feat(#1178): add list_containers tool to AgentServer (topology-scoped to descendants)

hive-sh4re/src/lib.rs

@@ -542,6 +542,12 @@ pub enum Request {
     },
     /// *(privileged)* List every schedule in the queue.
     ListSchedules,
+    /// List all containers that are topological descendants of the calling
+    /// agent (direct children + their subtrees). Scoped to the caller's
+    /// subtree; gated by the `lifecycle` tool group. The result includes all
+    /// known descendants regardless of whether the container is currently
+    /// running — use `running` to distinguish.
+    ListDescendants,
     /// *(privileged)* Fire a scheduled prompt out of band immediately.
     FireScheduleNow { id: i64 },
     /// *(privileged)* Edit an existing schedule's mutable fields.
@@ -627,12 +633,25 @@ pub enum Response {
     /// `ListSchedules` result. Snapshot of every schedule.
     /// Returned on the manager socket only.
     Schedules { schedules: Vec<WireSchedule> },
+    /// `ListDescendants` result: all descendant containers, with running
+    /// status. Ordered by topology depth (parents before children), then
+    /// alphabetically within each depth tier.
+    Containers { containers: Vec<ContainerInfo> },
 }
 
 /// Backwards-compatible response aliases.
 pub type AgentResponse = Response;
 pub type ManagerResponse = Response;
 
+/// One entry in a `ListDescendants` result.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ContainerInfo {
+    /// Logical agent name (no `h-` prefix).
+    pub name: String,
+    /// Whether the container is currently running.
+    pub running: bool,
+}
+
 /// Serde default for the `running` field; keeps wire backwards-compat
 /// with pre-running-field payloads. See
 /// `docs/conventions.md::Agent metadata`.