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

hive-c0re/src/agent_server.rs

@@ -425,6 +425,42 @@ async fn dispatch(req: &AgentRequest, agent: &str, coord: &Arc<Coordinator>) ->
             coord.emit_rebuild_queue_snapshot();
             AgentResponse::Ok
         }
+        AgentRequest::ListDescendants => {
+            tracing::debug!(%agent, "agent: list descendants");
+            // All containers known to nixos-container (running only).
+            let running_set: std::collections::HashSet<String> =
+                match crate::lifecycle::list().await {
+                    Ok(names) => names
+                        .into_iter()
+                        .filter_map(|c| {
+                            c.strip_prefix(crate::lifecycle::AGENT_PREFIX)
+                                .map(str::to_owned)
+                        })
+                        .collect(),
+                    Err(e) => {
+                        return AgentResponse::Err {
+                            message: format!("list containers failed: {e:#}"),
+                        }
+                    }
+                };
+            // Walk the full topology and collect every descendant.
+            let topo = crate::topology::read();
+            let mut names: Vec<String> = topo
+                .keys()
+                .filter(|name| crate::topology::is_descendant_of(name, agent))
+                .cloned()
+                .collect();
+            // Parents before children, then alpha within each tier.
+            crate::auto_update::topology_sort(&mut names, &topo);
+            let containers = names
+                .into_iter()
+                .map(|name| {
+                    let running = running_set.contains(&name);
+                    hive_sh4re::ContainerInfo { name, running }
+                })
+                .collect();
+            AgentResponse::Containers { containers }
+        }
         AgentRequest::RequestInitConfig { name, description } => {
             if !crate::topology::children_of(agent)
                 .iter()