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

hive-sh4re/src/lib.rs

@@ -529,6 +529,11 @@ pub enum Request {
     /// crashed-mid-turn sessions. See
     /// `docs/conventions.md::Broker delivery + ack cycle`.
     RequeueInflight,
+    /// Harness → c0re: "I saw the `GracefulStop` signal, ran my
+    /// stop-checkpoint turn (durable `/state` flushed) and am exiting my
+    /// serve loop now." Lets the `GracefulStop` orchestration stop the
+    /// container immediately instead of waiting out its timeout fallback.
+    GracefulStopComplete,
     /// *(capability-gated: `read_host_journal`)* Fetch recent lines
     /// from the host journal. Filters are all optional; omitting all
     /// returns the last `lines` entries from the global journal.
@@ -700,6 +705,15 @@ pub enum Response {
     /// status. Ordered by topology depth (parents before children), then
     /// alphabetically within each depth tier.
     Containers { containers: Vec<ContainerInfo> },
+    /// `Recv` result when a graceful stop is pending for this agent
+    /// (set by hive-c0re's `GracefulStop` orchestration). Returned in
+    /// place of `Messages` — it doubles as the inbound fence: the harness
+    /// stops consuming normal inbox messages and instead runs one
+    /// stop-checkpoint turn (flush durable `/state`), then reports
+    /// `GracefulStopComplete` and exits its serve loop so the container
+    /// can be stopped cleanly. New sends keep queueing in the broker for
+    /// the agent's next start.
+    GracefulStop,
 }
 
 /// Backwards-compatible response aliases.