test(maestro): one mock daemon instead of three answers

There were three answers to "how do I test against a daemon", and the CLI
— the thinnest client — had none, so its formatting and error handling
were exercised by compiling and forking the real binary plus tmux.

Adds crates/maestro-testing with a MockDaemon that serves the real /api/*
surface from maestro-protocol types, backed by a Vec<Session>. It replaces
two ad-hoc stubs: maestro-web's, which returned [{"id":"session-1"}] —
not a valid Session — and maestro-tui's scripted socket with a hardcoded
timeline.

maestro-cli gets its first tests against a daemon: six cases covering the
catalog, that DaemonInfo carries the version and presets its old private
copy dropped, that a structured failure surfaces the daemon's own message,
and that connection-refused stays distinguishable from an HTTP rejection.

maestro-web's proxy suite gains an end-to-end check that an upstream
rejection reaches the browser as a 4502 close carrying the daemon's
message — upstream_close_reason had only unit tests.

e2e keeps the tmux-shaped tests. cli_list_reads_from_daemon still runs the
shipped binary as a subprocess but now against MockDaemon, and
tui_integration.rs is deleted: the real daemon's /api/events contract is
covered by maestro-daemon/tests/local_api.rs and the client reducer by
maestro-tui/tests/catalog_ws.rs. The e2e suite drops from ~32s to ~20s.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

crates/maestro-testing/src/lib.rs

@@ -0,0 +1,364 @@
+//! An in-memory Maestro daemon for tests.
+//!
+//! Serves the real `/api/*` surface from `maestro-protocol` types, backed by a
+//! `Vec<Session>` instead of tmux. Use it whenever the subject under test is a
+//! client — request building, error decoding, the catalog reducer, the proxy —
+//! rather than session management itself. Tests that genuinely need tmux belong
+//! in `maestro-e2e` against a real daemon.
+
+#![deny(missing_debug_implementations)]
+
+use std::collections::HashMap;
+use std::net::{Ipv4Addr, SocketAddr};
+use std::sync::{Arc, Mutex};
+
+use axum::extract::ws::{Message, WebSocket, WebSocketUpgrade};
+use axum::extract::{Path, Query, State};
+use axum::http::StatusCode;
+use axum::response::{IntoResponse, Response};
+use axum::routing::{any, delete, get};
+use axum::{Json, Router};
+use chrono::Utc;
+use futures_util::{SinkExt, StreamExt};
+use maestro_protocol::{
+    routes, ApiError, CatalogEvent, CreateSessionRequest, DaemonClient, DaemonInfo, DirListing,
+    GitRoot, RecentDirs, Session, SessionStatus, PROTOCOL_VERSION,
+};
+use tokio::net::TcpListener;
+use tokio::sync::{broadcast, oneshot};
+use uuid::Uuid;
+
+/// Build a plausible `Session` for a test to hand to [`MockDaemon::add_session`].
+pub fn session(id: Uuid, cwd: &str, command: &str) -> Session {
+    Session {
+        id,
+        cwd: cwd.into(),
+        command: command.into(),
+        env: HashMap::new(),
+        metadata: HashMap::new(),
+        status: SessionStatus::Running,
+        created_at: Utc::now(),
+        foreground: None,
+        activity: Default::default(),
+        last_activity_at: Utc::now(),
+        current_cwd: None,
+    }
+}
+
+#[derive(Debug, Default)]
+struct Inner {
+    sessions: Vec<Session>,
+    info: Option<DaemonInfo>,
+    /// When set, every route answers with this instead of its normal response.
+    forced_error: Option<(u16, ApiError)>,
+}
+
+#[derive(Clone)]
+struct AppState {
+    inner: Arc<Mutex<Inner>>,
+    events: broadcast::Sender<CatalogEvent>,
+}
+
+impl std::fmt::Debug for AppState {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("AppState").finish_non_exhaustive()
+    }
+}
+
+/// A running mock daemon. Shuts down when dropped.
+#[derive(Debug)]
+pub struct MockDaemon {
+    addr: SocketAddr,
+    state: AppState,
+    _shutdown: oneshot::Sender<()>,
+}
+
+impl MockDaemon {
+    pub async fn start() -> Self {
+        let state = AppState {
+            inner: Arc::new(Mutex::new(Inner::default())),
+            events: broadcast::channel(64).0,
+        };
+        let app = Router::new()
+            .route(routes::SESSIONS, get(list_sessions).post(create_session))
+            .route(routes::patterns::SESSION, delete(kill_session))
+            .route(routes::INFO, get(daemon_info))
+            .route(routes::DIRS, get(list_dir))
+            .route(routes::RECENT_DIRS, get(recent_dirs))
+            .route(routes::GITROOT, get(git_root))
+            .route(routes::EVENTS, any(events_ws))
+            .route(routes::patterns::ATTACH, any(attach_ws))
+            .with_state(state.clone());
+
+        let listener = TcpListener::bind(SocketAddr::from((Ipv4Addr::LOCALHOST, 0)))
+            .await
+            .expect("bind");
+        let addr = listener.local_addr().expect("local_addr");
+        let (tx, rx) = oneshot::channel::<()>();
+        tokio::spawn(async move {
+            let _ = axum::serve(listener, app)
+                .with_graceful_shutdown(async move {
+                    let _ = rx.await;
+                })
+                .await;
+        });
+
+        Self {
+            addr,
+            state,
+            _shutdown: tx,
+        }
+    }
+
+    pub fn addr(&self) -> SocketAddr {
+        self.addr
+    }
+
+    pub fn http_base(&self) -> String {
+        format!("http://{}", self.addr)
+    }
+
+    /// A client bound to this daemon.
+    pub fn client(&self) -> DaemonClient {
+        DaemonClient::new(self.http_base())
+    }
+
+    /// Add a session and announce it, as a real spawn would.
+    pub fn add_session(&self, session: Session) {
+        self.state
+            .inner
+            .lock()
+            .expect("poisoned")
+            .sessions
+            .push(session.clone());
+        let _ = self
+            .state
+            .events
+            .send(CatalogEvent::SessionAdded { session });
+    }
+
+    /// Remove a session and announce it.
+    pub fn remove_session(&self, id: Uuid) {
+        self.state
+            .inner
+            .lock()
+            .expect("poisoned")
+            .sessions
+            .retain(|s| s.id != id);
+        let _ = self.state.events.send(CatalogEvent::SessionRemoved { id });
+    }
+
+    pub fn set_info(&self, info: DaemonInfo) {
+        self.state.inner.lock().expect("poisoned").info = Some(info);
+    }
+
+    /// Make every route answer with this error, so clients' failure paths — and
+    /// their [`ApiError`] decoding — can be exercised.
+    pub fn force_error(&self, status: u16, code: &str, message: &str) {
+        self.state.inner.lock().expect("poisoned").forced_error =
+            Some((status, ApiError::new(code, message)));
+    }
+
+    pub fn clear_error(&self) {
+        self.state.inner.lock().expect("poisoned").forced_error = None;
+    }
+
+    pub fn session_count(&self) -> usize {
+        self.state.inner.lock().expect("poisoned").sessions.len()
+    }
+}
+
+fn forced(state: &AppState) -> Option<Response> {
+    let guard = state.inner.lock().expect("poisoned");
+    guard.forced_error.as_ref().map(|(status, body)| {
+        (
+            StatusCode::from_u16(*status).expect("valid status"),
+            Json(body.clone()),
+        )
+            .into_response()
+    })
+}
+
+async fn list_sessions(State(s): State<AppState>) -> Response {
+    if let Some(r) = forced(&s) {
+        return r;
+    }
+    let sessions = s.inner.lock().expect("poisoned").sessions.clone();
+    Json(sessions).into_response()
+}
+
+async fn create_session(
+    State(s): State<AppState>,
+    Json(req): Json<CreateSessionRequest>,
+) -> Response {
+    if let Some(r) = forced(&s) {
+        return r;
+    }
+    let mut created = session(Uuid::new_v4(), &req.cwd.to_string_lossy(), &req.command);
+    created.env = req.env;
+    created.metadata = req.metadata;
+    s.inner
+        .lock()
+        .expect("poisoned")
+        .sessions
+        .push(created.clone());
+    let _ = s.events.send(CatalogEvent::SessionAdded {
+        session: created.clone(),
+    });
+    Json(created).into_response()
+}
+
+async fn kill_session(State(s): State<AppState>, Path(id): Path<Uuid>) -> Response {
+    if let Some(r) = forced(&s) {
+        return r;
+    }
+    let existed = {
+        let mut guard = s.inner.lock().expect("poisoned");
+        let before = guard.sessions.len();
+        guard.sessions.retain(|x| x.id != id);
+        guard.sessions.len() != before
+    };
+    if !existed {
+        return (
+            StatusCode::NOT_FOUND,
+            Json(ApiError::new("not_found", "no such session on this daemon")),
+        )
+            .into_response();
+    }
+    let _ = s.events.send(CatalogEvent::SessionRemoved { id });
+    StatusCode::NO_CONTENT.into_response()
+}
+
+async fn daemon_info(State(s): State<AppState>) -> Response {
+    if let Some(r) = forced(&s) {
+        return r;
+    }
+    let info = s
+        .inner
+        .lock()
+        .expect("poisoned")
+        .info
+        .clone()
+        .unwrap_or_else(|| DaemonInfo {
+            hostname: "mock-host".into(),
+            version: PROTOCOL_VERSION.into(),
+            home_dir: "/home/mock".into(),
+            presets: Vec::new(),
+        });
+    Json(info).into_response()
+}
+
+async fn list_dir(State(s): State<AppState>, Query(q): Query<PathQuery>) -> Response {
+    if let Some(r) = forced(&s) {
+        return r;
+    }
+    Json(DirListing {
+        path: q.path.into(),
+        entries: Vec::new(),
+        truncated: false,
+    })
+    .into_response()
+}
+
+async fn recent_dirs(State(s): State<AppState>) -> Response {
+    if let Some(r) = forced(&s) {
+        return r;
+    }
+    Json(RecentDirs {
+        dirs: Vec::new(),
+        truncated: false,
+    })
+    .into_response()
+}
+
+async fn git_root(State(s): State<AppState>, Query(_q): Query<PathQuery>) -> Response {
+    if let Some(r) = forced(&s) {
+        return r;
+    }
+    Json(GitRoot { root: None }).into_response()
+}
+
+/// Snapshot on connect, then live deltas — the same contract the daemon offers.
+async fn events_ws(State(s): State<AppState>, ws: WebSocketUpgrade) -> Response {
+    ws.on_upgrade(move |socket| events_loop(s, socket))
+}
+
+async fn events_loop(s: AppState, socket: WebSocket) {
+    let (mut sink, mut stream) = socket.split();
+    let mut rx = s.events.subscribe();
+    let snapshot = CatalogEvent::Snapshot {
+        sessions: s.inner.lock().expect("poisoned").sessions.clone(),
+    };
+    if sink
+        .send(Message::Text(
+            serde_json::to_string(&snapshot).expect("encode"),
+        ))
+        .await
+        .is_err()
+    {
+        return;
+    }
+    loop {
+        tokio::select! {
+            ev = rx.recv() => {
+                let Ok(ev) = ev else { break };
+                let text = serde_json::to_string(&ev).expect("encode");
+                if sink.send(Message::Text(text)).await.is_err() {
+                    break;
+                }
+            }
+            frame = stream.next() => {
+                match frame {
+                    None | Some(Err(_)) | Some(Ok(Message::Close(_))) => break,
+                    Some(Ok(_)) => {}
+                }
+            }
+        }
+    }
+}
+
+/// Echoes whatever it is sent, so a client's PTY plumbing can be exercised.
+async fn attach_ws(
+    State(s): State<AppState>,
+    Path(id): Path<Uuid>,
+    ws: WebSocketUpgrade,
+) -> Response {
+    let known = s
+        .inner
+        .lock()
+        .expect("poisoned")
+        .sessions
+        .iter()
+        .any(|x| x.id == id);
+    if !known {
+        return (
+            StatusCode::NOT_FOUND,
+            Json(ApiError::new("not_found", "no such session on this daemon")),
+        )
+            .into_response();
+    }
+    ws.on_upgrade(|mut socket| async move {
+        while let Some(Ok(msg)) = socket.next().await {
+            match msg {
+                Message::Binary(b) => {
+                    if socket.send(Message::Binary(b)).await.is_err() {
+                        break;
+                    }
+                }
+                Message::Text(t) => {
+                    if socket.send(Message::Text(t)).await.is_err() {
+                        break;
+                    }
+                }
+                Message::Close(_) => break,
+                _ => {}
+            }
+        }
+    })
+}
+
+#[derive(Debug, serde::Deserialize)]
+struct PathQuery {
+    #[serde(default)]
+    path: String,
+}