temp_endpoint(tag: &str) -> String {
let dir = std::env::temp_dir();
let pid = std::process::id();
let nanos = std::time::SystemTime::now()
.duration_since(std::time::UNIX_EPOCH)
.unwrap()
.as_nanos();
dir.join(format!("idea-mcp-bridge-test-{tag}-{pid}-{nanos}.sock"))
.to_string_lossy()
.into_owned()
}
fn bind(endpoint: &str) -> LocalSocketListener {
let name = endpoint.to_fs_name::<GenericFilePath>().unwrap();
ListenerOptions::new()
.name(name)
.reclaim_name(true)
.create_tokio()
.expect("bind test listener")
}
/// Endpoint absent ⇒ `connect_loopback` fails fast (no hang), so the bridge
/// would exit non-zero. Bounded by a test timeout well under CONNECT_TIMEOUT
/// for the "connect error" path (a non-existent socket errors immediately).
#[tokio::test]
async fn connect_to_absent_endpoint_errors_fast() {
let endpoint = temp_endpoint("absent");
let res = tokio::time::timeout(
Duration::from_secs(10),
connect_loopback(&endpoint),
)
.await
.expect("connect_loopback must not hang");
assert!(res.is_err(), "absent endpoint must yield an error");
}
/// `run_mcp_bridge` with a missing `--endpoint` returns a non-zero code.
#[test]
fn run_bridge_missing_endpoint_is_non_zero() {
let code = run_mcp_bridge(["--project", "p"]);
assert_eq!(code, ExitCode::FAILURE);
}
/// Full end-to-end over a **real** interprocess loopback: a test listener plays
/// the server (reads the handshake, echoes a canned response); the relay drives
/// it over an actual connection. Verifies the handshake crosses the real socket
/// and the response returns on the CLI stdout.
#[tokio::test]
async fn end_to_end_over_real_loopback() {
let endpoint = temp_endpoint("e2e");
let listener = bind(&endpoint);
let captured = Arc::new(tokio::sync::Mutex::new((String::new(), String::new())));
let captured_srv = Arc::clone(&captured);
// Fake server accepts one connection, reads handshake + request, answers.
let server = tokio::spawn(async move {
let conn = listener.accept().await.unwrap();
let (r, w) = tokio::io::split(conn);
let mut reader = BufReader::new(r);
let mut handshake = String::new();
reader.read_line(&mut handshake).await.unwrap();
let mut request = String::new();
reader.read_line(&mut request).await.unwrap();
*captured_srv.lock().await = (handshake, request);
let mut w = w;
w.write_all(b"{\"result\":\"pong\",\"id\":42}\n")
.await
.unwrap();
w.flush().await.unwrap();
// Hold until the bridge finishes (its stdin EOF will end it).
let mut rest = Vec::new();
let _ = reader.read_to_end(&mut rest).await;
});
let args = BridgeArgs {
endpoint: endpoint.clone(),
project: "proj-e2e".into(),
requester: "agent-e2e".into(),
};
let cli_in = b"{\"method\":\"ping\",\"id\":42}\n".to_vec();
let mut cli_out: Vec<u8> = Vec::new();
// Drive the whole bridge_over_loopback path (real connect + split + relay),
// but feed our own stdio streams via `relay` to avoid touching process std.
let conn = tokio::time::timeout(
Duration::from_secs(10),
connect_loopback(&endpoint),
)
.await
.expect("no hang")
.expect("connect to live endpoint");
let (lp_read, lp_write) = tokio::io::split(conn);
tokio::time::timeout(
Duration::from_secs(10),
relay(&args, &cli_in[..], &mut cli_out, lp_read, lp_write),
)
.await
.expect("relay must not hang")
.expect("relay ok");
server.await.unwrap();
let (handshake, request) = captured.lock().await.clone();
let hs: serde_json::Value =
serde_json::from_str(handshake.trim_end()).unwrap();
assert_eq!(hs["project"], "proj-e2e");
assert_eq!(hs["requester"], "agent-e2e");
assert_eq!(request.trim_end(), "{\"method\":\"ping\",\"id\":42}");
assert_eq!(
String::from_utf8(cli_out).unwrap(),
"{\"result\":\"pong\",\"id\":42}\n"
);
}
}