hive-c0re: graceful agent stop — quiesce harness, flush state, then stop

hive-c0re/src/coordinator.rs

@@ -125,6 +125,12 @@ pub struct Coordinator {
     /// the dashboard's `agents_crashing` banner warning via
     /// `recent_crash_counts`, which prunes entries older than its window.
     recent_crashes: Mutex<HashMap<String, Vec<std::time::Instant>>>,
+    /// Agents with a graceful stop in progress. Set by the `GracefulStop`
+    /// orchestration; read by `agent_server::handle_recv`, which returns
+    /// `Response::GracefulStop` (instead of polling the broker) while an
+    /// agent is in this set — the inbound fence. Cleared when the agent
+    /// reports `GracefulStopComplete` or the container is stopped.
+    graceful_stop_pending: Mutex<HashSet<String>>,
     /// Unified wire-facing event channel feeding the dashboard SSE
     /// stream. Carries broker messages (mirrored from `broker.subscribe`
     /// by the forwarder task in `main.rs`) and dashboard-only mutation
@@ -450,6 +456,7 @@ impl Coordinator {
             transient: Mutex::new(HashMap::new()),
             recent_transient: Mutex::new(HashMap::new()),
             recent_crashes: Mutex::new(HashMap::new()),
+            graceful_stop_pending: Mutex::new(HashSet::new()),
             dashboard_events,
             event_seq: AtomicU64::new(0),
             meta_updates_active: AtomicU64::new(0),
@@ -1128,6 +1135,28 @@ impl Coordinator {
         }
     }
 
+    /// Mark `name` as having a graceful stop in progress. While set,
+    /// `agent_server::handle_recv` returns `Response::GracefulStop` for
+    /// this agent instead of polling the broker (the inbound fence).
+    pub fn mark_graceful_stop(&self, name: &str) {
+        self.graceful_stop_pending
+            .lock()
+            .unwrap()
+            .insert(name.to_owned());
+    }
+
+    /// Whether a graceful stop is pending for `name`.
+    #[must_use]
+    pub fn is_graceful_stop_pending(&self, name: &str) -> bool {
+        self.graceful_stop_pending.lock().unwrap().contains(name)
+    }
+
+    /// Clear the graceful-stop flag for `name` (agent reported
+    /// `GracefulStopComplete`, or the stop finished / was abandoned).
+    pub fn clear_graceful_stop(&self, name: &str) {
+        self.graceful_stop_pending.lock().unwrap().remove(name);
+    }
+
     /// Set of agents whose transient was cleared within the last
     /// `grace` seconds — i.e. agents the operator just acted on,
     /// whose stop the crash watcher should NOT classify as a crash.