add graceful shutdown signal to coordinator and all background tasks

hive-c0re/src/coordinator.rs

@@ -8,7 +8,7 @@ use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::{Arc, Mutex};
 
 use anyhow::{Context, Result};
-use tokio::sync::broadcast;
+use tokio::sync::{broadcast, watch};
 
 use crate::agent_server::{self, AgentSocket};
 use crate::approvals::Approvals;
@@ -73,6 +73,10 @@ pub struct Coordinator {
     /// tokio mutex so the rescan can `await` `lifecycle::list` /
     /// `is_running` without blocking other coordinator paths.
     last_containers: tokio::sync::Mutex<HashMap<String, ContainerView>>,
+    /// Shutdown signal broadcast to all background tasks. Sending
+    /// `true` asks every loop to exit after its current work item.
+    /// Use `shutdown_rx()` to subscribe; `request_shutdown()` to fire.
+    shutdown_tx: watch::Sender<bool>,
 }
 
 /// Per-agent in-progress state that the dashboard surfaces between approve
@@ -140,6 +144,7 @@ impl Coordinator {
         let approvals = Approvals::open(db_path).context("open approvals")?;
         let questions = OperatorQuestions::open(db_path).context("open operator_questions")?;
         let (dashboard_events, _) = broadcast::channel(DASHBOARD_CHANNEL);
+        let (shutdown_tx, _) = watch::channel(false);
         Ok(Self {
             broker: Arc::new(broker),
             approvals: Arc::new(approvals),
@@ -152,9 +157,27 @@ impl Coordinator {
             dashboard_events,
             event_seq: AtomicU64::new(0),
             last_containers: tokio::sync::Mutex::new(HashMap::new()),
+            shutdown_tx,
         })
     }
 
+    /// Subscribe to the shutdown watch channel. Background tasks call
+    /// this at spawn time and break their loop when the receiver
+    /// transitions to `true` (via `Coordinator::request_shutdown`).
+    /// A closed channel (i.e. the Coordinator was dropped) also
+    /// signals tasks to exit.
+    pub fn shutdown_rx(&self) -> watch::Receiver<bool> {
+        self.shutdown_tx.subscribe()
+    }
+
+    /// Signal all background tasks to exit cleanly. The tasks break
+    /// out of their poll loop after completing their current work item.
+    /// Best-effort — does nothing if all receivers have already been
+    /// dropped (e.g. process is already mid-shutdown).
+    pub fn request_shutdown(&self) {
+        let _ = self.shutdown_tx.send(true);
+    }
+
     /// Subscribe to the unified dashboard event channel. Used by the
     /// `/dashboard/stream` SSE handler and by the broker-to-dashboard
     /// forwarder task.