fix(daemon): keep serving while a gated server waits

The autostart loop awaited each Start ack, and a gated start does not ack
until its wait-for condition resolves. Because the accept loop and the
signal handler are installed after that loop, a server gated on a socket
that is not there yet left the daemon deaf for the whole gate: `xy list`
hung in the backlog and SIGTERM went unhandled. Nothing consumed the ack,
so drop the await and let the gates run concurrently with the accept loop.

Also clear started_at before publishing Waiting. A crash-and-regate kept
the dead process's start instant, so `xy list` showed a growing uptime for
a server that had been down for minutes -- in the one state whose whole
purpose is to explain what is going on.

And log the spawn error when a wait-for command cannot be run at all, so a
misspelled binary is distinguishable from a condition that is merely not
met yet.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EGntTHCW3sEPy1VBRopNNp

crates/xy-supervisor/src/ready.rs

@@ -1,5 +1,6 @@
 use std::process::Stdio;
 use std::time::Duration;
+use tracing::debug;
 use xy_protocol::WaitCondition;
 
 pub(crate) async fn is_ready(condition: &WaitCondition, budget: Duration) -> bool {
@@ -21,7 +22,16 @@ pub(crate) async fn is_ready(condition: &WaitCondition, budget: Duration) -> boo
 
             match tokio::time::timeout(budget, cmd.status()).await {
                 Ok(Ok(status)) => status.success(),
-                _ => false,
+                Ok(Err(err)) => {
+                    debug!(
+                        command = %command.display(),
+                        error = %err,
+                        "wait-for command could not be run",
+                    );
+
+                    false
+                }
+                Err(_) => false,
             }
         }
     }
@@ -108,6 +118,16 @@ mod tests {
         assert!(!is_ready(&condition, ms(500)).await);
     }
 
+    #[tokio::test]
+    async fn a_command_that_cannot_be_run_is_not_ready() {
+        let condition = WaitCondition::Command {
+            command: PathBuf::from("/definitely/not/here/docker"),
+            args: vec![],
+        };
+
+        assert!(!is_ready(&condition, ms(500)).await);
+    }
+
     #[tokio::test]
     async fn a_command_that_outlasts_its_budget_is_not_ready() {
         let condition = WaitCondition::Command {

crates/xy-supervisor/src/supervisor.rs

@@ -346,6 +346,8 @@ impl<S: Spawner> SupervisorTask<S> {
             timeout: wait.timeout,
         });
 
+        self.started_at = None;
+
         self.set_state(ServerState::Waiting);
 
         let outcome = loop {
@@ -903,4 +905,105 @@ mod tests {
         ack_rx.await.unwrap();
         h.await.unwrap();
     }
+
+    #[tokio::test]
+    async fn shutdown_during_a_wait_ends_the_task_promptly() {
+        let cfg = cfg_with_wait(
+            "x",
+            WaitForConfig {
+                condition: WaitCondition::Path(PathBuf::from("/definitely/not/here.sock")),
+                timeout: Duration::from_secs(30),
+                interval: Duration::from_millis(10),
+            },
+        );
+
+        let queue = Arc::new(Mutex::new(Vec::new()));
+        let spawner = QueueSpawner { queue };
+
+        let (status_tx, mut status_rx) = watch::channel(initial_status(&cfg));
+        let (cmd_tx, cmd_rx) = mpsc::channel(8);
+        let task = SupervisorTask::new(cfg, sink("x"), spawner, status_tx, cmd_rx);
+        let h = tokio::spawn(task.run());
+
+        let (ack_tx, _ack_rx) = oneshot::channel();
+        cmd_tx
+            .send(SupervisorCmd::Start { ack: ack_tx })
+            .await
+            .unwrap();
+
+        wait_for(&mut status_rx, ServerState::Waiting).await;
+
+        let (ack_tx, ack_rx) = oneshot::channel();
+        cmd_tx
+            .send(SupervisorCmd::Shutdown { ack: ack_tx })
+            .await
+            .unwrap();
+
+        // The 30s gate timeout would swamp both of these if Shutdown were only
+        // observed once the gate resolved.
+        tokio::time::timeout(Duration::from_millis(2_000), ack_rx)
+            .await
+            .expect("shutdown must not wait for the gate timeout")
+            .unwrap();
+
+        tokio::time::timeout(Duration::from_millis(2_000), h)
+            .await
+            .expect("the supervisor task must return once shut down")
+            .unwrap();
+    }
+
+    #[tokio::test]
+    async fn a_server_waiting_on_its_gate_reports_no_uptime() {
+        let tmp = tempfile::tempdir().unwrap();
+        let file = tmp.path().join("sock");
+
+        std::fs::write(&file, b"").unwrap();
+
+        let mut cfg = cfg("x", RestartPolicy::Always, 5);
+
+        cfg.wait_for = Some(WaitForConfig {
+            condition: WaitCondition::Path(file.clone()),
+            timeout: Duration::from_millis(2_000),
+            interval: Duration::from_millis(10),
+        });
+
+        // Only one child: the gate must never clear again, so a second spawn
+        // would panic on the empty queue.
+        let (first, mut ctl) = MockChild::new(1);
+        let queue = Arc::new(Mutex::new(vec![first]));
+        let spawner = QueueSpawner { queue };
+
+        let (status_tx, mut status_rx) = watch::channel(initial_status(&cfg));
+        let (cmd_tx, cmd_rx) = mpsc::channel(8);
+        let task = SupervisorTask::new(cfg, sink("x"), spawner, status_tx, cmd_rx);
+        let h = tokio::spawn(task.run());
+
+        let (ack_tx, ack_rx) = oneshot::channel();
+        cmd_tx
+            .send(SupervisorCmd::Start { ack: ack_tx })
+            .await
+            .unwrap();
+        assert_eq!(ack_rx.await.unwrap(), StartAck::Started);
+        wait_for(&mut status_rx, ServerState::Running).await;
+        assert!(status_rx.borrow().started_at.is_some());
+
+        std::fs::remove_file(&file).unwrap();
+
+        ctl.exit_tx.take().unwrap().send(Some(1)).unwrap();
+
+        wait_for(&mut status_rx, ServerState::Waiting).await;
+
+        assert!(
+            status_rx.borrow().started_at.is_none(),
+            "a server waiting on its gate has no live process, so it has no uptime"
+        );
+
+        let (ack_tx, ack_rx) = oneshot::channel();
+        cmd_tx
+            .send(SupervisorCmd::Shutdown { ack: ack_tx })
+            .await
+            .unwrap();
+        ack_rx.await.unwrap();
+        h.await.unwrap();
+    }
 }